Replacing Switches & Outlets
This section and the next explain how to repair some common household electrical problems. Remember, always make sure the circuit you'll be working on is shut off.
When you shut off a breaker or pull a fuse, post a message at the service panel (or fuse box) notifying others so they don't try to restore power while you're working.
Also, replace any device (i.e. switch, outlet) with one having the same number of terminals and power rating -- unless you know the original device was wrong for the job.
Outlets (receptacles) have to withstand the wear and tear of yanking cords out of the sockets. If an outlet is loose, or anything that's plugged into it flickers on and off, it's time to be replaced.
On its back side, an outlet is rated for voltage and amperage (125 volts and 15 amps is most common). Make sure to get a replacement with the same ratings.
Turn off the circuit breaker that controls the outlet. Test that the power is off by sticking both circuit tester probes in the outlet slots of each socket. No light means the power is off.
Take off the cover plate. Just to be safe, test the circuit again. This time, touch the probe to the screw terminals on both sides where the wires are attached.
Start with the top set of screws, and then test the bottom set. No light means no power, so the outlet is safe to work on.
Next, unscrew the outlet and pull it out of the wall box by the mounting tabs. The wires should unfold and stretch out so you can access them.
A grounded outlet has a round hole on the face in addition to the two slots. If there are three holes in the outlet face, there should be three wires attached to the outlet.
The black (hot) and white (neutral) wires carry the current, and the copper wire is the ground. Note that the outlet's screw terminals are certain colors.
The white wire goes on the silver screw. The bare copper or green wire goes on the green screw. And the black wire gets attached to the brass screw.
If the terminals aren't easy to identify by color, the ground terminal may be marked with a "GR." Also, the white wire goes to the side with the longer slot on the face. And the black wire always goes to the short slot side.
Make a note of how the wires are arranged and unscrew them. Bend each wire in a clockwise direction. Hook them around the new outlet's terminals so when the screws tighten, the wire pulls inward for a better connection
Screw the wires onto the new terminals, carefully push the outlet back into the box so the wires don't kink and tighten down the mounting screws and cover plate.
Replacing Three-Way Switches
Electricians get many repair calls when a homeowner has wired a three-way switch incorrectly. Or, an old three-way switch has been accidentally replaced with a single-pole switch, which won't operate the light correctly.
It's not necessary to understand the whole theory of how a three-way switch system is wired. But it's important to remember which wire was connected to the common screw of the old switch.
Before doing any electrical work, turn off the circuit. Double-check it with a circuit tester to make sure that it's dead.
Put one test lead on the ground (copper or green color) wire or box if it's metal, and the other test lead on the hot wire, then the neutral wire. If the light stays off, the circuit is dead.
Take off the cover plate and unscrew the switch from the box. It's easy to identify a three-way switch because it has three screws (two brass and one dark).
Pull the switch out and label the wire hooked to the dark "common" screw.
Unhook the old switch and hook up the new one: ground wire pigtailed to the box, travelers to the light-colored screws (interchangeable), and most important, the labeled wire to the darker "common" screw.
Fold the wires back in the box, attach the switch to the box, and put on the cover plate.