NEMA_280_1990 Ground Fault Circuit Interrupters

STANDARDS PUBLICATION/NO. 280-1 990

NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION 21 O1 L STREET, N.W., WASHINGTON, D.C. 20037 Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMA

Document provided by IHS Licensee=Fluor Corp no FPPPV per administrator /usenew u/2110503106, User=AHESPINOZA, 05/26/2004 05:58:00 MDT Questions orcomments about this message: please call the Document Policy Group at

--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

~- ~ -

NEMA 280 90 = 6470247 0501687 920

n

U

L Z

No. 99: Ground Fault Circuit Interrupters (GFCI) (December 1985)

An inexpensive electrical device, if installed in selected household branch circuits, could prevent over two-thirds (about 350) of the electrocutions each year in and around the home. In addition, injuries to many thousands of consumers from electric shock and burns also could be prevented by installation of this device. The device is the ground fault circuit interrupter (GFCI). The GFCI protects peo- ple from electrical shock hazards.

THE PROBLEM

Have you ever experienced an electrical shock? If you did, the shock probably happened because part of your body, such as a hand, contacted a source of electrical current: your body provided a path for the electric current to return to ground, therefore you received a shock.

An unintentional electric path between a current source and a grounded surface is referred to as a “ground fault.” Ground faults occur when electric current is “I e a k i n g ” som e w h e re: i n effect , e I ec t r i c i t y is escaping to the ground. How it leaks is very important.

In the home, electric circuits are usually connected to the ground at all times. The connection to ground is provided by means of cold water pipes, foundation structures, metal drains, or metal rods driven into the earth. If your body provides a route for electricity to escape to the earth because you are serving as a ground connection, you could be injured, burned or electrocuted.

Some examples of consumer accidents underscore the hazard:

IN OCTOBER, 1984, TWO CHILDREN, AGES FIVE AND SIX, WERE ELECTRO- CUTED IN TEXAS WHEN A PLUGGED-IN HAIRDRYER FELL INTOTHETUB IN WHICH THEY WERE BATHING. THE HAIRDRYER SWITCH WAS IN THE “OFF” POSITION.

OLD KANSAS GIRL WAS ELECTROCUTED

TOP APPLIANCE AND A WATER PIPE IN THE SINK.

IN FEBRUARY, 1985, A THREE-YEAR-

WHEN SHE TOUCHED A FAULTY COUNTER-

HOW THE GFCI WORKS

Because it limits the duration of hazardous ground fault currents, the GFCI can prevent electrocutions, burns, and severe electrical shock injuries where it is used.

When installed in the home wiring system, the GFCI constantly monitors electricity flowing in a circuit to “sense” any loss of current. The device does so by checking the current flowing through the “hot” wire and the current flowing through the return “neutral” wire. If the current flowing through the hot wire differs from that returning in the neutral wire by a small predetermined amount, the GFCI quickly switches off power to that circuit. It does so because it senses that some current, much less than that needed to light a child’s night light, is escaping to ground some other way and not returning through the neutral wire. The GFCI inter- rupts power faster than the blinking of an eye to protect you against what otherwise could be a lethal dose of electricity. You may receive a painful shock in the time required for the GFCI to detect and interrupt a hazardous ground fault current, but you should not be electrocuted or receive a serious shock injury.

Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMA


--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

_ _ _ ~- ~ - - __ -__

NENA 280 90 = 6470247 0503688 867

Here is how the GFCI could work in your house:

Imagine that an electric appliance fell into a sink filled with water. If you were touching a grounded surface as you reached into the sink to remove the appliance, you could be electrocuted because electricity would travel through your body to the grounded surface. If a GFCI were protecting the circuit, the power would have been shut off before serious harm came to you.

AVAILABILITY OF GFCls

Three types of ground fault circuit interrupters are available for home use: wall-receptacle, circuit-breaker and portable.

Receptacle Type. This GFCI is used .in place of the standard duplex receptacle found throughout the house. It fits into the standard box and protects you against “ground faults” whenever an electrical product is plugged into the outlet. Most GFCl’s can be installed so that they protect all electrical outlets further down the circuit. If the GFCI shuts off the power, you would first correct the problem (such as unplugging an electric mixer that had fallen into the water), then reset the GFCI to restore power.

Circuit-Breaker Type. In homes equipped with circuit-breakers rather than fuses, a

2

dual-purpose GFCI can be installed to give protection at all or selected circuit- breakers. When mounted in the panel box, the GFCI wil l not only terminate electricity in the event of a “ground fault,’’ but wi l l also trip on overload currents. Protection wil l be extended to each outlet, lamp, heater, etc., served by the branch circuit equipped with the GFCI. Because the GFCI is in the panel box, you reset the GFCI in the panel box to restore power to the circuit.

Portable Type. Where permanent GFCls are not practical, portable GFCls may be used. It is plugged into a receptacle, then the electrical product is plugged into the GFCI. If there are no outdoor receptacles or if they are not protected by GFCls, a portable GFCI should be used whenever electrically operated garden equipment (mower, hedge trimmer, edger, etc.) is used. Home handymen can obtain similar protection by using the portable GFCI in conjuction with electric tools (drills, saws, sander, etc.) for do-it-yourself work in or around the house.

WHERE GFCls SHOULD BE CONSIDERED

In new homes that comply with the National Electrical Code, GFCI protection is required for bathroom receptacle circuits (since 1975), garage wall outlets (since 1978), and outdoor receptacles (since 1973). Owners of older homes or homes built where they are not covered



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

NEMA 280 90 m 6470247 0501689 7T3 m

by the code also should consider installing GFCls in these critical locations.

In view of the shock potential when standing on a concrete floor or contacting a grounded metal surface, it is strongly suggested that all basement circuits be protected by GFCls. GFCI protection also is recommended for receptacles in the kitchen, especially where portable electric appliances are used. By installing afeed- through receptacle-type GFCI in the first counter-top outlet in the circuit from the panel box, all outlets down-line from the GFCI would be protected. A circuit-breaker GFCI installed in this branch circuit wil l provide similar protection. Since water and electricity do not mix, this protection for you is invaluable in kitchens where electric appliances are used near the sink.

GFCI circuit breakers may be added in older homes to replace ordinary circuit- breakers. If your home has fuses, receptacle-type GFCls may be installed in the areas of greatest exposure, ¡.e., bathroom, kitchen, basement, garage and outdoor circuits.

INSTALLING GFCls

Consult a qualified electrician to install GFCls based on your residential needs. Installing an outlet-type GFCI is not as simple as replacing the outlet. Some jurisdictions require that all modifications

3

to residential wiring be performed by a licensed electrician.

Test the GFCI once a month to make certajn it is fully operational at all times. To check the unit, depress the test button. The GFCI immediately should indicate “open” or “off” by a physical indicator and should disconnect the power from the protected circuit. When you press the reset switch, power is restored.

SOME ELECTRICAL MISCONCEPTIONS

FUSES AND CIRCUIT-BREAKERS ARE INTENDED TO PREVENT ELECTROCUTIONS AND SHOCKS IN THE HOME. NOT TRUE!

PREVENT THE HOUSEHOLD WIRING SYSTEM FROM CAUSING FIRE, BUT ARE

FUSES AND CIRCUIT-BREAKERS HELP

NOT DESIGNED TO PROTECT THE CON- SUMER AGAINST SHOCK OR ELECTROCU- TION.

THREE-WIRE GROUNDED OUTLETS ASSURE SHOCK PROTECTION IN THE HOME. NOT ALWAYS. THE THIRD WIRE IN THE THREE-WIRE GROUNDING OUTLET IS SUPPOSED TO DIVERT ELECTRICAL CUR-

“GROUND FAULT,” BUT THIS PRESUP- POSES THAT EVERYTHING IS FUNCTION-

RENT TO THE GROUND IN THE EVENT OF A

ING PERFECTLY AT THE TIME: THAT THE GROUND CONNECTIONS FROM THE EARTH TO THE SYSTEM GROUND ARE GOOD ... THAT THE CONNECTION TO THE SYSTEM NEUTRAL CON D UCTOR IS FUNCTIONING . . .



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

NENA 280 90 m 6470247 O501690 415 m

THAT THE CONNECTiûN TO THE GROUND TERMINAL AT THE OUTLET IS EFFECTIVE ... AND THAT THERE IS GOOD CONTACT FROM THE GROUNDING PIN INTO THE RECEPTACLE. IF ANY ONE IS LACKING, THERE IS INSUFFICIENT PROTECTION

EVEN WHEN THE SYSTEM GROUND CONNECTIONS ARE ALL GOOD, A GROUND FAULT CAN OCCUR IN SUCH A WAY THAT A DANGEROUS VOLTAGE IS PRESENT FOR A PERIOD OF TIME AT THE GROUNDING CONNECTION OF A RECEPTACLE. THIS CAN PRESENT THE DANGER OF SHOCK OF ELECTROCUTION.

OFFERED BY THE THREE-WIRE OUTLET.

4

To report a product hazard or a product-related injury, write to the U.S. Consumer Product Safety Commission, Washington, D.C. 20207, or call the toll-free hotline: 800-638-CPSC. A tele-typewriter

~ for the deaf is available on the following num- bers: National 800-638-8270, Maryland only 800-492-8104.

This document is in the public domain. It may be reproduced in part or in whole by an individual or organization without permission. If it is reproduced, however, the Commission would appreciate knowing how it is used. Write the U.S. Consumer Product Safety Commission, Office of Information and Public Affairs, Washington, D.C. 20207.

The U.S. Consumer Product Safety Commission (CPSC) is an independent regulatory agency charged with reducing unreasonable risks of injury associated with consumer products. CPSC is headed by five Com- missioners appointed by the President with the advicr and consent of the Senate.

PRODUCT SAFETY, IT’S NO ACCIDENT.



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

NEMA 280-1990

280

APPLICATION GUIDE FOR GROUND FAULT CIRCUIT INTERRUPTERS

Published by:

National Electrical Manufacturers Association 2101 L Street, NW Washington, DC 20037

O1991 National Electrical Manufacturers AssociatiOn



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

TABLE OF CONTENTS a

_ _ _ _ _ _ ~~ .

NEVA 280 90 6470247 0503692 298

FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Section 1 REFERENCED STANDARDS ANDDE9"IONS Referencedstandards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Section 2 CHARACTERISTICS OF GROUND FAULT CIRCUlT "ERñUFTERS General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 PrinciplesofOperation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Double Grounded Neutral Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 TestMeans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 GFCI Tripping Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 QpesofGFCI's . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

BasicGFCI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 BlankFaceTypeGFCI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

ReceptacleType . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 PatableType . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 CordConnectedType . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Permanently Mounted Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Circuit Breaker Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Section 3 RATINGS Rating Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 RatedVoltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 RatedFrequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Rated Continuous Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Rated Withstand Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Rated Withstand Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 RatedInterruptingCurrent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Section 4 MARKINGS General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Types Which Are Permanently Connected into Current . . . . . . . . . . . . . . . . . . . . 9

ClassADevices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 CiassBDevices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Portables and Cord Connected Qpes ............................. 9

Section 5 GFCI APPLICATION CONSIDERATIONS GFCI Application Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Section 6 INSTALLATION GUIDELINES FOR ELECTRICAL SYSTEMS WlTH GFCI Location of GFCI on System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

At Load Center or Panelboard. Or a Permanently Mounted Type After Panelboard . . . . 13 At Outlet Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Wiring Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 AtLoad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Portableunits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Branchcircuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

14 12OV 2W41der Branch Circuits Without Grounding Conductor . . . . . . . . . . . . 14 12O/24OV 3W-With Equipment Grounding Conductor . . . . . . . . . . . . . . . . . 14

12OV 2W-With Equipment Grounding Conductor . . . . . . . . . . . . . . . . . . . .



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

120/240V 3W-Dedi~ated to an Appliance . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Section 7 FIELD TEST DEVICES Integral Test Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Supplemental GFCI Testers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

19 Supplemental Test Device on Circuiís Containing Leakage . . . . . . . . . . . . . . . 19 SupplementaiTestDeviceonCircuitWithOpenGroundingConductor . . . . . . . . 19 Supplemental Test Device on Circuit With Reversed Polarity . . . . . . . . . . . . . . 21 Supplemental Test Device on Circuit With Grounded and Equipment Grounding Conductors Interchanged . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Supplemental Test Device on Circuit Without Leakage . . . . . . . . . . . . . . . . . 21 SupplementalTestDeviceonCircuitWithReversalofLineandLoadWires . . . . . . 21

other Test Devices and Test Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 periodic Verification Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Possible Improper Indications When Using Supplementai Test Devim . . . . . . . . . .

Section 8 FELD TROUBLESHOOTING Line Side of GFCI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 AtTheGFCI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Load Side of GFCI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Load Side of Neutral Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Equipment Ground and Neutral Connected Together on Load Side 23 Excessive Leakage to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Multi-Wired Branch Circuits (Shared Neutral) . . . . . . . . . . . . . . . . . . . . . . . 23 High Moisture Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Inability to Reset Tripped GFCI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Circuit Breaker Tjpe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 “Supplemental Tester Does Not Trip GFCI. But Test Button Does” . . . . . . . . . . . . 23

. . . . . . . . . . . .

Appendix A GFCI CROSS REFERENCES TO NATIONAL, EXECîRICAL CODE-1990 EDITION . 25



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

_ _ _ - _ _ -~ ~ .. -

NENA 280 90 6470247 0503694 O60

Foreword This Application Guide for Ground Fault Circuit Interrupters was developed by the NEMA Joint

Sections Committee on Ground Fault Personnel Protection. The committee was comprised of the Ground Fault Personnel Protection Section, the Molded Case Breaker Section, and the Wiring Device Section of NEMA.

In the preparation of this application guide, input of interested individuais and organizations has been sought and evaluated. ?he application guide has been developed as an Authorized Engineering pubiicatim, except paragraphs identined as NEMA Standard. Inquiries, comments. and proposed revisions are welcomed and should be submitted to:

Vice President, Engineering National Electrical Manufacturers Association 2101 L Street, N.W., Suite 300 Washington, DC 20037-1526

1 Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMA


--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

- _ _ - ~ ~___- _ _ ~ __

NEMA 280 90 = 6470247 O503695 TT7

Scope This application guide covers ground fault circuit intermpiem (GFCI's) which are intended to

provide electrical shock hazard protection from line-to-ground fault currents on grounded circuits of 120, 120D0, 240 volt single phase, 208Y/120 volt, and 240 volt three-phase; two, three, and four-wire supplies.

GFCi's are designated as Class A or Class B in accordance with UL Standard 943 (January 1985), Ground Fault Circuit Intempters.* Unless otherwise indicated, this application guide applies to class A GFCI'S.

Covered in this guide are characteristics of the various types of GFCI's, construction details, markhg data, installation guidelines, field testhg recommendations, and field troubleshooting information.

Copk are avaüaMe from Underwriters Laboratories Inc., 333 Pfingsten Road, Northbrodt, IL 6ooá2

u Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMA


--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

NENA 280 90 b470247 0503b îb 933

280-1 990 Page 1

0 APPLICATION GUIDE FOR GROUND FAULT CIRCUIT INTERRUPTERS

Section1 . REFERENCED STANDARDS AND DEFINITIONS

1.1 REFERENCED STANDARDS These standards are referenced in whole, or in part, in this publication and available from the following sources:

National Electrical Manufacturers Association 2101 L Street, N.W.

suite 300 Washington, D.C. 20037-1526

NEMAPP 1-86

NEMA 250-1985

ANSI/NFPA 70-90*

Procedure for Evaluating Ground Fault Circuit Interrupters for Response to Conducted Radio Frequency Energy

Enclosures for Electrical Equipment (I O00 Volts Maxhum)

National fire Protection Association One Batterymarch Park

P.O. Box 9101 Quin~y, MA 02269-9101

National Electrical Code

Caierwriters Laboratories Inc. 333 Pfingsten Road

Northbrook,iL 6ooó2

ANSI/UL 943-1989* *Also available from the American National Standards Institute

Ground Fault Circuit Interrupters

1.2 DEFINITIONS Ambient Temperature -The temperature of the sur-

rounding medium that comes in contact with the device or equipment. (For an enclosed device, it is the tempra- ture of the medium outside the enclosure.)

Current Interrupting Rating -The value of the available rms symmetrical current at a specified voltage that the device is capable of interrupting under prescribed test COnditionS.

Electrical Shock Hazard -A condition which could result in injury or electrocution to a person caused by the flow of electrical current through the body.

Endurance Test - A test made to determine compli- ance with specified mechanical and eleciricai life requirements.

Ground Fault - An unintentional electrical path between a part operating normally at some potential to ground, and ground.

Ground Fault Circuit Interrupter (GFCI) - A device intended for the protection of personnel. It deener- gizes a circuit or portion thereof within an e s t a b i i s ~ ‘0

period of time when a current to ground exceeds some preúetermineú value that is less than that required to operate the overcurrent protective vice of the supply circuit.

1. Class A GFCI - A ground fault circuit intemrpter that is designed to trip when fault current to ground is 6 miiliamperes or more.

that is designed to trip when fault current to ground is 20 miiíiamperes or more.

GFCI Test -The integral part of a GECI which checks

Ground Fault Current - Current that flows through a ground fault.

Ground Fault Rip Time - The elapsed interval between the time when the ground fault current is first applied and the time when the circuit is interrupted.

Nuisance Trip - Tripping caused by conditions other than those for which the device is intended to respond.

Rated Continuous Current - The maximum rms current which a device or an assembly is designed to carry.

Rated Frequency- The frequency for which the device is designed.

2. Class B GFCI - A ground fault Circuit UitemrptW

thegn>undfaultsensingand~~ingfunctionofthedevice.



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

NENA 280 70 m b470247 0503677 87T m

2804 990 Page 2

Rated Maximum Ambient Temperature - The maximum ambient temperature at which the device is designed to carry rated continuous current.

Rated Voltage - The nominal rms voltage for which the device is designed to be used

Servke Conditions - The conditions under which a &vice is designed to be used.

n i p ~ r e e Device - A kvice wherein the tripping operation cannot be ovemdden manually.

Trip Threshold - the level of ground fault current which, when it is reached, will cause tripping of a GFCI.

Tripping - The automatic opening of a device.

0

a



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

- - - ~~

NEMA 280 90 W 6470247 0501678 706

280-1 990 Page 3

Section 2 CHARACTERISTICS OF GROUND FAULT CIRCUIT INTERRUPTERS

2.1 GENERAL GFCI’s are designed to interrupt the circuit when the

ground fault current exceeds a predetermined level. This level is based on physiological reactions of a human body to alternating current and, as such, is independent of the branch circuit rating. The level of current at which a GFCI intempts a circuit is extremely low when compared to that current required to operate the branch circuit ovexurrent protective devices. 2.2 PRINCIPLES OF OPERATION

The GFCI sensing system continuously monitors the current balance in the ungrounded “Hot” conductor and the neutral conducm. If the current in the neutrai wire be- comes less than the current in the “hot” wire, a ground fault could exist. Aportion of the cunent r e m s to the supply by some path other than the neutral wire. With a current imbalance as low as 6 milliamperes, the GFCI will interrupt the circuit and this will be shown by a trip or “off” indicator on the device. See Figures 2-1,2-2 and 2-3.

The GFCI does not limit the magnitude of the ground fault current. It limits the time that a current of given magnitude can flow. The trip level-time combinations are based on physiological data established for avoiding injury to normal healthy persons. These trip level-time combinations may be m high for persons with heart problems, such as those wearing a pacemaker or under mtment in health care facilities. 2.3 DOUBLE GROUNDED NEUTRAL PROTEG TION

A Class A GFCI is designed so that it will automatically üip if the neutral conductor is grounded on the load side of the sensor.

If a Ioadside neuaal fault to ground and also a ground fault occurred simultaneously, some of the fault current would flow through the neutral wire to the sensor and some would flow through the inadvertent ground path. If such a ground connection occurred, it would be possible for a person to contact a hot wire and ground, having the ground fault current flow through the inadvertent neutral ground and the neutrai to the service entrance. Under this condition,theremaynotbeenoughim~ceincurrentthrough the sensor to cause the GFCI to trip.

The double grounded neutral protection feature prevents this condition €?om occurring.

0

This protective feature demands proper load-side build- ing wiring. It continuously monitors the load-side wiring to detect a double-grounded neutral condition. 2.4 TESTMEANS

Each GFCI is equipped with a means of testing the ground fault trip capability. A simulated ground fault through a test resistor is applied to the sensor through the activation of the test means. It is important that user testing procedures be followed. (See Section 7.1). 2.5 GFCI TRIPPING CHARACTERISTICS

ure 2-4. 2.6 TYPES OF GFCI’S 2.6.1 Basic GFCI

The basic GFCI consists of a ground fault detecting means coupled with a circuit interrupting means.

The detecting means measures the ground fault current as the difference between outgoing and incoming load current on the protected conductors. The current difference is suitably processed to activate the circuit interrupting means.

The circuitry module and associated interrupting means which make up the basic GFCI should be mounted in an enclosure or combined with some other device in order to be suitable for installation on a wiring system. The basic GFCI is combined into a complete device to make up the various types described belm. 2.6.2 Blank Face Type GFCI

The blank face type GFCI has no receptacle openings. It provides both personnel ground fault protection and switching capabilities. It may be rated for motor switching if so marked. It is not intended to be used as a substitute for a wall-mounted switch.

This type of kvice may have flexible insulated leads or binding screw terminais or push-in terminals, and is to be mounted in an enclosure such as an outlet box. Means for five field connections are provided line, line neutral, load, I d neutral, and equipment grounding.

This device may be mounted in listed industrial control panels (UL 5û8Jnúustriul Control Equipment) and may be used as a motor controller if so marked. It may be mounted in other equipment and be listed by UL in combination with the equipment.

’Qpicai trip chatacteristics of GFCI’s are shown in Fig-



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

280-1 990 Page 4

____ -____ ___

NENA 280 90 m 6470247 0503699 b112 m

SOLD SHUNT STATE TRIP CRCUrnY j

I

I I I RESiST(X3

I

I I SWTTCHHG I JCONTACTS I n A c

--H 120 V LHE SOURCE I C -

T

Figure 2-1 CIRCUIT BREAKER TYPE

i RESISTOR

DEVICE

;,SN=

Figure 2-2 RECEPTABLE AND BLANK FACE TYPE GFCI



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

I _ ~ . ~ - -~ _ _ -

NENA 280 90 6470247 0501700 194

280-1 990 Page 5

Receptacle-type GFCk switch bah the ungrounded conductor and neutral

Figure 2-3 PORTABLE AND CORD TYPE GFCI

10.0 0.0 I 6.0

4.0

2 0

1 .o .a

.6 w v) .4 z w I-

-2

.1

.o8

.o4

.O3

.o2

.o1

" I 20 40 60 80 100 120 140 160 180 200 220 24.0 260

CURRENT IN MILLAMPERES 6 ma

Figure 2-4 GFCI TRIPPING CHARACTERISTICS



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

-~ _ _ . ~ _ ~

NENA 280 90 b470247 050L70L O20

280-1 990 Page 6

2.6.3 Permanently Mounted Type The permanently mounted type of GFCI has an integrai

enclosure as a part of the total unit, and is designed to be permanently wired into the supply circuit. 2.6.4 Circuit Breaker Type

The circuit breaker type G E I incorporates within one device the ability to provide all the functions of a circuit breaker as well as ground fault protection for personnel for the entire circuit.

It is intended to be mounted in an enclosure and fre- quently may be installeú as a direct replacement for a circuit breaker in a load center or a panelboard.

Circuit breaker type GFCI’s are available as single-pole and two-pole units with various plug-in and lug type electrical connections. Line neutral connections are usually made by means of a wire lead, and care should be taken to install the device according to the manufacturer’s instructions. 2.6.5 Receptacle Type

The receptacle type GFCI incorporates within one device one or more receptacle outlets, protected by the GFCI. It is available as a “nonfeeú-through” unit which provides GFCI protection only to the outlets in the unit, and as a “feed-through” unit which provides GFCI protection to loadside receptacles as well. The feed-through unit may also be used as a nonfeed-through unit. (See 5.9 thru 5.12).

Receptacle type GFCI’s are available with various ter- minating means, including flexible insulated leads, binding screw terminals or push-in terminals. The feed-through unit provides for five field COM~C~~OW h e , line neutral, load, load neutral, and equipment grounding. The nodeed-through unit provides connections for line, line neutral, and equipment grounding.

Receptacle type GFCI’s are intended to be mounted in an enclosure such as an outlet box. 2.6.6 Portable Type

f i e portable type GFCI is an easily transportable, self- contained, enclosed G E I with one or more integralrecep- tacle outlets protected by the GFCI module. In lieu of an integrai receptacle outlet, the load conductors may be attached by a cord and connectar. Portable type GFCI’s are normally connected to a supply receptacle by an integral aüachment plug or a plug and curd. Receptacle cord c ~ ~ e ~ t o r s and plugs are available in various general pw- pose and locking configurations.

nie enclosures for these units may be of the indoor type ortheoutdoortype. Indoortypesusuailyhavenonmetallic enclosures. nie outdoor types may have metallic or non- metaiiic enclosures suitable for the environment in which they are used. [See NEMA Standards Publication No. w), Enclosures for Electrical Equipment (loo0 Volts MaXi- m), for enclosure information.]

The portable type GFCI has a no-voltage release feature which wili automatically interrupt the circuit when any of the supply conductors is open.

26.7 Cord Connected Type A cord connected Type GFCI consists of an attachment

plug containing a GFCI or an in-line G E I and a connected cord. It provides GFCI protection on the loadside for the cord and equipment to which the cold is attached.

A cord connected type may be part of other equipment and is listed by üL in conjunction with the equipment.

The cord connected type GFCI also has a no-voltage release feature which will automatically interrupt the circuit when any of the supply conductors is open. (See Figure 2-3).



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

Section 3 RATINGS

3.1 RATING INFORMITION 3.1.3 Rated Frequency ïñe rating of a GFCI includes the following: class, rated The rated frequency of GFCI’s is 60 Hz.

The common continuous current ratings of GFCI’s are vo1@e, frequency, mb2.d cont.h”ls nt and, 3.1-4 Rated Continuais Current where applicaóle, current interrupting rating.

3.1.1 Class 15.20,25,30,40,50, and 60 amperes. The GFCI designated “Class A” will trip when there is

a fault current to ground of 6 miiiiamperes or mote. The GFCI designated “Class B” will trip when there is a fault current to ground of 20 miiiiamperes or more. “Class B” GFCI’s should be used oniy for underwater swimming pool lighting installed prior to M a y 1%5 (prior to the adoption of the 1%5 National Electrical Code). 3.1.2 Rated Voitage

The common ac voltage ratings of GEI’S are 120, 120/240, and 2Ao volts, single phase: and 208Y/120 and 240 volts, three phase.

_ . . . . .

3.1.5 Rated Withstand Current Receptacle, blank face, portable and cord connected

types have current withstand ratings. Typically they are 2ooo amperes, nns symmetrical. Permanently mounted types have current withstand ratings of 5ooo amperes, nns symmetrical. 3.1.6 Current Intertupting Rating

5ooo,1O,ooO, or 22,ooO amperes, mis symmetrical. Circuit breaker types have current interrupting ratings of



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

- - -

NEMA 280 90 W 6470247 0503703 ï T 3 W

280-1 990 Page 8

a

h



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

NEMA 280 90 W 6470247 0503704 83T

e 280-1990

Page 9

Section 4 MARKINGS

. 4.1 GENERAL

GFCI’s are marked with the manufacturer’s name ar trademark and electrical ratings. Additional information may also be marked on the GFCI or included with the manufacturer’s literature. 4.2 TYPES WHICH ARE PERMANENTLY CON- NECTED INTO CIRCUIT

For types which are permanently connected into a circuit, which include the blank face type, permanently mounted type, circuit breaker type, and receptacle type, the following additionai information should be provided.

I

1. Installation instructions* 2. Test instructions to operate upon installation and at

least monthly* 3. Test reminder with provisions for checking off

monthly tests* 4. Warning against use in wet locations* 5. Warning that GFCI does not protect against shock

hazard when both conductors are touched* 6. Statement - “For Use on Grounded Circuits

7. Class(AorB) 8. Roper conductor termination instnictions

only’*

0 Markings on the device or literature packaged with the device should include the following or equivalent statement:

‘To avoid accidental bypassing of protection, the load- circuit wiring should be separated from other wiring by suitable insulation, barriers, or restraints.”

%ese insbudions may appear in the literanire packed with the GFCL

4.2.1 Class A Devices Markings on a Class A GFCI or literature packaged with

the device should include the following or equivalent statement:

‘To minimize fahe tripping do not connect to swimming pool equipment installed before adoption of the 1%5 National Electrical Caie.” 4.2.2 Class B Devices

or equivalent statements: Marking on a class B GFCI should include the following

“Use only with underwater swimming pool lighting fixtures:

CAUTION-To avoid possible shock, disconnect power before servicing hture. To minimize false trip ping, do not coMect to more than ** feet of load conductor for the total one-way run.” **Specified by manuíacauer

4.3 PORTABLE AND CORD CONNECTED TYPES

For portabie and card c o ~ e ~ t e d types, the following additional information should be m o v i a

1. 2.

3.

4.

5.

Load capacity in watts. The word WARNING and a statement to the effect, to ensure protection against electric shock, the test instructions should be followed befofe an appliance is plugged into any receptacle on the device. The marking describes the significance of the test and informs the user that, in the event of an indication of improper functioning, the cause of the malfunction should be corrected before further use of the device. Unless a portable or cord connected GFCI has been found suitable for use in wet locations, it should be marked “Do not use where water is likely to enter case” oc equivalent. Aportable or cord connected type device should be marked with a statement to the effect that the device does not guard against electric shock resulting from (1) some possible defects or faults in an extension cord or other wiring supplying the GFCI, or (2) contact with both circuit conductors. Unless otherwise marked, a cord connected GFCI not pvided with a permanently attached cord 6 feet (1.8 meters) or longer in length should be marked “This product should be used only with a threecon- ductor, 120 volts, - *** ampere supply coici set employing Type ST, SO, STO, SrT, SJO, or SrrO cord. In event of cord set damage, it should be replaced only with an equivalent cord set”or similar wording.

***Fifteen. ZO, or 30 a m p . to be specifiul by manufaaurer.



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

280-1 990 Page 10

~ - -___I-- - .___ _-____ ~

NEMA 280 90 m 6470247 0503705 776 m



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

~~ ~- -

NEMA 280 90 m 6470247 0503706 602 m

280-1990 Page 11

Section 5 GFCI APPLICATION CONSIDERATIONS

5.1 In most cases tripping of a GFCI is an indication of a dangerous condition that needs correction. GFCI tripping

cause of the tripping should be identified and corrected

5.2 Uníess the device is a circuit breaker type GFCI, it will not protect the circuit conductors against overcurrent. Separate overcurrent protection must be provided.

5.3 Grounding and GFCI protection are. used to comple- ment one another, not to replace one another.

5.4 periodic tripping tests should be made in accordance with the manufacturers recommendations, using the test means on the unit. When the test button is pushed, a predetermined value of ground fault current is supplied to the GFCI, tripping the unit and thereby testing the GFCI . 5.5 To avoid damage to the GFCI, it must be disconnected before feeders or branch circuits are subjected to a megger, high voltage, or hi-pot test. Disconnect the electrical power s m l y and load conductors to isolate the GFCI.

f i under such conditions is not “nuisance” tripping. The

NEMA Standard 9-5-1990.

- - - NEMA Standard 945-1990.

5.6 Carefully read the manufacturer’s instnictions before installation of the GFCI.

5.7 AGFCI does notprmct a person who comes in contact

5.8 A GFCI does not protect a person from feeling and reacting to a shock

5.9 When using a feed-through receptacle type GFCI, be certain that outlets to be protected are on the load terminals or wires of the GFCI.

with two ‘W’ wires or any “hot” wire and the neutral wire.

5.1 O When a feed-through receptacle type GFCI is used only to protect its own receptacle, the unused load wire c o ~ t ~ t i o n s , if any, should be properly insulated to prevent electrical hazard.

5.1 1 When a feed-through receptacle type GFCI is used to protect an entire branch circuit or only a portion of a branch circuit, the “load“ wires or terminais should be ~ o ~ e c t e d to the remaining receptacles in the branch. THE LINE AND LOAD CûNNEClïONS MUST NOT BE REVERSED; OTHERWISE THE GFCI’S OWNRECEP- TACLE WILL BE UNPROTECTED AND WILL RE- MAINENERGIZEDAFTERTHEUNITHASTRIPPED.

NEMAStandard 9-5-1990

5.12 Depending upon where it is installed on a branch circuit, a feed-through receptacle type GFCI can protect al l of the receptacles on the circuit, a portion of the receptacles on the circuit, or only its integral receptacle.

5.13 Suitable enclosures should be used for GFCl’s or receptacles protected by GFCI’s. This is especially important in the presence of moisture or a corrosive atmos- phere.

5.14 The GFCI contains an electronic circuit which is designed to be resistant to electrical interference. In the same way that a television set or radio suffers firom mo- mentary “static” in the presence of interference, so may the GFCI. However, in the television or radio, the interference is merely a temporary nuisance. The GFCI, as a safety device, may interpret this interference as a ground fault and trip. Therefore, the GFCI should not be used in an application where continuity of service takes precedence over the personnel protection feature, such as life sustaining equipment in health care facilities.

5.15 The trip characteristics established for the GFCI ground fault sensor are based on physiological data taken for normal healthy persons. These levels may be too high for persons with heart problems such as those wearing pacemakers or those under treatment in health care facilities. (See 2.2).

5.16 Portable or cord connected GFCI types will not protect the receptacle or any portion of the branch circuit into which it is plugged. It will protect only those conductors and devices connected to its load side.

5.17 Equipment with high temperature sheathed heating elements such as dishwashers and electrical space heaters tend to have high electrical leakage which may cause tripping when used with GFCI’s. This type of equipment should instead be effectively grounded.

5.1 8 Permanently connected lights, without receptacles, need not be protected by GFCI’s.

5.19 Stationary appliances such as sump pumps and clothes washers should be effectively grounded. These types of appliances may have high electrical leakage caused by moisture. Refrigerators and freezers, particu- larly older units, may also have this type of leakage. When these appliances are on a GFCI protected circuit, the leakage currents could exceed the GFCI trip threshold and cause the GFCI to trip.

NEMA Standard 9-5-1990



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

- -~ - ~ _ _ _

NENA 280 90 6470247 0503707 5 4 9 W

280-1 990 Page 12

5.20 High moisture conditions may result in electrical leakage of portable tools. This will cause the GFCI to trip in some instances even if the tool is turned off, if the leakage exceeds the GFCI trip value.

5.21 High moisture conditions may result in leakage of unprotected extension cord connectors and aged cord insulation. Replace or repair any aged wiring, extension cord, or portable tool which, under high moisture, causes the GFCI to trip.

5.22 GFCI protection cannot be used for ranges, ovens, cooking units, and clothes áryers when the frame of the appliance is connected to the grounded circuit Conductor. (See 2.3)


5.23 If a GFCI is used with a smali portable genera-, the circuit supplying the GFCI circuit should be turned off when starting the generator until the generator has attained constant speed and stabilized output voltage.

5.24 A GFCI feeding an isolation transformer, which supplies circuits such as underwater swimming pool fixtures, wiii not detect a ground fault on the secondary side of the transformer.

5.25 GFCI’s should be used only on systems with a grounded circuit conductor. A G E I can be used on a two-wire circuit without a ground (green) wire as long as the circuit has a grounded circuit conductor. *It should be noted that the equipment ground conductor “green wire” is completely independent of the GFCI circuitry.

5.26 TheNational Electrical Code requires that the white (or grounded circuit) conductor be grounded only at the service entrance. If this conductor is grounded again on the load side of the G E I , tripping will occu. (See 2.3).

NEMAS- 9-5-1990

5.27 A 12ûl24CWolt two-pole circuit-breaker-type GFCI need not have the load side neutral connected for 24oV rated loads.

5.28 certain portable voltage testers or test lamps, when connected between line and ground on the load side of the GFCI, may cause the GFCI to trip.

5.29 Some office and labratory equipment (e.g. per- sonal mputers) exhibit ground leakage currents due to designed-in feanires such as RFi filtering and transient voltage surge suppression. While this current is permiaed by applicable product standards it can result in tripping of a GFCI. This possibility is increased when two or more pieces of equipment, each with some leakage current are conne~ted to the samebranch circuits.

After a GFCI has tripped and the cause has been deter- mined to be a result of this accumulated permitted leakage current, the number of such devices on one branch circuit must be reduced It may be necessary to provide dedicated circuits or individual GFCI receptacles if this inherent leakage is high.


The equipment manufacturer should be contacted if there is any question pertaining to the expecteleakage current level.

5.30 GFCI’s are specifïcaliy tested for immunity to radio frequency noise. See NEMA FT 1, Pr0cedrP.e for Evdu- atkg Ground Fault Circuit Interrupters for Response to Conducted Radio Frequency Energy.

5.31 Circuit breaker or receptacle type GFCIs are not intended to be field wired to an attachment plug to create a portable GFCI. Such an arrangement will not provide the full protection afforded by aportable or cord connected GFCI.



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

-

NEMA 280 90 m bY70247 0501708 485 m

280-1 990 Page 13

Section 6 INSTALLATION GUIDELINES FOR ELECTRICAL SYSTEMS WITH GFCls

6.1 LOCATION OF GFCI ON SYSTEM

61.1 At Load Center or Panelboard, Or a Permanently Mounted Type After Panelboard.

6.1.1.1 CircuitbreakertypeofGFCI’shavebuilt-inover- current protection. Permanently mounted type GFCI’s must be installed on the load side of an overcurrent p t ec - tive device. The electrical power should be turned off before attempting instaliation of the GFCI.

6.1.1.2 The handle of the breaker type GFCI should be in the “OFF”‘ position before installing.

6.1.1.3 The G E I should be connected and installed in accordance with the manufacturer’s instructions. Care should be taken to observe the markings on the device to maintain polarity of branch circuitry.

6.1.1.4 After the installation is complete, the electrical power can be restored and the handle of the breaker type GFCI can be moved to the “ON” position.

normal,thecircuitbreakerwillremainon. Thetest bum should be depressed; if the handle now moves tothe‘~’positionandthebranchciIuJitbecomes & ~ t h e G E I i s ~ g ~ y . Toreset the breaker, the handle M d be mved to the“0FF’ position and then to the ‘ON position for normal Operation, (some circuit breaker type GFCI’s have a common‘~and0FF’position.)

2. If the breaker handle moves to the ‘TRIP” position, the following steps should be taken: a. Move the handle to the “OFF‘ position. b. T m off the electrid power to the p a n e l W . c. Disconnect the load power and load neutral

wires from the GFCL Recheck line connections.

d Restore electrical power to the panel. e. Move the handle of the GFCI to the “ON”

position. (1) If the handie remains in the “ON” position

and trips when the test button is depressed, the G E I is operating p p e r í y and the fault is in the branch circuit system. The fault should be corrected and the GFCI &vice reconnected as above.

(2) If the GFCI handle again moves to the “TRIP” position, replace the device.

NEMAStandard9-5-1990

1. Ifthemstallationiscorrectandtheldcircuitis

6.1.2 At Outlei Box To install a receptacle or blank face type GFCI, the steps

listed below should be taken:

6.1.2.1 Check to be sure that the device to be repiaced is energized (wiii supply power to a connected load). If it is a duplex receptacle, be sure that both halves are checked.

6.1.2.2 T m off power to the &vice by removing the fuse or switching the branch circuit breaker to its “OFF” position. If the specific fuse or circuit breaker is unknown, it can be located by removing fuses or switching circuit breakers one at a time while checking for power at the device to be replaced (both halves if duplex).

If both halves of a duplex receptacle are not on the same circuit, do not install a receptacle type GFCI since it will not function properly. A two-pole circuit breaker type GFCI may be used instead (See 6.1.1).

6.1.2.3 Install the GFCI device in accordance with the manufacîurer’s instructions, being sure to maintain polarity.

6.1.2.4 If the GFCI has the feed-through feature, input connections must be ma& to the line terminals only. Otherwise, GFCI protection is not provided to the units own rsceptacle(s). (See 5.11).

6.1.2.5 Restore power by repiacing the fuse or by switching the branch circuit breaker to its “ON” position.

6.1.2.6 D e p s the reset button on the GFCI. This should energize any load connected to the GFCI device.

6.1.2.7 Depress the test button. An indicator on the GFCI should show the device has tripped. A load should be plugged into the GFCI to verify that the unit’s own receptacle(s) are de-energized If not, recheck the input line and the output load connection.

If the GECI is used as a feed-through device, a load should also be. plugged into each protected receptacle to verify that each is de-energizeú when the GFCI is in the trip mode.

CAUTION If, an indicator does not show that the device has tripped after the test button is depressed, immediately turn off the power at the circuit breaker or fuse panel, and recheck the electrical connections and repeat steps 6.1.2.1 thni 6.1.2.7. If the condition persists, replace the device.

N E M A S M 9-5-1990



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

~- ~ _ _ _ NENA 280 90 W 6470247 0503709 333 W

280-1 990 Page 14

6.2 WIRING CONSIDERATIONS

6.2.1 At Load

6.2.1.1 The neutral should not be grounded at the load.

6.2.1.2 The load neutral should not be connected to any other circuit neutral.

6.2.1.3 Certain types of equipment tend to have high leakage current and cause tripping of GFCI's. niese include units with high temperature sheathed heatllig elements, submersible water pumps and some computers. (See 5.17,5.19 and 5.29).

6.2.1.4 Loads at excessive distances fiom the GFCI may cause tripping due to inherent leakages from the intercon- necting wiring.

6.2.1.5 On 120/240Volt 2-pole circuit breaker type GFCI's the neutral load wire need not be connected if it does not carry current. However, its supply neutral wire must be connected for proper operation.


6.2.2 On Construction Sites

6.2.2.1 High moisture conditions may result in high leakage in unprotected extension cord connectors and in aged cords and tools.

6.2.2.2 All Wiring connections should be kept off the earth and protected from mud and water.

6.2.2.3 Receptacles protected by GFCI's on construction sites should not be installed on branch circuits which supply temporary lighting.

6.2.2.4 Proper grounding should be maintained even though GFCI protection is present.

6.2.3 Portable Units The manufacturer's instructions packed with the

GFCI should be read carefully in addition to the instructions which are marked on the GFCI. 6.2.4 Branch Circuits

6.2.4.1 12ûV 2W-Wmi EQUIPMENT GROUNDING CONDUCTOR

Figures 6-1 and 6-2 show how some of the National Electrical Code GFCI requirements of a typical dwelling unit can be met either by one single-pole circuit breaker type GFCI or by one feed-through receptacle type GFCI. (See the Appendix for a tabulation of NEC requirements.)

6.2.4.2 1mV 2WaLDER BRANCH CiRCUrrS WITHOUT GROUNDING CONDUCTOR

For many years, the National Electrical Code has required that equipment grounding conductors and grounding type receptacles be used for 15 and 2ûAbranch circuits. However, there are many wiring systems still in use which were installed before these requirements. Thus when it is desired to install GFCI protection on a branch circuit without an equipment grounding conductor or grounding type receptacles, special care must be exercised.

If a circuit breaker type GFCI is to be used, no special considerations are involved other than making sure that the neutral is not shared with other circuits. The GFCI insial- lation is identical to that on abranch circuit with equipment ground, and personnel protection is pvided to the two- wire receptacles.

If a receptacle type GFCI is to be used, the requirements of Section 210-7 of the National Electrical Code regarding grounding of the equipment-grounding terminal of the receptacle type G E I must be met, A feed-through receptacle type GFCI will provide personnel protection to load side, two-wire receptacles or three-wire receptacles.


6.2.4.3 12û/24ûV 3W-Wmi EQUIPMENT GROUNDING CONDUCTOR

Thetwo20-ampsnallapp~ebranchcircuitsrequired by the National Electrical Code in dwelling units are fkequentiy installed with a common neutral conductor.

A mistake often made with single-pole G E I circuit breakers and GFCI receptacles is to try to install them on only one leg of a three-wire common neutral branch circuit. This won't work. Since the neutral carries the load current of both hot legs, the current in the neutral will be different from the current in each individual hot leg, when both hot legs are carrying load currents. The GFCI will sense this difference as aground fault and will trip, even though there is no ground fault.

Figures 6-3 and 6-4 illustrate two good ways to provide GFCI protection for three-wire 120/2clOVolt common neutral circuits:

6.2.4.4 120/240v 3WaEDEATED TO AN APPUANCE

In many cases, the National Electrical Code permits outlets dedicated to certain appliances to be unprotected by GFCI's. See Figure 6-5 for an example of how to install GFCI's and leaving such receptacles off the protected portion of the circuits.



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

280-1 990 Page 15

FIRST FLOOR NEUTRAL BATHROOM BUS - -

GFCI

0

t

tl I RECEPTACLE GARMiE UNIT

-

a

l

IC I4

_ _ - - -

NENA 280 90 6470247 050L7LO 033

CONNECTION BETWEEN NEUTRAL BUS AND GROUND BUS MUST BE MADE ONLY AT SERVICE PANEL. SEE 6.2

1-POLE

SECOND FLOOR BATHROOM

I I I I

FIRST FLOOR BATHROOM

NEUT BUS

Figure 6-1 USING A 1-POLE CIRCUIT BREAKER TYPE GFCI

SECOND F L û û R BATHROOM

Figure 6-2 USING ONE FEED-THROUGH GFCI



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

280-1 990 Page 16

CONNECTION BETWEEN NEUTRAL BUS AND GROUND BUS MUST BE MADE ONLY AT SERVICE PANEL. SEE 6.2 I

l I

SERVICE PANEL

t 4

120 V DUPLEX RECEPTACLE

1 ‘c I I BUS

Figure 6-3 USING A TWO-POLE GFCI CIRCUIT BREAKER

COMECTDN ORWEEN NEUTRAL Bus A M GROUND BUS MUST BE MADE ONLY AT SERVICE FANEL. SEE 8 2

TO

OUTLETS -+OTHER

TO + OTHER OLmETS

Figure 6-4 GFCl’s USING TWO FEED-THROUGH RECEPTAB LE



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

Cû"ECTK>N BEMIEEN NELITRAL Bus AND GROUND BUS WST BE MADE ONLY AT SERVICE PANEL CEE 6 2

Figure 6-5 USING FEED-THROUGH RECEPTACLE GFCk

FOR KITCHEN COUNTER RECEPTACLES

-~ _ _

NEMA 280 90 6470247 050L7L2 706

280-1 990 Page 17



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

.- .- -_- - --__.___I__

NENA 280 90 b470247 050117113 842

280-1 990 Page 18



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

280-1 990 Page 19

Section 7 FIELD TEST DEVICES

7.1 INTEGRAL TEST DEVICES The integraí test circuit on a GFCI creates a differential

current using the ungrounded (or “hot”) and the grounded (or neutrai) circuit conductors. The built-in test circuit verifies that the GFCI is functional, when installed prop &y, and is the preferred method of testing GFCI operation. 7.2 SUPPLEMENTAL GFCI TESTERS There are a number of devices and test instruments

whose function is to give an indication of whether M not a GFCI is operating progerly. These “GFCI testers” vary in the amount of information that they p v i d e the user. Before any GFCI tester is used, poiarity should be correct or problems will result. There are single plug-in devices which will give an indication under certain conditions as to whether or not a given receptacle is protected by a GFCI. These devices have commercial tolerances and are not precise test instruments. There are also test instruments with greater sophistica-

tion which will give more precise information. These instruments can create either discrete step or continuously varying values of ground fault current by means of internai circuitry, which connects the ungrounded C‘hot’’) conductor to the grounding conductcr. 7.2.1 Possible Improper Indications when

t

Using Supplemental Test Devices

7.2.1.1 SUPPLEMENTAL TEST DEVICE ON CIRCUITS CONTAINING LEAKAGE

If there is no leakage current on the circuit prior to using

leakage current (it) will be pvided by the tesm. figure 7-2 illustrates a circuit with no leakage current other than the current caused by the supplemental test device. ’Ihe total circuit leakage It as seen by the GFCI is Itd; It = Itd. If, as in Figure 7-3, the circuit contains leakage current

(Ie) while the supplementai test device is in use, the tester could give a misleading indication, since the total circuit leakage current (It) as seen by GFCI is the sum of Itd and E (It=Itd+E), e.g. if Itd=3ma and k 3 m a and the GFCI tripped, one might assume that the GFCI was defective and it tripped below its rated range of 46ma. Actuaiiy, at 6ma the GFCI would be functioning properly, as It=Itd+k3ma+3ma=óma.

To ensure that the tester is providing an indication of the proper triplevel current, the branch circuit should be checked for leakage beyond the GFCI, on the ungrounded conductor, grounded conductor, or load to ground. If leakage is suspected, disconnect aií loads on the GFCI. 7.2.1.2 SUPPLEMENTAL TEST DEVICE ON CiRcUn

theslqq>lementd test device (EigUre7-1), the totalcircuit

wmi O m GROUNDING CONDUCTOR Supplemental GFCI testers operate by using the equip-

ment grounding conductor in the test circuit. If the equip WSH

TO TEST

SOUD STATE

CIRCUITRY

I

I

l I i SWITCHING I CONTACTF

SENSOR SENSOR L

N 4

A

120 v LOAD 120 V UNE SOURCE

1

I I I I I

G EQUIPMENT GROUNDING CONDUCTOR

kptade- type GFCls swïch bolh lhe ungrounded condudor and nwtrai

Figure 7-1 CIRCUIT WITHOUT LEAKAGE

(No Ground Fault Current and Prior to Using the Supplemental Test Device)



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

280-1 990 Page 20

PUSH TO

TGST

SOLID STATE

CIRCUITRY SHUNT TRIP

I

I I I

I I

I I ! i

i I /%%E= I L 4 A

120 V LINE W R C E 1

T N 4

EQUIPMENT GROUNDING CONWCTOR

Receptecle-lype GFCls switch both the ungromdad conductor and neiitral

Figure 7-2

(Ground Fault Current Created by Tester) SUPPLEMENTAL TEST DEVICE ON CIRCUIT WITHOUT LEAKAGE

~ ~~ ___-

NENA 280 90 m 6470247 0503735 635 m

e .l

7

e

a r

I ?IF I- j

I 1 !

WSH TO

TEST I

IM V LNE COURCE 54 T

EQUIPMENT GROUNDING CONWCTOR

Receptacle-type GFCIs switch both the ungrounded and neubd

Figure 7-3 SUPPLEMENTAL TEST DEVICE ON CIRCUIT WITH LEAKAGE

(Ground Fault Current From Circuit and Tester)



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

- - _ _ -

NENA 280 90 W 6470247 050L7Lb 5 5 1 W

280-1 990 Page 21

ment grounding conductor is open as illustrated in Figure 74, the tester will not be able to cause the GFCI to trip, and this will give the impression that the GFCI is defective.

GFCI’s integrai test is successful since the integral test circuit does not use the equipment grounding conductor.

7.2.1.3

I The correct functioning of the GFCI can be verified if the

SUPPLEMENTAL TEST DEVICE ON CIRCUIT 5

Wmi REVERSED POLAFIITY If the u n ~ a n d g r o u n d e d c o n d u c t o t s are rev-

as shown in Figure 7-5, there will not be a voltage across the GKX tester, and test current wil l not be able to flow. As no testcurrentwillflow,theGFCIwiilnottripandthustheGF€!I might erroneously be considered defective.

7.2.1.4 SUPPLEMENTAL TEST’DEVICE ON C~RCUIT Wmi GROUNDED AND EQUIPMENT GROUND EIG CONDUCTORS INTERCHANGED

If the grounded (neutral) and equipment grounding conductors are reversed at the supplemental test point as illustrated in Figure 76, the current through the GFCI tester wiU not pass around the sensor but wiU return through the sensor and will be sensed as a normal lœd The GECI will not trip and thus might erroneously be considered defective.

7.2.1.5 SUPPLEMENTAL TEST DEVICE ON C i ~ u r r WMUT LEAKAGE

Asuppkmentaitestdevioe<xeatesdiEfaentiaicurrentusing the m m (or ‘%or) and equipment g l c d i n g circuit

wfia.etheequ;pnentgroirndingcircuitand~isaniaed.

conductorsi~~illustratedinFigure7-2 S t @ d c ; E c I testersarenotabletotestGFCI’sconnectedtotwo-wirecircuits

7.2.1.6 Supplemental Test Device on Circuit With Reversal of tine and Load wires

in a feed through type GFCI, the unit’s own receptacie(s) are Connected internally to the load terminals. When the supply line is incorrectly connected to the lœd tenninals and the GFCI tester is plugged into the GFCI’s own reap- tacle, the tester will indicate failure to trip. The GFCI might erroneously be considered defective.

MENTS When voltmeters, voltage testers, or other testing devices

areusedonGEcIprotected~ts,thepossibilityoftripping aGFCIexists Aslongasbothinstrumen t connections are made hot-@neutral on the line side, orhot-@neutralon the load side, no problem should be encountered.

However, if a hot connection on the line side and a neutral connection on the load side is made, or vice versa, the current through the instrument can cause the GFCI to trip if it exceeds the minimum trip value of the GEI . 7.4 PERIODIC VERIFICATION CHECKS

GFCI’s should be tested reguiarly, as specified by the manufacturer, by using the built-in test button. Date of test should be recorded on record sheets provided for conven- ience by the manufacturer of the GFCI. Portable and curd connected GECIs should be tested before each use.

UNDEX NO CONDITIONS SHOULD THE LOAD CONDUCTORS OF A GFCI BE JUMPERED To TEST THEOPERAIION OFTHE GFCI. High fault currents can cause a shock or burn hazard to individuais and can damage the branch circuit or its components.

7.3 OTHER TEST DEVICES AND TEST INSTRU-

Figure 7-4 SUPPLEMENTAL TEST DEVICE ON CIRCUIT WITH OPEN GROUNDING CONDUCTOR



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

280-1 990 Page 22

Figure 7-5 SUPPLEMENTAL TEST DEVICE ON CIRCUIT WITH REVERSED POLARITY

(Ground Fault Current Too Small to Operate GFCI)

I

I SWITCHING I I I

! i ,CONTACTS'

I i / i

A L 4 I i 120 V LNE SOURCE

I N 4 1

! T

120 v LOAD .-

DEVICE

Figure 7-6 TEST DEVICE ON CIRCUIT WITH GROUNDED

AND EQUIPMENT GROUNDING CONDUCTORS INTERCHANGED (Test Device Current Cannot be Recognized)



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

280-1990 Page 23

Section 8 FIELD TROUBLESHOOTING

8.1 UNE SIDE OF GFCI The system neutral and equipment grounding conductor

should be grounáed at the service entrance in accordance with the National Electrical Code. Connections to the GFCI should be in aciccordance with the manufacturer’s instructions. if the test button does not trip the GFCI, the line connections should be checked for p p e r voltage. If p p e r voltage exists, the GFCI should be repiaced. 8.2 ATMEGFCI

For receptacle type, reversal of line and load conductors at a GFCI receptacle will not provide GFCI protection for the unit’s own receptacle(s). Plug a test iamp into the GFCI and press the test button on the GFCI. If the test lamp stays on, it may indicate incorrect wiring. ïkrefore, check circuit connections for correctness (line and load, hot, neutral, and grounding). (Refer to 7.2.1.6) 8.3 LOAD SIDE OF GFCI 8.3.1 Load Side of Neutral Ground

The GFCI is designed to trip if the neutral is grounded on the load side of the GFCI. If the GFCI trips as soon as energized, but with 110 load on the circuit, a grounded neutral on the load side is a possible cause. The ground fault to ground of the load neutrai should be located and corrected for proper operation of the GFCI protected cir- Cuit. 8.3.2 Equipment Ground and Neutral Connected Together on Load Side

8.3.3 Excessive Leakage to Ground

GFCI will cause the GFCI to trip as designed. (See 2.2) 8.3.4 Muiti-Wired Branch Circuits

This condition will cause the device to trip. (See 8.3.1)

Leakage current in excess of the trip level rating of the

(Shared Neutral) When GFCI’s are used on circuits with shared neutrals,

special considerations are required or tripping will wu. This is a problem that may not be detected until a load is connected to the circuit. (See 6.2.4.3) 8.3.5 High Moisture Conditions

When a GFCI trips in the presence of moisme, it is doing its intended job of preventing a hazard The solution is to eliminate the leakage current caused by the presence of moisture. 8.3.6 Inability to Reset Tripped GFCI

Ali connected equipment and appliances should be re- moved fim the load side of the GFCI. If the GFCI will

not reset, circuit conductors should be disconnected from the load side of the GFCI and an attempt made to reset. If the GFCI still will not reset, it should be r e p l a d If after disconnecting all circuit loads the GFCI resets, each load should be connected individually. If a GFCI trips when a load is connected, that load should be checked as the possible cause of the problem. If a summation of faults appears to be the cause, the connected loads on the GFCI circuit should be limited and an a d d i t i d GFCI used. 8.3.7 CircuR BreakerType

A circuit breaker type GFCI provides proteCton in the event of an overioad, short circuit or high level ground fault, as well as providing low level ground fault protection and ground fault protection for personnel. Any of these conditions could cause breaker tripping, and there may be no indication of which condition caused the trip. Unless the cause is obvious, the breaker should be reset. If the breaker trips again, circuit wiring should be disconnected i h m the load side of the GFCI and an attempt made to turn iton. Ifthebreaker~snottunion,itshouldbereplaced. If the breaker does not trip, the pb lem is in the branch circuit and should be located.

The problem could be with either the circuit conductors or with connected loads. The ampere load should be checked to ensure the breaker rating is not exceeded. Motor Starting currents should also be considered. If the circuit rating is exceeded, the load on the circuit should be limited and additional circuits used. If overloading is not the cause, each load should be connected individually. If one load causes a trip, the equipment should be checked for faults. If individual loads do not cause tripping, multiple loads should be connected. If multiple loading causes tripping, the leakage of each load should be checked as a summation of leakage currents could be the cause. If this is the case, the load on this circuit should be limited and

8.3.8 “Supplemental Tester Does Not Trip GFCI, But Test Button Does” Supplemental GFCI testers operate by using the equip

ment grounding conductor in the test circuit. If the equip ment grounding conductor is open or not present, the tester will not trip the GFCI, giving the impression that the GFCI is defective. The GFCI Test Button uses an integral test circuit that is not connected to the equipment grounding conducm. If theTest Button verifies correct functioning of the GFCI, while the supplemental tester does not, this may indicate a deficiency of either the tester or the wiring of the GFCI. (See Section 7 and 8.2.)

sbdditional GEI-pr~tected circuits used.



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

~- -

NENA 280 90 6470247 0503739 260

280-1 990 Page 24



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

280-1 990 Page 25

t

NEC Page Artide Subject

10 35 35 36 36 36 36 36 36 37 37 37 46 134

r

145 322 346 350 461 492 542 550 558 558 558 559 567 570 575 58 1 635

100 Definition of GFCI 210-7B Exception N0.2 Effective Grounding of Grounding Contacts

210-7d Exception 210-8

210-8(a)

210-8(a) (2) 210-8(a) (3) 210-8(a) (4) 2104a) (5)

210-Na) (6)

21O-w (1)

210-8(b) 215-9

Table 300-5 305-6

422-8(d) (3) 426-31 Exception 427-26 Exception

517-20 (i) 511-10

550-8(b) 550-23(d) 551-4qc)

551-41(c) (1) 55141(c) (2) 55141(c) (4)

55 1-53(a) 551-71 555-3 m11

680-5(b)

Repiacement of "bo Wire Receptacles Branch Circuit Ground Fault protection for Personnel Dwelling Units Receptacles in Bathroom Receptacles in Garage Receptacles Outdoors Receptacles in Unfinished Basements and Crawl S p e s Kitchen Countertop Receptacles Receptacles in Boathouses Receptacles in Bathtooms of Hotels and Moteis Feeder Ground-Fault Protection for Personnel Burial Depth for Conductors Protection by GFCI's Receptacles on Construction sites GFCI Protection of High Pressure Spray Washers Outdoor De-Icing-Impedance Heating Voltage Limitation-Exception Fmeú Heating of Piplines-Impedance Heating Wltage Limitation-Exception Receptacles in Auto Repair Facilities Receptacles in Wet Locations of Patient Care Areas of Health Care Facilities Mobile Home Receptacles Outdoors, in Bathrooms and Within 6 ft of Sinks Mobile Home Service Equipment Additional Receptacles Recreational Vehicles on Branch Circuit Recreational Vehicles Receptacles Adjacent to Bathroom Lavatory Recreational Vehicles Receptacles within 6 ft of Lavatory or Sink Recreational Vehicles Receptacles on Exterior of Vehicles Recreational Vehicles-lighting Fixtures over Bathtub or Shower Recreation Vehicle Park Receptacle Marine & Fbat Yard Receptacles Outdoor Portable Signs -Intemal W h g

. I Swimming pools - GFCI '@pes &rmiaed



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

280-1 990 Page 26

NEC Page Artiele Subject

635 680-5(c) Swimming Pool - Wiring GFCPs 635 680-6(a) (1)&(3) Exception Swimming Pool Receptacle+ 635 638 640 642 643 644 645 645 646 647 647 633 633 634 634

680-6(b) (2) 680-20 680-21 680-24

@0-Z(b) (2) 6 8 O - W ) 0)

680-3 1

680-40 680-41 (a)

680-41 0) 680-51 (a) 680-56 (a) 680-62 (a) 680-62 (0 680-70

Swimming Pool Lighting Swimming Pool Underwater Lighting Fixtures Swimming Pool Enclosures for GECI'S Swimming Pool Grounding of GFCI's Swimming Pool - Methods of Grounding Exception No. 2 Electrically Operated Pool Covers Storable Pool - GFCI's Required Outdoor Spas and Hot Tubs-Listed Cord C o ~ e ~ t e d Exception No. 2 Indoor Spa and Hot Tub Receptacles Indoor Spa & Hot Tub Lighting Fixtures & Outlets

Fountains - Cord & Plug Co~ected Equipment

Therapeutic Tub Receptacles Hydromassage Bathtubs - GFCI's Required

Fowitains - GFCPS Required

Theraputic 'Iiibs - GFCI'S Required



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

~ ~~

NENA 280 90 m 6470247 0503722 855 m

NEMA STANDARDIZATION

The purpose of NEMA Standards. their classification and status are set forth in certain clauses of the NEMA

@ Standardization Policies und Procedures manual and are referenced below:

FurpaædSland9rds

National Electrical Manufacturers Association Standards are adopted in the public interest and are designed to eliminate misunderstanáhgs between the manufacturer and the pirchaser and to assist the purchasx in selecting and obtaining the proper product for their paaticular needs. Existence of a National Electrical Manufacturers Associafion Standard does not in any respect preclude ariy member or nonmember from manufachiring or seliing produus not conforming to the standard.

&

P

{Standardmion Policies and Procedures, p. 1) Defhitkn of a Standard

A standard of h e National Electrical Manufacturers Association defines a product, process or procedure with reference to m e or more of the following: nomenclature, composition, constniction, dimensions, tolerances. safety. operating characteristics, performance, rating, testing, and the service for which they are designed.

{Standardization Poiicies and Procedures, p. 2) Dimendoiu

Whexe dimensions are given for interchangeability purposes. altemate dimensions satisfying the other provisions of the Standards Publication may be capable of otherwise equivaient performance.

{Standardization Policies and Procedures, p. 8)

Categoibs d Standards

National Electrical Manufacturers Association Standards are of three classes: 1. NEMA Standard, which relates to a product, process or procedure commercially standardized and subject to repetitive manufacture, which standard has been approved by at least 90 percent of the members of the Subdivision eligible to vote thereon; 2. Suggested Standard for Future Design, which may not have been regularly applied to a commercial product, but which suggests a sound engineering approach to future development, which standard has been approved by at least two-thirds of the members of the Subdivision eligible to vote theran. 3. Adoptive Standard, which is adopted in whole or in part fiaan the standards of another organization, eithex domestic, regional, or mtemational.

{Standardization Polkies and Procedures, pp 7 & 16)

Authorized Engineering Informatbn

Authorized Engineering Information consists of explanatory data and other enginerring information of an informative character not falling within the classification of NEMA Standard or Suggested Standard for Future Design, which standard has been approved by at least two-thirds of the members of the Subdivision eligible to vote on the standard.

(Standardization Policies and Procedures, pp. 7 & 16)

Official Standards Roposal

An Onicial Standards Proposai is an official draft of a proposed standard which is formally recommended to an outside organization(s) for consideration, comment andor approval, and which has been approved by at least 90 percent of the members of the Subdivision eligible to vote thereon. (Standardization Policies and Procedures, pp 7 & 16)

Identification of Status

Standards in NEMA Standards Publications are identified in the foreword or following each standard as "NEMA Standard or "Suggested Standard for Future Design." These indicate the status of the standard. These words are followed by a date which indicates when the standard was adopted in its present form by the Association.

The material identified as "Authorized Engineering Information" and "Official Standards Proposai" is designated

July 17,1990 (o similarly.

.1, 5



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

_.__ _ _ _ ~____ _ _ _ ~ NENA 280 90 m b470247 0501723 791 m

O GROUND FAULT PERSONNEL PROTECTION SECTION

OF THE NATIONAL ELECTRICAL MANUFACTURERS ASSOCLATION

MEMBER COMPANIES 4

American Circuit Breaker Corp. GE

! Aibemarle, NC 28001

Arrow Hart Wiring Devices

Fairfield, Ci' 06431

Hubbell Incorporated Syracuse, NY 13221 Orange,CT 06477-4024

Bryant, inc. Leviton Manufacîuring Compny, hc. Little Neck, NY 11362

Pass & Seymour/hgrand Syracuse, NY 13221

Miíford,Cï 06460

challenger Electrical Equipment Corp. Malvem, PA 19355

Crouse-Hinds Electrical Construction Materials Siemens Energy &Automation, hc. Syracuse, NY 13221 Alpharetta,GA 30201

Daniel Woodhead Company Square D Company Northbrodr,IL 60062 Palatine,IL 60067

Eagle Electric Manufacturing Company, hc. Technology Reseatch Corporation Long Island City, NY 11 101 Clearwater,FL 34620

Eaton Corporation Cleveland, OH 441 14

Westinghouse Electric Corporation Pittsburgh,PA 15222

Ericson Mfg. Company, Inc. WiUoughby,OH 44094



--`,,,,```,,``````,```,``````,,-`-`,,`,,`,`,,`---

Documents

NEMA_280_1990 Ground Fault Circuit Interrupters