Things You'll Need
14/2 electrical cable
When remodeling an older home or adding an addition, you may want to add extra electrical outlets. Wiring from an existing power source, like a light fixture, makes sense in these cases -- you already know where to tap into the power, and it makes it easy to add a switched outlet into your house. Switched outlets can be very useful when you want to coordinate lighting throughout the room to a single switch or dimmer on the wall.
Turn off the power to your light outlet at the breaker box. Put a note or piece of tape on the breaker box to warn others not to turn the breaker back on.
Remove your lighting fixture from the wall or ceiling. Lighting fixtures vary, but these general steps always apply: remove the shade or cover for the light, then undo the nut that holds the fixture in place. Pull the fixture away from the wall or ceiling and disconnect it from the existing wall/ceiling wiring by undoing the wire nuts connecting the wires. Put the light fixture to the side for the time being.
Run a new stretch of wiring from the light fixture to where you'll be locating the outlet. Secure the cable along the way with cable staples -- be careful not to nick the insulation of the wire with the cable staples.
Nail your gang box in place on a stud at the location of the new outlet. Push the new cable in through the opening.
Strip the ends of the new cable so that each strand, white and black, have 1/2 inch of bare wire exposed. Connect the bare wire to the new outlet -- black to the brass-colored screw, and white to the silver-colored screw. Secure the outlet in place in the gang box with its screws.
Connect the black and white wires at the light fixture end to the wires from the power source and light fixture, respectively. You'll put all three black cables into one wire nut, and all three white wires into the other wire nut.
Replace the light fixture, turn the power back on and test operation of the new outlet. Remember that it's a switched outlet -- it won't be live unless the light fixture is on.