2014 NEC Instructor Manual and Student Worksheets Level 3

2014 Electrical Instructors Manual and Student Worksheets -- Level 3 1

2014

ELECTRICAL INSPECTOR

INSTRUCTORS’ MANUAL

LEVEL III

NC Code Officials Qualification Board 322 Chapanoke Road

Raleigh, NC 27603


ARTICLE TITLE PAGE TM

90 INTRODUCTION TO THE NEC 70-23 4

100 DEFINITIONS 70-27 8

110 REQUIREMENTS FOR ELECTRICAL INSTALLATIONS 70-36 11

220 BRANCH CIRCUIT, FEEDER AND SERVICE CALCULATIONS 70-66 15

230 SERVICES 70-83 22

240 OVERCURRENT PROTECTION 70-94 25

250 GROUNDING AND BONDING 70-106 28

280 SURGE ARRESTOR 70-139 32

300 WIRING METHODS 70-142 35

310 CONDUCTORS FOR GENERAL WIRING 70-154 38

314 OUTLET, DEVICE, PULL, AND JUNCTION BOXES; CONDUIT BODIES;

FITTINGS; AND HANDHOLE ENCLOSURES 70-184 43

326 ARTICLE 326 INTEGRATED GAS SPACER CABLE: TYPE IGS 70-198 47

328 ARTICLE 328 MEDIUM VOLTAGE CABLE: TYPE MV 70-199 50

336 POWER AND CONTROL TRAY CABLE: TYPE TC 70-206 53

392 CABLE TRAYS 70-247 56

400 FLEXIBLE CORDS AND CABLES 70-262 60

408 SWITCHBOARDS AND PANELBOARDS 70-285 64

427 FIXED ELECTRIC HEATING EQUIPMENT FOR PIPELINES AND VESSELS 70-320 68

430 MOTORS, MOTOR CIRCUITS, AND CONTROLLERS 70-323 71

445 GENERATORS 70-359 80

450 TRANSFORMERS AND TRANSFORMER VAULTS 70-360 84

460 CAPACITORS 70-370 88

470 RESISTORS AND REACTORS 70-371 91

490 EQUIPMENT OVER 600 VOLTS NOMINAL 70-374 94

500 HAZARDOUS (CLASSIFIED) LOCATIONS, CLASSES I, II AND III

DIVISIONS 1 AND 2 70-382 97

501 CLASS I LOCATIONS 70-391 101

502 CLASS II LOCATIONS 70-401 105

503 CLASS III LOCATIONS 70-407 109

504 INTRINSICALLY SAFE SYSTEMS 70-410 112

505 CLASS I, ZONE 0, 1 AND 2 LOCATIONS 70-413 115

513 AIRCRAFT HANGARS 70-440 118

515 BULK STORAGE PLANTS 70-448 121

516 SPRAY APPLICATION, DIPPING, AND COATING PROCESSES 70-453 125

517 HEALTH CARE FACILITIES 70-462 130

530 MOTION PICTURE AND TELEVISION STUDIOS

AND SIMILAR LOCATIONS 70-495 135

610 CRANES AND HOISTS 70-551 138

660 X-RAY EQUIPMENT 70-594 142

665 INDUCTION AND DIELECTRIC HEATING EQUIPMENT 70-596 146

668 ELECTROLYTIC CELLS 70-598 149

Revision 2008 Electrical Instructor Manual Level III 2


669 ELECTROPLATING 70-600 152

705 INTERCONNECTED ELECTRICAL POWER PRODUCTION SOURCES 70-662 155

708 CRITICAL OPERATIONS POWER SYSTEMS 70-667 158

THE PAGE NUMBER LISTED ABOVE CORRESPONDS TO THE ARTICLE LOCATION IN THE NORTH

CAROLINA ELECTRIC CODE BOOK (THE NEC 2008). THE “TM” NUMBERS TO THE RIGHT OF THE ARTICLE

NUMBERS CORRESPONDS TO THE PAGE NUMBERS IN THE TRAINING MANUAL FOR THE STARTING PAGE

FOR EACH ARTICLE LISTED.


INTRODUCTION TO THE NATIONAL ELECTRIC CODE

ARTICLE 90

LEVEL III

OBJECTIVES:

Each student should become familiar with:

1. The purpose and scope of the National Electrical Code.

2. The definitions and fundamental rules covered by the Code.

MATERIALS NEEDED:

National Electrical Code (NEC) 2014 edition

INTRODUCTION:

By this level of instruction each student should have had both Level I and II. Any student

who hasn’t had Levels I and II should be given the work sheets from those levels as a study

guide. This student will need a lot of special attention...

This lesson should give the students a clear picture of how the Code is organized so they may

find information more easily in later assignments and on the job. The Code is not a set of

laws; it is a set of rules. It is intended for use by governmental bodies exercising legal

jurisdiction over electrical installations and for use by insurance inspectors.

PRESENTING THE LESSON:

The National Electrical Code, Article 90, Introduction, outlines the purpose and explains the

scope, arrangement, enforcement, and formal interpretations of the Code. It also contains details of safety examinations of equipment, future wiring expansion and units of

measurement used in the Code.

The purpose of this Code is to safeguard people and property from electrical hazards by outlining provisions that are necessary for safety. Many hazards that occur are due to

overloading wiring systems or exceeding the provisions of this Code; therefore, it is

important to plan for future increases in the use of electricity.


This Code is not an instruction manual for untrained persons. Many areas are covered by this

Code, but there are also a lot of areas not covered. Pay close attention to the requirements

listed in Section 90.2.

90.2 Scope

90.2(B) (5) Explain-controlled by electric utilities

90.2(C) See definition Article 100

90.5 Mandatory Rules etc.

90.6 See Vol. I-A, NC State Bldg. Code, post this link on the board for the students to reference,

http://www.ncdoi.com/OSFM/Engineering/Interpretations.asp

Remind the students that the Chief Electrical Inspectors usually exercise legal jurisdiction

over electrical installations through city or county ordinances or laws based on the NEC. The

instructor should lead a class discussion of the material contained in the appropriate

sections of the Code. After each section distribute the worksheets for the students to

complete and answer any questions they may have.

APPLICATION:

If time allows, let the class answer questions on the worksheet.

CHECKING AND FOLLOW-UP:

If time will allow, correct the worksheets and discuss the results.

http://www.ncdoi.com/OSFM/Engineering/Interpretations.asp



ARTICLE 90

LEVEL III

1. The purpose of this Code is which of the following?

a. The safeguarding of persons and property from hazards arising from the use of

electricity.

b. The practical safeguarding of persons and property from hazards arising from the use of

electricity.

c. The safeguarding of property and persons from hazards arising from the improper use

of electricity.

d. The health safety and welfare of the general public

2. A rule that is characterized by the use of the terms shall be permitted or shall not be required is which of the following?

a. Mandatory rule

b. Permissive rule

c. Explanatory rule

d. None of the above



ARTICLE 90

Level III

ANSWER KEY

1. b. Practical safeguarding 90.1(A) 2. b. Permissive rule 90.5(B)


DEFINITIONS

ARTICLE 100 Level III

OBJECTIVE:

Each student should become familiar with Article 100, definitions essential to the proper use of

the NEC.

INTRODUCTION:

The definitions in Article 100 are terms normally found more than one Article of the Code. We

will cover Part II of Article 100 briefly. Determine if students have questions about Part I, and

then discuss if needed.


Briefly review Part I of Article 100, then discuss Part II (Over 600 Volts, Nominal). Students

will be returning to Article 100 constantly to look at a definition of particular terms in code

articles.

APPLICATION:

If time will allow, let the class answer questions on the worksheet.




DEFINITIONS

ARTICLE 100

Level III

WORKSHEET

1. By definition, which of the following is correct concerning disconnecting means for equipment?

I. The disconnecting means is used to disconnect the circuit conductors from their source

of supply.

II. A disconnecting means must be at no more than 50 feet from the equipment it serves.

a. I only

b. II only

c. Both I and II

d. Neither I nor II

2. A volatile flammable liquid is a liquid having a flash point below which of the following?

a. 60C

b. 70C

c. 38C

d. 36C

3. To be in sight from or within sight of means to be within which of the following?

a. 100 ft. .

b. 75 ft

c. 50 ft

d. 25 ft.


DEFINITIONS

ARTICLE 100

Level III

ANSWER KEY

1. a, I only 2. c, 38C

3. c, 50 ft.


ELECTRICAL

ARTICLE 110

Level III

OBJECTIVE:

To assure that student is familiar with Article 110, Part III, installations over 600 volts,

nominal; indoors and outdoors.

INTRODUCTION:

Explain to class that you will cover Article 110, Part III, in detail, as this is important

because more installations of this type are being installed.

Also Part IV Tunnels and Part V Manholes will be

covered


Discuss Article 110, Part III in detail, giving illustration on board, use handouts.

Also discuss both indoor and outdoor installations.

Discuss Table 110.34 (A) in 110.34 (A), pointing out the difference from the

Table 110.26 (A) (1).

Discuss Part IV covering raceways, bonding and ventilation. Discuss Part V and point out that this has been moved from Article 314 pointing out that

this covers all voltages.

APPLICATION:

If time will allow let the class answer questions on the worksheet.




ELECTRICAL

ARTICLE 110

Level III

WORKSHEET

1. In general at least one entrance shall be provided to give access to the working space

about electric equipment over 600 V. This space shall be a minimum width of:

a. 12 inches

b. 18 inches c. 24 inches

d. 30 inches

2. Electrical equipment, using 2400 volts, with exposed live parts on one side and no live or

grounded parts on the other side of the working space shall have a minimum working

space in front of the equipment of:

a. 3 feet

b. 4 feet

c. 5 feet d. 6 feet

3. Unguarded live parts operating at 1,200 volts between phases shall be elevated above a

working space by a least which of the following?

a. 8 ft.

b. 9 ft.

c. 10 ft. d. no requirement

4. The entrances to a room containing exposed live parts operating at over 600 volts shall

be:

a. Kept Locked

b. Unlocked at all times

c. Provided with signs “Danger-High Voltage-Keep Out” d. Both a and c

5. A wall, screen, or fence used to enclose an outdoor electrical installation to keep out

persons who are not qualified shall not be less than which of the following in height?

a. 6 ft.

b. 7 ft.

c. 8 ft. d. 5 ft.


6. Where electrical equipment operating at 240 volts is located in a room with equipment operating at 12,000 volts, the high voltage equipment shall be separated from the low

voltage equipment by:

a. a partition

b. a screen

c. a fence

d. any of the above

7. Electrical controls for the ventilation system shall be arranged in which of the following

manners?

a. So that the airflow can be reversed.

b. So that the airflow cannot be reversed.

c. In a manner that will allow access.

d. So that the motors can be reached.

8. Manhole covers shall be over which of the following weights or otherwise designed to

require the use of tools to open.

a. 100 kg

b. 45 pounds

c. 100 kPa

d. 100 pounds


ELECTRICAL

ARTICLE 110

Level III

ANSWER KEY

1. c, 24 inches 110.33(A)

2. a, 3 feet Table 110.34(A), condition1

3. b, 9 ft. Table 110.34(E)

4. d, both a and c 110.34(C)

5. b, 7 ft. 110.31

6. d, any of the above 110.34(B)

7. a. so airflow can be reversed. 110.57

8. d. 100 pounds 110.75(D


BRANCH CIRCUIT AND FEEDER CALCULATIONS


OBJECTIVE:

Each student should become familiar with the requirements for determining the number

of branch circuits required and for computing branch circuit and feeder loads using

different voltages, and ratings in commercial applications.

INTRODUCTION:

This lesson should review the basic electrical formulas and methods used to determine sizes

of branch circuits and feeders. Explain to class that this is a brief review of Level I and II

materials. Make sure that class knows the difference in residential and commercial

applications.


Briefly review Article 220 for residential and commercial requirements for Level I and II

feeders and branch circuits and their calculations.

Point out 210.19 (page 49 on the NEC) for continuous and noncontinuous loads.

APPLICATION:

If time will allow, let the class answer the questions on the worksheet.





ARTICLE 220

Level III

WORKSHEET

1. A multi-family dwelling unit complex, consisting of nine units is supplied by a 120/240

volt single-phase, 3 wire service. Each unit has 900 square feet and a calculated load of

37,000 volt amperes. Using Article 220.84 (optional method to calculate the service for

this complex), which of the following is the minimum volt amperes to size the

ungrounded service entrance conductor?

a. 139,860

b. 143,190

c. 233,100

d. 333,000

2. A 3600 square foot store building is supplied by a 120/208 volt, 4-wire, three phase

service with 60 linear feet of non-continuous show window lighting. Which of the

following is the minimum number of 120 volt, 2-wire, 20 amp branch circuits to serve

both the general lighting load and show window load?

a. 8 b. 9

c. 10

d. 11

3. A 25 KW, 480 volt, 3-phase, continuous load is to be supplied with THHW copper.

Which of the following is the minimum ampacity to size the load?

a. 30 amperes

b. 38 amperes

c. 75 amperes

d. 87 amperes

4. A 25 KW, 240 volt, single phase continuous load for electric heat is to be supplied with

THW aluminum conductors. Which of the following is the minimum size conductor

permitted for the load?

a . #1 b . #1/0

c . #2/0

d . #3/0


5. A school building is supplied by a 120/208 volt, 3-phase, 4-wire service and it has been

determined to have a total connected load of 150 KVA for the previous one year period.

The existing 3-phase service consists of two separate sets (in parallel) of 350 KCmil,

THW copper conductors protected by 700 amp fuses. Which of the following is the

maximum connected load permitted to be added to this service?

a. 79 amps

b. 99 amps

c. 183 amps d. 223 amps

6. A 120/240 volt, single phase, 3-wire service is to supply a 1000 square foot single-family

dwelling. This dwelling has a 120/240 volt 12 KW range, a 120/240 volt 5 KW dryer, 240

volt 4.5 KW water heater, a 240 volt 10 KVA central electric space heating load, and a

240 volt 2 KW AC unit. Using the optional method (220.82), the total compiled load for

sizing the ungrounded service entrance conductor in Volt Amps is:

a. 16,000

b. 21,600 c. 24,100

d. 27,600

7. A 277/480 volt, 3-phase, 4-wire feeder is supplying 100 KVA of noncontinuous load and

185 KVA of continuous load. The neutral conductor will have the full capacity of the

phase conductors because of the presence of harmonic currents in the system. What is the

minimum size overcurrent device allowed to protect this feeder?

a. 300 Amperes

b. 400 Amperes c. 225 Amperes

d. 350 Amperes

8. What ampacity would be used in determining the proper size conductor for the load in

question #7?

a. 600 amp

b. 350 amp c. 400 amp

d. 499 amp


9. What is the minimum size feeder conductors required to supply the following 208 volt, 3-

phase commercial kitchen appliances?

(1) 20 KVA deep fat fryer

(1) 50 KVA dishwasher

(1) 14 KVA water heater

(1) 30 KVA range

(1) 30 KVA oven

(2) 4 KVA steamers

a. 250 Kcmil TRW copper

b. 300 Kcmil TRW copper

c. 300 Kcmil TRW aluminum

d. 250 Kcmil TRW aluminum

10. A high school home economics classroom has (10) 208 volt, single phase, 12 KW ranges

connected to a 208 volt, 3-phase feeder. What is the minimum ampacity of the feeder

conductors?

a. 85 amps

b. 125 amps

c. 65 amps

d. 96 amps

11. Size the minimum ampacity of the service conductors for a school with a 277/480 volt, 3-

phase, 4-wire supply. It has been decided to size the service conductors for this school

under the optional calculation allowed in Section 220.86. The building is 40,000 square

feet in area and has the following connected loads:

Interior and exterior lighting 75 KVA

Kitchen equipment 65 KVA

Space heating 250 KVA

Air conditioning 190 KVA

Other loads 102 KVA

a. 480 amperes

b. 600 amperes

c. 720 amperes

d. 310 amperes


12. A new restaurant has total electric power. The total connected load is 476 KVA. Using the

optional method, what is the minimum allowable KVA that will be used to size the

service equipment?

a. 400 KVA

b. 238 KVA

c. 325 KVA

d. 425 KVA

13. If a 120/208 volt, 3-phase service is used, what is the minimum ampacity of the service in

question (12) above, using a single main circuit breaker?

a. 800 amps

b. 600 amps

c. 700 amps

d. 1200 amps



ARTICLE 220

Level III

ANSWER KEY

1. b, (37,000 x 9 x .43) = 143,190 VA

2. d, (3600 x 3 x 1.25) + (60 x 200) / 120 / 20 = 10.6 = 11 circuits

3. b, (25,000 x 1.25) / 1.732 / 480 = 37.6 amps = 38 amps

4. c, (25,000 x 1.25) / 240 = 130.2 amps [drop minor fraction - Table 310.16, 130 amps;

use 2/0 THW Al.]

5. b, Total amps of conductors = 310 x 2 = 620 amps; additional

load = 620 - (150,000 / 360 x 1.25) = 99 amps [220.86]

6. c, [220.82] Heat = 10,000 x .65 = 6500 VA

* The instructor should explain heat calculation at percentage versus A/C calculation at

100 percent to determine largest load.

Other Loads:

General Lighting 1000 x 3 = 3000 VA

Small Appliance 1500 x 2 = 3000 VA

Laundry 1500 x 1 = 1500 VA

Range (Nameplate) 12,000 VA

Dryer (Nameplate) 5000 VA

Water heater (Nameplate) 4500 VA

Subtotal 29,000 VA

1st 10,000 x 1.00 = 10,000 VA

Remainder = 19,000 x .4 = 7600 VA

Electric Heat = 6500 VA Total Load 24,100 VA

7. b, 400 amperes [210.19] Calculate the continuous load at 125% and the noncontinuous

load at 100%. 185,000 X 1.25 = 231,250 VA. Plus 100,000 VA = 331,250/831= 398.61

amperes, rounded to 399 amperes.

8. c, 399 amp


9. b, 300 Kcmil THW copper [220.56]

Step 1: Find the total connected load: 20+50+14+30+30+4+4 = 152 KVA

Step 2: Find the demand factor from the table (220.56) for 7 appliances-this is: 65% of

connected load.

Step 3: 152 X .6 = 98.8 KVA

Step 4: Compare the two largest pieces of equipment to the 65% demand,

obtained in Step 3. Select the larger of the two, which in this case is 98.8 KVA.

Step 5: Calculate the ampacity required, 98.800/360 = 274.4 amperes

Step 6: Selection of conductor from the wire tables (310.16)

10. d, 96 amps [220.55]

Step 1: 220.55 requires the load to be computed on twice the number of ranges connected

between any two phases. Each range equals 2/3 of the three phases, for 10 ranges

this occurs four times. Double this and use 8 ranges to select the minimum

demand, form table 220.55 for (8) ranges (table 220.55 is based on 12 kw.). This

selected value is 23,000 VA.

Step 2: Find the current per phase: 23,000/2 = 11,500. Step 3: Find the 3-phase equivalent circuit: 11,500 X 3 = 34,500 VA.

Step 4: Find the minimum ampacity of the feeder: 34,500/360 = 96 amperes. Use 96

amperes

11. a, 480 amperes [220.86]

Step 1: Find the total continuous load, omitting the smaller, the heat or the air conditioner. 75+65+250+102 = 492 KVA connected.

Step 2: Find the demand VA per square foot for the building: 492,000/40,000 = 12.3 VA per square foot.

Step 3: Use the table 220-86 to calculate the demands. The first 3 VA per square foot has a demand of 100%. This is 40,000 X 3 = 120,000 VA.

Step 4: Use the table for the remaining 9.3 VA at 75%. 40,000 X 9.3 X .75 = 279,000 VA.

Step 5: Total demands 120,000 + 279,000 = 399,000 VA Step 6: Find the minimum ampacity, 399,000/831 = 480 amperes. Use 480

amperes.

12. b, 476 KVA x 50% = 238 KVA

13. c, 700 238,000/360 = 661 = 700Amp


SERVICES

ARTICLE 230

Level III

OBJECTIVE:

Each student should understand requirements for services over 600 volts nominal.

INTRODUCTION:

Explain to class that we will cover services in Part VIII of Article 230. Briefly discuss

previous sections of 230, under 600 volts.


Go over Article 230, Part VIII in detail; discuss wiring methods, warning signs, supports,

disconnecting means, overcurrent protection. (Refer to Article 240.100) for overcurrent

protection.

APPLICATION:

If time will allow, let the class time answer questions on the worksheet.




SERVICES

ARTICLE 230

Level III

WORKSHEET

1. Above ground Service Entrance conductors over 600 V shall be installed in which of the following:

a. Rigid Metal Conduit

b. Intermediate Metal Conduit

c. Rigid Non-metallic Conduit

d. All of the above

2. In general, service Entrance Conductors over 600 V, not in cable, shall be a minimum

size of:

a. #8 copper

b. #6 copper

c. #4 copper

d. #3 copper

3. When using fuses to protect service entrance conductors over 600 volts, which of the following

is the maximum fuse permitted to protect a conductor that is rated at 145 amps.

a . 400 b . 450

c . 500

d . 600


SERVICES

ARTICLE 230

Level III

ANSWER KEY

1. d, all of the above 230.202(B) 2. b, #6 230.202(A)

3. a, 400; 230.208

145 x 3 = 435 400 < 435


FUSES AND CIRCUIT BREAKERS

GREATER THAN 600 VOLTS

ARTICLE 240

Level III

OBJECTIVE:

Each student should be familiar with the requirements for overcurrent protection for over 600 volts nominal applications.

MATERIALS NEEDED:

Show pictures and literature of over 600 volt fuses and circuit breakers.


The approach to the design and manufacture of the over 600 volt fuses and circuit breakers

is quite different than that take for protective devices of lower voltages. Consequently different

requirements for the protection of feeder and branch circuit conductors have been included in

sections 240.100 and 240.101.

In order to illustrate the above it is suggested that conductors and code allowed overcurrent

devices be selected for a typical 200 ampere branch circuit at both voltage levels-- 600 volts and

say 5000 volts in rigid metal conduit and copper conductor.

Ex. 600 V 3/0 THW 200 amperes OC device

Ex. 5000 V 2/0 XLPE - 90o C 400 amperes OC device

APPLICATION:





FUSES AND CIRCUIT BREAKERS

GREATER THAN 600 VOLTS

ARTICLE 240

Level III

WORKSHEET

1. A 4160 volt feeder consisting of #2 conductors, with an ampacity rating of 140 amps, is to be

protected with fuses. Which of the following is the maximum size fuse permitted to protect

this feeder?

a . 200 b . 300

c . 400

d . 450

2. A 4160 volt feeder consisting of #4 conductors, with an ampacity rating of 97 amps is to be

protected with a circuit breaker. Which of the following is the maximum size breaker

permitted to protect this feeder?

a . 300 b . 400

c . 500

d . 600


FUSES AND CIRCUIT BREAKERS GREATER THAN 600

VOLTS ARTICLE 240

Level III

ANSWER KEY

1 . c, 400 240.101(A)

140 x 3 = 420 420 > 400

2 . c, 500 240.101

97 x 6 = 582 582 > 500


GROUNDING OVER 1000 VOLTS

ARTICLE 250

Level III

OBJECTIVE:

Each student should understand the requirements for grounding of systems over 1000 volts

nominal, part X of Article 250.

INTRODUCTION:

Make the class aware that you will be covering Article 250. Part X, High Voltage, make them

aware that more installations of this type are being installed.


Discuss Article 250, Part X in detail; briefly review grounding requirements of previous

Sections of 250.

Explain that 250.50 of the Code is a North Carolina amendment. Be sure the students have the

amendments in their Code book or hand out the amendments. You can also give them the web

site for DOT, www.ncdoi.com

APPLICATION:

Tf time will allow, let the class answer questions on the worksheet.


Tf time will allow, correct the worksheets and discuss the results.

http://www.ncdoi.com/


GROUNDING OVER 1000

VOLTS ARTICLE 250

Level III

WORKSHEET

1. When using insulated conductors, in a solidly grounded neutral system over 1 KV,

without exception, the minimum insulation level for neutral conductors is:

a. 150 volts

b. 250 volts

c. 300 volts d. 600 volts

2. When grounding equipment, grounding conductors not an integral part of a cable

assembly shall not be smaller than:

a. #6 Copper

b. #4 Copper

c. #3 Copper d. #2 Copper

3. A high voltage, Impedance grounded neutral system is operating at 13.8 KV. The phase

conductors are insulated for 15 KV. The systems neutral conductor must have a

minimum insulation level of:

a. 600 volts

b. 0 volts, it can be bare c. 1000 volts

d. 15,000 volts

4. The ampacity of a neutral conductor operating at over 1kv shall be of sufficient ampacity for

the load imposed on the conductor but not less than which of the following percentage of

the phase conductors.

a. 100 percent of the ampacity

b. 70 percent of the ampacity

c. 33 1/3 percent of the ampacity d. Two trade sizes smaller


5. An impedance grounded neutral high voltage service shall have the grounding impedance

connected at which of the following points?

a. Ahead of the insertion of the grounding impedance

b. Between the supply grounding electrode and the neutral point of the supply

transformer or generator

c. At the center point of the wye



GROUNDING OVER 1000 VOLTS

ARTICLE 250

Level III

ANSWER KEY

1. d, 600 volts 250.184(A)(1) 2. a, #6 Copper 250.190(C)

3. d, 15,000 volts 250.187(B) 4. c, 33 1/3 percent of the ampacity 250.184(A)(2)

5. b, beyond the point of the ground impedance 250.187(A)


SURGE ARRESTOR

ARTICLE 280 Level

III

OBJECTIVE:

Each student should be familiar with a surge arrestor, what its purpose is, where and why it is

normally used, and the minimum size of connecting conductors required.

INTRODUCTION:

Explain to class that you will cover Article 280, Parts I, II, and III. Types and sizes of

conductors utilized depend on KV of circuit.


Cover Article 280 where arrestors are to be connected, one to each ungrounded conductor, to

the grounded service conductor, or grounding electrode conductor. Conductor size will differ in

circuits of 1 KV and over. Arrestors may be located inside or outside.

APPLICATION:





SURGE ARRESTOR

ARTICLE 280 Level

III

WORKSHEET

1. Which of the following is correct concerning the installation of surge arrestors?

I. Unless listed for installation in accessible locations, surge arrestors shall be made

inaccessible to unqualified persons.

II. Surge arresters shall be installed outdoors only.

a. I only

b. II only

c. Both I and II

d. Neither I nor II

2. For circuits of I KV and over, the conductor between the surge arrester and the line and

surge arrester and the grounding connection shall not be smaller than:

a. #8 Copper

b. #4 Copper

c. #6 Copper

d. #3 Copper


SURGE ARRESTOR

ARTICLE 280 Level

III

ANSWER KEY

1. a, I only 280.11

2. b, #6 Copper 280.23


WIRING METHODS -OVER 1000 VOLTS

ARTICLE 300

Level III

OBJECTIVE:

Each student should understand requirements for wiring methods over 1000 volts.

INTRODUCTION:

We will cover Part II in its entirety.


Go over Part II, Article 300 briefly; discuss conductors, conductor bending radius, and

protection against heating. Note that Section 300.40 requires that metallic shielding

components such as tapes, wires, or braids, or combinations thereof, shall be connected to a

grounding conductor, grounding busbar, or a grounding electrode. Also note the changes to

footnote 3 part d, Table 300.50

APPLICATION:





WIRING METHODS-OVER 1000 VOLTS

ARTICLE 300

Level III

WORKSHEET

1. When using non-shielded conductors, the conductor shall not be bent to a radius less

than:

a. 4 times the overall diameter of the conductor

b. 6 times the overall diameter of the conductor

c. 8 times the overall diameter of the conductor

d. 12 times the overall diameter of the conductor

2. Where direct burial conductors that are shielded and rated above 2000 volts, and the

circuit voltage over 1000 volts. The cable shall be buried a minimum of which of the

following?

a. 36 inches

b. 30 inches

c. 18 inches

d. 6 inches

3. Over 350 Kcmil through 500 Kcmil copper installed in vertical raceways shall be

supported at which of the following distances?

a. 75 feet

b. 50 feet

c. 100 feet

d. 25 feet


WIRING METHODS-OVER 600 VOLTS

ARTICLE 300

Level III

ANSWER KEY

1. c 300.34 2. b 300.50(A)

3. b T300.19(A)


CONDUCTORS FOR GENERAL WIRING – OVER 600

VOLTS ARTICLE 310

LEVEL III

OBJECTIVE:

Each student should be familiar with conductors for general wiring in high voltage

applications.

Review Article 310 in Level II. Note Section 310.4 (E) that states; Where parallel equipment grounding conductors are used, they shall be sized in accordance with 250.122.

Sectioned equipment grounding conductors smaller than 1/0 AWG shall be permitted in

multiconductor cables in accordance with 310.13, provided the combined circular mil area

in each cable complies with 250.122.

Review the shielding requirements. The purpose of shielding is to confine the voltage

stresses to the insulation. Insulation shields shall be connected to a grounding electrode

conductor, grounding busbar, or a grounding electrode.

APPLICATION:

If time will allow, let the class answer questions on the

worksheet. CHECKING AND FOLLOW UP :



CONDUCTORS FOR GENERAL WIRING

ARTICLE 310

LEVEL III

WORKSHEET

1. The minimum size-awg for a conductor operating at 12000 Volts is:

a . 8 b . 6

c . 2

d . 1

2. The maximum voltage permitted for a direct buried, non-shielded, multiconductor cable

with an overall metallic sheath or armor is:

a. 2000 Volts

b. 2001 Volts

c. 5000 Volts

d. 8000 Volts

3. The required minimum insulation thickness of a 500 Kcmil XHHW conductor to be

operated at 1500 volts is:

a. 65 mils

b. 95 mils

c. 100 mils

d. 110 mils

4. The ampacity of a 3/0 THW insulated conductor operating at 1 KV where three conductors are

installed in a raceway at an ambient temperature of 38 degrees C is 310.16 with amp

correction factor applied:

a. 176 amps

b. 188 amps

c. 145 amps

d. 189 amps


5. The allowable ampacity of a 1/0 insulated single aluminum conductor is isolated in air with a

conductor temperature of 90 degrees C and an ambient air temperature of 40 degrees C,

operating at 23 KV is:

a. 175 amps

b. 200 amps

c. 230 amps

d. 270 amps

6. The allowable ampacity of 4/0 single copper conductor cables triplexed in air with a conductor

temperature of 90 degrees C and ambient temperature of 40 degrees C, operating at 12,000

volts is:

a. 335 amps

b. 345 amps

c. 270 amps

d. 395 amps

7. Three 500 Kcmil Aluminum conductors operating at 15,000 volts are installed in a one circuit

underground electrical duct. Based on the conductors operating in an ambient earth

temperature of 20 degrees C, 100% load factor, RHO of 90,and conductor temperature of

90 degrees C, the allowable ampacity of the conductor is:

a. 230 amps

b. 290 amps

c. 370 amps

d. 465 amps

8. A six circuit underground electrical duct contains 1/0 copper conductors operating at 5,000

volts. Based on the following factors, what is the allowable ampacity of the conductors?

Ambient earth temperature of 20 degrees C, 100% load factor, RHO of 90, and conductor

temperature of 90 degrees C.

a. 135 amps

b. 165 amps

c. 200 amps

d. 155 amps


9. An insulated 90 degrees C 1/0 three conductor aluminum triplex cable supplies the primary

voltage to a 25,000 volt transformer. The cable is installed outside in free air. The

allowable ampacity of the triplex is:

a. 145 amps

b. 170 amps

c. 185 amps

d. 215 amps

10. A single #1 insulated non-shielded solid dielectric copper conductor rated at 3,500 volts

suitable for dry locations (without a jacket) shall have an insulation thickness of:

a. 45 mils

b. 90 mils

c. 110 mils

d. 125 mils


CONDUCTORS FOR GENERAL WIRING

ARTICLE 310

LEVEL III

ANSWER KEY

1. c 310.106 (A)

2. c 310.10 (F) exception No 2

3. b Table 310.104(A)

4. a Table 310.15(B)(16) and Table 310.15(B)(2)(a)

5. b Table 310.60(C)(70)

6. b Table 310.60(C)(68)

7. c Table 310.60(C)(78)

8. a Table 310.60(C)(77) See six circuits bottom of table

9. b Table 310.60(C)(72)

10 .c Table 310.104(D)


OUTLET, DEVICE, PULL AND JUNCTION BOXES; CONDUIT BODIES

AND FITTINGS OVER 600 VOLTS NOMINAL

ARTICLE 314

Level III

OBJECTIVE:

Each student should understand requirements of article 314 applying to over 600 volts.

(under 600 volts have been covered in Level I.)

MATERIALS NEEDED:

Samples of outlet boxes, pull and junction boxes, conduit bodies and fittings. Handouts

with examples of sizing pull and junction boxes.

INTRODUCTION:

Article 314 covers the installation and use of all boxes, conduit boxes and fittings as required

by Section 300.15 used as outlet, junction, or pull boxes, depending on their use. Cast, sheet

metal, nonmetallic, and other boxes such as FS, FD, and larger boxes are not classified as

conduit bodies. Review Section 314.4, Note that metal boxes shall be grounded and bonded

in accordance with Parts I, IV, V, VI, VII, and X of Article 250 as applicable, except as

permitted in 250.112(I).


Article 314 requirements are very important when considering safety of electrical

installations. Time should be spent reviewing the requirements covered in the Level I course.

Emphasis should be placed on Part IV of the article which deals with pull and junction

boxed on systems of over 600 Volts nominal.

APPLICATION:


worksheet. CHECKING AND FOLLOW UP :



OUTLET, DEVICE, PULL AND JUNCTION BOXES; CONDUIT BODIES

AND FITTINGS OVER 600 VOLTS NOMINAL

ARTICLE 314

Level III

WORKSHEET

1. What length box is required for three #1 lead-covered conductors at 1600 volts for a straight

pull? #1 outside diameter is .585.

a . 15”

b . 19”

c . 22”

d . 29”

2. What length box is required for seven #1 nonshielded conductors at 1600 volts for a

straight pull? #1 outside diameter is .585.

a . 15” b . 22”

c . 22”

d . 29”

3. What size box is required for two #2 and two #4 lead covered conductors at 1600 volts for

an angle pull? #2 outside diameter is .505 and #4 is .445.

a. 14” b. 19”

c. 20”

d. 25”

4. What size box is required for two #2 and two #4 nonshielded conductors at 1600 volts for an

angle pull? #2 outside diameter is .505 and #4 is .445.

a. 14” b. 19”

c. 20”

d. 25”


5. Warning signs for boxes exceeding 600 volts shall have the following wording:

a. DANGER KEEP OUT

b. DANGER 600 VOLTS

c. DANGER HIGH VOLTAGE KEEP OUT

d. DANGER HIGH VOLTAGE


OUTLET, DEVICE, PULL AND JUNCTION BOXES; CONDUIT

BODIES AND FITTINGS OVER 600 VOLTS NOMINAL

ARTICLE 314

Level III

ANSWER KEY

1 . 2 .

3 . 4 .

5 .

d, 29” b, 19”

c, 20” a, 14”

c.

314.71(A) .585 X 48 = 28.08 = 29” 314.71(A) .585 X 32 = 18.72 = 19”

314.71(B) .505 X 36 = 18.18+.050+.445+.445 = 19.58 314.71(B)Ex. No. 2

.505 X 24 = 12.12 + .050 + .445 + .445 = 13.06 = 14”

DANGER- HIGH VOLTAGE -KEEP OUT 314.72(E)

= 20”


INTEGRATED GAS SPACER

CABLE ARTICLE 326

Level III

OBJECTIVE:

Each student should know the requirements included in the Article for this wiring method.

MATERIALS NEEDED:

Pictures and manufacturing literature of IGS cable.


This wiring method is comparatively quite expensive and unlikely to be encountered except

in very special applications requiring thorough engineering. It is suggested that the time

spent on this Article be limited.

APPLICATION:


worksheet. CHECKING AND FOLLOW-UP:



INTEGRATED GAS SPACER CABLE

ARTICLE 326

Level III

WORKSHEET

1. An underground run of 3" IGS cable with two 90 degree bends is to be installed. The minimum bending radius permitted is:

a . 12" b . 24"

c . 35"

d . 48"

2. The ampacity of a 1500 KCMIL cable and conduit is:

a. 168 amperes

b. 238 amperes

c. 292 amperes

d. 357 amperes

2014 Electrical Instructors Manual and Student Worksheets – Level 3 49

INTEGRATED GAS SPACER CABLE

ARTICLE 326

Level III

ANSWER KEY

1. c 326.24 Table 326.24.

2. c 292 amperes 326.80 Table 326.80


MEDIUM VOLTAGE CABLE

ARTICLE 328

Level III

OBJECTIVE:

Each student should be familiar with the uses permitted and not permitted for MV cable.

INTRODUCTION:

Explain to the class that this is not a very popular installation, and that a small amount of

time will be spent on this article.


Briefly explain and discuss Article 328, particularly section 328.2 “Definition”, 328.10

“Permitted Uses”, and 328.14 “Installation.”

APPLICATION:






ARTICLE 328

Level III

WORKSHEET

1. Type MV Cable shall be permitted for systems rated up to:

a. 2001 Volts

b. 4160 Volts

c. 7200 Volts

d. 35,000 Volts



ARTICLE 328

Level III

ANSWER KEY

1. d, 328.10


POWER AND CONTROL TRAY CABLE TYPE TC

ARTICLE 336

Level III

OBJECTIVE:

Each student should be familiar with the definition of this cable, where it can and cannot

be used, and the normal sizes of conductors.

INTRODUCTION:

Explain to the class that you will briefly cover Article 336. This is seen very seldom in the

field, and a small amount of time should be spent on this Article.


Discuss Article 336 with class; cover permitted use and non-permitted use of cable, sizes

of copper and aluminum conductors. Explain that Type TC Power and Control Cable is for

the use in industrial power or control circuits where small diameter cables are used.

Primary installations include cable trays, raceways and outdoor locations where supported

by a messenger wire. Discuss the eight (8) listed permitted used in 336.10.

APPLICATION:

If time will allow, let the class answer questions on the worksheets.




POWER AND CONTROL TRAY CABLE

ARTICLE 336

Level III

WORKSHEET

1. Normally, the minimum size of copper conductor permitted for TC cable is:

a. #18

b. #16

c. #14

d. #12

2. Which of the following is correct concerning the use of TC cable?

I. TC Cable is permitted to be used in Cable Tray.

II. TC Cable is approved for power, lighting, control and signal circuits.

a. I only

b. II only

c. Both I and II

d. Neither I nor II


POWER AND CONTROL TRAY CABLE

ARTICLE 336

Level III

ANSWER KEY

1. a, 18 336.104

2. c, Both I and II 336.10


CABLE TRAYS

ARTICLE 392

LEVEL III

OBJECTIVE:

Each student should be familiar with the requirements for cable tray wiring systems.

MATERIALS NEEDED:

Photos of cable tray, conductors samples if available.

INTRODUCTION:

Cable tray systems are a widely used wiring method and are used primarily in industrial

applications though not limited to such use. They offer a practical and flexible solution

to electrical power distribution when used for electrical services, feeders, and branch

circuits, especially when larger size conductors and cables are used. Note the additions

that may be included in cable trays to Table 392.10(A) Wiring Methods.


Point out minimum single conductor sizes [392.10(B)(1)(a)]. Emphasize the restrictions

that apply when cable tray is used for equipment grounding [392.10(B)(1)(c)] and

reference the metal requirements and other provisions that apply for cable trays used as

equipment grounding conductors (392.60).

Discuss 392.22 and the accompanying tables. Work an example using these tables in

conjunction with Table 5 in Chapter 9 to demonstrate proper procedure in regard to

conductor fill. Also note 2014 change in section 392.18(H) that the danger marking(s) or

labels shall comply with 110.21(B).

APPLICATION:





CABLE TRAYS

ARTICLE 392

LEVEL III

WORKSHEET

1. The maximum allowable rung spacing for a ladder cable tray where 1/0 and 4/0

single conductor cable is used?

a. 6”

b. 7”

c. 8”

d. 9”

2. Which of the following is an acceptable means of bonding a cable tray used as an

equipment ground?

a. Bonding jumpers

b. Bolted mechanical connectors

c. both A and B

d. neither A nor B

3. The minimum cross sectional area of an aluminum cable tray used for equipment

grounding and housing conductors protected by 500 amp circuit breaker is: a. .20 sq. in.

b. .30 sq. in.

c. .40 sq. in.

d. .60 sq. in.

4. Where ventilated channel cable trays contain single-conductor cables are which of

the following width, the sum of the diameters of all single conductors shall not exceed the inside width of the channel.

a. 75 mm (3 in.)

b. 100 mm (4 in.)

c. 150 mm (6 in.)

d. all of the above


5. Where cable trays are continuously covered for more than which of the following,

with solid unventilated covers, the ampacities for No. 1/0 through 500 kcmil cables shall not exceed 60% of the allowable ampacities in Tables 310.17 and 310.19.

a . 4’

b . 6’

c . 10’

d . 8’

6. The ampacities for Nos. 1/0 and larger single conductor cables rated 2001 volts or

larger in uncovered cable trays shall not exceed which of the following percentage of

the allowable ampacities in Table 310.69 and 310.70.

a . 50%

b . 80%

c . 60%

d . 75%


CABLE TRAYS

ARTICLE 392

LEVEL III

ANSWER KEY

1. d 392.3(B)(1)(a)

2. c 392.7(B)(4)

3. c Table 392.7(B)(2)

4. d 392.10(B)

5. b 392.11(B)(2)

6. d 392.13(B)(1)


FLEXIBLE CORDS AND CABLES

ARTICLE 400

Level III

OBJECTIVE:

Each student should be acquainted with the installation and use requirements for Flexible

Cords and Cables.

INTRODUCTION:

This article covers the requirements for use and installation of Flexible cords and Cable and

including the requirements for portable cables over 600 V, nominal.


Review Level I Article 400. Cover the requirements in Part III on Portable Cables over 600 volts, nominal.

APPLICATION:






ARTICLE 400

Level III

WORKSHEET

1. What is the allowable ampacity rating for # 4 types SO cord when nine conductors are carrying current?

a. 42 amps

b. 60 amps

c. 70 amps

d. 85 amps

2. What is the allowable ampacity rating for # 18 types SO cord when three conductors are

carrying current?

a. 5 amps

b. 7 amps

c. 10 amps

d. not permitted

3. Under what conditions, if any, may a cord be spliced?

a. Not permitted

b. hard-service and junior hard service cords only

c. #14 and larger only

d. repair of b & c together

4. SJO cord is to be marked, on the cord, at intervals not to exceed?

a. 12 inches

b. 18 inches

c. 24 inches

d. 36 inches

5. Unless specifically permitted in 400.7, flexible cords and cables shall not be used for

which of the following:

a. as a substitute for the fixed wiring of a structure.

b. where run through holes in walls, ceilings, or floors.

c. where concealed behind building walls ceilings or floors.

d. all of the above

2014 Electrical Instructors Manual and Student Worksheets – Level 3

62

a. # 8 AL

b. # 1/0 Cu

c. # 6 AL

d. # 12 Cu

6. The minimum size for conductor for portable cables over 600 volts shall be?



ARTICLE 400

Level III

ANSWER KEY

1. a, 42 amps [Table 400.5(A)(1) and Table 400.5(A)(3)] # 4 SO = 60 amps [400.5] nine

conductors at 70% 60 amps X 70% = 42 amps

2. b, 7 amps Table 400.5(A) 3. d, repair of b and c together 400.9

4. c, 24 inches 400.6 5. d, all of the above 400.8

6. d, # 12 Cu 400.31(A)


SWITCHBOARDS AND PANELBOARDS

ARTICLE 408

Level III

OBJECTIVE:

Each student should be familiar with the installation requirements of Switchboards and

Panelboards.

INTRODUCTION:

This article covers the requirements for use and installation of Switchboard and Panelboards.


Review Level I Article 408. See Level I Article 408 Lesson plan for reference. Emphasize the

requirements for installing switchboards and panelboard in hazardous locations.

APPLICATION:






ARTICLE 408

Level III

WORKSHEET

1. On a switchboard or panelboard supplied from a 4-wire delta-connected system, the high-leg conductor is identified by which color?

a. Blue

b. Red

c. Orange

d. White

2. The phase arrangement on a three phase bus as viewed left to right shall be?

a. b c a

b. a b c

c. c b a

d. any of the above

3. The dedicated space in Section 110.26 shall extend from the floor to a height of ____ above

the equipment or to the structural ceiling to a height of which of the following?

a . 6’ b . 10’

c . 6’ 6”

d . 6’ 4”

4. Minimum distances between the top of switchboard to combustible ceiling if not totally

enclosed is:

a. 0 feet

b. 1 foot

c. 2 feet

d. 3 feet

5. The conduit or raceways shall not rise more than what distance above the bottom of

switchboard enclosures?

a. 1 inch

b. 2 inches

c. 3 inches

d. 4 inches


6. A panelboard shall be provided with physical means to prevent the installation of more

overcurrent devices than which of the following?

a. That number for which the panelboard was designed, rated, and listed.

b. Not more than 42 overcurrent devices.

c. Not more than the panelboard directory allows.

d. Not more than the Authority Having Jurisdiction will allow.



ARTICLE 408

Level III

ANSWER KEY

1. c 408.3(E) FPN – see 110.15

2. b 408.3(E)

3. a 110.26(E)(1)(a)

4. d 408.18(A) 5. c 408.5

6. a 408.54


FIXED ELECTRIC HEATING EQUIPMENT FOR PIPELINES AND VESSELS

ARTICLE 427

Level III

OBJECTIVE:

Each student should be familiar with electrically energized heating system and the installations of the systems used with pipelines or vessels.

INTRODUCTION:

This Article covers electrically energized heating systems and the requirements for installing

them when used with pipelines or vessels such as (1) resistance heating elements, (2)

Impedance heating, (3) induction heating, and (4) skin effect heating.


Cover definitions, application of other Articles and branch-circuit sizing (427.2, 3, & 4).

Review the installation requirements, emphasizing the need of posting appropriate caution

signs. (Part II)

Cover requirement for resistance heating elements, emphasizing power supply bends, electrical

connections, grounding and equipment protection. (Part III)

Cover requirements for impedance heating, emphasizing voltage limitations, the use of an

isolation transformer, and grounding. (Part IV)

Cover requirements for induction heating, emphasizing the need for personnel protection. (Part V)

Cover the requirement for skin effect heating, emphasizing grounding. (Part VI) Cover

the requirement for disconnecting means, controls, and overcurrent protections.

APPLICATION:






ARTICLE 427

Level III

WORKSHEET

1. Branch circuit conductors supplying fixed electric heating equipment for pipelines shall have an ampacity not less than what percentage of the total load of the heaters?

a . 125% b . 100%

c . 250%

d . 110%

2. Which of the following may be used for protection of power supply loads to resistance heater elements where they emerge from electrically heated pipe lines?

a. rigid metal conduit

b. intermediate metal conduit

c. electrical metallic tubing

d. all of the above

3. Ground fault protection of equipment shall not be required where there is alarm

indication of ground faults and:

I. conditions of maintenance and supervision ensure that only qualified person

will service the installed system.

II. Continued circuit operation is necessary for safe operation of equipment or process.

a. I only

b. II only

c. I and II

d. Neither I nor II

4. The maximum voltage for impedance heating of a pipeline if a ground fault circuit-

interrupter for personnel protection is provided is which of the following?

a. 150 volts

b. 30 volts

c. 24 volts

d. 80 volts



ARTICLE 427

Level III

ANSWER KEY

1 . 125% 427.4

2 . d. 427.18(B) 3 . c, 427.22

4 . d 427.27


MOTORS, MOTOR CIRCUITS, AND CONTROLLERS

ARTICLE 430

Level III

OBJECTIVE:

Each student should be familiar with the installation requirements of motor, motor circuits and

controllers.

INTRODUCTION:

This Article covers the requirements for the installation of motors, motor circuits, and

controllers with additional requirements for over 600 volts, nominal.


Review Level I and II Article 430. See Level I and II Article 430 lesson plan for reference.

Cover the requirements for conductors, overcurrent protection, overload protection, fault-

current protection and disconnecting means for over 600 volts, nominal installations. Note to

the students that motor overload protection that is separate from the motor shall be based on

the motor nameplate rating and not the Electrical Code sections. (430.6)(A)(2)

APPLICATION:






ARTICLE 430

Level III

WORKSHEET

1. Motor controller disconnecting means for motors over 1000 volts shall be capable of

which of the following?

a. Being locked in the closed position.

b. Being locked in the open position.

c. Being serviceable from the open position.

d. Being capable of being locked out

2. The ampacity of conductors for motors over 1000volts shall not be less than the current at

which of the following is set to trip?

a. The motor overload device.

b. The thermal overcurrent device.

c. The motor controller trip-set device.

d. The circuit breaker overcurrent rating.

3. The full-load rating of a motor found on the nameplate is 30.4 amperes and that found in Table

430.250 is 30.8 amperes. Which value is required to be used when determining the minimum

size branch-circuit conductor permitted?

a. The figure in 430.248

b. The figure in 430.250

c. The figure on the motor.

d. The nameplate rating.

4. Branch-circuit conductors that supply a single motor used for continuous duty shall have

an ampacity not less than which of the following percentage of the motors full-load

current rating?

a . 140%

b . 125% c . 175%

d . 250%


5. Feeder tap conductors shall be enclosed by a controller or raceway not more than which of

the following lengths.

a. 25 feet

b. 5 feet

c. 6 feet

d. 10 feet

6. Without exception, what is the maximum percentage allowed when using an inverse time

circuit breaker for the motor branch-circuit short circuit and ground-fault protective

device?

a . 125%

b . 150% c . 250%

d . 350%

7. When fuses are used for motor overload protection, a three phase motor shall have an

overload protection inserted in which of the following?

a. In each main breaker.

b. In each breaker in the panel.

c. In all feeders. d. In each phase conductor.

8. Complete the following requirements for a 15 HP, 230 volt, 3-phase, induction type, A-C

motor with a service factor of 1.15, no code letter and without separate overload

protection.

Full Load Current _________________________ (Table 430.250)

Branch-circuit Ampacity ____________________ (Section 430.22)

Disconnecting Means _______________________ (Section 403.110)

Overcurrent Protection ______________________ (Table 430.52)

(Time delay fuse)

Heater Size _______________________________ (Section 430.32) (430.6)(A)(2)


9. A motor is to be connected to a feeder tap not over 25 feet in length: Which of the

following is correct?

I. Tap conductors must have an ampacity at least one-third that of the feeder

conductor.

II. Be protected from physical damage.

a. I only

b. II only c. both I and I

d. neither I nor II

10. Three motors are supplied by the same feeder, one with a full load ampacity of 28 amps

protected by a 50 amp dual element fuse, the other two with a full load ampacity of 22

amps each, protected by 30 amp dual element fuse each. Which of the following is the

maximum size fuse permitted to protect the feeder?

a. 70 amps

b. 80 amps

c. 90 amps d. 100 amps

11. The branch-circuit conductors for a motor are protected by time-delay (Dual element)

fuses. If the fuses are not holding on the line, they may be increased to a maximum of:

a . 150% b . 175%

c . 200%

d . 225%

12. A feeder is to supply two motors, with a full load ampacity of 28 amps each and a non-

continuous lighting load of 100 amps. Which of the following is the minimum size

conductor permitted for this feeder, using THHN copper?

a . # 2 b . # 1

c . # 1/0

d . # 2/0


13. A 7 1/2 HP, 230 volt, 3-phase motor, has it’s control circuit conductors tapped from the line

side of the magnetic starter. This motor has multiple start-stop stations, located at different

locations, to control this motor. The motor is protected by a 60 ampere circuit breaker. What is

the minimum size of the control circuit conductors, when protected by the branch circuit short

circuit device?

a. 16 AWG, copper

b. 14 AWG, copper

c. 12 AWG, copper d. 10 AWG, copper

14. Which of the following statements is/are true about the disconnecting means for

stationary motors rated at 2 hp or less and 300 volts or less?

(1) A general-use switch having an ampere rating not less than twice the full-load

current rating of the motor

(2) A listed manual motor controller having a horsepower rating not less than the

rating of the motor and marked “Suitable as Motor Disconnect”

a. 1 only b. 2 only

c. Both 1 and 2 d. Neither 1 nor 2

15. When sizing a motor circuits protective components, the motor ampacity listed in tables

430.247 through 430.250 shall always be used instead of the full load ampacity given on

the motor nameplate EXCEPT for:

a. branch circuit conductors

b. motor overloads c. short circuit device

d. single phase motor


16. A 460 volt, 3-phase feeder is supplying the following continuous duty, squirrel cage

induction motors, (1) 50 HP, (1) 60 HP, (1) 75 HP, (1) 100 HP, (1) 125 HP. All of the above

motors are full voltage start, code letter “F”, with a service factor of 1.2. Answer all of the

following questions about this motor feeder.

A. Using THW copper, size each of the motor supply conductors (a) 50 HP _______________________________________

(b) 60 HP _______________________________________

(c) 75 HP _______________________________________

(d) 100 HP _______________________________________

(e) 125 HP ______________________________________

B. What are the proper size overloads for each of the motors?

(a) 50 HP _____________________________________

(b) 60 HP _____________________________________

(c) 75 HP _____________________________________

(d) 100 HP ____________________________________

(e) 125 HP ____________________________________

C. Using inverse time circuit breaker, size the breaker for all the motors of the group:

(a) 50 HP _______________________________________

(b) 60 HP _______________________________________

(c) 75 HP _______________________________________

(d) 100 HP _______________________________________

(e) 125 HP ______________________________________

D. Using THHN copper conductors, what are the minimum size feeder conductors

required for the above 460 volt, 3-phase motors? Use (2) conductors in parallel per

phase, install all (6) current carrying conductors in the same raceways. The ampacity

correction factors of 310.15(B)(2) [310.15(B)(3)(a)] must be applied.

(a) 2 X 300 Kcmils

(b) 2 X 350 Kcmils

(c) 2 X 400 Kcmils

(d) 2 X 500 Kcmils


E. Size all the feeder taps for all the motors of the above group. The maximum tap

length between the feeder and the motors, short circuit protective device is between 16

and 24 feet. (Use 75°C conductors)

(a) 50 HP (b) 60 HP

(c) 75 HP

(d) 100 HP

(e) 125 HP

F. Using an inverse time circuit breaker, what is the minimum size of this feeder’s short

circuit protective device?

a. 700 amperes

b. 800 amperes

c. 600 amperes

d. 100 amperes


78


ARTICLE 430

Level III

ANSWER KEY

1. b. being locked in the open position 430.227

2. a. a motor overload device 430.224

3. b. the figure in 430.250 430.6(A)(1)

4. b. 125% 430.22

5. d. 10 feet 430.28

6. c. 250 T 430.52

7. d. In each phase conductor 430.36 8. Full load current - 42

Branch-circuit Size - 52.5 (42 X 125% = 52.5)

Disconnecting Means - 48 (42 X 115% = 48.3)

Overcurrent Protection - 80 (42 X 175% = 73.5;

go up to 80 ampere) Time delay fuse - 80 amps

Heater Size - 52.5 (42 X 125% = 52.5) 9. c, both I and II 430.28

10. c, 90 amps, 50 + 22 + 22 = 94 amps = 90 amps 430.62 11. d, 225% 430.52 exc.2(b)

12. d, #2/0, (28 X 125%) + 28 + 100 = 163 amps 430.25

(110.14(C) conductor was chosen from the 75 degree column)

13. b, 14 AWG, copper 430.72(B) 14. c, both 1 and 2 430.109(C)

15. b, motor overloads 430.6(A)(2)

16. FEEDER QUESTIONS 16. A. Motor Branch Circuit Conductors 430.22(A)

(a) 65 amps X 125% = 81.25 amperes, use #4 Cu.

(b) 77 amps X 125% = 96.25 amperes, use #3 Cu. (c) 96 amps X 125% = 120 amperes, use #1 Cu.

(d) 124 amps X 125% = 155 amperes, use #2/0 Cu. (e) 156 amps X 125% = 195 ampere, use #3/0 Cu.

16. B. Overloads 430.32(A)

(a) 65 amps X 125% = 81.25 amperes, use 81.25

(b) 77 amps X 125% = 96.25 amperes, use 96.25

(c) 96 amps X 125% = 120 amperes, use 120

(d) 124 amps X 125% = 155 amperes, use 155

(e) 156 amps X 125% = 195 ampere, use 195


(a) 65 amps X 250% = 162.5 amperes, go up to a 175 amp.

(b) 77 amps X 250% = 192.5 amperes, go up to a 200 amp.

(c) 96 amps X 250% = 240 amperes, go up to a 250 amp.

(d) 124 amps X 250% = 310 amperes, go up to a 350 amp.

(e) 156 amps X 250% = 390 ampere, go up to a 400 amp.

16. D. Feeder Conductors 430.24

(See correction factors of Table 310.15(B)2(a) 310.15 (B)(3)(a)

Answer: b, (156 X 1.25 = 195) + 124 + 96 + 77 + 65 = 557 amps

Find the minimum parallel ampacity, adjust this ampacity to compensate for (6) current

carrying conductors in the same raceway. 557/2 = 278.5 amps/.8 (correction factor) =

348 amperes.

Select a 90º C conductor capable of carrying 348 amperes, a 350 Kcmil, 90º C can carry

350 amperes. Select the 350 Kcmil conductor each.

Answer: 2 x 350 Kcmil, 90 degree c conductors in parallel per phase

16. E. Feeder Taps 430.28

Find the adjusted ampacity of 2 x 350 Kcmil in parallel, when (6) current carrying

conductors are in the same raceway. 350 amps X .8 (correction factor) = 280 X 2, for a

feeder adjusted ampacity of 560 amperes.

Find the minimum tap, which must have 1/3 the ampacity of the feeder conductors, in

this application. 560/3 = 186.67 amperes. Select a 3/0, 75º C conductor for the

minimum tap conductor allowed by 430.28

(a) 3/0 (b) 3/0 (c) 3/0

(d) 3/0 (e) 3/0

16. F. Select the Feeder Overcurrent Device 430.62

Answer: a, select the largest branch overcurrent device (400) plus the full load current of

all other motors of the group. 400 + 124 + 96 + 77 + 65 = 762 amperes, go down to a 700

amp circuit breaker

16. C. Inverse Time Circuit Breakers 430.52 & Table 430.52


GENERATORS

ARTICLE 445

Level III

OBJECTIVE:

Each student should be familiar with the installation requirements for generators.

INTRODUCTION:

This Article covers general requirements for generators but the applicable provisions of

Articles 230, 250, 700, 701, 702, and 705 must also be met.


Cover location requirements as found in 445.10, requirements for overcurrent protection as

found in 445.12 and 445.13 for conductor ampacity.

APPLICATION:

If time will allow, let the class answer the questions on worksheet.




GENERATORS

ARTICLE 445

Level III

WORKSHEET

1. The ampacity of the phase conductors from the generator terminals to the first

overcurrent device shall not be less than what percentage of the generator nameplate

current?

a . 125%

b . 115% c . 50%

d . 150%

2. Where wires pass through an opening having sharp edges which of the following shall be used

to protect the conductors?

a. Bushing

b. Shim

c. Grounding Bushing

d. Shielded Circuit Conductor

3. Constant-voltage generators, except ac generator exciters, shall be protected from

overloads by which of the following?

a. inherent design

b. circuit breakers

c. fuses

d. any of the above

4. Overcurrent devices protecting a three-wire, direct current generator shall consist of:

a. fuses only

b. three pole circuit breaker

c. double pole circuit breaker

d. any of the above


5. Live parts of generators operated at more than which of the following voltages to ground shall

not be exposed to accidental contact?

a . 25 b . 50

c . 600

d . 1000

6. Each generator shall be provided with a name plate containing which of the following?

a. rated frequency

b. power factor c. KVA rating

d. all of the above


GENERATORS

ARTICLE 445

Level III

ANSWER KEY

1. b. 115% 445.13

2. a. Bushing 445.16

3. d, any of the above 445.12(A)

4. c, double pole circuit breaker 445.12(E)

5. b, 50 445.14

6. d, all of the above 445.11


TRANSFORMERS AND TRANSFORMER VAULTS

ARTICLE 450

Level III

OBJECTIVE:

Each student should be familiar with the requirement for installations of transformers.

INTRODUCTION:

This Article covers the requirement for the installation of transformers and transformer vaults including installations over 600 volts, nominal.


Review Level II Article 450. See Level II Article 450 lesson plan for reference.

Cover the overcurrent protection requirements for transformers over 600 volts, nominal

[450.3(A)]

Cover the requirements for dry-type transformers rated over 35,000 volts. [450.21(C)]

Cover the requirements for liquid filled transformers. [450.23, 24 & 25]

APPLICATION:






ARTICLE 450

Level III

WORKSHEET

1. A 500 KVA, 3-phase transformer has a 25 KV, delta primary and a 4.16 KV wye connected

secondary. The transformer is located in an unsupervised location and has 4%

impedance. Size the fuses for primary and secondary.

a. primary: ___________________

b. secondary: __________________

2. A 100 KVA, 3-phase transformer has a 480 volt, delta connected primary and a 120/208 volt,

wye connected secondary. The secondary overcurrent device is set at 125%. What is the

maximum permitted inverse time circuit breaker, for the secondary?

a. 200 amps b. 300 amps

c. 350 amps

d. 400 amps

3. A transformer rated at 600 volts or less and equipped with coordinated thermal overload

protection by the manufacturer and arranged to interrupt the primary current shall be

permitted to have primary overcurrent protection rated or set at a current value that is not

more than ________ the rated current of the transformer for transformers having not

more than 6 percent impedance and not more than________ the rated current of the

transformer for transformers having more than 6 percent but not more than 10 percent

impedance.

4. What is the maximum number of overcurrent devices permitted on the secondary side of a

transformer, in lieu of a single overcurrent device?

a. not permitted b. 6

c. 8

d. 2


5. A 112.5 KVA, 480 volt, 3-phase transformer is tapped from a 300 ampere feeder. The

secondary of the transformer is 120/208 volts, 3-phase. The transformer is protected at

125% on the secondary side. Answer the following questions about the above

arrangement.

1. Can the 300 amp overcurrent device protecting the feeder also protect the primary

side of the transformer?

2. What is the maximum size of the secondary current device?

6 A 300 KVA, dry type transformer is installed outdoors, adjacent to a building of

combustible construction. What is the minimum clearance between the transformer and

the building?

a. 18 inches

b. 12 inches

c. 24 inches

d. 36 inches



ARTICLE 450

Level III

ANSWER KEY

1. 25000 X 1.732 = 43250 and 4160 X 1.732 = 7,205

a: 35 amps, [Table 450.3(A)] 500,000 VA/43,250 = 11.56 amperes X 300% [Table 450.3(A)] = 34.65 amps. Select a 35 ampere fuse.

450.3(A) Note 1] = 34.68 amps. Select a 35 ampere fuse.

b: 175 amps, [Table 450.3(A)] 500,000 VA/7,205 = 69.39 amperes X 250% [Table

450.3(A)] = 173.47 amps. Select a 175 ampere fuse.

c: 175 amps, [Table 450.3(A)] 500,000 VA/7,205 = 69.39 amperes X 250% [Table 450.3(A) Note 1] = 173.47 amps. Select a 175 ampere fuse.

Note the question is asking for fuse size which is different for breaker size

2. c, 350 amps, [Table 450.3(B)] 100,000/360 = 277.77 amperes X 1.25 = 347.21 amperes.

Select a 350 amp circuit breaker. See 240.6, and read Note 1 to Table 450.3(B).

3. six times, four times table 450.3(B) note three

4. b. 6, [450.3(A)] Note: 2 & 450.3(B) Note: 2

5. 1. yes, [Table 450.3(B)]Compare feeder protection to 250% of the full load of the

transformer. 112,500/831 = 135.38 amperes X 250% = 338.44 amperes. The feeder

is within allowed limits.

2. 112500/360 = 312.5, 312.5 X 125% = 390.625> 350

6. d. 12 inches, [450.22]


CAPACITORS

ARTICLE 460

Level III

OBJECTIVE:

Each student should be familiar with installation requirements for capacitors over 600 volts.

INTRODUCTION:

This article covers requirements for capacitor installations. It should be noted that the inspector will not often encounter such installations and surge capacitors or capacitors included

as a component part of other apparatus and conforming to the requirements of such apparatus are

excluded from these requirements.


Review Level II Article 460. Briefly cover requirements for capacitors over 1000 volts as found

in Part II of Article 460.

APPLICATION:





CAPACITORS

ARTICLE 460

Level III

WORKSHEET

1. For capacitors over 1000 volts, Nominal a means shall be provided to reduce the residual

voltage of a capacitor to which of the following?

a. 30 volts or less within 5 minutes of disconnection.

b. 50 volts or less within 5 minutes of disconnection. c. 24 volts or less within 30 seconds of disconnection.

d. 12 volts or less within 10 seconds of disconnection.

2. Capacitor cases if grounded shall be grounded in accordance with which Article?

a. Article 250

b. Article 230

c. Article 210 d. Article 460


CAPACITORS ARTICLE 460

Level III

ANSWER KEY

1. b. 50 volts; 5 minutes 460.28(A) 2. a. 250 460.27


RESISTORS AND REACTORS

ARTICLE 470

Level III

WORKSHEET

1. Resistors over 1000 volts shall have a clearance of not less than which of the following distances from combustible materials?

a. 12 inches

b. 24 inches

c. 6 inches

d. 18 inches

2. Insulated conductors used for connections between resistance elements and controllers

shall be suitable for an operating temperature of not less than:

a. 60º C

b. 75º C

c. 90º C

d. 110º C

3. Clearances from resistors and reactors to grounded surfaces shall be:

a. adequate for the voltage

b. at least 12 inches

c. at least 24 inches

d. no requirements

4. To protect personnel from accidental contact with energized parts of reactors, the reactors

shall be:

a. isolated by enclosure

b. isolated by guarding only

c. isolated by elevation

d. either A or C


5. Without exception, which of the following statements about the grounding of resistor and

reactor cases or enclosures is correct?

I. Shall be connected to the grounded circuit conductor.

II. Shall be connected to the equipment grounding conductor.

a. I only

b. II only

c. both I and II

d. neither I nor II

6. Installation of oil-filled reactors, in addition to other requirements, shall comply with

applicable requirements of which Article of the Code?

a. 450

b. 800

c. 430

d. chapter 9


RESISTORS AND REACTORS ARTICLE 470

Level III

ANSWER KEY

1. a, 12 inches 470.18(C)

2. c, 90° C 470.4

3. a, adequate for the voltage 470.18(D)

4. d, either A or C 470.18(B)

5. b 470.19

6. a, 450 470.20


EQUIPMENT OVER 1000 VOLTS

ARTICLE 490

Level III

OBJECTIVE:

Each student should be familiar with the general requirements for equipment operating at over

1000 volts.

INTRODUCTION:

This Article covers requirements for equipment operating at more than 1000 volts.

See 490.2 Definition of “High Voltage”


Discuss Part II. Note the requirements for circuit breakers and fuses installed indoors.

Emphasize requirements for warning signs.[490.21(B)(6)], [490.21(B)(7)], [490.21(C)(2)],

[490.21(E)(3)]. Show examples of Table 490.24 – minimum clearances. Discuss accessibility

rules: [490.35]

APPLICATION:


CHECKING AND FOLLOW - UP:




ARTICLE 490

Level III

WORKSHEET

1. Power fuses of the vented type shall not be used in which of the following positions unless identified for that use.

a. in a vertical position

b. where exposed to the weather

c. outdoors

d. indoors

2. Cover plates intended to be removed for inspection of energized parts or wiring shall

be equipped with lifting handles and shall not exceed 12 square feet in area or which

of the following in weight, unless they are hinged and bolted or locked.

a. 60 pounds

b. 100 pounds

c. 50 pounds

d. 6 pounds



ARTICLE 490

Level III

ANSWER KEY

1. d, indoors 490.21(B)(1)

2. a. 60 pounds 490.38


HAZARDOUS (CLASSIFIED) LOCATIONS

ARTICLE 500

Level III

OBJECTIVE:

Each student should be familiar with the three basic classifications of hazardous

installations, Class I, Class II, and Class III. Be sure student is familiar with the differences

in the three Locations, and also how the locations are also similar in some cases.

INTRODUCTION:

Explain to students that you will cover Article 500 in detail, also sections 500.1, 500.2,

and 500.3, difference in class locations, and wiring methods permitted and not permitted.


Discuss Article 500 of NEC very thoroughly. Talk about Class I, Class II, and Class III.

Explain the differences in three locations, such as gases, dust, fibers. Use pictures of

location if available, and samples of equipment used in each location. Samples of material

and handouts are available from manufacturer. Classification and listing of equipment in this

location is extremely important.

APPLICATION:





HAZARDOUS (CLASSIFIED) LOCATIONS

ARTICLE 500

Level III

WORKSHEET

1. Which of the following is correct concerning hazardous (classified) locations?

I. Article 501 deals with the hazard involved normally with gases or vapors.

II. Article 502 deals with the hazard involved with easily ignitable fiber or flying

particles.

a. I only

b. Both I and II

c. II only

d. Neither I nor II

2. All of the following locations are normally involved in Class I location except:

a. Gasoline dispensing units

b. Commercial garage pits, below floor level

c. Spray booths of paint room

d. Textile manufacturing plants

3. Which of the following would be a Class I Group A CLASSIFICATION?

a. acetone

b. methanol

c. acetylene

d. gasoline

4. Hazardous location equipment identified as T2 shall have a maximum temperature of:

a. 40° C

b. 300° C

c. 842°C

d. 104° C


I. A Class II Division I location contains quantities of combustible dust in the air under

normal operating conditions will ignite.

II. A Class II Division 2 location dust is never present

a. I only

b. II only

c. Both I and II

d. Neither I nor II

6. A class III Division I location contains:

a. combustible dust

b. ignitable fibers

c. flammable vapors

d. any of the above

7. Equipment approved for Hazardous location use shall be marked with:

a. (a ) class

b. (b) group

c. (c) temperature range

d. (d) all of the above

5. Which of the following is/are correct regarding Class II locations?


HAZARDOUS (CLASSIFIED) LOCATION ARTICLE

500

Level III

ANSWER KEY

1. a, I only 500.1

2. d, Textile manufacturing plants 500.5

3. c, acetylene 500.6(A)(1)

4. b, 300 degrees C Table 500.8(B)

5. a, I only 500.5(C)(1),

6. b, ignitable fibers 500.5(D)

7. d, all of the above 500.8(B)


CLASS I LOCATION HAZARDOUS

ARTICLE 501

Level III

OBJECTIVE:

Each student should be acquainted with requirements for selecting wiring methods and

equipment necessary for these locations.

MATERIALS NEEDED:

Manufacturer’s literature covering the equipment required in such hazardous locations is

readily available and is a "must" to supplement samples and selected pictures.

INTRODUCTION:

This Article only includes requirements used in the selection of suitable equipment for use in

Class I locations. Point out that material included in other Articles must initially be used to

classify the area prior to use of Article 501.

PRESENTATION OF LESSON:

Review the several definitions that apply specifically to hazardous locations. Briefly review

requirements included in Article 500 which apply to the classification of Class I area.

Emphasis must be placed on the importance of requiring listed equipment when applying the

requirement applicable to wiring methods and specific equipment installed in such areas. This

is equally true for both standard and intrinsically safe equipment.

As the various sections included in this article are covered, incorporate specific examples,

diagrams, and or pictures to clearly illustrate intent. Whenever possible, enumerate reasons for

the specific requirements.

APPLICATION:





CLASS I HAZARDOUS LOCATION

ARTICLE 501

Level III

WORKSHEET

1. In a class I, Division I location all of the following are approved wiring methods except:

a. Threaded Rigid metal conduit

b. Threaded steel intermediate metal conduit

c. MI cable d. Electrical metallic tubing

2. When installing seal-off fittings in a Class I , Division I location, the minimum thickness

of sealing compound shall not be less than which of the following?

a. 1/8 inch

b. 3/8 inch

c. 1/2 inch d. 5/8 inch

3. When installing sealing compound in a seal-off fitting in a Class I, Division II location,

the compound shall have a melting point of not less than:

a. 93° C

b. 125°F

c. 175° F d. 200°C

4. In a Class I Division I location, conduit seals for enclosures shall normally be installed

within a distance from the enclosure of:

a. 12 inches

b. 15 inches

c. 18 inches d. 24 inches

5. For Class I, Division I pendant fixture stems longer than 12 inches, permanent bracing shall

be provided at a level not more than which of the following above the lower end of the

stem.

a. 18 inches

b. 6 inches

c. 24 inches

d. 12 inches


6. In a conduit run passing from a Class I, Division 2 location into an unclassified location,

the seal-off fitting(s) shall be:

a. installed on either side of the locations

b. installed in the Class I division location only

c. permitted on either side of the boundary

d. permitted in the unclassified side only

7. Wiring methods for non-incendive circuits in a Class 1, Division 2 location shall be:

a. rigid conduit only

b. I.M.C. only

c. type PLTC cable only

d. any method suitable for ordinary locations

8. All of the following are permitted to be installed between a seal fitting and an enclosure in a

Class I Division I location except:

a. explosion proof junction boxes

b. explosion proof couplings

c. explosion proof conduit bodies

d. explosion proof elbows

9. A metal conduit which does not contain any fittings, boxes, etc. and passes through a Class

I Division 1 location will not be required to contain seal-offs provided the conduit

extends at least how far beyond the hazardous location into an unclassified location.

a. 18 inches

b. 10 feet

c. 20 feet

d. 12 inches


CLASS I HAZARDOUS LOCATION

ARTICLE 501

Level III

ANSWER KEY

1. d, electrical metallic tubing 501.10(A)(1)

2. d, 5/8 501.15(C) (3)

3. a, 93 degrees C 501.15(C)(2)

4. c, 18 inches 501.15(A)(1)(2)

5. d, 12 inches 501.130(A)(3)

6. c, permitted on either side of the boundary 501.15(B)(2)

7. d, any method suitable for ordinary locations 501.10(B)(3)

8. a, explosion proof junction boxes 501.15(A)(1)

9. d, 12 inches 501.15(A)(4)Ex.1


CLASS II HAZARDOUS LOCATIONS

ARTICLE 502

Level III

OBJECTIVE:

Each student should be acquainted with the particular class location in Article 502, the

difference in Class II, Division I and Class II, Division II, and wiring methods permitted.

INTRODUCTION:

Explain to the class that you will cover Article 502 in detail; also refer back to Article 500.

Refer back to Article 100. Definitions, this is a very important installation, not often seen in

field, but very important when encountered.


Cover Article 500 briefly, Article 100, definition of Hazardous equipment, then article 502 in

detail. Cover places normally involved in 502, such as flour mills, grain bins.

Discuss wiring methods for Division I and Division II of Class II location. Show samples and

pictures of equipment in class. Manufacturer listing and labeling of equipment for Class II

location is extremely important.

APPLICATION:





CLASS II HAZARDOUS LOCATIONS

ARTICLE 502

Level III

WORKSHEET

1. In a Class II, Division I location, all of the following are approved wiring methods

except:

a. Threaded rigid metal conduit

b. MI cable c. Threaded steel intermediate metal conduit

d. Rigid non-metallic conduit

2. In a class II, Division II location Dry-type transformers shall operate at not over:

a. 120 volts

b. 240 volts

c. 300 volts d. 600 volts

3. In a Class II, Division II location, all of the following are approved wiring methods

except:

a. Rigid metal conduit

b. UF cable

c. Intermediate metal conduit d. Electrical metallic tubing

4. Unless identified for such locations, explosionproof equipment and wiring in which of the

following locations shall not be required and shall not be acceptable?

a. Class I locations

b. Class II locations

c. Class IV locations d. Class III locations

5. No transformer shall be installed in a location where all of the following dusts are present

except:

a. magnesium

b. aluminum bronze powders

c. aluminum d. wood


a. be provided with telescoping or close-fitting covers

b. be a minimum size of 20 cubic inches

c. have no openings which after installation would allow escape of sparks

d. be dust tight

7. Which of the following is correct regarding Bonding in a Class II location?

I. Double locknut types of contact shall be allowed as a means of bonding

II. Locknut-bushing type of contact shall be allowed as a means of bonding.

a. I only

b. II only

c. Either I or II

d. Neither I nor II

8. In a Class II, Division 2 location, flexible conduit shall be installed with internal or

external bonding jumpers except:

a. The flexible conduit is 6 ft. or less

b. overcurrent protection in the circuit is limited to 10 amps maximum.

c. the load is not a power utilization load.

d. all the above

9. Flexible cords used in Class II locations shall:

a. be of extra-hard usage

b. not be allowed

c. be of a junior-hard service type

d. the lamp temperature rating

10. Each lighting fixture approved for Class II locations shall be clearly marked to indicate:

a. the manufacturer

b. the ampacity

c. the maximum wattage of the lamp

d. the lamp temperature rating.

6. Boxes located in Class II, Division 2 locations which contain taps or connections shall:


CLASS II HAZARDOUS LOCATIONS ARTICLE 502

Level III

ANSWER KEY

1. d, rigid non-metallic conduit 502.10(A)(1)

2. d, 600 volts 502.100(B)(3)

3. b, UF cable 502.10(B)(1)

4. b 502.5

5. d, wood 502.100(A)(3)

6. d 502.10(B)(4)

7. d, neither I nor II 502.30 (A)

8. d, all of the above 502.30 (B)Ex.

9. a, be of extra-hard usage 502.140(B)(1)

10. c, the maximum wattage of the lamp 502.130(A)(1)


CLASS III HAZARDOUS LOCATIONS

ARTICLE 503

Level III

OBJECTIVE:

Each student should be acquainted with hazards involved in Class III locations, requirements in

the NEC for this type location, wiring methods for Div. I and Div. II locations, and where you

would normally see a Class III location.

INTRODUCTION:

Explain to the class that you will cover Article 500 briefly, then on to Article 503 in detail. Refer to Article 100 Definition briefly. You will explain the difference in a Class III, Division I, and a

Class III, Division II location.


Briefly cover Article 100 (related parts only) Article 500, then Article 503. Discuss in detail location difference in a Division I and a Division II location in Class III installations. Discuss

wiring methods in a Class III, Division I and Division II location. You would see this type of

installation in a Textile mill for example. Manufacturer listing and labeling instructions for

equipment in Class III locations are very important.

APPLICATION:






ARTICLE 503

Level III

WORKSHEET

1. In a Class III, Division I location, all of the following are approved wiring methods

except:

a. Rigid Metal Conduit

b. Intermediate Metal Conduit

c. Electrical Metallic Tubing

d. UF Type Cable

2. In a Class III, Division II location, in areas used solely for storage and containing no

machinery, which of the following are approved wiring methods:

a. open wiring on insulators

b. Rigid metal conduit

c. Electrical metallic tubing

d. all of the above

3. In a Class III, Division I, location, pendant luminaires supported by stems consisting of

threaded rigid metal conduit must be braced, if the stems are longer than:

a. 6 inches

b. 8 inches


4. Under normal conditions, fixed lighting luminaires installed in a Class III location shall

not exceed an exposed surface temperature of which of the following under normal conditions

of use?

a . 165°C b . 175°C

c . 90°C

d . 40°C

5. Boxes and fittings in Class III, Division I locations shall be:

a. of any type

b. dusttight c. anodized aluminum only

d. none of the above



ARTICLE 503

Level III

ANSWER KEY

1. d, UF Type Cable 503.10(A) 2. d, all of the above 503.10(B) Exception

3. d, 12 inches 503.130(C) 4. a, 165ºC 503.130(A)

5. b, dusttight 503.10(A)(2)


INTRINSICALLY SAFE SYSTEMS

ARTICLE 504

Level III

OBJECTIVES:

Each student should be acquainted with the requirements included in this Article, which cover the installation of intrinsically safe (I.S.) apparatus, wiring, and systems for Class I, II, and III

locations.

INTRODUCTION:

The use of some wiring methods in hazardous locations can be extremely expensive. For

economical reasons, more and more I.S. wiring was being used which brought about the need

for specific regulations covering such installations.


1. Thoroughly cover the requirements included in the scope, equipment approval, and

the definitions included within the Article.

2. Point out the importance of complying with installation limitations that may be in the

instructions included with the equipment listing and/or included in Section 504.10 as to

location.

3. Cover the remaining material included in the Article which provides installation

specifics.

4. Use manufacturer's literature, pictures, and samples to more thoroughly illustrate the

intended application and installation methods.

APPLICATION:





113


ARTICLE 504

Level III

WORKSHEET

1. All of the following terms are included in the definitions in Section 504.2 except:

a. Different Intrinsically Safe Circuits

b. Associated Apparatus

c. Intrinsically Safe System d. Cold Arc Circuit

2. Within enclosures, conductors of intrinsically safe circuits shall be separated from

conductors of any non-intrinsically safe circuit, a minimum distance of:

a. 2 inches

b. 4 inches


3. The maximum spacing between labels used to identify "Intrinsic Safety

Wiring" is:

a. 6 inches

b. 24 inches

c. 6 feet d. 25 feet



ARTICLE 504

Level III

ANSWER KEY

1. d, Cold Arc Circuit 504.2 2. a, 2 inches 504.30(A)(2)(1)

3. d, 25 feet 504.80(B)


CLASS I, ZONE 0, 1, AND 2

LOCATIONS ARTICLE 505

LEVEL III

OBJECTIVE:

Each student should be knowledgeable of an alternate method of classifying hazardous gases and

liquids for grouping and classification.

INTRODUCTION:

Explain the different group classifications. Reference the 2012 edition of NFPA 497 –

Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of

Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas.


Explain the zone group classification and group wiring methods and other hazardous location

articles as applied to zone locations, according to the design standards and specifications as

required by the registered design professional.

APPLICATION:





CLASS I, ZONE 0, 1, AND 2 LOCATIONS

ARTICLE 505

LEVEL III

WORKSHEET

1. An atmosphere containing acetylene is classified in which Group?

a. Group II A

b. Group II B

c. Group II C


2. In which area are ignitable concentrations of flammable gases or vapors which may be

present for long periods of time being found?

a. Class I, Division I

b. Class I, Zone 0

c. Class I, Zone 1

d. Class I, Zone 2

3. Equipment shall be marked to show the class, zone, gas, and temperature classification

referenced to an ambient temperature of which of the following?

a. 40°C

b. 60°C

c. 90°C

d.100°C


CLASS I, ZONE 0, 1, AND 2 LOCATIONS

ARTICLE 505

LEVEL III

ANSWER KEY

1. c, Group II C 505.6(A)

2. b, Class I, Zone 0 505.5(B)(1)

3. a, 40°C 505.9(C)(1) and (D)(1)


AIRCRAFT HANGARS

ARTICLE 513

Level III

OBJECTIVE:

Each student should be familiar with the wiring and equipment methods pertaining to aircraft hangars.

INTRODUCTION:

This Article applies to locations used for storage or servicing of aircraft in which gasoline, jet

fuels, or other volatile flammable liquids or flammable gases are used.


Explain the various classifications as outlined in 513.3 and what is required to declassify adjacent locations.

Make sure the student is aware that equipment and wiring methods utilized in Class I areas must comply with Article 501 (previously covered). All other fixed wiring in a hangar shall be

installed in metallic raceways or shall be Type MI, TC, or Type MC cable.

Particular emphasis should be placed on:

a) Grounding equipment not within Class I areas b) Arcing equipment above Class I areas

c) Warning signs on mobile stanchions d) Restrictions on battery chargers and required signs on mobile chargers

e) Restrictions for external power sources for energizing aircraft. f) mobile servicing equipment requirements

APPLICATION:





AIRCRAFT HANGARS


WORKSHEET

1. All fixed wiring in a hangar but not installed in a Class I location as classified in 513.3

shall be installed in metal raceways or shall be which of the following?

a. Type MI

b. Type TC c. Type MC

d. All of the above

2. External power sources for energizing aircraft shall be a minimum of which of the

following inches above floor level.

a. 6 inches

b. 18 inches c. 24 inches

d. 12 inches

3. Mobile equipment to be used in hangars shall be marked and kept at least which of the

following distance clear of aircraft engines and fuel tanks.

a. 3 ft.

b. 5 ft. c. 8 ft.

d. 10 ft.

4. All wiring installed in or under the hangar floor shall comply with the requirements for

which of the following locations?

a. Class 1, Division 2

b. Class 1, Division 1 c. Class 1, Division 3

d. Class 2, Division 2

5. All wiring located within 10 ft of an aircraft in a hanger used for painting shall be

classified how?

a. Class 1, Division 1

b. Class 1, Division 2 c. Class 2, Division 1

d. Class 2, Division 2


AIRCRAFT HANGARS


ANSWER KEY

1. d. all of the above 513.7(A) 2. b, 18 inches 513.10(C)(1)

3. b, 5 feet 513.10(D)(1) 4. b. Class 1, Division 1 513.3(A)

5. a, Class 1, Division 1 513.3(C)(2)


BULK STORAGE

PLANTS ARTICLE 515

Level III

OBJECTIVE:

Each student should be familiar with the wiring and equipment methods pertaining to bulk

storage plants.

INTRODUCTION:

This Article applies to areas where flammable liquids are received, stored, or blended for bulk

distribution. For further information see NFPA 30-2012.


Inform the students that all wiring and equipment in the Class I locations defined in this Article

shall comply with applicable provisions of Article 501.

Cover the various Class I locations in Table 515.3. Remind the students that these areas are

outlined in NFPA 30 Chapter 5. Any areas deviating from these requirements must be

classified by the inspector (authority) having jurisdiction.

Cover the various underground wiring methods (515.8) and those permitted above the Class I

area (515.7).

If gasoline dispensing is carried on at the bulk location, the applicable provisions of Article

514 shall apply.

APPLICATION:





BULK STORAGE PLANTS


WORKSHEET

1. A Class I Division I area shall extend how far from the edge of all indoor equipment

installed in accordance with NFPA 30 2012, extending in all directions.

a. 3 feet

b. 5 feet

c. 10 feet d. 25 feet

2. A Class I Division II area shall extend how many feet from roof of a storage tank.

a. 3 feet

b. 5 feet c. 10 feet

d. 25 feet

3. A bulk storage plant is:

a. that portion of a property where flammable liquids are stored.

b. that portion of a property where flammable liquids are stored or blended.

c. that portion of a property where flammable liquids are stored or blended in bulk.

d. that portion of a property where flammable liquids are stored or blended in bulk

and are received and distributed by pipelines, tank car, or tank vehicle.

4. How would office and/or restroom without opening into a classified location be

classified?

a. Class I, Division I

b. Class I, Division II c. Unclassified (ordinarily)


5. Threaded steel intermediate metal conduit shall be used for which of the following

distances where rigid nonmetallic conduit is used underground at a bulk storage plant?

a. The last 2 feet

b. The last 4 feet c. The last 6 feet

d. The last 10 feet


123

6. All fixed wiring above Class I locations at a bulk storage plant shall be in?

a. metal raceways

b. PVC schedule 80 c. neither a or b

d. both a and b


BULK STORAGE PLANTS

ARTICLE 515

Level III

ANSWER KEY

1. b, 5 Table 515.3

2. c, 10 Table 515.3

3. d, that portion of a property where flammable liquids are stored

or blended in bulk and are received and distributed by pipelines,

tank car,

or tank vehicle 515.2 515.1

4. c, Unclassified (ordinarily) Table 515.3

5. a, 2 515.8(A)

6. d, both a and b 515.7(A)


SPRAY APPLICATION, DIPPING, AND COATING PROCESSES

ARTICLE 516

Level III

OBJECTIVE:

Each student should become familiar with the wiring methods and equipment associated with

spray application, dipping, coating processes and printing processes.

INTRODUCTION:

This Article covers the specific hazards associated with applying various finishes or coatings to

material. Call attention to the various NFPA manuals and Volume 5 “Fire Protection” which

provides additional information.


Cover the classification of the following areas.

1. Class I or Class II, Division I

2. Class I or Class II, Division II 3. Adjacent locations

4. Non-hazardous locations

Emphasize that equipment must be installed according to its listing and labeling. The problem

of paint residue build up renders most explosion proof light fixtures unsuitable for spray areas.

(516.4(B))

Portable equipment shall not be used in the spray area during spray operations. Cover the two

exceptions [516.4(D)]

Bring out that interlocking the ventilation system with the spraying equipment reduces the

Class I or Class II Division II area from the openings in spray booths or rooms. 516.3 (D)2

informational note

Cover Electrostatic equipment and state the differences between this and other methods of

application.

a) Fixed equipment [516.10(A)]

b) Hand spraying equipment [516.10(B)]

c) Powder coating [516.10(C)] emphasize that this involves combustible dusts and

equipment must comply with Article 502.

Cover the problems associated with wiring and equipment above Class I and Class II locations.

Cover the problems associated with wiring and equipment above Class I and Class II

Locations.

2014 Electrical Instructors Manual and Student

Worksheets – Level 3 126

APPLICATION: If time will allow, let the class answer questions on the worksheet.

CHECKING AND FOLLOW-UP: If time will allow, correct the worksheets and discuss the results.



ARTICLE 516

Level III

WORKSHEET

1. Which of the following space(s) shall be considered Class I, Division 1, or Class I, Zone 0, as applicable:

(1) The interior of any open or closed container of a flammable liquid

(2) The interior of any dip tank or coating tank

a. (1) only

b. (2) only

c. Both (1) and (2)

d. Neither (1) nor (2)

2. The space between 10 feet vertically and 20 feet horizontally of unenclosed spraying

shall be classified as:

a. Class I division 2

b. Class 1 division 1

c. Class 2 division 2

d. unclassified

3. When in open spray areas and outside the Class I division 1 location, the vertical height of

the Class I division 2 location is:

a . 20’ b . 10’

c . 15’

d . 5’

4. Which of the following statements is/are true concerning portable electric lamps used in

Class I division 1 locations?

I- The plug in terminates outside of the Class I division 1 locations

II- The Portable Electric lamp is approved for Class I division 1 locations.

a. I only

b. Both I and II

c. II only

d. Neither I nor II


5. Fixed wiring where cables are used above Class I division 2 locations includes which of

the following?

a . N M

b . A C

c . M C

d . U F

6. Switches which arc and spark above Class I division 2 locations must:

a. Be guarded

b. Totally enclosed

c. Elevated

d. Not allowed

7. When shall metal raceways, metal-jacketed cables, and all noncurrent-carrying metal parts of fixed or portable equipment be grounded?

a. regardless of voltage

b. over 300 volts to ground

c. over 250 volts to ground

d. 480 volts phase to phase



ARTICLE 516

Level III

ANSWER KEY

1. c, Both (1) and (2) 516.3(A)

2. b, Class 1 division 1 516.3(D) 1

3. b, 10’ 516.3(D) 1

4. c, II only 516.4(D)Ex. 1

5. c, MC 516.7(A)

6. b, totally enclosed 516.7(B)

7. a, regardless of voltage 516.16


HEALTH CARE FACILITIES

ARTICLE 517

Level III

OBJECTIVE:

Each student should be acquainted with the various types of facilities in Article 517, such as hospitals, nursing homes, residential custodial cares facilities, doctor's offices, and dental

offices.

MATERIALS NEEDED:

Overhead projections of FPN figures:

517.30, No. 1 517.30, No. 2 517.41(B), No. 2 517.41, No. 1

INTRODUCTION:

Explain to students that you will cover Article 517 in detail, definitions are very important. You will cover different types of facilities in this Article, and the requirements for each one. Emphasis will be placed on essential electrical systems in clinics, medical and dental offices, out patient facilities, nursing homes, residential custodial care facilities, hospitals, and other

health care facilities serving patients.


Discuss facilities, such as a hospital, nursing home, and residential custodial care facility. Cover wiring requirements for each type, to include services, branch circuits, and emergency

services for facilities.

Discuss where certain types or numbers of circuits are required in specific locations or areas of a facility.

Discuss the areas that are more critical than others, such as an operating room in a hospital.

It will also be necessary to cover requirements for essential electrical systems in hospitals.

Divide the emergency system into two mandatory branches: 1) Life Safety 2) and the critical

branch. Connection to alternative power sources along with essential electrical systems for

nursing homes and residential care facilities as well as systems for clinics need to be covered in

this lesson.


HEALTH CARE FACILITIES

ARTICLE 517

Level III

WORKSHEET

1. To be classified as a nursing home, a facility is used for lodging, boarding and nursing

care on a 24 hour basis, with a minimum number of:

a. 4 persons

b. 6 persons

c. 8 persons d. 10 persons

2. In General Care areas (without exceptions), each patient bed location shall be provided

with a minimum of:

a. 2 receptacles

b. 3 receptacles

c. 8 receptacles d. 6 receptacles

3. In Critical Care areas, each patient bed location shall be provided with a minimum of:

a. 2 receptacles

b. 4 receptacles c. 6 receptacles

d. 8 receptacles

4. In a location where flammable anesthetics are employed, the entire area shall be

considered to be Class I, Division I location which shall extend upward to a level

above the floor of:

a. 3 feet

b. 4 feet

c. 5 feet d. 6 feet

5. When wiring above hazardous anesthetizing locations all of the following are approved

wiring methods except:

a. Rigid metal conduit

b. Intermediate metal conduit

c. Electrical metallic tubing d. Type NMC Cable


6. Which of the following is the minimum number of independent power sources for

essential electrical systems in hospitals?

a. 1

b. 2 c. 3

d. 4

7. Wiring of the life safety branch and the critical branch shall be permitted to occupy the

same raceways, boxes, or cabinets of other circuits not part of the branch where such wiring complies with one of the following?

a. Is in transfer equipment enclosures

b. Is in exit or emergency luminaires (lighting fixtures)supplied from two sources

c. Is in a common junction box attached to exit or emergency luminaires (lighting

fixtures) supplied from two sources

d. Is for two or more emergency circuits supplied from the same branch

e. All of the above

8. The life safety branch shall be installed and connected to the alternate source of power so that

functions shall be automatically restored to operation within how much time of the failure

of normal power?

a. 10 seconds

b. 20 seconds

c. 30 seconds

d. 60 seconds

9. Part II of article 517 applies to which types of health care facilities?

a. hospitals

b. dental offices

c. all health care facilities

d. nursing homes


10. Which of the following wiring methods is not permitted in the patient care areas of a

medical doctor’s offices?

a. rigid metal conduit with an insulated copper equipment grounding conductor

installed in the conduit.

b. intermediate metal conduit with an insulated copper equipment grounding

conductor in the conduit.

c. electrical metallic tubing with an insulated copper equipment grounding

conductor installed in the conduit.

d. rigid nonmetallic conduit with an insulated copper equipment grounding

conductor installed in the conduit.

11. A service to a hospital is 277/480, 3-phase. The main is 4,000 amperes and there are 12

feeders off of this service, 3 of which are 1,000 amperes or larger. Which of the

following statements are true about Ground Fault Protection of Equipment for this

system?

a. Only the 4,000 ampere main requires GFPE protection.

b. Only the (3) feeder 1,000 amps or larger require GFPE protection.

c. The main and all (12) feeders require GFPE protection

d. The main and the (3) feeders of 1,000 amps or larger require protection.

12. All of the following loads may be connected to the Life Safety Branch, EXCEPT:

a. nurse call systems

b. elevators

c. fire alarms

d. exit signs


HEALTH CARE FACILITIES ARTICLE

517

Level III

ANSWER KEY

1. a, 4 persons 517.2 definitions

2. c, 8 receptacles 517.18(B)

3. c, 14 receptacles 517.19(B)(1)

4. c, 5 feet 517.60(A)(1)

5. d, Type NMC 517.61(B)(1)

6. b, 2 517.35(A)

7. 1. In transfer switches

2. In exit or emergency lighting fixtures supplied from two

sources

3. In a common junction box attached to exit or emergency

lighting fixtures supplied from

two sources 517.30(C)(1)

8. a. 10 seconds 517.42

9. c, all health care facilities 517.10(A)

10. d, rigid nonmetallic conduit with an insulated copper equipment

grounding conductor installed

in the conduit. 517.13(A)

11. c, the main and all (12) feeders require

GFPE protection. 517.17(A)(B)

12. a, nurse call systems 517.32


MOTION PICTURE AND TELEVISION STUDIOS AND SIMILAR LOCATIONS

ARTICLE 530

Level III

OBJECTIVE:

Each student should be familiar with the requirements of Article 530 for places where film or

tape over 7/8 inch (22mm) in width is exposed, developed, printed, cut, edited, rewound,

repaired, or stored.

INTRODUCTION:

This Article covers wiring normally associated with motion picture and television productions.


These installations are not regularly encountered in inspection work. Discuss the contents of

article 530 and make the students aware of requirements that exist. Inform them of what to

look for when a field installation occurs.

Cover special wiring requirements, sizing of feeder conductors [Table 530.19(A)] and wiring

in film storage vaults.

APPLICATION:






ARTICLE 530

Level III

WORKSHEET

1. What permanent wiring methods are permitted on stage or sets of motion picture studios?

a. MC

b. MI

c. approved raceways

d. a, b, and c

2. A demand of what percentage of the maximum possible connected load shall be

permitted for all portable feeders.

a . 100%

b . 60% c . 75%

d . 50%

3. Stage cable for stage lighting shall be protected by means of overcurrent devices set at

not more than?

a . 125% b . 200%

c . 300%

d . 400%

4. Lamps in cellulose nitrate film storage vaults shall be controlled by a switch:

a. Located outside the vault.

b. Located inside the vaults.

c. Located outside the vault and provided with a pilot light.

d. Located inside or outside if keyed.



ARTICLE 530

Level III

ANSWER KEY

1. d, a, b, and c 530.11

2. d, 50% 530.19(B)

3. d, 400% 530.18(A)

4. c, located outside the vault and provided with

a pilot light. 530.51


CRANES AND

HOISTS ARTICLE 610

Level III

OBJECTIVE:

Each student should be familiar with the requirements for wiring cranes, monorail hoists, hoists

and all runways.


Briefly mention that all equipment operating in hazardous locations shall comply with Articles

500 through 503.

Cover wiring methods and conductors; emphasizing that ampacity is as stated in Table

610.14(A) not 310.16.

Contact conductors are usually factory assembled and field installed as listed units. Briefly

acquaint the students with the terminology involved and state that no other loads can be

supplied 610.21(H).

Point out the requirements for runway conductor disconnecting means and the exception that

permits the motor circuit switch to be omitted.

Overcurrent protection is basically the same as other motor overcurrent requirements except

that the demand factors of Table 610.14(E) are applied.

Point out that cranes and hoists controls include limit switches (610.55) to limit travel and 2 1/2

feet of working space is required where live parts must be accessed (610.57).

APPLICATION:





CRANES AND HOISTS


WORKSHEET

1. Conductors shall be enclosed in raceways or what type cable?

a. MC or AC

b. NM or NMC

c. AC or SNM

d. USE or UF

2. #8 THWN conductors used to supply a 15 minute motor on a crane are rated at:

a. 60 amps

b. 55 amps

c. 67 amps

d. 69 amps

3. The smallest conductor allowed to be used for electronic circuits:

a . #16

b. #14

c . #18

d . #20

4. Four cranes are supplied by a common conductor system with a total computed load of 50

amps. What size conductor would be needed if the longest time-rated motor is 60

minutes?

a . # 8

b. #14

c . #18

d . #20

5. Where bridge wire contact conductors have a span exceeding 80 feet, insulating saddles

shall be placed at intervals not exceeding:

a. 25’

b. 50’

c. 10’

d . 40’


6. The continuous ampere rating of a switch or circuit breaker used as a disconnect switch

shall not be less than what percentage of the combined short-time ampere rating of the

motors or not less than what percentage of the sum of the short-time rating of the motors

required for any single motion?

a . 100%-75% b . 50%-75%

c . 50%-50%

d . 75%-50%

7. Control circuits shall have overcurrent protection not more than what percentage of the

ampacity of the control conductors?

a . 100% b . 200%

c . 300%

d . 400%


CRANES AND HOISTS ARTICLE

610 Level III

ANSWER KEY

1. a, MC or AC 610.11

2. c, 67 amps (see note under table) 610.14(E) & Table 610.14(A)

3. d, #20 610.14(C)(2)

4. a, #8 610.14(E)(3) &

50 X 87% = 43.5 < 55 Table 610.14(A) and (E)

5. b, 50 ft. 610.21(D)

6. b, 50%-75% 610.33

7. c, 300% 610.53


X-RAY EQUIPMENT

ARTICLE 660

Level III

OBJECTIVE:

Each student should be familiar with the requirements for all x-ray equipment used for industrial or other nonmedical or nondental use.

INTRODUCTION:

Explain that medical and dental x-ray equipment is covered in Article 517-V and that Article

660 is not applicable for those installations.


Explain that this Article is concerned with electrical safety and not health hazards or radiation from the equipment.

Proper application of this Article depends upon understanding the definitions outlined in 660.2.

Cover all of these.

Explain that fixed equipment can only be cord and plug connected if it can be properly

supplied by a branch circuit rated 30 amperes or less. Portable, mobile and transportable

equipment of any capacity shall be permitted to be connected by hard service cable or cord.

Explain that the rating of the disconnecting means, conductor ampacity, and overcurrent

protection are different from normal equipment because of the short duration of service. Be

sure to emphasize calculations using momentary ratings may result in smaller sizing of

conductors; however, voltage regulation may require larger conductors for proper equipment

operation.

APPLICATION:





X-RAY EQUIPMENT

ARTICLE 660

Level III

WORKSHEET

1. Article 660 covers x-ray equipment in which of the following locations?

a. Hospitals

b. Dental offices

c. nursing homes


2. A momentary rating is a rating based on an operating interval that does not exceed which of

the following?

a. 5 seconds

b. 1 minute

c. 30 seconds

d. 5 minutes

3. An x-ray disconnecting means is required to provide adequate capacity for:

a. 50% of the input required for momentary input

b. 100% of the input for the long time rating

c. Both A and B

d. Whichever is greater of A or B

4. The minimum ampacity of the branch circuit conductors for an x-ray machine with a

momentary rating of 100 amperes and a long time rating of 50 amperes is:

a. 50 amperes

b. 100 amperes

c. 200 amperes

d. 225 amperes

5. Transformers and capacitors that are part of x-ray equipment must comply with:

a. Transformers must comply with Article 450

b. Capacitors must comply with Article 460

c. Both a and b

d. Neither a nor b


6. A feeder supplies four x-ray machines. The x-ray machines have the following momentary

ratings: 100 amperes, 60 amperes, 30 amperes, and 32 amperes. What is the minimum

ampacity of the feeder conductors?

a. 92.4 amperes

b. 100.21 amperes c. 160.4 amperes

d. 125 amperes


X-RAY EQUIPMENT

ARTICLE 660

Level III

ANSWER KEY

1. d, none of the above 660.1

2. a, 5 seconds 660.2

3. d, Whichever is greater A or B 660.5

4. a, 50 amperes 660.6(A)

5. d, neither a nor b 660.35

6. a, 92.4 amperes 660.6(B)


INDUCTION AND DIELECTRIC HEATING EQUIPMENT

ARTICLE 665

Level III

OBJECTIVE:

Each student should be familiar with the requirements of Article 665 for induction and dielectric heating equipment.

INTRODUCTION:

Explain that this Article does not cover heating equipment for medical or dental applications,

appliances, or line frequency pipelines and vessels heating.


Start off by explaining the difference between the two types of heating systems. Dielectric

heating is heating a nominally insulated material as compared to heating a nominally

conductive material.

Warning labels or signs shall be attached to the equipment in such a manner as to be fully

visible even when doors are open or panels are removed. Compliance with Article

110.21(B) is required.

Cover interlocks requirements as outlined in 665.25.

Explain that motor-generator equipment is basically a motor load and that supply conductors,

overcurrent protection and disconnecting means shall be as specified in Article 430. The

generator output is normally isolated from ground.

Cover the safety precautions necessary when using remote controlled switching.

Heating equipment other than motor-generator types shall have overcurrent protection in

accordance with Article 240.

APPLICATION:






ARTICLE 665

Level III

WORKSHEET

1. Article 665 covers what type of applications? a. Induction and dental applications.

b. Industrial and scientific applications.

c. Welding and heating applications.

d. Guarding and grounding applications

2. Warning labels or signs shall be attached on equipment and be plainly visible even when

doors are open or panels are removed if the voltage is over which of the following?

a. 125 Volts AC or DC

b. 600 Volts AC or DC

c. 150 Volts AC or DC

d. Not required

3. Equipment other than motor generator shall have overcurrent as specified in which Article?

a. 430

b. 665

c. 240

d. 310



ARTICLE 665

Level III

ANSWER KEY

1. b. Industrial and scientific applications 665.1 2. c. 150 volts ac or dc 665.23

3. c. 240 665.11


ELECTROLYTIC CELLS


OBJECTIVE:

Each student should be acquainted with the requirements for installation of electrical

components of electrolytic cells and cell lines.

INTRODUCTION:

Article 668 applies to the installation of electrical components of electrolytic cells and cell

lines. It does not apply to cells used as a source of electrical energy (storage batteries).


Cover scope of Article (668.1) to make students familiar with where this article applies.

Emphasis should be placed on Informational Notes to 668.1.

Go over definitions found in 668.2.

Cover applications of other articles as found in 668.3.

Discuss space requirements for cell line working zone as covered in 668.10 and differences in

grounding practices from those normally used as found in 668.11, 668.15, 668.20, 668.21,

668.30, 668.32(A). Cover requirements for Cranes and Hoists found in 668.32.

APPLICATION:





ELECTROLYTIC CELLS


WORKSHEET

1. The provisions of Article 668 applies to the installation of electrolytic cells except for


a. A source of electric energy.

b. The production of copper.

c. The production of aluminum

d. The production of chlorine.

2. A tank or vat in which electrochemical reactions are caused by applying electrical energy for

the purpose of refining or producing usable materials is which the following?

a. Cell

b. Electrolytic cell

c. Cell Vat

d. Vat

3. The frames and enclosures of portable electrical equipment used within the cell line

working zone shall not be required to be?

a. Bonded

b. Grounded

c. Electrically continuous

d. Shielded


ELECTROLYTIC

CELLS ARTICLE 668

Level III

ANSWER KEY

1. a. energy source 668.1

2. b. 668.2 Definitions

3. b. Grounded 668.20(A)


ELECTROPLATING

ARTICLE 669

Level III

OBJECTIVE:

Each student should be acquainted with the requirements for electroplating installations.

INTRODUCTION:

This Article applies to electroplating, anodizing, electro polishing, and electro stripping. The

term electroplating is used to identify any or all of these processes in this Article.


Cover requirements for branch circuit conductors (669.5), wiring methods (669.6) and warning

signs (669.7).

APPLICATION:





ELECTROPLATING

ARTICLE 669 Level

III

WORKSHEET

1. Branch circuit conductors supplying electroplating equipment shall have an ampacity of not less than which of the following percentage of the total connected load.

a . 125% b . 175%

c . 50 %

d . 80 %

2. Where bare conductors are present in electroplating applications, which of the following is required?

a. Warning alarms

b. Warning language

c. Warning lights

d. Warning signs


ELECTROPLATING


ANSWER KEY

1. a. 125% Section 669.5

2. d. warning signs Section 669.7


INTERCONNECTED ELECTRICAL POWER PRODUCTION SOURCES

ARTICLE 705

Level III

OBJECTIVE:

Each student should be acquainted with the requirements for interconnected electrical power

production sources installations.

INTRODUCTION:

This Article applies to interconnected electrical power production sources. This article covers

the installation of one or more electric power production sources operating in parallel.


Cover the definitions outlined in 705.2. Explain in detail that other articles such as 445

Generators, 690 Solar Photovoltaic Systems, 692 Fuel cell systems, apply to the use of this

section.

Cover in detail 705.12 Point of attachment, inverters and overcurrent.

705.20 Through 705.22 for disconnecting means of sources and equipment and their

prospective locations.

705.30 overcurrent protection of solar photovoltaic systems, transformers, fuel cell systems,

utility interactive inverter and generators.

APPLICATION:





INTERCONNECTED ELECTRICAL POWER PRODUCTION SOURCES

ARTICLE 705

Level III

WORKSHEET

1. The point at which the power production and distribution network and the customer interface occurs in an interactive system is which of the following?

a. Point of attachment

b. the weather head

c. point of common coupling


2. A dedicated overcurrent and disconnect shall be made at a dedicated:

a. circuit breaker

b. fusible disconnecting means

c. nonfused disconnect

d. either a or b

3. Which of the following statements are true concerning the loss of one phase of a three

phase interconnected power production sources?

I. When one phase opens an audible and visual warning must come on

II. Shall automatically disconnect the system

a. I only

b. II only

c. both I and II

d. neither I nor II


INTERCONNECTED ELECTRICAL POWER PRODUCTION SOURCES ARTICLE

705

Level III

ANSWER SHEET

1. d 705.2

2. d 705.12(D)(1)

3. b II only 705.42


CRITICAL OPERATIONS POWER SYSTEMS

ARTICLE 708

LEVEL III

OBJECTIVES:

Each student should be familiar with and understand the nature of Article 708 as it relates to

systems necessary for emergency operations of governmental systems.

INTRODUCTION:

Explain the background and reasoning behind instituting guidelines and requirements for

maintaining certain public electrical and utility systems during extreme conditions caused by loss

of services due to weather related or human caused events


Discuss different aspects and concerns based on the Authority Having Jurisdiction and who that

may be to take control and maintain order during catastrophic events where loss of power and

other systems lead to extreme environmental conditions for the inhabitants of the affected

community.

Explain the comparisons between emergency systems covered in Article 700 and how those

requirements there are necessary in addressing similar conditions under Article 708.

Relate the needs for planning by emergency management and proper governmental agencies

responsible for enduring the event and the recovery afterwards to move toward normal

conditions.

APPLICATION:

Allow the class time to complete worksheet


Correct the worksheets and discuss the answers with the class.


CRITICAL OPERATIONS POWER SYSTEMS

ARTICLE 708

LEVEL III

WORKSHEET

1. Critical Power Operations Systems are those systems classed by which of the following?

a. Municipal agency

b. State agency

c. Federal Agency

d. Any of the above

2. When establishing critical operations systems, a Commissioning Plan shall be:

a. planned and approved

b. developed and documented

c. commissioned by the governing agency

d. made by the local authority having jurisdiction

3. Hazards to be considered at a minimum shall include, but shall not be limited to which of the

following:

I. Naturally occurring hazards (geological, meteorological, and biological)

II. Human-caused events (accidental and intentional)

a. I only

b. II only

c. Neither I nor II

d. Both I and II

4. Physical security shall be provided for critical operations power systems in accordance with


I. Risk Assessment

II. Restricted Access

a. I only

b. II only

c. Both I and II

d. Neither I nor II


160

5. The feeder-and branch-circuit overcurrent devices shall be accessible to which of the following?

a. qualified persons

b. only government officials

c. only military personnel

d. authorized persons

6. Alternate power sources shall be capable of operating the COPS for a minimum of:

a. 24 hours

b. 72 hours

c. 48 hours

d. 96 hours


CRITICAL OPERATIONS POWER SYSTEMS ARTICLE 708

LEVEL III

ANSWER KEY

1. d, any of the above 708.1

2. b, 708.8(A)

3. d, both I and II 708.4(B)

4. c, both I and II 708.5

5. d, authorized persons 708.50

6. b, 72 hours 708.22(C)

Documents

2014 NEC Instructor Manual and Student Worksheets Level 3