Perhaps a remodelling job has left an old electrical switch in a location that makes it impossible to find in the dark. Or perhaps a large piece of furniture has been positioned so that you cannot reach the light switch. No matter the reason, a poorly situated electrical switch can be a constant source of annoyance. The effort invested in moving that electrical switch box to a more practical location could make the job well worth the time and expense.
Turn off the electrical breaker for the light and switch box. Unscrew the face plate of the light switch. Unscrew the light switch from the gang box. Pull the light switch out of the gang box. Make a note on paper, for later reference, of how the black, white and copper wires are attached to the switch. Unscrew the wires from the electrical switch.
Mark the new switch location on the wall by outlining a new gang box with pencil. Make certain there are no studs behind the new location by hammering nails through the new wall location in several places. Move the switch location laterally if necessary to avoid all studs. Cut out the outlined section with a drywall saw or utility knife.
Mark two horizontal lines on the wall with a pencil and straight edge about 4 and 8 inches above the floor level between the old and new switch locations. Locate the wall studs nearest to the old and new switch locations with a stud finder or by hammering nails into the drywall. Mark two vertical lines connecting the two horizontal lines in the centre of the studs closest to the old and new switch locations. Cut and remove the rectangular piece of wall that you have marked using a drywall saw or utility knife, making shallow cuts so as not to damage any pipes or wires in the wall. Drill 1-inch holes horizontally in all studs through which the electrical wire must be run between the old and new switch location.
Measure the horizontal distance along the floor between the old and new switch locations. Measure the vertical distances from the floor to both of the switch locations and add 18 to 24 inches to the sum of those measurements. Cut a piece of 12-2 electrical wire this length. Strip the insulation off both ends of this wire, similar to how the existing wire in the switch box was stripped.
Create an opening in the bottom rear of the old switch box by striking a knockout hole with a hammer and screwdriver. Insert one end of the 12-2 wire into the old switch box through the knockout hole down inside the wall and out the hole near the floor. Pull the wire through all holes drilled in the studs. Run the wire up inside the wall and out the hole for the new switch.
Remove one of the knockout holes in the new gang box with a hammer and screwdriver. Run the 12-2 wire through that hole from the back of the gang box. Insert the gang box into the hole in the wall. Tighten the two mounting screws with a screwdriver.
Attach the light switch to the 12-2 wire in the new gang box, identical to how it was previously attached. Press the excess wire into the gang box. Screw the switch to the gang box. Screw the cover plate over the switch.
Attach both white wires together in the old gang box using wire nuts. Repeat this with both black wires and with the copper wires. Press the excess wire into the gang box. Screw a blank gang wall plate over the old gang box.
Repair the hole in the wall with sheet rock, plaster joint compound and drywall tape. Paint the wall. Turn the electrical breaker back on.
Note that it will rarely be feasible to literally "move" the electrical switch box, since building codes require you to leave a box in the old location to protect the electrical connections. If for some reason you do choose to move the old box to the new location, install a new box in the old location to house the electrical connections. This, however, will require more work than simply installing a new box in the new location. An "old work" electrical gang box is perfectly suited for this job, since it fastens snugly into the hole you cut in the drywall, instead of needing to be nailed to a stud like a "new work" box. 12-2 wire contains 1 white wire, 1 black wire and 1 bare copper wire (ground wire). 12-2 wire will be sufficient for the majority of electrical switches. If your switch requires more wires, buy a wire that contains the required number of wires inside.
Do not attempt to work with electricity if you are not properly trained or if you do not know the local electrical codes and standards.