Power Cords

Any cord-and-plug combination is subject to damage and wear. Lots of pulling and twisting, especially when a plug is pulled out by the cord rather than by grasping the plug itself, can cause the wires inside the insulation to break. This is particularly true with lamp cords because they use wire composed of multiple strands with a very small gauge. If the insulation protecting a cord cracks open, you could get a short circuit. It’s usually a better idea to replace these cords than to repair them.
Although it is less likely that you’ll ever have to replace a 240-volt appliance cord, these also can be changed out:

• Unplug the cord and unscrew the end that’s attached to the appliance, noting which wire (by color) went with which screw.
• Buy an exact replacement for the cord and plug.
• Connect the new cord to the terminal screws on the appliance, noting any color coding on the screws to match the individual wires (black to black, and so on).

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.