How to replace a GFCI outlet and test that it works

Replace a GFCI outlet by shutting off the correct breaker, proving the box is dead, identifying the line and load wires before you remove the old device, and wiring the new GFCI the same way. Then restore power and use TEST and RESET to confirm the receptacle and any protected downstream outlets work as they should.

What this guide helps you do, and when to stop

This guide covers a standard GFCI outlet replacement in a single-pole circuit. You’re swapping one receptacle for another and keeping any downstream protection intact.

Stop and call a licensed electrician if you find damaged insulation, melted plastic, scorch marks, water in the box, aluminum wiring, brittle cloth wiring, or signs that the box is overcrowded and stressed. Those are not normal swap conditions.

If you see multiple cables you can’t sort out confidently, or the breaker trips again after you restore power, treat that as a wiring problem, not a bad outlet.

What you need before you start

Have everything ready before you turn off power. That keeps the box open for less time and lowers the chance of mixing up wires.

• Replacement GFCI outlet that matches the circuit rating and fits the box; many homeowners choose tamper-resistant models where local code requires them.
• Phillips screwdriver, and a flat screwdriver if your device uses it.
• Non-contact voltage tester or multimeter.
• Plug-in outlet tester if you want a quick downstream check after the install.
• Wire stripper, if the conductors need fresh ends.
• Flashlight.
• Painter’s tape or small labels to mark wires before removal.
• Cover plate if the old one is cracked or won’t sit flat.

Check the new GFCI’s instructions before you begin. Terminal markings, back-wire clamps, and fit in the box can vary by model, so do not assume every device wires the same way. If the old receptacle is crowded, a pigtail may help on the grounding side or for a better splice arrangement, but don’t plan on improvising in a tight box.

Turn off power and prove it’s off

Shut off the breaker that controls the outlet, then verify the outlet is dead at the device itself. Do not trust the breaker label alone; labels are often wrong or incomplete.

1. Plug a lamp or tester into the outlet if something is already connected, and note whether it turns off after you open the breaker panel.
2. Switch off the suspected breaker in the breaker panel.
3. Return to the outlet and check the receptacle with a non-contact voltage tester or a multimeter.
4. Test both slots and, if possible, the box ground as well.
5. Confirm that the tester shows no power before you touch any wires.

Find line, load, and any downstream outlets

You need to know which cable is the incoming feed, because that belongs on the GFCI’s line terminals. If the old outlet protected other receptacles, those outgoing conductors belong on load. That choice determines whether the downstream outlets stay protected.

Look for more than one cable in the box. One cable usually brings power in from the panel, and another may leave to feed other receptacles. The incoming cable is often the one that remains hot when you separate the old device, but don’t rely on guesswork. Mark the cables before anything comes off.

If there is only one cable in the box, the old GFCI may have been protecting only that location, and the new one will usually use line only. If extra receptacles went dead when the old GFCI tripped, they are likely downstream outlets and should stay on load if that was the original arrangement.

Remove the old GFCI and record the wiring

Take a clear photo before loosening anything, then label the wires if needed. That gives you a backup if the box is crowded or the conductors are different colors than expected.

1. Remove the cover plate.
2. Unscrew the receptacle from the box and pull it forward gently.
3. Photograph the wire positions on the old GFCI, including which terminals were line and which, if any, were load.
4. Loosen the terminal screws and remove the conductors one at a time, keeping the wire sets separate.
5. Check whether the old device used backstab-style holes. If it did, move the conductors to screw terminals on the new device instead of repeating the shortcut.

A dead or stubborn GFCI is often a line/load mix-up rather than a bad outlet. Clear notes now save time later, especially if the old outlet protected downstream receptacles.

Wire the new GFCI the right way

Connect the incoming hot, incoming neutral, and ground to the line side of the new GFCI first. Use the load terminals only if the old outlet was feeding downstream receptacles and you want the new GFCI to protect them too.

1. Find the line terminals on the new device. They are usually marked and may be brass for hot and silver for neutral.
2. Attach the incoming hot wire to the line hot terminal, and the incoming neutral wire to the line neutral terminal.
3. If there were protected wires on the old outlet, connect those to the load terminals in the same way the device labels indicate.
4. Attach the bare or green ground wire to the green ground screw.
5. Tighten each screw to the device instructions, making sure the conductor is under the clamp correctly and no bare copper is exposed where it should not be.

If the old outlet had only one cable, leave the load terminals unused unless the manufacturer’s instructions say otherwise. Don’t guess. A reversed line and load connection is one of the most common reasons a GFCI clicks but will not reset.

Fold the wires back and mount the outlet

The hard part is often not the wiring itself but getting the conductors folded back without loosening anything. Work slowly and keep the bend gentle.

1. Tuck the wires into the box so the ground wire and insulated conductors are not pinched under the device.
2. Keep the terminal screws facing the same direction as the wire bends when possible. That reduces stress on the connections.
3. Seat the GFCI in the box without forcing it. If it won’t sit flat, the box may be too crowded and need a different layout or a deeper box.
4. Screw the receptacle into place evenly.
5. Install the cover plate so it lies flat without bending the device or trapping insulation.

Do not over-tighten the mounting screws. A slightly twisted or crushed box can loosen terminals later and make the outlet fail intermittently.

Restore power and test the result

Turn the breaker back on, then use the GFCI’s reset button before testing it. A GFCI that appears to work until you press TEST has not really proven anything yet; the test button is the real check.

1. Turn the breaker on.
2. Press RESET on the new GFCI.
3. Plug in a lamp or outlet tester and confirm the receptacle has power.
4. Press TEST on the GFCI.
5. Confirm that power drops off and the reset button trips out.
6. Press RESET again and confirm power returns.
7. Check any downstream outlets that should be protected by this GFCI, and make sure they lose and regain power in the expected way.

If protected outlets stay dead after reset, or if they only work when the GFCI is bypassed, that usually means the load wiring is wrong or loose.

If it doesn’t work, use the symptom to narrow the cause

Use the symptom to narrow the problem before you assume the new GFCI is defective. In a lot of cases, the issue is wiring or an upstream fault.

• No power at the new outlet: the breaker may still be off, the line wires may be on the wrong terminals, or there may be an open connection upstream.
• GFCI will not reset: there may be no power on the line side, the line and load may be reversed, or the wiring may be loose.
• Trips immediately: the conductors may be miswired, a downstream fault may be present, or the device may be protecting a real ground fault.
• Downstream outlets are dead: the load wires may have been left disconnected, landed on the wrong terminals, or not secured well.

If the breaker trips after you restore power, stop and recheck your work with the power off. If the wiring looks correct but the outlet still misbehaves, the problem may be upstream in the circuit, at the breaker, or in a hidden splice. That is the point where a licensed electrician can test the circuit safely and sort out whether the fault is in the receptacle, the branch wiring, or the panel.

Conclusion

When the job is done right, the new GFCI powers up, RESET restores power, TEST trips it, RESET brings it back, and any downstream outlets on the load side behave the same way. If that sequence doesn’t happen, stop there and track the fault before you close the wall back up.