Many home remodeling projects need a light switch, or electric outlet moved from its current location to another spot; sometimes on a totally different wall. A fairly straightforward job, until the new wire reaches the first wall stud. Often keeping drywall damage to a minimum becomes this project's major challenge.
When working with electricity, safety must always remain the number one concern. Never work on a live circuit and always turn the power off at the circuit breaker. Before starting this type of project, check the local building codes to determine if the project requires a licensed contractor and a permit.
Sometimes the electric-service panel does not have proper circuit-breaker identification. If this is the case, plug a lamp into the outlet or turn on the light switch. Turn the suspected room's circuit breaker off. If the light did not turn off, try a different circuit breaker. Repeat this until the light turns off, and then mark the appropriate circuit breaker for future reference. Keep the circuit breaker off for the remainder of the project.
Identify the Circuit's Wire Requirements
Remove the switch or outlet's wall plate. Loosen the mounting screws and carefully pull the device out of its electrical box without touching the wire terminals. Use a multimeter, set to its VAC position, to double-check the circuit for voltage. Hold one probe on the ground wire and press the other probe against each wire terminal. The meter should always read zero. If not, identify the circuit breaker powering the switch or outlet and turn it off.
Take note of the wire positions on the existing device. Labeling helps keep the wires straight while working on complicated circuits, especially GFCI outlets. A GFCI outlet uses "Line" and "Load" terminals and the wire set from the circuit breaker must connect to the "Line" terminals. The new outlet or switch's wire connections will mimic the original. Normally the wire with the black insulation attaches to an outlet's "Hot" or "Live" terminals, and the white insulated wire connects to the neutral side. A standard switch should break the live wire; three-way switches also require a "Traveler" wire. The traveler wire lets both 3-way switches work together.
Identify and purchase the correct wire type and size. A 15-amp outlet or switch requires at least 14-gauge wire. A 20-amp device needs at least 12-gauge wire. A wire marked 14/2 NM-B with ground contains two insulated strands of 14-guage wire and an uninsulated strand inside of a non-metallic shield; a 12/2 marking indicates 12-gauge wire strands.
Prepare the New Light Switch or Electric Outlet's Location
Determine the new switch or outlet's approximate position on the wall. The exact location depends on the box's mounting style and the position of the wall studs. Some boxes attach to a wall stud, while others mount in a hollow area. Locate the wall studs, using either an electronic stud-finder or rap on the drywall while listening for the hollow area between the wall studs.
Hold a high-voltage remodel box against the wall. Trace the boxes outline on the wall with a pencil. Score the line with a utility knife. The blade tip should slice through the drywall's paper layer. Cut the hole with a drywall saw. Carefully pull out the rectangular drywall cutout. Look into the hole and verify that no obstructions exist, such as plumbing pipes, and move the hole appropriately. If the box mounts on a stud, remove enough drywall for the mounting bracket.
Install the New Wire
The new wire's route depends on the old and new electrical box's positions, and the obstacles between them. Simple applications, such as when the boxes share the same stud space, only require a short section of wire without much planning. The problem arises when the new box mounts in a different wall, especially when the drywall remains up.
Normally the solution involves drilling holes in the wall's top plate and fishing the new wire through the wall space. If the wire encountered a fire block, a piece of bracing that spans the space between two wall studs, open the drywall and drill a hole through the bracing for the wire to pass through. Remove a small section of drywall above the box. Reach a hand into the wall space and pull the wire down to the box. Loosen one of the existing outlet box's wire clamps, if equipped. Force about six inches of wire through the wire clamp and into the box.
Drill a hole in the top plate above the new outlet's stud space. Run the new wire across the attic. Estimate the distance from the top plate down to the new outlet box's position on the wall and add two feet; for example, a room with an eight-foot ceiling and a new light switch would need about 6.5 feet of wire. Cut the wire at the appropriate place. Push the wire through the top plate and fish the wire through the stud space. Pull the end of the wire out of the new outlet's drywall hole.
Mount the New Electrical Outlet Box
Push about 5 inches of wire into the new electrical outlet box. Tighten the wire clamp, if applicable. Plastic remodel boxes use tabs to hold the wire in place. The tabs close against the wire shield, preventing it from backing out. Push the wire and box into the hole. Secure the electrical box, using the appropriate method. Some remodel boxes use screw-activated locking tabs; others have a flange that attaches directly to the wall stud.
Making Proper Wire Connections
Proper wire connections keep the circuit safe and functional. The conductors within each wire set must touch solidly. Usually, an electrician uses a wire nut as a connection device; other devices are sometimes available, but seldom used.
Remove about 5 inches of the new wire set's shield with a utility knife. Use care to avoid nicking the wire insulation. Either straighten or cut off the bent ends of the old wire set. Strip 1/2 inch of the insulation from each wire strand.
Group the wires by function; for example, the white wires in each set usually acts as neutral. Select one group and position the bare ends against each other. Twist the ends clockwise with a set of pliers. Tighten a wire connector over the twisted ends. Some technicians wrap a short section of electrical tape around the end of the wire nut. Repeat this procedure for each wire group.
Carefully fold one wire grouping and position it to the rear of the electrical box. Repeat this with each set of wires. Cover the electrical box with a blank plate.
Wire New Light Switch or Electric Outlet
Pull the end of the wire set out of the new outlet box. Cut off the wire shield and strip the insulation as needed. Attach the wires to the device, using the notes taken during the old device's removal. Mount the light switch or outlet in the box. Install an outlet cover or switch plate. Turn on the circuit breaker and test the circuit.
© 2014 Bert Holopaw
Marina from Clarksville TN on December 28, 2014:
A great hub. Good to know some people can do this themselves.