How to Splice in a Switch
- 1). Turn the power off to the circuit where the cable will have the switch attached, by switching off the circuit breaker that supplies power to that circuit in the home's breaker box -- if the cable has been directly connected to the breaker box, or has been wired to an existing outlet, the lights will go off.
- 2). Mark the electrical cable at the point where the switch will be connected, using a black felt tip pen. Place the cable in the jaws of a wire cutter, and squeeze the cutter's handles together to cut right through the cable. Strip back 3 inches of the cable's outer sheathing from the cable on each side of the cut, by running the tip of a utility knife blade carefully along the center of the cable. Cut the stripped sheathing from the cable with the utility knife.
- 3). Place each black and white wire 3/8-inch from the end of each wire, in the correct slot on one jaw of a pair of wire strippers -- each slot along both of the stripper's jaws are marked for the size of gauge wire they strip. Close the stripper's handles together, and push the strippers towards the end of the wire.
- 4). Knock out a cable access cove at the top and bottom of a light switch box using a screwdriver. Push the stripped cables through each access hole, and position the box on the wall. Use a pencil to mark the box's screw holes, against the wall. Run a stud finder across the wall in the location of the box -- if a stud exists in the location of the hole marks, install 1 5/8-inch screws through the box screw holes into the wall stud, using a screw gun. If there is not a stud in this location, push the end of a small screwdriver through the drywall at each screw mark. Push a wall plug into each hole, and screw the switch box directly into the wall plugs.
- 5). Hold the bare ends of the two white wires together, and screw on a wire nut. Cut a 6-inch piece of ground wire to length, using the tape measure and the wire cutter. Hold one end of the 6-inch ground wire to the two ends of the ground wires in the box, and screw on a wire nut. Bend the ends of the two black wires, and the remaining end of the 6-inch ground wire into hook shapes, using long-nosed pliers.
- 6). Attach one black wire end to each of the light switch's terminal screws, and attach the ground wire end to the switch's ground screw. Tighten the terminal screws to the wires with the screwdriver. Push the wires and switch into the box. Attach the switch to the box, and attach the faceplate to the front of the switch with the screws using the screwdriver. Turn on the power at the circuit breaker.
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