Troubleshooting
 This section explains 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.
Changing Outlets
 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.
Repairing Lamps
 A common problem for lamps is a bad connection with the bulb and contact tab in the bottom of the socket. Make sure the lamp is unplugged. Use a screwdriver tip to scrape off any corrosion, and then prying it up a little.
If the problem remains, take apart the socket. Most sockets have a "PRESS" mark stamped into the upper cover. Squeeze the cover there, and work it off.
Remove the insulating cardboard sleeve. Check the wire connections. If they look good, the next thing to troubleshoot is the cord.
Remove the wires from the screw terminals, noting how they're connected. If there's a silver wire and a copper wire, the copper goes on the brass screw. If both leads are copper, the lead with the ridge on the side of the insulation goes to the brass screw.
 Use a continuity tester to check the cord. If there's a switch somewhere on the lamp or cord, make sure it's "ON" when you test.
If there's continuity in the cord, replace the inner socket. Be sure to get a replacement that matches the original.
We also add an "underwriters" knot that protects the new leads from being yanked off the terminals.
 Then connect the wires to the new socket. Twist the bare ends of the wire, hook them clockwise around the terminals and screw them down.
Put the socket inside the sleeve, and the sleeve inside the cover. Push the cover back down on the base and orient the switch in the desired direction.
If the lamp still doesn't work, it's a good idea to have a professional take a look at it.
Fixing Cord Plugs
 The plug end of a lamp or appliance cord may pull lose of it's cord connection. Replacement is fairly easy, however.
For basic flat cords, you can use a "quick-connect" plug. The plug pulls apart by squeezing the prongs together.
Feed the end of the plug through the back of the cover. Spread the prongs apart and insert the wire into the back of the core.
Squeeze the prongs together. They have small metal spikes that penetrate the cord's insulation to make contact with the copper wires inside.
Slide the cover down onto the core to complete the job. For a little stronger connection, use a plug with screw terminals.
 Start with a clean end on the cord -- sometimes called "zip cord" because the two side pull apart easily. Strip about 3/4" off the end of the two wires and twist the lead strands together tightly.
Hook each lead to fit around the screw terminals and attach the lead that has a ridge on the insulation to the silver terminal.
If the screws aren't color-coded, this lead goes to the wider plug prong. Work the cover back down over the core.
Fixing Grounded Cord Plugs
 Most cords with grounding plugs are molded right onto the cord end. However, they can fray and work loose. If this happens, it's best to replace the plug.
Cut off the old plug and strip the ends of the wire. Many cords have an outer sheathing of insulation. Strip it back about 1 1/2" with a utility knife and cut off the excess.
Strip about 3/4" off the end of each lead. Feed the cord through the plug's back cover and connect the wires. The plug terminals are located in the back.
 NOTE: Terminals on the face of replacement plugs covered by a removable cardboard disk are illegal and not a safe choice.
The green (ground) lead goes to the green screw. The white (neutral) lead goes on the silver terminal. The black lead goes around the brass screw.
Finally, put the cover over the plug and screw down the cord clamp.
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