How to Extend Electrical Wires in Your Home

Never work on a live electrical circuit. 

1. Locate and turn off the breaker switch for the circuit where you’ll work. 

2. If you’re uncertain which circuit to shut off, turn off the main breaker switch to cut power to the entire house. 

3. Use your non-contact voltage detector, multimeter, or both to ensure there is no current where you’re working.

Running a new cable and making connections is more manageable after removing the existing box.

1. Remove the existing fixture or socket and wire caps using your multi-bit screwdriver. 

2. Loosen and remove the retaining ring of the cable connector on the side of the box.

3. With a stud finder, determine which side of the box the wall stud is on.

4. With a pry bar or screwdriver, coax the box away from the stud enough to see the mounting nail or screw.

5. With a metal blade on a reciprocating, oscillating, or keyhole saw, cut the nail or screw. Be careful to avoid hitting the electrical cable.

6. Pull the box out of the hole while leaving the wire in the wall cavity.

7. Loosen and remove the cable clamp connector.

Getting the new wires in place can be the trickiest part of the project.

1. Using fish tape, run the new non-metallic electrical cable from the location of the new fixture to where you're connecting it to the existing circuit. 

2. Through the back of the old work electrical box, slide the new and the old cables through the clamping tabs. Leave about six inches of the cable coming out of the box.

3. Insert the box into the wall and tighten the securing wings with a screwdriver.

The old wires may not need much preparation. However, it’s easier to work with untwisted wire ends.

1. On the old cable wires, trim the twisted end off and strip about a 1/2-inch from the wire covers. 

2. On the new cable wires, Use a cable ripper tool or utility knife to remove the protective cable casing as far back in the box as you can reach with tools. 

3. Strip the hot and neutral wire ends to about 1/2 inch. 

If you’re reinstalling the old fixture, support it from below while connecting its wiring.

1. Gather the bare copper grounding wires and twist them together tightly with a linesman’s pliers. If you’re reinstalling the old fixture, include its ground wire in the connection. If not, simply connect the new wire to the old wire.  

2. Twist the proper-size wire nut (or cap) over the twisted end.

3. Repeat steps one and two with the black and neutral (white) wires. Again, if you’re reusing the old fixture, include its wires. 

4. Tuck the wires into the electrical box.

If you choose not to reinstall the old fixture, you must cover the box with an NEC-approved cover.

1. Attach the old fixture or new cover plate to the electrical box.

2. Turn the electricity back on to the circuit.