Building Inspection, Diagnosis & Repair Info

AFCI wiring details showing the black and white circuit and white breaker wire connectcions (C) Daniel Friedman at InspectApedia.com GFCI Installallation Options & Wiring

Ground Fault Circuit Interrupters, GFCI Device Choices & Wiring Details

How to choose a GFCI device and how to install GFCI circuit breakers, receptacles, or portable, stand-alone GFCI protection devices.

This article series GFCI and AFCI protection for buildings.

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GFCI Options, Installation & Wiring Instructions

GFCI circuit breaker wiring, 120V adapted from Siemens, cited in this article (C) InspectApedia.comAs we introduce also if certain high-risk electrical circuits in your home or building is not already protected by GFCI devices in the electrical panel or at the appropriate electrical receptacles ("wall plugs"), we recommend that you have that protection added.

The high shock risk areas for which GFCIs add significant safety protection are damp or wet locations or locations where a person is likley to be handling an electrical device and be close to a sink, tub, shower or other plumbing or water equipment.

The GFCI detects a tiny (about 4 to 5 milliamps) flow of electrical current between the electrical circuit or something plugged-in to a GFCI-protected electrical receptacle) and the circuit "ground" or the earth.

On detection of this current flow the GFCI quickly trips (in about a tenth of a second) to turn off the electrical circuit to reduce the chances of a dangerous or even fatal shock.

Typical GFCI-protected locations include bathrooms, garages, kitchens, at outdoor electrical circuits and of course near swimmng pools. That's not the whole list. At GFCI PROTECTION, GFCI CODES we provide a full list of the locations where electrical codes require this protection in new or renovation construction.

Watch out: never plug any life-saving devices into a GFCI electrical receptacle that will lose power during testing. Every receptacle that will lose power when a GFCI trips should be labelled GFCI-Protected.

We also caution against plugging a refrigerator or freezer or other critical cold-storage equipment into a GFCI-protected receptacle (for example downstream from the actual GFCI devicve) as any condition that trips the GFCI can leave the cold storage equipment off without notice.

Some electrical circuits that need to be assured of continuous operation include medical equipment, refrigerators, freezers, and sump pumps.

See also FREEZE-PROOF A BUILDING where we describe GFCI protection on heat tape circuits powering heat tapes for manufactured and mobile homes.

Similar issues regarding building water entry control are discussed

at SUMP PUMP PROTECTION

Four Ways to Add GFCI Protection

  1. GFCI circuit breaker: Install a GFCI circuit breaker in the electrical panel, replacing the original breaker, to protect an entire circuit, such as a kitchen, garage, or outdoor receptacle circuit

GFCI circuit breakers in an electrical panel (C) Daniel Friedman at InspectApedia.com

Below is a Siemens 120V single pole ground fault circuit interruptor circuit breaker or GFCI breaker. The company provides a range of GFCI breakers including 1-pole and 2-poles, from 15A to 60A in size.

Siemens GFCI circuit breaker at InspectApedia.com

The company's data sheet for this GFCI breaker series notes that while a load neutral wire is not required on the circuit, the coiled white pigtail wire from the breaker must be connected to the neutral bus in the electrical panel for the GFCI to work.

GFCI circuit breaker wiring, 120V adapted from Siemens, cited in this article (C) InspectApedia.com

Other brands and models of GFCI circuit breakers require that

AFCI wiring details showing the black and white circuit and white breaker wire connectcions (C) Daniel Friedman at InspectApedia.com

Watch out: before buying a GFCI circuit breaker be sure that the breaker is the proper one for the brand and model of electrical panel into which it is to be installed.

OK so what are the exact steps in wiring up or installing a GFCI device?

At CIRCUIT BREAKER REPLACEMENT we describe in further detail the steps followed to replace an existing circuit breaker with a GFCI-type (or AFCI-type) circuit breaker in an electrical panel.

GFCI Add-on Space Limitations in Some Electrical Panels

Standard circuit breaker widths, using Siemens as an example are 1" for a 120V breaker and 2" for a 240V breaker. In some electrical panels, such as our electrical panel photo shown just above on this page, you may find both full-width and half-width breakers already installed.

If the electrical panel is full or quite crowded you may find that you need to replace several normal-width circuit breakers with narrow half-width circuit breakers - a procedure called "skinnying-up" in the panel - in order to make room for a full-width GFCI breaker.

Watch out: if you have to change some circuit breakers from full to half-width or "skinny" circuit breakers AND if there are multi-wire shared-neutral circuits originating in the electrical panel, you will need to take care in locating those circuit breaker pairs to assure that each breaker is on a different panel bus connector and phase.

Details are at MULTI-WIRE CIRCUITS

GFCI wall receptacle installed in a kitchen (C) Daniel Friedman at InspectApedia.com

  1. GFCI wall receptacle: Install a GFCI electrical receptacle to replace an existing electrical receptacle in a high-risk location such as a bathroom or kitchen etc.

    The GFCI receptacle will protect any device plugged in to that receptacle and it will protect all of the electrical receptacles (and devices plugged into them) that are wired "downstream" from the receptacle where the GFCI is placed.

    In some buildings bathroom receptacles are wired in series between two or more baths and a GFCI is placed in the first receptacle in that string.

GFCI receptacle wiring connections (C) Daniel Friedman at InspectApedia.com

  1. Portable GFCI devices: Use a plug-in or portable GFCI protection device that is connected to a wall receptacle.

    Often a portable GFCI device is simply a short extension cord that includes at one end its own GFCI protection. Devices that are then plugged into the GFCI-protection device are themselves protected, as are their users.

    We often use a portable GFCI protector in construction projects to run our power tools because we don't count on every building or home where we work to have properly-installed GFCI protection.

Yellow Jacket 2516 14/3 Portable GFCI Protected 4-outlet extension cord - sold at electrical suppliers and online such as by Amazon - here shown at InspectApedia.com

Shown above: a Yellowjacket-brand portable GFCI protected extension cord.

  1. GFCI-protected tools, devices, appliances: some devices may include their own built-in GFCI device. Shown below: Toughbuilt TB-S560 universal miter saw stand with its own built-in GFCI protection, sold at Home Depot stores and by other suppliers.

Toughbilt miter saw stand that includes its own GFCI protection - at InspectApedia.com

GFCI Installation Guides & Device Specifications

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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2020-12-04 by (mod) - use pigtailing to avoid nuisance tripping at GFCIs

GFCI receptacle wiring hook up connections make line and load sices clear (C) Daniel Friedman at InspectApedia.comBrian

Indeed some electricians have recommended the pigtailing trick to wire the GFCI as a means to stop nuisance tripping. Electrically it means that the current to the other device on the circuit (the fan) is not passing through the GFCI device.

I'm not 100% confident that pigtailing works in every wiring situation but certainly you've shown that it can in the one you describe.

Your note will certainly help other readers.

Thank you.

On 2020-12-04 by Brian

The GFCI has two holes for each terminal into which wires can be inserted (2 line +, 2 line -, 2 load +, 2 load -).

I had the supply cable from the basement attached to one set of line holes and the fan attached to the other set.

So I guess yes, they share a neutral to the extent that the neutral from the fan is directly connected to the same terminal that the GFCI is using to connect to the main circuit neutral. Yesterday I pigtailed the GFCI (the ground was already pigtailed) and that stopped the tripping!

So they are both still ultimately connecting to the same neutral cable going to the basement in the box but the fan is not connected to the GFCI directly. Thank you for your help!

On 2020-12-04 by (mod) - common causes of GFCI Nuisance Tripping or Ghost Tripping

Brian

Can you determine whether or not the kitchen vent van and GFCI receptacle are using the same neutral wire? A shared neutral will indeed cause nuisance tripping on a GFCI device.

Other causes of nuisance tripping of GFCI's and AFCIs

(other than a shared neutral wire)

Other sources of GFCI nuisance tripping have been described by some electrical engineers and other sources as including

Fluke, a maker of electrical test equipment has a helpful discussion of GFCI nuisance tripping at

This article makes an important point: when a GFCI is tripping do not assume that it's a harmless "nuisance trip" - as in fact the GFCI may be doing its job and keeping you from getting zapped.

Unfortunately few homeowners have the training nor equipment (a clamp-type current leakage monitoring instrument) to actually measure the leakage at the GFCI.

On 2020-12-01 by Brian - kitchen fan trips GFCI

GFCI receptacle in kitchen with vent fan on wall above. Feed runs from basement to line terminals on GFCI.

Fan, also on line side, causes GFCI to trip when turned on. Not clear why this happens when all is on line side -- thought GFCI shouldn't react to things on line side?

Fan is old mode with old switch that is likely basically 2 bits of metal with fan vent door opening action causing them to get closer and closer. At some stage the gap is small enough for a spark to jump before being fully in contact and this trips the GFCI.

I don't think the switch is bad, just primitive. Plugging the fan into an outlet on the GFCI doesn't cause it to trip, it's the switch being turned on is the problem.

I was wondering if instead of sharing line terminals on the GFCI itself if I instead put the GFCI on a pigtail would that be enough to isolate it from the fan branch?


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