Matthew Steger WIN Elizabethtown

Ground Fault Circuit Interrupters (GFCIs)

We’ve all seen them.. they are normally located in kitchens and bathrooms, among other places. They are the receptacles with the little TEST and RESET buttons. Some have red and black buttons and some have buttons that match the color of the actual receptacle (normally white or cream colored). We’re talking about the trusty Ground Fault Circuit Interrupter or GFCI.                             

GFCIs come in receptacle form (1st photo below) as well as circuit breaker form (2nd photo below.. notice the 4 breakers with the light green test buttons) but each do the same thing. They are designed to help protect people from shock or electrocution when it comes to water contact.


GFCIs entered residential construction standards back in the early 1970s and, at that time, were only required at most exterior receptacle locations and at pools. Over time, like most things in the building code, the number of required locations for GFCI protection increased. In new construction today, GFCI protection is required at bathrooms, kitchen countertops, garages, unfinished basements, crawl spaces, laundry sinks, exterior, etc. This essentially covers all places that water and electricity can potentially meet. Notice that I didn’t say that GFCIs need to be installed at each of the above areas, but instead, these areas simply require GFCI protection. There is a difference.. more on that later down the page.

GFCIs work by monitoring the amount of electrical current on the hot (black) and neutral (white) wiring feeding the GFCI. If it senses an imbalance between the two wires (such as 5 Amps on the neutral wire, and 4.5 Amps on the hot wire) it assumes the extra electrical current (0.5 Amps) is leaking out (such as shocking the user) and should trip. GFCIs are designed to trip at an unbalance of 5 mA (which is a pretty small level of current). GFCIs can trip in about 1/40th of a second. GFCIs do not require a grounding conductor in order to function, so GFCIs can easily be added in older homes that were only wired with 2-wire systems, such as knob and tube (K&T) [pre-1950] and 2 wire Romex/NM cable [mid to late 1940s to about the mid-1960s]. In this case, the “No Equipment Ground” stickers that come with GFCIs should be installed at the downstream-protected receptacles so that the home’s occupants know they are not actually grounded.

The electrical code stipulates what receptacles inside or outside a home must be GFCI protected but it does not say where the resets must be located. As mentioned above, where GFCI protection is required and where the GFCIs must exist are two different things. In many homes from the 1980s and 1990s, sometimes all of the exterior and bathroom receptacles were protected by a single GFCI (in a bathroom, for example). Therefore, one GFCI device can protect receptacles in multiple areas. Most electricians in newer homes nowadays often will install GFCI receptacles in each bathroom and at each exterior receptacle. Generally, modern kitchens will have 2 or more GFCIs installed. The garage receptacles (including ones on the ceiling) are normally all tied to a single garage wall GFCI receptacle. This provides more convenience since the user only has to reset the GFCI right in the bathroom, kitchen, etc. versus having to go to a different area of the home to reset the GFCI if it trips.

As part of a home inspection, per the ASHI (American Society of Home Inspectors) Standard of Practice part 7.1.A paragraph 9, “the inspector shall inspect ground fault circuit interrupters”.  By ‘inspecting’, it means to TEST them. The best way of testing a GFCI is to use its test button. For a GFCI receptacle, pressing the TEST button will easily determine if the unit is working as designed. If it trips, good. Next press the RESET button. If it does not trip or reset, then something is wrong. It could be a faulty GFCI.  Modern GFCI receptacles are designed so that if they are wired backwards (hot/neutral reversed), they will trip but won’t reset. This feature is meant to force the user to fix the wiring problem. Older GFCI receptacles could trip, yet still have receptacles downstream that are still powered. The ‘won’t reset’ feature is designed to prevent this.

For testing a GFCI breaker, again, press its TEST button. The breaker handle should move to the center location and you should hear the breaker trip. Next, you fully turn off the breaker (from the middle ‘tripped’ position) and back to the ON position. If a GFCI breaker or receptacle won’t reset or continues to trip, this indicates a problem warranting the attention of a qualified electrician.

One difficulty that often occurs to home inspectors is when testing receptacles to determine if they are GFCI protected, it may trip a GFCI device elsewhere in the home. Finding the actual GFCI to reset it can sometimes border on the 'nearly impossible', if it is located in a different room since we can't hear the actual 'click'. In many homes, especially cluttered homes, the tripped GFCI is located behind shelving, boxes, furniture, or other clutter where the inspector would have no chance of ever finding it. If we can't see the GFCI, we can't test and/or reset the GFCI. Remember, home inspectors don't move the sellers belongings to perform the inspection.

GFCI breakers and receptacles should not be confused with AFCI (arc fault circuit interrupter) breakers and receptacles. They often look very much alike. GFCIs are designed to help protect from shock or electrocution, whereas AFCIs are designed to prevent a house fire. GFCI and AFCI devices will be clearly labeled on the unit’s front or side to differentiate one from the other. AFCI devices are required in modern homes (post-2002).

Also, a regular receptacle may be GFCI protected without you knowing it. It may be connected downstream of a GFCI receptacle or breaker.

Also, GFCI protection is generally not installed at refrigerator/freezer locations since if a GFCI were to trip, the refrigerator/freezer would not be powered until someone figured it out and reset the GFCI. This is why electrical standards don’t require all kitchen receptacles to be GFCI’d but only receptacles that serve the kitchen countertop. Also, for the same reason as stated above, refrigerators/freezers should ideally not be plugged into garage receptacles since all garage receptacles must be GFCI’d nowadays.

Adding GFCI protection in older homes is a worthwhile and inexpensive safety upgrade. When inspecting homes without GFCI protection installed (generally pre-1970s), home inspectors should add a recommendation in their report about adding GFCIs as a good safety upgrade.

GFCI Basic History  - locations where GFCI protection is required and their code cycle years.
note - the below listed years are based upon the National Electric Code (NEC) cycle). Most cities and townships in PA didn't start following these 'requirement' until recently.

1971 - swimming pools, exterior
1975 - the above, plus bathrooms
1978 - the above, plus garages
1987 - the above, plus kitchen (within 6' of the sink), unfinished basements
1990 - the above, plus crawl spaces
1996 - the above, plus the kitchen requirement changed to all receptacles serving a counter (more than just within 6' of the sink)
2005 - the above, plus laundry/utility sinks

Watch this video about Ground Fault Circuit Interrupters (GFCIs):

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© 2019 Matthew Steger

Matthew Steger, owner/inspector of WIN Home Inspection, is a Certified Level 1 Infrared Thermographer, an ASHI Certified Inspector (ACI), and an electrical engineer. He can be reached at: 717-361-9467 or msteger@wini.com.

WIN Home Inspection has provided a wide array of home inspection services in the Lancaster, PA area since 2002. This article was authored by Matthew Steger, ACI - owner of WIN Home Inspection in Lancaster, PA. No article, or portion thereof, may be reproduced or copied without prior written consent of Matthew Steger.