Rules for GFCI Outlets and How to Install One

A GFCI outlet in a bathroom.
  • 1-3 hours
  • Intermediate
  • 55-100
What You'll Need
GFCI outlet
Pencil and paper/paper tape
Electrical tape
Wire stripper or knife
Circuit tester
Flashlight/headlamp/battery operated area light
As ALWAYS, proper safety equipment like eye protection and gloves

You’ve probably seen those outlets with the little buttons in bathrooms and kitchens. They’re called Ground Fault Circuit-Interrupters (GFCIs) and if you’re not noticing them in many rooms throughout a house, that house is not up to code. They are required in all bathrooms and in kitchen receptacles at counter height or within six feet of a wet area.

How They Work

These outlets are meant to save lives, either by stopping personal electrocution or preventing fires due to insulation damage. They way they work is by sensing the outgoing and incoming electricity through the outlet. If the interrupter detects a variation as small as five milliamps, it will shut down the circuit. This can happen in as little as 1/40 of a second and can save your life if the variation of incoming and outgoing electricity is due to it flowing through you in search of a ground.

Example: You’re in the basement, using a corded reciprocating saw to demo what you think are dry plumbing pipes. However, there’s water in them and it gets on the tool and you. Electricity can flow with that water into your body in search of a ground. This can be very hazardous to your health. Luckily, the saw is plugged into a GFCI outlet and the outlet senses that there is less electricity coming back than going out and it shuts down in time to prevent any injury.

Now you think, “But I’m in the basement. Aren’t those outlets only for bathrooms and maybe kitchens?” That’s where we have to look at the codes. As currently stated, unfinished basements (at or below grade) are a must for GFCI. Same goes for crawl spaces of the same situation. The only exception being dedicated outlets for alarm systems. Kitchens and bathrooms require GFCI, along with laundry/utility/wet bars, garages, boat houses, and outdoor outlets. (check with your current code for any variations)

And this gets you thinking again, “I want to be safe, but I have to replace all those outlets?” Don’t worry, it’s easy. Here’s how.

Step 1 - Check and double-check

Once you’ve identified the outlet you want to upgrade to GFCI, find it on your circuit breaker and cut the power. Then double-check that the power is definitely off using a circuit tester. No need to rush this stage. Triple-check if you want to.

Rules for GFCI Outlets and How to Install One, circut tester, Nico Rosso

Step 2 - Out With the Old

Now that the power is off, you might need some light, so a flashlight, headlamp or battery powered lantern could come in handy, depending on the time of day and how many windows you have around you.

Remove the plate from the front of your existing outlet and unscrew the outlet from the junction box. It’s a good idea at this time to mark which wires are going to which terminals if you need to. You can use pencil and paper to draw a diagram, or mark the wires with paper tape. You can also take a picture with your phone.

Once you know where everything goes, remove the old outlet from the wires.

Rules for GFCI Outlets and How to Install One, nico rosso

Step 3 - In With the New

Attach the existing wires to your new GFCI outlet. Make sure you read all the instructions for the new outlet, but commonly, black or red wires are live and are attached to the brass screws. White wires are neutral and attached to silver screws.

Rules for GFCI Outlets and How to Install One, nico rosso

The ground is either green or bare and is attached to the green screw on the outlet. Some outlets have slots for wire attachment while others have the screws you need to wrap the wires around. Again, work with the instructions for the individual device.

Rules for GFCI Outlets and How to Install One

If you need some extra exposed wire, use strippers or a knife to carefully remove insulation. On the kind of outlet with the wire wrapped screws, you can use a layer of electrical tape to cover the top, bottom, and sides once everything is connected.

Step 4 - Clean It Up and Test It

With the GFCI outlet connected to all the wires, carefully insert it into the junction box, without stressing the wires too much. Screw it into place and attach the cover.

Time to check your work. Turn the breaker back on and use the circuit tester to see if power is flowing properly through the outlet. Then you can use the test button on the outlet to make sure the power is cut off when it’s supposed to be. Reset the outlet for proper use after that.

Rules for GFCI Outlets and How to Install One, nico rosso

And that’s it. With just a few minutes of your time, you’ve brought the outlet up to code and made it safe. A small investment for a big payoff in protection.