What does a GFCI outlet do?

A GFCI outlet cuts power when electricity leaks out of the circuit, which is what happens when current passes through a person or through water. Its job is to stop a serious shock before it does harm. The U.S. Consumer Product Safety Commission says GFCIs can prevent electrocutions.^[1]

How it works

An ordinary outlet delivers power until a breaker trips from an overload or short circuit, and that can be too slow or too weak a response to protect a person. A ground fault circuit interrupter compares the current going out on the hot wire with the current coming back on the neutral. If some of it is going somewhere else, for example through your body to a wet floor, the device shuts the circuit off almost immediately.

You can see the parts on the face of the outlet: a test button and a reset button. When the outlet trips, the reset button pops out and everything it feeds goes dead until you press it back in.

Why it matters near water

The CPSC puts the risk plainly: mixing electricity and water can result in an electric shock or fire hazard, and using a GFCI reduces the chance of a serious shock or electrocution.^[1] That is why the CPSC points to kitchens, bathrooms, garages, unfinished basements and the area near laundry tubs or wet bar sinks.^[1] For the locations Virginia's code covers, read where Virginia code requires GFCI outlets.

The CPSC also advises against portable heaters in bathrooms, and says that if you use one, it should be plugged into a GFCI outlet or have a GFCI plug.^[1] Counter-top appliances near a sink are a similar case: if you cannot move them away, the CPSC says to plug them into GFCI-protected outlets.^[1]

One GFCI can protect other outlets

A GFCI receptacle can be wired so that it also protects ordinary outlets further along the same circuit, which are then "downstream" of it. That is why a GFCI in a garage or bathroom can be the reason an outlet somewhere else is dead. If an outlet has no power and no reset button, look for a GFCI nearby that has tripped. The longer story is in when to call an electrician about a dead outlet.

Testing and replacing

The CPSC says to test every GFCI once a month according to the manufacturer's instructions.^[1] Its fallback method is to plug in a light and turn it on, press the test button, and see whether the light goes out, then press reset and see whether it comes back on. If either step fails, the CPSC says to replace the GFCI.^[1] A GFCI can fail without showing any sign of failure, so regular testing may save your life.^[1]

Plug-in GFCI adapters exist too. The CPSC says portable GFCIs are as effective as installed GFCIs,^[1] which makes one a sensible stopgap for an outdoor outlet or a tool while you arrange a permanent fix.

When to call a licensed pro

Pressing test and reset is fine for anyone. Swapping the device is a different matter, because it means working on wiring that may be live and on a circuit that can feed other outlets. The Code of Virginia defines a tradesman as any individual who engages in, or offers to engage in, work for the general public for compensation in the trades of electrical, plumbing and heating, ventilation and air conditioning,^[2] and says no individual shall engage in, or offer to engage in, work as a tradesman unless licensed under that article, apart from individuals working under the supervision of a licensed tradesman in that specialty.^[3]

Call an electrician if a GFCI will not reset, trips again right away, feels warm, or was damaged by water. A GFCI that will not reset can mean the device has failed or that there is a fault on the circuit, and only testing on site tells you which. Look up the licence first with how to check if a contractor is licensed in Virginia.

Next steps

For price, see how much it costs to replace a GFCI outlet in Virginia. You can browse more electrical repair answers or electrical services.

If a GFCI is dead, tripping or failing its test, describe the problem once and licensed local electricians quote the repair.