Short Circuits

One telltale sign of a short circuit is black, smoky residue on switch or receptacle cover plates. Frayed or damaged cords and plugs also can be sources of short circuits. You need to check further for the source of the problem if your circuit goes dead and …

➤ You cannot find any visible signs of an electrical short.
➤ The circuit is not overloaded.

Before replacing the fuse or resetting the breaker, turn off all the loads and unplug everything from the receptacles. If the new fuse blows or the breaker trips right away, your problem is either in one of the devices (a switch or a receptacle) or in the wiring itself. To make sure the current is dead, remove all the cover plates and examine each device for charred wires or black residue. Clip the ends of any affected wires, strip off sufficient insulation, and install a new device. Replace the fuse or reset the breaker, and test the circuit again.
What if the circuit doesn’t short immediately after you set the breaker or replace the fuse? In that case, activate each load one at a time and then turn each one off. Check the load that eventually causes the short. The problem will be either in the fixture or appliance itself or in its wiring. Replace the offender and check the circuit again. If it still shorts out, you have a problem in the wiring itself and should call an electrician. Shorts in the wire almost always are at the device or fixture box, so the problem should be visible when you do your own inspection. Sometimes, however, the problem is caused by a splice or junction box buried in the wall and is therefore unnoticed upon first inspection. In the case of a plug-in appliance or lamp, if the circuit goes dead as soon as you insert the plug, you can assume the short is in the cord or the plug (both of which can easily be replaced). If the short doesn’t occur until after the appliance is turned on, the problem isn’t in the cord or the plug but in the appliance itself. You should then repair or replace the appliance.

Hot Electrical Equipments

The cover plate on a light switch or receptacle should not feel excessively warm and certainly should not be hot. A dimmer is an exception because dimmers dissipate the heat from dimming through the fins of the dimmer and often transfer some of that heat to the screws holding on the cover plate. Cords and plugs shouldn’t feel hot, either. Heat is a sign that the load is demanding current in excess of the ampacity of the electrical cable and/or the plug and cord attached to the load. If you replace a 60-watt light bulb with one of a larger wattage (one whose wattage exceeds the rating for the fixture), the wire or cable will still supply the current, even if doing so makes the fixture dangerous.
Heat signals that you should examine the total load on a circuit or a cord and plug.
In the case of a hot circuit, you should …

• Make sure the circuit breaker or fuse is the correct amperage for the circuit itself and the cable or wire that forms the circuit.
• Total the combined load on the circuit.
• If the load exceeds the circuit’s design, reduce the load. The real danger of an overloaded circuit is a wire heating up unseen inside your walls to the point where it can start a fire.

Electrical Warning Signs

Life is full of warning signs, but we don’t always pick up on them. A circuit that constantly burns out its fuse does not need a larger-amperage fuse. Instead, reduce some of the loads and their demand for current. Remember, electrical systems are very logical and safe when used intelligently. If you push them beyond their limits, all bets are off as to how well they’ll behave.
An orderly electrical system doesn’t overheat, start fires, or inordinately dim your lights. These are all signs that you have problems. (A fire means you’re too late.) If you have an older system that still uses fuses and does not have a grounding conductor, you need to be more observant of your usage and how your system reacts. Electrical problems sometimes require detective work. When an appliance doesn’t work at one receptacle, try it in another before you start tearing it apart. It might just be a bad receptacle or a loose terminal screw.
Remember that older, fuse-based systems weren’t designed for all the electrical loads we surround ourselves with today. These systems are safe when used judiciously.

Electrical Safety Rules

These are the basic safety rules you must remember:

• Never work on a live circuit, fixture, or device.
• Shut off power to a circuit before repairing a device or load on the circuit. Keep one arm behind your back (or otherwise away from the panel) when shutting off or turning on a circuit.
• Use a fuse puller to remove and replace fuses. Consider shutting off the power to the fuse box at the main disconnect.
• Tape over or otherwise mark a main switch, fuse socket, or circuit breaker that’s been shut off if you’re working anywhere on your electrical system. This tells others not to turn the power on. (Post a large note on the fuse box or service panel as well.)
• Always test to make sure the circuit has been shut off before doing any repairs.
• Always unplug a cord-and-plug appliance, lamp, or other similarly connected load before repairing it.
• Never stand in a puddle or on a wet surface when doing electrical repairs. Place a piece of wood on a damp floor and wear thick rubber boots to insulate your feet.

Trouble, Troubleshooting, and Safety

Residential electrical systems, especially newer installations or upgrades, usually just keep humming along. Cartoonists could depict billions of smiling, happy electrons zipping around our wires, one little electron holding hands with the next, doing our electrical bidding. But things can go bad. Bare wires can cross each other, appliances can short out, and lamp cords can become frayed. Your electrical system, unlike the institution of democracy, might not require constant vigilance, but you have to keep an eye on it. Circuit breakers that trip regularly and fuses that burn out too often are signs of a problem circuit. Dimming lights are a romantic touch when you control them with a dimmer switch but not when they dim on their own. Likewise, if your electric can opener shoots sparks like a Roman candle, it means you have a problem.
Safety should be emphasized as always, and you should pass this emphasis on to your children and anyone else living in your house. Thousands of people are electrocuted every year, many of them children, and they often require hospital care. A safe, monitored electrical system will prevent many needless injuries and possibly even deaths. Without any further lecturing, we’ll move on to scrutinize your wiring, devices, and appliances.

Plaster and Drywall Repair

Plaster is applied wet and is forced into wood or metal lath. As it dries, the material that has oozed onto the back side of the lath forms plaster keys that hold the plaster in place. After you’ve cut the lath away to run your cable, you have to either patch in new lath for backing or use a small section of drywall for your repair. The cleaner your access holes, the easier your repairs. You might have to repaint the entire wall (maybe the rest of the room, too), depending on how much the paint has faded.
Patching a hole in drywall is a little easier than doing the same with plaster. All you need to do is …

• Even up the hole in the wall by tracing an outline an inch or so in each direction. Take these dimensions and cut out an even rectangle or square of new drywall.
• Hold the drywall patch against the wall, trace around it, and cut out an even, level hole.
• Cut a second drywall patch two inches larger in each dimension.
• Drill a hole in the center of the larger patch and pass a cord through it, knotting one end so it holds tight against the hole.
• Apply construction adhesive to the outer two inches of the face of the patch.
• Insert the patch into the wall and align it with the hole. Pull it tight to the wall with the cord.
• Tie the other end of the string to a pencil or a small piece of scrap wood, and twist it until the patch holds tight. Tape the end of the wood to the patch so it doesn’t slip. (You also can screw through the wall and secure the patch.)
• After the adhesive has set, test the smaller patch for fit and trim down the edges if necessary. Drill a hole in the middle of the patch.
• Pull the cord through the second patch, and glue the smaller patch to the larger patch, securing it by twisting the cord.
• After the patch has set, cut the string and push any excess back into the hole. Apply fiberglass drywall tape to the edges, and cover the patch with a thin application of joint compound.
• When it’s dry, lightly sand the patch with 100-grit paper and apply a second coat of joint compound, spreading it slightly beyond the tape. Sand it when dry and apply a third coat if necessary.
• Run your hand over the patch after each layer of joint compound has dried. (You don’t want to end up with a lump.)

The Finish Work

Electrical boxes must be set so they’re flush with the surrounding wall or ceiling when wood framing is used for construction (NEC Section 370-21). The gaps around the box cannot be greater than 1/8 inch; anything greater must be filled with patching plaster. The code wants to diminish the possibility of a fire spreading if a device or fixture has a short circuit. Boxes are secured by
…
➤ Nailing to the stud or joist.
➤ Plaster ears.
➤ Snap-in brackets.

Metal boxes can be used with …

➤ Nonmetallic cable.
➤ Armored cable.
➤ Metal conduit.

Nail-on plastic or nonmetallic boxes can be used with nonmetallic cable. Others are rated for use with plastic conduit.