How to Wire a GFI Branch Circuit

Turn off the main breaker. Use a screwdriver to remove the outer cover on the electrical panel. Hold the cover with one hand while you remove the screws holding the cover. Use both hands to remove the cover.

Use the voltmeter to ensure the power is off. Set the meter to a minimum of 250 volts a/c. Touch one of the probes to the ground terminal strip and the other probe to either hot-buss. Confirm that there is no voltage in the accessible area.

Route the appropriate wire from the panel to the proposed outlet's location. The wire size depends on the rating of the GFI breaker. The type of wire depends on the location of the outlet. If it is in the wall, non-metallic cable is appropriate. If it is exposed and the wiring will be in conduit, then individual wire such as THHN is appropriate.

Mount the GFI breaker in the panel. Hold the breaker at a 45-degree angle and hook it onto either outer buss. Lower the breaker until it snaps into position. Pull the white pigtail wire attached to the breaker to straighten it. Strip 1/2-inch of insulation from the wire and attach it to the neutral terminal strip in the panel.

Strip 1/2-inch of insulation from the other wires. Attach the green wire to the ground terminal strip. This will be connected to the neutral terminal strip if you are working with the main panel. It will be a separate strip if you are wiring with a sub-panel. Connect the neutral white wire to the neutral terminal on the breaker. Connect the black or red wires to the hot terminals on the breaker.

Wire the receptacle by stripping the ends of the wires and connecting them as appropriate. Attach the green ground wire to the green screw. Attach the white wire to the silver terminal and the red or black wires to the gold terminals. Wrap the wires around the screw terminals and tighten the screws securely. If you are installing a two-pole breaker, you will have two hot wires. A single-pole breaker will have one hot wire.

Mount the receptacle in the enclosure and attach the cover. Replace the cover on the panel and hold it in place while inserting the screws. Turn on the main breaker and the GFI breaker. Test the GFI breaker by pushing the test button to ensure that it trips when activated.