What a GFI outlet does and why you might need to replace one

A GFI outlet (ground fault interrupter) is a safety device that cuts power when ready if it detects water or a short circuit. Unlike a regular outlet, it has two buttons in the center — a black "Test" button and a red "Reset" button. When the GFI senses a ground fault, the Reset button pops out and the outlet stops supplying power.

You need to replace a GFI when it stops resetting, trips constantly without reason, or no longer responds to the Test button. Some GFIs straightforward wear out after 15 to 20 years. Others fail because water got inside the outlet box or because the wiring behind it is damaged. If an outlet trips and won't reset, or if it resets but trips again within seconds, replacement is usually the fastest fix.

GFI outlets are required by code in bathrooms, kitchens, garages, and anywhere within six feet of water. If yours fails, the outlet itself is inexpensive — usually $10 to $25 — but the job requires turning off power at the breaker and working with live wires, so safety matters more than cost.

Key Takeaways

  • Turn off power at the breaker before you touch anything inside the outlet box, and use a voltage tester to confirm the power is actually off.
  • Remove the old outlet by unscrewing the two terminal screws and pulling the wires free, then note which wire goes where before you disconnect anything.
  • Connect the new GFI outlet the same way the old one was wired — black wire to brass, white wire to silver, and the bare copper or green wire to green.
  • Push the outlet into the box, screw the faceplate on, and test it with the Test button before you restore power to the breaker.

Turn off the breaker and confirm power is off

Locate your electrical panel — usually in the basement, garage, or utility closet. Open the door and find the breaker that controls the outlet you are replacing. The breaker label should say "Bathroom" or "Kitchen" or list the room. Flip that breaker to the Off position. If the label is missing or unclear, turn off the main breaker instead, but that will cut power to the whole house.

Do not rely on the breaker label alone. Use a voltage tester (a battery-powered device that lights up or beeps when it detects electricity). Plug it into the outlet you are about to work on. If it does not light up or beep, the power is off. If it does light up, go back to the panel and flip the correct breaker. Test again. This step takes 30 seconds and prevents serious injury.

Remove the faceplate and unscrew the old outlet

Once power is confirmed off, unscrew the faceplate (the plastic or metal cover) and set it aside. You will see the outlet itself, held in the box by two screws — one at the top and one at the bottom. Unscrew both of these and gently pull the outlet straight out toward you. Do not yank it; the wires are still attached.

You will now see the terminal screws on the sides of the outlet. There are four of them: two brass-colored screws on the right side and two silver-colored screws on the left side. The wires are wrapped around these screws. Loosen each screw by turning it counterclockwise until the wire comes free. Take a photo of the wiring before you disconnect anything, or write down which wire color goes to which screw. This takes one minute and saves confusion later.

Connect the new GFI outlet

A new GFI outlet has the same four terminal screws as the old one. The wiring rules are strict: the black wire (hot) always goes to a brass screw, the white wire (neutral) always goes to a silver screw, and the bare copper or green wire (ground) always goes to the green screw. If your outlet box has no ground wire, connect only the black and white wires.

Strip about half an inch of insulation from the end of each wire if it is damaged or frayed. Wrap the black wire clockwise around one of the brass screws and tighten the screw. Wrap the white wire clockwise around one of the silver screws and tighten it. Wrap the ground wire clockwise around the green screw and tighten it. Pull gently on each wire to make sure it does not slip. The wires should be snug but not crushed.

If your outlet box has two sets of wires — one coming in and one going out — you will have two black wires, two white wires, and possibly two ground wires. Connect one black wire to each brass screw, one white wire to each silver screw, and one ground wire to the green screw (or both ground wires to the same screw if there is only one green terminal). This allows the GFI to protect outlets downstream as well.

Push the outlet into the box and find it

Carefully push the outlet back into the box, making sure the wires fold neatly behind it and do not get pinched. The outlet should sit flush against the box. Screw the top and bottom mounting screws back in and tighten them until the outlet is snug. Do not overtighten; you only need enough pressure to hold it in place.

Screw the faceplate back on. Make sure the outlet is centered in the opening and the faceplate sits flat. If the outlet is crooked, loosen the mounting screws slightly, adjust the outlet, and tighten again.

Test the new outlet before restoring power

Go back to the breaker panel and flip the breaker back to the On position. Return to the outlet and press the Test button. You should hear a click and feel the Reset button pop out. This means the outlet is working and the safety circuit is functioning. Press the Reset button to restore power to the outlet, then plug in a lamp or phone charger to confirm it supplies power.

If the outlet does not click when you press Test, or if it does not supply power after you reset it, turn the breaker off again and check your wire connections. Make sure each wire is wrapped tightly around its screw and that no bare wire is touching the outlet box or another wire. If the connections look correct, the new outlet may be defective — replace it with another one.

When to call an electrician instead

If the outlet box is wet or shows signs of water damage, do not install a new GFI. Water inside the box means there is a leak or moisture problem that needs to be fixed first. Call a licensed electrician or a plumber to find and repair the source.

If you have aluminum wiring instead of copper, or if the wires are cloth-wrapped and brittle, stop and call an electrician. Aluminum wiring requires special handling and cloth-wrapped wiring is a fire hazard that should be replaced by a professional. If you are unsure what type of wiring you have, take a photo and show it to an electrician before you proceed.

If the breaker trips when ready after you restore power, or if you smell burning plastic or see scorch marks inside the outlet box, turn the breaker off right away and call an electrician. These are signs of a short circuit or damaged wiring that you should not attempt to repair yourself.

Frequently Asked Questions

Can I replace a GFI outlet if I have never done electrical work before?

Yes, if you follow the safety steps carefully. The most important rule is turning off the breaker and testing with a voltage tester before you touch any wires. If you are uncomfortable working inside an outlet box or unsure about your wiring, hiring an electrician costs $100 to $200 and takes less than an hour.

What if the new outlet trips when ready after I turn the breaker back on?

Turn the breaker off and check your wire connections. Make sure the black and white wires are not touching each other or the outlet box. If the connections are correct, the new outlet may be faulty. Replace it with another GFI outlet from a different package or brand. If a second outlet also trips, the problem is likely in the wiring itself, and you should call an electrician.

Do I need to replace the whole outlet box or just the outlet?

Just the outlet. The box itself rarely fails. If the box is cracked, wet, or corroded, you may need to replace it, but that is a separate job. Start by replacing the outlet and see if that solves the problem.

Can I use a regular outlet instead of a GFI in a bathroom or kitchen?

No. Building code requires GFI outlets in bathrooms, kitchens, garages, and within six feet of water. A regular outlet does not have the safety circuit to cut power if water is present. Using a regular outlet in these locations is a code violation and a fire hazard.

How long does a GFI outlet usually last?

Most GFI outlets last 15 to 20 years before they wear out or stop responding to the Test button. Some fail sooner if they are exposed to moisture or temperature swings. If your GFI is more than 15 years old and stops working, replacement is usually the best option.