Ground Fault Circuit Interrupters (GFCIs) 101

We’ve all seen them before: those strange-looking outlets with two buttons in between the power plugs. But how many of us know what they’re actually for? And along those same lines, how many of us know what to do if one of those outlets is giving us trouble?

Knowing the answers to those questions is more important than you might think as a homeowner. To start, let’s address exactly what those strange-looking outlets are.

The Ground Fault Circuit Interrupter Outlet

You guessed it (or maybe you didn’t): those funky outlets are called Ground Fault Circuit Interrupter Outlets, and they’re designed to protect you from electrical shock.

The most common type of GCFI in a residential setting is the receptacle type—the GFCI outlet—which incorporates as a GFCI device within one or more outlets. Though sometimes the button colors on these outlets vary, in general, you can expect a GFCI outlet in your home to look about like this:

Photo courtesy of EPC International.


Why is it called a ground fault circuit interrupter? Because its job is to ‘interrupt’ a ground-fault, which occurs when there is a break in the low-resistance grounding path from a tool or electrical system. GFCIs work by monitoring the amount of current flowing from hot to neutral and tripping the circuit when there’s an imbalance (break) in the current.

In a residential setting, that break could potentially mean that current from the outlet is flowing through a person or through water. In either case, there’s a high possibility of (deadly) electric shock—which is exactly what the GFCI is designed to prevent.

When a GFCI detects a break in the grounding path, it shuts power off (in as fast as 1/40th of a second). When a GFCI is working properly, it will save you from deadly shock by that hair dryer you drop in the sink or that drill you’re using out in the rain. (GFCIs also protect from fire, overheating, and destruction of wire insulation.)

GFCIs are required in kitchens, bathrooms, unfinished basements, garages, outdoors, and anywhere that electricity is required and water is present (i.e. near sinks, bathtubs, etc.).

Testing and Troubleshooting a GFCI Outlet 

GFCIs only protect you when they’re functioning properly. A step that can help protect you, but that many people fail to do regularly, is testing your GFCI outlets.

Testing your GFCI outlets is easy. Simply push the ‘test’ button (you may have to press firmly). You should hear a pop, and the outlet should shut off power. If you want to be certain that the outlet is no longer providing power, test it out by plugging in a lamp or something similar that you know already works. If it won’t turn on, the outlet did its job; the reverse is true if it does. Once you’ve tested the outlet, you should hit the ‘reset’ button (on the bottom of most GFCI outlets), and the outlet should go back to working normally.

We recommend checking your GFCI outlets—all of them—once a month. Learn where the GFCI outlets are in your house and the other outlets they are controlling, and make it a point to test them out every single month. They only protect you when they’re functioning, and you can only know that by testing!

If power doesn’t cut out when testing, it’s time to call an electrician to replace your GFCI outlet. Similarly, it may be time to do the same if the power doesn’t turn back on when you reset the outlet. Note, however, that many homes have a GFCI breaker (located within your circuit breaker housing) that operate similarly to a GFCI outlet. If you have an outlet that won’t come back on, it’s possible that there’s a GFCI breaker that needs to be reset as well.

The Takeaway

GFCIs are a great modern safety device, but like any other electrical device in your home, they require some maintenance. Be sure to check once a month so you know for certain all of your GFCI outlets are working properly—it never hurts to be too careful!

Have a question about a GFCI outlet in your house that’s giving you trouble, looking for a residential electrician, or want to learn more about Hiller Electric and any of the services we offer? Don’t hesitate to reach out and let us know! You can get in touch by phone at 402.339.0524, or visit our Contact Us page for more information.