Master Examination

Practice Drill #3 2011

O 1. Given: Two (2) rigid metal conduits (RMC) are to support a weatherproof 18 cu. In. device box, with threaded hubs, which contains a 125-volt, 20-ampere receptacle outlet. The conduits are to be threaded wrench tight into the hubs and, in general, shall be secured with at LEAST _____ of the enclosure.A. 8 inchesB. 12 inchesC. 18 inchesD. 24 inches

Question

Answer

Reference NEC PG. #

1. C 314.23(F) 181

O 2. In general, if the cablebus system is rated 95 amperes, the MAXIMUM allowable rating of the overcurrent device used to protect the cablebus is _______.A. 80 amperesB. 90 amperesC. 95 amperesD. 100 amperes

Question

Answer

Reference NEC PG. #

2. D 370.5 227240.4(B)(2)&(3)

90

240.6(A) 91

O 3. A twenty-five (25) ft. long tap conductor tapped from a 100 ampere rated feeder conductor, shall have an ampacity of NOT less than ________.A. 50 amperesB. 75 amperesC. 25 amperesD. 33.3 amperes

Question

Answer

Reference NEC PG. #

3. D 240.21(B)&(B)(2)(1)

92&93

100 amperes/3 = 33.3 amperes

O 4. Disregarding exceptions, bonding between Class I locations and the point of grounding for service equipment may be done by _________.A. Double locknutsB. Bonding jumpersC. Insulated bushingsD. Metal raceways

Question

Answer

Reference NEC PG. #

4. B 501.30(A) 381

O 5. Determine the demand load, in VA, on the ungrounded service-entrance conductors, for the general-lighting and receptacles for a 25,000 sq. ft. office building that has one hundred-fifty (150) general-purpose duplex receptacles. Consider the service overcurrent protection device is NOT listed for continuous use.A. 112,075 VAB. 106,000 VAC. 90,200 VAD. 127,875 VA

Question

Answer

Reference NEC PG. #

5. D Tbl. 220.12 63

220.14(I) 63

220.44 64

Tbl. 220.44 64

Art. 100 27

230.42(A)(1) 8225,000 sq. ft. x 3.5 VA x 125% (lighting) = 109,375 VA150 receptacles x 180 VA each = 27,000VA 1st 10,000 VA @ 100% = 10,000 VA27,000 VA – 10,000 VA = 17,000 VA @ 50% = 8,500VA

Total = 127,875 VA

O 6. When an electrical service is required to have a grounded conductor present, what is the smallest grounded conductor permitted for an electric service using size 1000 kcmil copper undergrounded (phase) conductors?A. 3/0 AWG copperB. 2/0 AWG copperC. 1/0 AWG copperD. 4/0 AWG copper

Question

Answer

Reference NEC PG. #

6. B 250.24(C)(1) 105Tbl. 250.66 115

O 7. Determine the MINIMUM number of 20-ampere, 277-volt, general-lighting branch circuits required for a 150,000 sq. ft. department store, when the actual connected lighting load is 400 kVA,A. 72 branch circuitsB. 82 branch circuitsC. 91 branch circuitsD. 102 branch circuits

Question

Answer

Reference NEC PG. #

7. C 210.19(A)91) 52210.11(B) 51

400 kVA = 400,000 VA x 125% (continuous load) = 500,000 VA (bldg.)

277 volts x 20 amperes = 5540 VA (one circuit)

500,000 VA. (bldg. lighting) 5,540 VA (one circuit) = 90.2 = 91 circuits

*NOTE – Circuits need only to be installed to service the connected load.

O 8. Where a two-gang box contains two (2) single-pole switches, unless the box is equipped with permanently installed barriers, the voltage between the switches shall NOT be in excess of _______.A. 120 voltsB. 277 voltsC. 240 voltsD. 300 volts

Question

Answer

Reference NEC PG. #

8. D 404.8(B) 268

O 9. An aluminum grounding electrode shall be _________.A. Installed at least 18 inches above the

earthB. Installed at least 24 inches above the

earthC. In direct earth burialD. Prohibited

Question

Answer

Reference NEC PG. #

9. D 250.52(B)(2) 112

O 10. A panelboard is limited to 42 overcurrent protective devices where ________.A. The panelboard is a power

panelboardB. The panelboard is a “split-bus”

type panelboardC. The panelboard supplies lighting

branch-circuits onlyD. One is installed

Question

Answer

Reference NEC PG. #

10. B 408.36, Ex. 2 276

O 11. When rigid polyvinyl chloride conduit (PVC) is used to enclose conductors feeding a wet-niche luminaire in a permanently installed swimming pool, a ______ insulated copper grounding conductor shall be installed in this conduit, unless a listed low-voltage lighting system not requiring grounding is used.A. 12 AWGB. 10 AWGC. 8 AWGD. 6 AWG

Question

Answer

Reference NEC PG. #

11. C 680.23(B)(2)(b)

581

O 12. In general, what is the largest size transformer, in kVA, that may be installed in an area or room that is NOT constucted in a fire-resistant manner?A. 75 KVAB. 112 ½ KVAC. 150 KVAD. 50 KVA

Question

Answer

Reference NEC PG. #

12. B 450.21(B) 352

O 13. When calculating the total load of an office building, and the number of general-purpose receptacles to be installed is not yet determined, an additional load of _____ volt-amp(s) per square foot is required for the receptacle outlets.A. OneB. TwoC. One-HalfD. Three

Question

Answer

Reference NEC PG. #

13. A 220.14(K)(2) 63

O 14. When sizing time-delay Class CC fuses for motor branch-circuit, short-circuit and ground-fault protection, they are to be sized at the same value as ________.A. inverse-time circuit breakersB. Nontime-delay fusesC. Instantaneous trip circuit

breakersD. Adjustable trip circuit breakers

Question

Answer

Reference NEC PG. #

14. B Tbl. 430.52, Note 1

323

O 15. Conductors other than service-entrance conductors shall be permitted to be installed in a cable tray with service-entrance conductors provided __________.A. A solid fixed barrier of material

compatible with the cable tray is installed to separate the systems

B. The conductors are not in excess of 480 volts to ground

C. The voltage between the conductors is not in excess of 600 volts

D. The conductors have equal insulation and temperature ratings

Question

Answer

Reference NEC PG. #

15. A 203.44, Ex 82

O 16 The MAXIMUM allowable ampacity of a size 750 kcmil XHHW aluminum conductor where there are six (6) current-carrying conductors in the raceway, installed in a dry location, where the ambient temperature will reach 22°C is ________A. 323.40 amperesB. 365.40 amperesC. 361.92 amperesD. 348.00 amperes

Question

Answer

Reference NEC PG. #

16. C Tbl. 310.15(B)(16)

154

Tbl. 310.15(B)(2)(a)

150

Tbl. 310.15(B)(3)(a)

152Size 750 kcmil AL ampacity (before derating) = 435 amperes435 amps x 1.04 (temp correction) x .8 (adj. factor) = 361.92 amperes

O 17. In which of the following locations is a cable tray prohibited to be installed?A. BasementB. Storage RoomsC. Sealed Ceiling SpacesD. When Passing Through a Wall

Question

Answer

Reference NEC PG. #

17. C 392.18 (D)&(E)

240

O 18. What is the MINIMUM size copper common grounding electrode conductor required to run through a building to four (4) separately derived systems (transformers) each having size 3/0 AWG copper secondary conductors.A. 4 AWGB. 2 AWGC. 3/0 AWGD. 8 AWG

Question

Answer

Reference NEC PG. #

18. C 250.30(A)(6)(a)(1)

108

O 19. Where a commercial building has a 600 ampere, 3-phase, 208Y/120 volt service supplied with two (2) paralled sets of size 350 kcmil copper conductors installed in separate raceways, determine the MINIMUM size aluminum grounding electrode conductor permitted to the metal water piping system used as the grounding electrod.A. 250 kcmilB. 4/0 AWGC. 3/0 AWGD. 2/0 AWG

Question

Answer

Reference NEC PG. #

19. B 250.66 115Tbl. 250.66 115

350 kcmil x 2 conductors = 750 kcmil

*NOTE – A size 4/0 AWG aluminum grounding electrode conductor should be selected

O 20. The NEC permits trade size 3/8 in. flexible metal conduit (FMC) to be used to enclose tap conductors for luminaires, provided the length of the FMC does NOT exceed __________.A. 4 feetB. 6 feetC. 8 feetD. 10 feet

Question

Answer

Reference NEC PG. #

20. B 348.20(A)(2)c.

206

O 21. What is the MAXIMUM distance allowed to support intermediate metal conduit (IMC) from a junction box, where structural members do not readily permit fastening?A. 3 feetB. 5 feetC. 6 feetD. 8 feet

Question

Answer

Reference NEC PG. #

21. B 342.30(A)(2) 203

O 22. All of the following listed copper conductors are to be installed in an electrical metallic tubing (EMT) that is in excess of 24 inches long.24-size 10 AWG with TW insulation10-size 10 AWG with THW insulation14-size 12 AWG with THHN insulation

Determine the MINIMUM trade size of EMT required.A. 2 in.B. 2 ½ in.C. 3 in.D. 3 ½ in.

Question

Answer

Reference NEC PG. #

22. A Chpt. 9, Tbl. 5 717&718

Chpt. 9, Tbl. 4 712Size 10 AWG TW = .0243 sq. in. x 24 = .5832 sq. in.Size 10 AWG THW = .0243 sq. in. x 10 = .2430 sq. in.Size 12 AWG THNN = .0133 sq. in. x 14 = .1862 sq. in.

TOTAL = 1.1024 sq. in. *NOTE – Trade size 2 inch EMT with a permitted fill of 1.342 sq. in. @ 40% should be selected

O 23. When combination surface nonmetallic raceways are used both for signaling and for power and lighting circuits, the different systems shall be ________.A. ProhibitedB. Run in the same compartmentC. Separated by at least ½ in.D. Run in separate compartments

Question

Answer

Reference NEC PG. #

23. D 388.70 238

O 24. When sizing fuses for a branch circuit serving a hermetic refrigerant motor-compressor, the device shall NOT exceed ____ of the rated load current marked on the nameplate of the equipment.A. 115 percentB. 125 percentC. 175 percentD. 225 percent

Question

Answer

Reference NEC PG. #

24. D 440.22(A) 343

O 25. Where rigid metal conduit (RMC) is used to protect a grounding conductor, the conduit must ________.A. Be isolated from the grounding

conductorB. Be electrically continuous from

cabinet to ground clampsC. Be identified with green paintD. Not be connected to or touching

the ground clamp

Question

Answer

Reference NEC PG. #

25. B 250.64(E) 114

Click here to advance to non-timed drill

O 1. Given: Two (2) rigid metal conduits (RMC) are to support a weatherproof 18 cu. In. device box, with threaded hubs, which contains a 125-volt, 20-ampere receptacle outlet. The conduits are to be threaded wrench tight into the hubs and, in general, shall be secured with at LEAST _____ of the enclosure.A. 8 inchesB. 12 inchesC. 18 inchesD. 24 inches

Question

Answer

Reference NEC PG. #

1. C 314.23(F) 181

O 2. In general, if the cablebus system is rated 95 amperes, the MAXIMUM allowable rating of the overcurrent device used to protect the cablebus is _______.A. 80 amperesB. 90 amperesC. 95 amperesD. 100 amperes

Question

Answer

Reference NEC PG. #

2. D 370.5 227240.4(B)(2)&(3)

90

240.6(A) 91

O 3. A twenty-five (25) ft. long tap conductor tapped from a 100 ampere rated feeder conductor, shall have an ampacity of NOT less than ________.A. 50 amperesB. 75 amperesC. 25 amperesD. 33.3 amperes

Question

Answer

Reference NEC PG. #

3. D 240.21(B)&(B)(2)(1)

92&93

100 amperes/3 = 33.3 amperes

O 4. Disregarding exceptions, bonding between Class I locations and the point of grounding for service equipment may be done by _________.A. Double locknutsB. Bonding jumpersC. Insulated bushingsD. Metal raceways

Question

Answer

Reference NEC PG. #

4. B 501.30(A) 381

O 5. Determine the demand load, in VA, on the ungrounded service-entrance conductors, for the general-lighting and receptacles for a 25,000 sq. ft. office building that has one hundred-fifty (150) general-purpose duplex receptacles. Consider the service overcurrent protection device is NOT listed for continuous use.A. 112,075 VAB. 106,000 VAC. 90,200 VAD. 127,875 VA

Question

Answer

Reference NEC PG. #

5. D Tbl. 220.12 63

220.14(I) 63

220.44 64

Tbl. 220.44 64

Art. 100 27

230.42(A)(1) 8225,000 sq. ft. x 3.5 VA x 125% (lighting) = 109,375 VA150 receptacles x 180 VA each = 27,000VA 1st 10,000 VA @ 100% = 10,000 VA27,000 VA – 10,000 VA = 17,000 VA @ 50% = 8,500VA

Total = 127,875 VA

O 6. When an electrical service is required to have a grounded conductor present, what is the smallest grounded conductor permitted for an electric service using size 1000 kcmil copper undergrounded (phase) conductors?A. 3/0 AWG copperB. 2/0 AWG copperC. 1/0 AWG copperD. 4/0 AWG copper

Question

Answer

Reference NEC PG. #

6. B 250.24(C)(1) 105Tbl. 250.66 115

O 7. Determine the MINIMUM number of 20-ampere, 277-volt, general-lighting branch circuits required for a 150,000 sq. ft. department store, when the actual connected lighting load is 400 kVA,A. 72 branch circuitsB. 82 branch circuitsC. 91 branch circuitsD. 102 branch circuits

Question

Answer

Reference NEC PG. #

7. C 210.19(A)91) 52210.11(B) 51

400 kVA = 400,000 VA x 125% (continuous load) = 500,000 VA (bldg.)

277 volts x 20 amperes = 5540 VA (one circuit)

500,000 VA. (bldg. lighting) 5,540 VA (one circuit) = 90.2 = 91 circuits

*NOTE – Circuits need only to be installed to service the connected load.

O 8. Where a two-gang box contains two (2) single-pole switches, unless the box is equipped with permanently installed barriers, the voltage between the switches shall NOT be in excess of _______.A. 120 voltsB. 277 voltsC. 240 voltsD. 300 volts

Question

Answer

Reference NEC PG. #

8. D 404.8(B) 268

O 9. An aluminum grounding electrode shall be _________.A. Installed at least 18 inches above the

earthB. Installed at least 24 inches above the

earthC. In direct earth burialD. Prohibited

Question

Answer

Reference NEC PG. #

9. D 250.52(B)(2) 112

O 10. A panelboard is limited to 42 overcurrent protective devices where ________.A. The panelboard is a power

panelboardB. The panelboard is a “split-bus”

type panelboardC. The panelboard supplies lighting

branch-circuits onlyD. One is installed

Question

Answer

Reference NEC PG. #

10. B 408.36, Ex. 2 276

O 11. When rigid polyvinyl chloride conduit (PVC) is used to enclose conductors feeding a wet-niche luminaire in a permanently installed swimming pool, a ______ insulated copper grounding conductor shall be installed in this conduit, unless a listed low-voltage lighting system not requiring grounding is used.A. 12 AWGB. 10 AWGC. 8 AWGD. 6 AWG

Question

Answer

Reference NEC PG. #

11. C 680.23(B)(2)(b)

581

O 12. In general, what is the largest size transformer, in kVA, that may be installed in an area or room that is NOT constucted in a fire-resistant manner?A. 75 KVAB. 112 ½ KVAC. 150 KVAD. 50 KVA

Question

Answer

Reference NEC PG. #

12. B 450.21(B) 352

O 13. When calculating the total load of an office building, and the number of general-purpose receptacles to be installed is not yet determined, an additional load of _____ volt-amp(s) per square foot is required for the receptacle outlets.A. OneB. TwoC. One-HalfD. Three

Question

Answer

Reference NEC PG. #

13. A 220.14(K)(2) 63

O 14. When sizing time-delay Class CC fuses for motor branch-circuit, short-circuit and ground-fault protection, they are to be sized at the same value as ________.A. inverse-time circuit breakersB. Nontime-delay fusesC. Instantaneous trip circuit

breakersD. Adjustable trip circuit breakers

Question

Answer

Reference NEC PG. #

14. B Tbl. 430.52, Note 1

323

O 15. Conductors other than service-entrance conductors shall be permitted to be installed in a cable tray with service-entrance conductors provided __________.A. A solid fixed barrier of material

compatible with the cable tray is installed to separate the systems

B. The conductors are not in excess of 480 volts to ground

C. The voltage between the conductors is not in excess of 600 volts

D. The conductors have equal insulation and temperature ratings

Question

Answer

Reference NEC PG. #

15. A 203.44, Ex 82

O 16 The MAXIMUM allowable ampacity of a size 750 kcmil XHHW aluminum conductor where there are six (6) current-carrying conductors in the raceway, installed in a dry location, where the ambient temperature will reach 22°C is ________A. 323.40 amperesB. 365.40 amperesC. 361.92 amperesD. 348.00 amperes

Question

Answer

Reference NEC PG. #

16. C Tbl. 310.15(B)(16)

154

Tbl. 310.15(B)(2)(a)

150

Tbl. 310.15(B)(3)(a)

152Size 750 kcmil AL ampacity (before derating) = 435 amperes435 amps x 1.04 (temp correction) x .8 (adj. factor) = 361.92 amperes

O 17. In which of the following locations is a cable tray prohibited to be installed?A. BasementB. Storage RoomsC. Sealed Ceiling SpacesD. When Passing Through a Wall

Question

Answer

Reference NEC PG. #

17. C 392.18 (D)&(E)

240

O 18. What is the MINIMUM size copper common grounding electrode conductor required to run through a building to four (4) separately derived systems (transformers) each having size 3/0 AWG copper secondary conductors.A. 4 AWGB. 2 AWGC. 3/0 AWGD. 8 AWG

Question

Answer

Reference NEC PG. #

18. C 250.30(A)(6)(a)(1)

108

O 19. Where a commercial building has a 600 ampere, 3-phase, 208Y/120 volt service supplied with two (2) paralled sets of size 350 kcmil copper conductors installed in separate raceways, determine the MINIMUM size aluminum grounding electrode conductor permitted to the metal water piping system used as the grounding electrod.A. 250 kcmilB. 4/0 AWGC. 3/0 AWGD. 2/0 AWG

Question

Answer

Reference NEC PG. #

19. B 250.66 115Tbl. 250.66 115

350 kcmil x 2 conductors = 750 kcmil

*NOTE – A size 4/0 AWG aluminum grounding electrode conductor should be selected

O 20. The NEC permits trade size 3/8 in. flexible metal conduit (FMC) to be used to enclose tap conductors for luminaires, provided the length of the FMC does NOT exceed __________.A. 4 feetB. 6 feetC. 8 feetD. 10 feet

Question

Answer

Reference NEC PG. #

20. B 348.20(A)(2)c.

206

O 21. What is the MAXIMUM distance allowed to support intermediate metal conduit (IMC) from a junction box, where structural members do not readily permit fastening?A. 3 feetB. 5 feetC. 6 feetD. 8 feet

Question

Answer

Reference NEC PG. #

21. B 342.30(A)(2) 203

O 22. All of the following listed copper conductors are to be installed in an electrical metallic tubing (EMT) that is in excess of 24 inches long.24-size 10 AWG with TW insulation10-size 10 AWG with THW insulation14-size 12 AWG with THHN insulation

Determine the MINIMUM trade size of EMT required.A. 2 in.B. 2 ½ in.C. 3 in.D. 3 ½ in.

Question

Answer

Reference NEC PG. #

22. A Chpt. 9, Tbl. 5 717&718

Chpt. 9, Tbl. 4 712Size 10 AWG TW = .0243 sq. in. x 24 = .5832 sq. in.Size 10 AWG THW = .0243 sq. in. x 10 = .2430 sq. in.Size 12 AWG THNN = .0133 sq. in. x 14 = .1862 sq. in.

TOTAL = 1.1024 sq. in. *NOTE – Trade size 2 inch EMT with a permitted fill of 1.342 sq. in. @ 40% should be selected

O 23. When combination surface nonmetallic raceways are used both for signaling and for power and lighting circuits, the different systems shall be ________.A. ProhibitedB. Run in the same compartmentC. Separated by at least ½ in.D. Run in separate compartments

Question

Answer

Reference NEC PG. #

23. D 388.70 238

O 24. When sizing fuses for a branch circuit serving a hermetic refrigerant motor-compressor, the device shall NOT exceed ____ of the rated load current marked on the nameplate of the equipment.A. 115 percentB. 125 percentC. 175 percentD. 225 percent

Question

Answer

Reference NEC PG. #

24. D 440.22(A) 343

O 25. Where rigid metal conduit (RMC) is used to protect a grounding conductor, the conduit must ________.A. Be isolated from the grounding

conductorB. Be electrically continuous from

cabinet to ground clampsC. Be identified with green paintD. Not be connected to or touching

the ground clamp

Question

Answer

Reference NEC PG. #

25. B 250.64(E) 114