Adding a much-needed outlet to any room may be as simple as replacing an existing wall switch with a combination switch outlet. This can be done if the switch to be replaced is wired with the power source coming to it first, before being routed to the light fixture it controls.
Step 1: As with all electrical projects, use the breaker or fuse in your circuit panel to turn off the power to the switch to be replaced.
Step 2: Remove the switch cover plate and carefully pull the switch out of the outlet box. Leave all wires attached and use a voltage sensor to confirm the power is off before proceeding. Excluding the green or bare ground wires, if there are four wires running into the outlet box, with two being attached to the switch and the other two being tied together and not attached to the switch, you should be able to replace the switch with an outlet/switch combination.
Step 3: Without removing any wires, turn the power back on and use a voltage sensor to identify the single hot wire running to the switch. If there is more than one hot wire in the box, do not proceed any further. You will need to consult an electrician before continuing.
Step 4: Using the circuit panel, turn off the power to the switch again. Remove the hot wire from the existing switch. Use a wire nut and two short pieces of black 14-gauge solid wire to pig tail the hot wire onto the two black screws located on the combo switch. This will allow power to go to the switch and the outlet at the same time.
Step 5: Detach the second wire from the original switch and attach it to the silver screw on the side of the switch portion of the combo switch. Be sure to always wrap the wires clockwise so when the terminal screw is tightened the wire will be pulled in beneath it.
Step 6: Using an additional white piece of 14 gauge solid strand wire as a pig tail and a wire nut, attach one end of the pig tail to the two wires which are tied together and not attached to the existing switch. Attach the other end of the pig tail to the remaining gold screw located on the outlet side of the combo switch.
Step 7: If there is a ground wire attached to the old switch, remove it and attach it to the green screw on the combo switch. Check to be sure all wires on the combo switch are securely tightened beneath the terminal screws and wrap the outer edge of the combo switch with electrical tape.
Step 8: Carefully press the combo switch back into its outlet box, secure with mounting screws, attach a new cover plate designed to accommodate the combo switch and turn the power back on.