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Electrical Repair Basics
Your home's plumbing and electrical systems may seem as different as any two things could be. But there are significant parallels. Water enters your home through a pipe under pressure, and, when you turn on a tap, the water flows at a certain rate (gallons per minute). Electricity enters your home through wires, also under pressure (called voltage, measured in volts). When you turn on an electrical device, the electricity flows at a certain rate (current, measured in amperes, or amps).Unlike water, which is used as it comes from the tap, electricity is meant to do work: It is converted from energy to power, measured in watts. Since household electrical consumption is relatively high, the unit of measure most often used is the kilowatt, which is equal to 1,000 watts. The total amount of electrical energy you use in any period is measured in terms of kilowatt-hours (kwh).
 ©2006 Publications International, Ltd. The electrical service drop, or supply line, and the meter are as far as the local utility company is involved in your home's electrical system. From that point on, the system is your responsibility. |
The second type of electric meter performs the same function, but, instead of having individual dials, it has numerals in slots on the meter face, much like an odometer in a car. This meter is read from left to right, and the numbers indicate total electrical consumption. Some meters also use a multiplying factor -- the number that appears must be multiplied by ten, for instance, for a true figure in kilowatt-hours. Once you know how to read your meter, you can verify the charges on your electric bill and become a better watchdog of electrical energy consumption in your home.
Three main lines (older houses may have two) are responsible for supplying 110-120/220-240 volts AC (alternating current) to your home. The exact voltage varies depending on several external factors. This three-wire system provides you with 110-120-volt power for lighting, receptacles, and small appliances as well as 220-240-volt power for air conditioning, an electric range, a clothes dryer, a water heater, and, in some homes, electric heating.
Electricity enters your home through the power company's service equipment, which is simply a disconnect device mounted in an approved enclosure. It's used to disconnect the service from the interior wiring system. Usually called a main fuse, main breaker, main disconnect, or often just "the main," this disconnect might be a set of pull-out fuses, a circuit breaker, or a large switch.
Although main disconnects can be mounted outdoors in a weatherproof box, they are nearly always inside the house in a large enclosure that also contains the fuses or circuit breakers, which handle the distribution of power throughout the building. This is called a main entrance panel, a main box, or an entrance box. The three wires from the meter enter this box. Two of them -- the heavily insulated black and red lines -- are attached to the tops of a parallel pair of exposed heavy copper bars, called buses, at the center of the box. These two lines are the "live," or "hot," wires. The third wire, generally bare, is the "neutral." It is attached to a separate grounding bar, or bus, that is a silver-color strip in the main box. In most homes this ground bus is actually connected to the ground -- the earth -- by a heavy solid copper wire clamped to a cold water pipe or to an underground bar or plate.
Overload Protection
Power is distributed through your house through various electrical circuits that start in the main entrance panel. The 110-120-volt circuits have two conductors -- one neutral (white) wire and one hot (black) wire. The 220-240-volt circuits may have two hot wires alone or a third, neutral wire may be added. In all cases, the hot lines are attached directly to the hot main buses. The neutral wire is always connected to the ground bus and never, under any circumstances, should it pass through a fuse or circuit breaker.
 ©2006 Publications International, Ltd. Circuit breakers do not blow like fuses. They are switches that automatically trip open to interrupt the flow of electrical current when it overloads the circuit. |
Caution: Never try to defeat this built-in safety system by replacing a fuse with one of a higher current-carrying capacity. The fuse or circuit breaker capacity should be equal to or less than the current-carrying capacity of the conductors. For example, don't replace a 15-ampere fuse with a 25-ampere fuse. Replace fuses and breakers only with ones of the same size and amperage.
Circuit breakers do not blow like fuses; they are switches that automatically trip open to interrupt the flow of electrical current when it overloads the circuit. To reset a tripped breaker, turn it fully off and then back on.
Branch and Feeder Circuits
Circuits to all the devices in your home that require electrical power start from the fuses or circuit breakers. There are two types of circuits: feeder and branch. Feeder circuits use thicker cables that travel from the main entrance panel to smaller distribution panels called subpanels, or load centers. These auxiliary panels are located in remote parts of a house or in outbuildings, and they are used for redistribution of power, such as in a garage. Feeder circuits aren't found in all houses.
All of the circuits in a home that run from either the main entrance panel or from other smaller panels to the various points of use are branch circuits. For 110-120-volt needs, a circuit branches out through a circuit breaker from one of the main buses and from the ground bus. For 220-240 volts, many circuits use only the two main buses. But all three wires are needed for devices that operate on both 110-120 volts and 220-240 volts.
 ©2006 Publications International, Ltd. Newer homes have three incoming power lines that supply 110-120⁄220-240 volts AC. This provides 110-120 volts for lighting, outlets, and small appliances and 220-240 volts for heavier appliances. |
A 15-amp circuit can handle a total of 1,800 watts, while a 20-amp circuit can handle a total of 2,400 watts, but these figures represent circuits that are fully loaded. In practice, you should limit the load on a 15-amp circuit to no more than 1,440 watts, and the load on a 20-amp line should exceed no more than 1,920 watts.
How can you know the load on a circuit? Add up the individual wattages for all lamps and appliances plugged into each circuit. When computing the load on each branch circuit, allow for motor-driven appliances that draw more current when the motor is just starting up than when it's running. A refrigerator, for example, might draw up to 15 amps initially but will quickly settle down to around 4 amps. Suppose the refrigerator is plugged into a 20-amp branch circuit and a 1,000-watt electric toaster (which draws a little more than 8 amps) is also plugged into that circuit. If the refrigerator motor starts while the toaster is toasting, the total current load will exceed the current-carrying capacity of the circuit, and the fuse will blow or the circuit breaker will trip.
Keep reading to learn about proper safety practices when you're working with your home electricity system.
Electrical Safety Tips
Some home electrical repairs require a licensed electrician, but the repair or replacement of many electrical components can be done by a do-it-yourselfer. Make safety your first priority, and you'll be amazed at what you can do to maintain and upgrade the electrical devices in your home.All electrical devices and electrical wires are designed to provide the greatest measure of electrical safety, but you can defeat any built-in safeguards with carelessness and ignorance. To work safely with electricity, be aware of the following hazards and precautions:
- Never do anything that would break the conductor's insulation. Do not, for example, staple an extension cord to a baseboard or wall. The staple can cut through the insulation and create a short circuit, which, in turn, can start a fire. Moreover, you should examine all wiring regularly and discard any cord with brittle insulation. Replace the old cord with a new one that has good insulation.
©2006 Publications International, Ltd.
Examine wiring regularly for safety reasons. Replace cords
that have brittle or damaged insulation.
- Turn the power off before replacing a receptacle or a switch or doing any other work on a circuit. If your system operates with fuses, remove the fuse for the circuit you're working on and slip it into your pocket or toolbox. If you leave it nearby, someone might put the fuse back in while you're working on the circuit. If your home's electrical system uses circuit breakers, trip the appropriate circuit breaker to its OFF position. Then, to make sure no one accidentally flips the circuit breaker back on while you're working, put a piece of tape and a sign over the circuit breaker's handle telling people what you're doing.
- When you work on an electrical circuit, make all wire joints and connections inside an approved electrical box. There are several ways to join wires, but the best way is to use solderless connectors of either the crimp-on or screw-on wirenut kind. Never connect wires together in a behind-the-wall or in-the-ceiling location that is not accessible by simply opening an electrical box. In addition, when joining insulated wires to one another or when fastening them under terminal screws, make sure no uninsulated or bare wire extends beyond the connection. The insulation should go right up to the solderless connector or terminal screw.
©2006 Publications International, Ltd.
One of the best ways to join wires is to use solderless connectors called
wirenuts. Twist the conductor ends together, and screw the wirenut
into the twisted ends. Make sure no bare conductor is exposed.
- Everyone in the family should know where and how to throw the master switch that cuts off all electrical current.
- If there's a chance of contact between water and electricity, do not wade in water until the master switch has been shut off.
- Always assume an electrical receptacle or apparatus is energized until you prove otherwise with a circuit tester or by pulling a fuse or tripping the disconnect plug.
- Use only insulated pliers when working with electricity.
- Stand on a dry board or wooden platform when working with a fuse box or circuit breaker box. Also, use a wooden rather than an aluminum stepladder to minimize the risk of shock when working with electrical wiring.
- You can save time by determining which electrical circuits activate which receptacles in your home and then diagramming or printing the information inside the circuit breaker or fuse box.
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 coldwater 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 electrical safety 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 and Cope With a Power Outage
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, and 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 once in a while 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 fault, 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, wind storms, or other problems? Even if it's not, you would be well served to make an emergency blackout kit that includes the following items:
 ©2006 Publications International, Ltd. Some items for a blackout kit. |
- 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 pull 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
- Wirenuts and electrical tape
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 Check Receptacle Polarity and Replace a Receptacle
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.
 ©2006 Publications International, Ltd. A plug-in polarity checker can enable you to make sure your outlets are installed properly. |
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
Nearly 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.
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You may never do anything as foolish as sticking a paper clip 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:
 ©2006 Publications International, Ltd. When replacing a receptacle, see whether it accepts only plugs with two flat blades or whether it can take plugs that have a rounded ground prong. |
Step 2: Take off plate that covers receptacle by removing center screw with screwdriver. If cover doesn't come off easily, it's probably being held in place by several coats of paint. Carefully cut paint closely around edge of cover plate with razor blade or utility knife.
Step 3: Remove two screws holding receptacle in electrical box. Carefully pull receptacle out of 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.
 ©2006 Publications International, Ltd. 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 5: Carefully fold wires into space in electrical box behind receptacle, then push receptacle into 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 receptacle so cord will hang down without a loop.
Step 6: Tighten the two screws that hold receptacle in receptacle box, then replace 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.
Keep reading to learn how to do another useful home electrical repair: replacing a wall switch.
How to Replace a Wall Switch
Sometimes a light fixture that's in perfect operating condition doesn't work because the wall switch to the receptacle is faulty. There are several primary symptoms of switch failure:
Here are the tools you will want to have on hand when replacing a wall switch.
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- the switch loses its snap or there is no clear distinction between the ON/OFF positions
- flipping the switch no longer turns the light on or off
- flipping the switch makes the light flicker, but the light will not stay on or off
- the switch may work occasionally, but you have to jiggle it back and forth several times to keep the light on
Step 1: Deenergize electrical circuit that controls switch.
Step 2: Remove switch cover plate. If cover plate doesn't come off easily, it is probably being held in place by several layers of paint. Use razor blade or utility knife to cut paint closely around edge of plate to free it.
 ©2006 Publications International, Ltd. There are different types of switches available, but all work on the same general principles. Usually, you can base your selection of a replacement switch on the features you like best. |
Step 4: Prepare new switch for installation. Some kinds of wall switches have no terminal screws for conductor attachments. Instead, switch has small holes that are only slightly larger than bare copper conductors. Remove about 1/2 inch of insulation from ends of wires, then push bare ends into holes. Locking tabs make electrical connection and grip wires so they can't pull out. If necessary, release wires from old switch by inserting narrow-blade screwdriver in slots next to wire-grip holes.
 ©2006 Publications International, Ltd. Some switches and receptacles don't have terminal screws. They have holes into which the stripped wire ends are inserted. Other types, like this one, have both holes and terminal screws. |
Step 6: Loosen one of the old terminal screws, remove wire, and attach wire to corresponding terminal screw on new switch. Repeat with remaining wires. Take care to connect wires so all bare wire is safely under screw heads; clip off any excess uninsulated wire. Procedure is the same whether you're working with simple ON/OFF switch or three-way switch, but you must be more careful with the latter. Verify wiring by comparing it with manufacturer's diagram on packaging of new switch.
Step 7: If you're installing modern wire-grip type of wall switch, cut off end of each wire to leave only 1/2 inch of bare wire. Push one bare end wire into each wire-grip hole, and check that wires have caught properly by tugging gently on them. Caution: If wires or insulation going into electrical box are brittle or frayed, that part of circuit should be professionally rewired.
 ©2006 Publications International, Ltd. If a switch has only two terminal screws with wires attached, it's a simple ON/OFF (single-pole) switch. This type of switch is very easy to install. Connect the line wires to the screws, secure the switch, and replace cover plate. |
Step 9: Put switch back into place, using two mounting screws provided with new switch. Oval holes in mounting bracket allow you to fasten switch so it's straight up and down even when screw holes in electrical box are tilted.
Step 10: Attach cover plate with screws you took out earlier, and replace circuit fuse or trip circuit breaker back on.
 ©2006 Publications International, Ltd. Three-way switches allow you to turn a light on and off from two different locations, such as at the top or the bottom of a stairway. |
Need to rewire a lamp? Keep reading to find out how.
How to Rewire a Lamp
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Lamp cord is known as Type SPT, or zip cord. The #18 size is satisfactory for most lamp applications. Zip cord is available in many colors, the most common being black, brown, white, and transparent. Match the cord color to the lamp stand or the wall that holds the receptacle. The customary length is 6 feet, but you can use as much cord as you need to reach from the lamp to the receptacle.
To figure out how much cord to buy, calculate the length of the cord (including cord that is hidden in the lamp), and add 1 foot for attachments to socket and plug and for slack. In terms of safety and appearance, it's better to have an adequate length of cord than to compensate for a short one with an extension cord.
Follow these steps for rewiring a lamp:
Step 1: Pull plug out of wall socket. You should never do any work while lamp is connected.
 ©2006 Publications International, Ltd. Fixing a lamp is not difficult; the electrical components are inexpensive and easy to replace. The parts that are most often responsible for lamp failure are the socket, the cord, and the plug. |
Step 4: To remove tight cord, cut wire off about 12 inches from lamp's base, slit cord's two conductors apart, and strip about an inch of insulation off ends. Do the same to one end of new length of cord.
 ©2006 Publications International, Ltd. On screw-type plugs, insert the cord, tie the wires into a knot, and pull the knot down into the plug. Then loop each wire around a prong before tightening the bare end under the screw head. This helps keep the wires from touching each other accidentally. |
Step 5: Once you pass new cord through lamp, split end so you have about 3 inches of separated conductors. Use wire stripper tool to strip about 3/4 inch of insulation from end of each conductor, then twist strands of each together. Be careful not to nick strands when you strip insulation.
Step 6: Bend twisted end of each wire into clockwise loop, and place each loop under terminal screw on socket with loop curled clockwise around screw. Tighten terminal screws. As each screw is tightened, clockwise loop will pull wire tighter under screw head. (A counterclockwise loop would tend to loosen wire.)
Clip off excess bare wire with diagonal cutters. All uninsulated wire must be under screw heads, with no loose strands or exposed bare wire. If bare wire is visible beyond screw heads, unscrew terminals, remove wires, and make connection again.
Step 7: Slide socket shell over insulator, and slip shell and insulator over socket. Then snap shell and socket into cap.
 ©2006 Publications International, Ltd. A quick-clamp plug is very easy to install. Metal prongs inside the plug bite through the cord's insulation and pierce the copper wires inside to make the electrical connection. |
Step 9: Tighten wires under screw heads, and clip off any excess uninsulated conductor before you plug in lamp.
Now that you know how to rewire a lamp, we'll shed some light in the next section on how to replace an incandescent fixture.
How to Replace an Incandescent Light
Replacing a light fixture is relatively simple. In fact, the biggest problem you'll probably encounter is the mechanical complexities of attaching a new fixture to older mounting hardware.
Here are the tools you will want to have on hand when replacing an incandescent light fixture.
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Step 1: Before you replace or repair any light fixture, deenergize the electrical circuit by pulling the appropriate fuse or by tripping the proper circuit breaker.
Step 2: Take off the light cover, unscrew bulb(s), and disassemble all mounting hardware. Usually there are just screws holding the fixture against the wall or ceiling. If the light fixture has no visible mounting hardware, it could have a decorative feature that doubles as a fastener. Take off the mounting hardware and withdraw the fixture from the electrical box.
 ©2006 Publications International, Ltd. The simplest fixture installation uses a fixture strap secured to the electrical box. Connect white wire to white and black to black. |
For fixture installation in standard electrical box:
Make sure you have about 3⁄4 inch of bare copper conductor on the end of each line wire before you start to connect the wires of your new lighting fixture. If necessary, remove enough insulation from the line wires so you can twist each line wire end together with the end of each light fixture wire, white wire to white wire and black to black. Screw the wirenut tightly over each pair of twisted ends. Hold onto the fixture to support its weight until you attach the mounting screws; otherwise, you might break a connection or damage the fixture wires.
If fixture has more than one socket:
Connect the black wire from each socket to the black line wire and the white wire from each socket to the white line wire. When three or four socket wires are joined to the line, use the larger wirenut.
 ©2006 Publications International, Ltd. Some fixtures don't use a mounting strap; the fixture is secured to the stud with a "hickey," or reducing nut. |
Step 5: Tighten the screws, being careful not to overtighten them; they should be just snug enough to hold the fixture firmly in place. If you tighten the mounting screws too much, you may distort and misalign the fixture. With the fixture mounted properly, screw in the bulbs and attach the globe or cover.
Step 6: Replace the fuse or trip circuit breaker back on.
 ©2006 Publications International, Ltd. If there is more than one socket, connect the white wire from each socket to the white line wire and the black wire to the black line wire. |
Other light fixtures are not strap-mounted. Instead, a nipple is connected to the box stud with a reducing nut or an adapter called a "hickey." A reducing nut is threaded at one end to fit the stud and at the other end to fit the nipple. To mount a fixture that uses a reducing nut, screw the nut onto the stud and the nipple onto the nut. Set the fixture onto the nipple, set the fixture into place, and screw a cap nut onto the nipple to hold the fixture in place. To mount a fixture with a hickey, screw the hickey onto the stud, and then mount the fixture the same way.
What if the fixture you need to replace is fluorescent, not incandescent? On the next page, we'll discuss the finer points of replacing fluorescent lighting fixtures.
How to Install a Fluorescent Light
How does a fluorescent lamp work? In a fluorescent circuit, beginning at the left-hand prong of the plug, current goes through the ballast, through one of the lamp filaments, through the closed switch in the starter, through the other filament in the lamp, and out the right-hand prong of the plug. The current heats the two small elements in the ends of the fluorescent tube; then the starter opens and current flows through the lamp.
The ballast is a magnetic coil that adjusts the current through the tube. It makes a surge of current arc through the tube when the starter opens, and then it keeps the current flowing at the right rate once the tube is glowing. In most fluorescent fixtures, the starter is an automatic switch. Once it senses that the lamp is glowing, it stays open. The starter closes whenever you deenergize the fixture.
 ©2006 Publications International, Ltd. A fluorescent fixture has three main parts -- the bulb, ballast, and starter. When one of these components malfunctions, replacement is usually the answer. |
Since there are only three primary parts in a fluorescent lamp, you can usually take care of any repairs yourself. All fluorescent lamps grow dimmer with age, and they may even begin to flicker or flash on and off. These are warning signals, and you should make the necessary repairs as soon as you notice any change in the lamp's normal performance. A dim tube usually requires replacement, and failure to replace it can strain other parts of the fixture. Likewise, repeated flickering or flashing will wear out the starter, causing the insulation at the starter to deteriorate.
 ©2006 Publications International, Ltd. To install a new fluorescent tube, insert the tube's prongs into the holder and twist the tube to lock it into place. Change the tube when it dims, flickers, or flashes on and off. |
 ©2006 Publicatioins International, Ltd. To install a starter in a fluorescent fixture, simply insert the starter and twist it to secure it in its socket. |
The ballast is also rated according to wattage, and a replacement ballast -- like a replacement starter -- must match the wattage of the tube and the type of fixture. The ballast is the least likely part to fail and most difficult to replace, so leave the ballast for last when you start replacing parts. If neither the tube nor the starter is defective, the problem must be the ballast. To replace a faulty ballast, deenergize the circuit, disassemble the fixture, transfer wires from the old ballast to the new one -- one at a time, to avoid an incorrect connection -- and, finally, reassemble the
fixture.
If the tube, the starter, and the ballast are all working properly but the lamp still doesn't light, check for a defective switch. If the lamp is controlled by a wall switch, replace the switch, as detailed in the next section. If the lamp has a push-button switch, the old switch can be replaced by a new one of the same type. To deenergize the circuit before working on the switch, remove the circuit's fuse or trip the circuit breaker.
In most cases, the switch screws into a threaded mounting nut on the inside of the lamp. Two wires from the switch are connected, usually with wirenuts, to four wires from the fluorescent tube. Disassemble the fixture as far as necessary to gain access to the back of the switch, then screw in the new switch and transfer wires from the old switch to the new one, one at a time to avoid an incorrect connection. Reassemble the fixture, and reenergize the circuit.
If you're considering installing a new ballast or a new switch, consider putting in an entirely new fixture. An old fluorescent fixture suffers the same aging effects that an incandescent fixture does. Of course, you can also replace an old incandescent lamp with a new fluorescent model. Either replacement is well within the capabilities of the do-it-yourselfer.
Here are the steps to take when installing a fluorescent fixture:
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Step 2: Remove old hardware that holds existing lamp fixture in place, and disconnect lamp wires from circuit line wires. Then disassemble new fluorescent lamp as far as necessary to gain access to fixture wires.
Step 3: Connect fixture wires to line wires with wirenuts or crimp-type solderless connectors. Match wires by color: white wire to white, black to black.
Step 4: Position fixture against ceiling, and fasten it with screws packaged with new lamp. You may have to reassemble fixture, either before or after mounting it, depending on its style. Restore power.
Keep reading to learn how to troubleshoot and repair your doorbell.
How to Repair a Doorbell
When your doorbell or door chime doesn't ring, the fault could be in any part of the circuitry -- the button, the bell or chime, or the transformer. The transformer is the electrical component that steps down the 110-120-volt current to the 10 to 18 volts at which doorbells and chimes operate. You can work safely on all parts of a doorbell circuit except the transformer without disconnecting the power. If you don't know which part of the circuit is faulty:
Here are the tools you'll want to have on hand when repairing a doorbell.
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Step 2: Pull out button as far as circuit wires allow, then detach wires by loosening terminal screws on button. Bring the two bare wire ends together. If bell rings, you know fault is in button. Install new one by connecting the two wires to terminal screws of new button and reattaching button to your house. Doorbell button is a single-pole switch (two wires attached), and you can place either wire under either screw.
Step 3: If bell doesn't ring when you bring the two bare wire ends together, fault lies elsewhere -- in bell or chime assembly, wiring, or transformer. Remove snap-on cover of bell or chime. Removal may be harder than you expect; there are several different types of covers, and you may have to try several procedures. Try lifting cover slightly upward and then pulling it out. If this doesn't work, pull it straight out without first lifting it up. Or look to see whether snap-on cover is held to bell or chime assembly with prongs; if so, depress prongs and pull cover to release it. Whatever you do, never pull so hard that you risk damaging decorative cover.
Step 4: Once cover is removed, look for two, three, or more terminals and wires, depending on how many tones ring in your doorbell system. A standard bell or buzzer has two wires. Detach wires by loosening terminal screws, then connect them to 12-volt circuit tester, or attach them to terminal screws on substitute bell or chime. An inexpensive bell or buzzer or a 12-volt car lamp bulb in a socket with two wires can be used for testing purposes. If test bell or buzzer sounds or bulb lights when you push doorbell button, you will have to install new bell or chime.
 ©2006 Publications International, Ltd. If your doorbell or chime doesn't work, the fault could be in any part of the circuitry -- from a push button to the bell or chimes to the transformer. Before removing any wires at the terminal strip, it's a good idea to tag them so they can be replaced correctly. |
Step 6: If bell doesn't ring or bulb doesn't light at button or bell box, both are okay. By process of elimination, you now know problem must be in transformer or wiring. You'll usually find transformer mounted on electrical junction box, subpanel, or main entrance panel. Bell wires are attached to exposed terminal screws on transformer. Connect test bell directly to exposed low-voltage transformer terminals; don't touch any other screws. If bell doesn't ring, transformer is defective or not getting power. Caution: Transformer is connected directly to power supply, and it carries current that can hurt you. Before working on transformer, deenergize branch circuit that supplies power to transformer. Remove appropriate fuse, trip correct circuit breaker, or throw main switch to shut off all electricity in your home.
Step 8: If transformer is defective, deenergize circuit, and remove transformer. Buy replacement transformer of the same voltage and wattage. You can find electrical information stamped on transformer, and you should find installation instructions on package. Follow instructions carefully. Use crimp-on connectors or wirenuts to attach new transformer to circuit line wires of your electrical system. Then connect bell wires to low-voltage screw terminals on transformer, turn power back on, and press doorbell button. If you've installed transformer properly, you should hear bell or chime.
Step 9: If transformer and its power circuit prove to be working, the only possibility left is a break or loose connection somewhere in bell wiring. Trace bell circuit from transformer to bell or chime to push buttons, searching for loose terminal screw or wire joint. If this proves unsuccessful, you'll have to check each segment of circuit with continuity tester.
Step 10: To test each segment of circuit, disconnect bell wires at transformer to deenergize bell circuit. A continuity tester can never be used on an energized circuit. Disconnect transformer wires at bell or chime, and twist them together so they make contact with one another. Go back to transformer and touch probe leads of continuity tester to bare ends of bell wires. If tester lights up or you get a reading on meter dial, circuit has continuity and there are no breaks or loose connections in line. That part of the circuit is all right. If tester does not register, there's a break somewhere. If that segment is fault-free, go on to next segment and check it the same way.
Step 11: If there is a break, you must try to locate it and make repairs. Sometimes, however, especially where much of the bell circuit wiring is hidden within walls or is otherwise inaccessible, the easiest course of action is to run new segment of bell wire along whatever path is easiest and forget about old wiring segment.
Last but not least on our list of home electrical projects are ceiling fans, which are covered in the next section.
How to Install a Ceiling Fan
Ceiling fans are a popular home feature. Luckily, replacing a light fixture with a new ceiling fan is an easy process. With just a little more work, you can add a new lighting fixture to the bottom of the fan unit. Only basic tools and skills are needed when installing ceiling fans. Here's how to do it:
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Step 2: Remove original light fixture from ceiling. Most fixtures are bolted or screwed into ceiling and can be disconnected once cover is removed.
Step 3: Lower fixture, and disconnect wires. Mark each with piece of masking tape for identification later.
Step 4: Review manufacturer's instructions on color coding of wiring and recommended ceiling fan installation procedures. In most homes, there will be two wires in circuit and three in fixture. Connect black wires together and white wires together, then connect remaining ground (bare or green) wire to metal junction box or other location suggested by manufacturer. Use wirenuts to make connections and, once connected, check them for tightness.
 �2006 Publications International, Ltd. Follow manufacturer's instructions when installing a ceiling fan, but usually you will connect the black wires together, the white wires together, and the bare or green wire to the junction box. |
Step 6: Attach fixture to junction box or hangers as directed by manufacturer.
Step 7: If you're installing a light below fan, make sure two parts are of the same brand and designed to work together (this will make process much easier). Remove bottom cover from fan unit, and pull out ends of any loose wires. Follow manufacturer's instructions for connection. Typically that means connect black to black, white to white, and ground to ground.
Step 8: Reenergize circuit and test system.
Many home electricity repairs are within reach for the do-it-yourselfer. Just be sure you take appropriate safety precautions, and don't hesitate to call in a professional when necessary.
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