Proper grounding of your electrical system is essential to your safety. Electricity always follows the path of least resistance, and that path could be you whenever an appliance or another electrical component is not grounded.
Grounding directs electrical energy into the earth by providing a conductor that is less resistant than you are. This is accomplished by attaching one end of the wire to the frame of an appliance and fastening the other end to a cold water pipe. Most plastic-coated electrical cable contains a bare wire, which carries the grounded connection to every electrical box, receptacle, and appliance in your home. You can usually tell whether your electrical system is grounded by checking the receptacles. If you have the kind that accepts plugs with two blades and one prong, your system should have three wires, one of which is a grounding wire. The prong carries the safety ground to the metal frame of any appliance that has a three-wire plug and cord.
An appliance’s metal frame can pose a safety hazard to you and your family. If a power cord’s insulation wears away just at the point where the cord enters the metal frame, contact between the metal current conductor and the metal frame could make the whole appliance alive with electricity. Touching a charged metal frame of the appliance while simultaneously touching a water faucet or a radiator will make the current surge through you.
There are other places throughout the electrical system where conductor/metal contact is a distinct possibility and a safety hazard. Be sure to inspect, maintain, and make repairs wherever wires enter a metal pipe (conduit), where the cord enters a lamp or lamp socket, and where in-wall cable enters an electrical box. Surfaces at these points must be free of burrs that could chafe the wire and damage its insulation. Washers and grommets protect the wire at these various points of entry. However, the best thing you can do to ensure a safe electrical system is to make sure the whole system is grounded, and the ground circuit is electrically continuous, without any breaks.
The bottom line is that you need to make
a top priority whenever you do home repairs. Furthermore, don’t hesitate to call on a professional electrician when necessary. On the next page, we’ll take a look at how to restore a circuit and what steps you should take in a power outage.
How to Restore a Circuit
The fuses or circuit breakers in your home electrical system are there for a purpose: to blow or trip if the circuit is overloaded. When that happens, as it does from time to time in almost every home, what do you do?
The first step should be taken even before a circuit trips. If you haven’t already done so, make a list of all the branch circuits in your home by number and by what area each one controls. Then you can figure out which receptacles and fixtures are on each branch circuit. If you aren’t sure the list is accurate and complete, you can verify it with a very simple procedure. Remove a fuse or trip a circuit breaker to its OFF position, then check to see what equipment or devices are deenergized. Of course, it’s easy to see when a ceiling light goes out, but you can check a receptacle just as easily by plugging in a lamp. A small night-light is an ideal indicator. Once you know exactly which receptacles, fixtures, and appliances are connected to each branch circuit, write all the information on a card, and attach the card inside the door of the main entrance panel.
When a circuit goes off, there may be some visual or audible indication of the trouble spot, such as a bright flare from a lamp or a sputtering, sparking sound from an appliance, that will immediately lead you to the source of the trouble. If so, disconnect the faulty equipment. Take a flashlight and go to the main entrance panel. Check to see which fuse is blown or which breaker has tripped, and determine from your information card which receptacles, appliances, and lighting fixtures are on the circuit. Then disconnect everything on that circuit you can then inspect those fixtures you can’t easily disconnect for signs (or smells) of malfunction.
Replace the fuse or reset the breaker. If the circuit holds, it’s possible something you disconnected is faulty. Check for short circuits or other problems. If there’s no evidence of electrical fault in the fixtures, the problem may be too much current draw for the circuit to handle. In this case, remove some of the load from the circuit.
If the new fuse blows or the circuit breaker refuses to reset, the problem lies in either the equipment that’s still connected or in the circuit cable itself. Check the still-connected items, examining each for faults until you find the offending equipment. If the circuit still goes out when there are no loads connected to it, the wiring is faulty, probably due to a short in a junction or receptacle box or in the cable itself. If you suspect faulty electrical wiring, call an electrician.
A circuit breaker is a remarkably trouble-free device, but occasionally a breaker does fail. The result is the circuit will not energize, even when it’s fault-free. When a circuit goes out, if the circuit breaker itself has a distinctive burnt plastic smell, if the trip handle is loose and wobbly, or if the breaker rattles when you move it, the breaker has probably failed. Turn off the circuit, check the breaker with a continuity tester, and replace it as needed.
Coping With a Power Outage
What do you do when all the power in the house goes off? Usually this is due to a general power outage in an entire neighborhood or district, but sometimes the problem lies in an individual residential wiring system.
The first step is to see whether the outage is a general power outage or restricted to your home. If it’s nighttime, look around the neighborhood to see if everyone else’s lights are off. During the day, call a neighbor to see if others are affected. Or, if you have a circuit breaker main disconnect, check to see whether it has tripped to the OFF position. If the main entrance is wired with fuses, pull the fuse block out and slip the fuses free. Check them with a continuity tester to see if they are still good. With a probe lead touched to each end of the fuse, the tester light will come on if the fuse is good.
If the trouble is a general power outage, all you can do is call the power company. If your main breaker is still in the ON position or both main fuses are good, but your neighbors have power and you don’t, the fault lies between your main entrance panel and the power transmission lines. The reason could be a downed service drop, a faulty or overloaded pole transformer, or some similar problem. Call the power company; this part of your system is their responsibility. If you find a tripped main breaker or blown main fuses in your main entrance panel, the problem lies within the house and may be serious. Do not attempt to reset the breaker or replace the fuses. The difficulty may be a system overload, using more total current than the main breaker can pass. Or there may be a dead short somewhere in the house.
The first step is to go back through the house and turn off everything you can. Then, if you have a circuit breaker panel, flip all the breakers to the OFF position. Once the breakers are off, reset the main breaker to the ON position. One by one, trip the branch circuit breakers back on. If one of them fails to reset, or if the main breaker trips off again as you trip the branch breaker on, the source of the trouble lies in that circuit. The circuit will have to be cleared of the fault.
If all the breakers go back on and the main breaker stays on, you’re faced with two possibilities. One is that something you disconnected earlier is faulty. Go back along the line, inspect each item for possible faults, and plug each one back in. Sooner or later, you’ll discover which one is causing the problem, either visually or by noticing that a breaker trips off when you reconnect it. The other possibility is systemwide overloading.
This is characterized by recurrent tripping out of the main breaker when practically everything in the house is running but there are no electrical faults to be found. To solve this problem, you can either lessen the total electrical load or install a new larger main entrance panel with new branch circuits to serve areas of heavy electrical usage and help share the total load. This job requires a licensed electrician.
The troubleshooting approach is similar if the main panel has fuses, except you’ll need a supply of fuses on hand. First, pull all the cartridge fuses and unscrew all the plug fuses in the panel. Replace the main fuses and put the fuse block back into place. Then, one by one, replace each fuse or set of fuses until the one that’s causing the outage blows out again. This is the circuit that must be cleared. General overloading, however, will cause the main fuses to go out again. If this happens, call in an electrician, who can test for overloading and suggest remedies.
Assembling an Emergency Blackout Kit
Is your home susceptible to power outages due to the local utility company, windstorms, or other problems? Even if it’s not, you would be well served to make an emergency blackout kit that includes the following items: Candles or oil lamps and matches for area lighting
- Flashlight, battery lantern, or other auxiliary light source for troubleshooting
- Correct and up-to-date circuit directory posted on main entrance panel door
- Tool kit with appropriate tools for making electrical repairs
- Circuit tester, preferably the voltage-readout type
- Two replacement plug fuses of each amperage rating in use, preferably Type S
- Four replacement cartridge fuses, including main fuses, of each amperage rating in use
- One replacement pulls circuit breaker of a rating equal to the smallest size in use or one of each size in use
- One replacement double-pull circuit breaker of each amperage rating in use
Selection of lightbulbs - One replacement duplex receptacle to match existing units
- One replacement single-pole switch to match existing units
- One replacement three-way or other special switches to match existing units
- Wire nuts and electrical tape
With a little preparation and knowledge, you’ll be able to handle your next power outage without being left in the dark. It also takes preparation and knowledge to do repairs and maintenance checks on home electrical receptacles. We’ll show you how to perform these tasks in the next section.
How to Restore a Circuit
Residential wiring systems installed in older homes use a two-wire system in the 110-120-volt branch circuits. One conductor is hot, and the other is neutral. The neutral may also serve as a ground, but, unfortunately, it usually does not. When this is the case, the system is ungrounded, and the situation is potentially hazardous.
You can easily tell if your circuits are of this type by looking at receptacles. There are only two slots for each plug-in ungrounded receptacles. Modern wiring calls for the installation of a third conductor. Receptacles used with this system have three openings: two vertical slots and a third, rounded hole centered below or above them. Either two-prong or three-prong plugs can be plugged into these receptacles, but only the three-prong kind will carry the equipment grounding line to the electrical equipment. Also, one of the vertical slots is different in size from the other, so the newer types of two-pronged plugs can be inserted in only one direction. This ensures that the equipment being connected will be properly polarized, hot side to hot side and neutral to neutral.
For proper operation and safety, make sure all receptacles on each circuit are installed with the individual conductors going to the correct terminals so there are no polarity reversals along the line. Unfortunately, receptacles are not always connected this way, even in new wiring systems installed by professional electricians. Check out your receptacles with a small inexpensive tester called a polarity checker, designed for this purpose. It looks like a fancy three-pronged plug and contains three neon bulb indicators.
To check your receptacles for polarity, plug a polarity checker into a receptacle. The lights will tell you if the polarity is correct and, if not, which lines are reversed. If there is a reversal, turn the circuit off, pull the receptacle out of the electrical box, and switch the wires to the proper terminals. If the equipment-grounding circuit is open (discontinuous), trace the circuit with a continuity tester until you find the disconnection or missing link; reconnect it to restore the effectiveness of the circuit.
Replacing an Electrical Receptacle
| What You’ll NeedHere are the tools you’ll want to have when replacing an electrical receptacle:Replacement receptacleScrewdriverSingle-edge razor blade or utility knifeGrounding screws or clipsWire stripper with cutting bladeNearly everyone has come across an electrical receptacle that doesn’t work as well as it should or one that doesn’t work at all. How does it happen that a receptacle fails to do its job efficiently and safely? There are two possible explanations.An electrical receptacle can be permanently damaged through improper use. Sticking a hairpin or a paperclip in it, for example, can shorten a receptacle — and your — life. You may never do anything as foolish as sticking a paperclip in an electrical receptacle, but you can do the same damage when you plug in an appliance with a short circuit. Regardless of how the damage occurred, the damaged electrical receptacle must be replaced.Another possible explanation for an electrical receptacle that doesn’t work efficiently and safely is that it is just so old and has been used so often that it’s worn out. There are two clear indications of a worn-out electrical receptacle: the cord’s weight pulls the plug out of the receptacle, or the plug blades do not make constant electrical contact within the receptacle slots. At that point, the old electrical receptacle should be replaced. This is not difficult, but you must follow the correct installation procedures precisely. Here’s what you should do:Step 1: Before working on the electrical receptacle, deenergize circuit that controls it. Inspect old receptacle to see whether it can take a plug with a round prong (for grounding) in addition to two flat blades. Buy a new receptacle with a 20-amp rating of the same type — grounded or ungrounded — as one you’re replacing.Step 2: Take off the plate that covers the receptacle by removing the center screw with a screwdriver. If the cover doesn’t come off easily, it’s probably being held in place by several coats of paint. Carefully cut paint closely around the edge of the cover plate with a razor blade or utility knife.Step 3: Remove two screws holding the receptacle in the electrical box. Carefully pull the receptacle out of the box as far as attached line wires allow. Loosen terminal screws on receptacle and remove line wires. Caution: If wires or insulation is brittle or frayed, that part of circuit should be professionally rewired.A replacement receptacle must match the one you are removing. If you have the grounded type, you must buy a receptacle that has a ground terminal screw and slots for three-prong grounded plugs.Step 4: Connect wires to the new electrical receptacle with white wire under silver-color screw and black wire under dark-color screw. If you discover a green wire or a bare wire in a box, fasten the wire under a screw that has a dab of green color on it, then fasten it to the box with a grounding screw or clip. Make sure to loop line wires in clockwise direction under heads of terminal screws so screw heads will pull wire loops tighter. Also take care to connect wires so all wire without any insulation is secured safely under screw heads. Clip off any excess uninsulated wire.Step 5: Carefully fold wires into space in the electrical box behind the receptacle, then push the receptacle into the box. Although there’s no such thing as right side up for a two-blade receptacle, there is a correct position for receptacles designed to handle three-prong grounding plugs. Grounding plugs often attach to their cords at a right angle, so you should position the receptacle so the cord will hang down without a loop.Step 6: Tighten the two screws that hold the receptacle in the receptacle box, then replace the cover plate. Restore fuse or trip circuit breaker.Slots in some electrical receptacles are not identical; one is wider than the other. The wider one connects to the white or neutral wire, while the narrower slot connects to the black or hot wire. Some plugs, in fact, are designed with one wide and one narrow blade, and these plugs will fit into the receptacle in only one way. The idea behind such a polarized plug is to continue the hot and neutral wire identity from the circuit to the appliance. |