Moving a light switch (or other electrical connection, such as a receptacle) may seem like a daunting project. However, if you take necessary safety precautions and follow directions carefully, you can pull it off in five easy steps. The process described here can help you move a switch from one side of the wall to the other—for example, from the wall inside one room to the next room or hallway.
Step 1 - Take Safety Precautions Before Moving Your Light Switch
Safety Note: To prevent hazards from electrical shock, you must turn the circuit breaker off at the main panel. Confirm this is done by checking if the fixture or appliance attached still comes on when you flip the switch you want to move. Attach a message to the door of your circuit breaker panel warning anyone else not to touch any of the switches inside the panel while you're working.
Step 2 - Remove the Switch from the Wall
Since you're just moving the switch through a wall to the other side, you shouldn't need to install additional cables—the existing wiring should be fine.
2.1—Using a screwdriver, remove the cover plate from the switch box, then remove the screws holding the switch and pull the switch and wires out of the box as far as it goes. Put a multimeter across the black wire going to the switch's terminal and ground to confirm that it's not powered. Remove all the wire nuts and undo all connections, making a note where each wire goes.
If there are two cables inside the box, one of them goes to the fixture, while the other comes from the main panel's circuit breaker.
If there's only one cable, the cable brings the hot wire right from the fixture.
2.2—With the wires stretched out of the way, assess how the box is secured to the stud and remove screws or nails holding it in place. If that's not possible, you can gently pry the box away from the stud with a large flat screwdriver or a prybar, then use a saber saw with a short metal-cutting blade between the box and the studs to cut the nails off and release the box. The cable will keep the box from dropping out.
2.3—With the box loose inside the wall, look at where the cable goes in the box and grab the opposite end with pliers, and tilting it forward, pull on the box to bring it out of the wall through the opening but being careful not to damage the opening. If two cables go in at each end, one end can be freed by removing the locking nut from the cable connector then pushing the cable connector with all its wires inside the wall. You can then proceed with removing the box.
2.4—With the box out, you can remove the cable from the box by loosening the cable connector. The box should be or might be reusable for the other side.
Step 3 - Identify the New Location
3.1—With the long drill bit secured in the drill, place the drill bit perfectly horizontal up against the stud at the top corner of the opening and drill a hole through the drywall on the other side of the wall. You can then bring the bit down to the bottom corner of the opening and drill a second hole along the stud. Those two holes will provide you with the location of one side of the electric box at the new location.
3.2—Standing on the other side of the wall, trace a vertical line between the two holes previously drilled.
3.3—Place the electric box flat against the wall and, after positioning it along the line, trace the contour of the box on the wall.
Step 4 - Reinstalling the Box
4.1—Use a keyhole saw or a jigsaw to cut the opening in the drywall carefully. If carefully cut, the piece can be used to patch the old switch opening.
4.2—Bring the cables out through the opening. Pass one cable through the knock-out up to the cable connector and secure it to the box with the lock nut.
4.3—All the wires from the 2nd cable (if there was more than one) must be taped together along with a string about 10 inches long. You can then put the string through the 2nd knock-out from the outside in without pulling the wires through. That will permit reinsertion of the box in place exactly as it was removed, only in reverse order.
4.4—Align the box with the wall's surface, and with the long screwdriver bit and two screws, secure the box in place.
4.6—With this done, you can now pull on the string to bring the wires, and the cable connector in and secure it with the locking nut.
5.1—With all your wires stretched out of the box, take the ground wires, attach or twist them together, and connect them to the grounding screw terminal inside the box with an extra piece that will connect to the green ground terminal screw on the switch.
5.2a—You can now connect the two black wires to each of the two switch terminals and pigtail the two whites together, securing them with a wire nut.
5.2b—or if there is only one cable, connect it to one of the switches terminals while the white wire connects to the other terminal.
Back in Operation
You can now go back to the main panel and turn the breaker back on. All should be good to go and the switch should work fine.
With this done, the job can be completed by using the piece of drywall from step 4.1. Secure a thin piece of wood about six inches long to block the first opening, and screw it on level with the wall surface you're ready to patch.