By Sarah
By Sarah
The electrical protective system in your home acts as a safety device. It cuts off the electricity flowing through wiring (circuits) when wiring becomes overloaded or there is a short in the circuit. There are two protective systems: plug or cartridge fuses and circuit breakers.
Both types of protective safety devices serve the same purpose -they shut off power when a circuit carries more current than it should. Fuses destroy themselves (blow) and must be replaced. Circuit breakers function as switches that automatically trip open when current exceeds the circuit breaker rating. Most circuit breakers can be reset manually by pushing the handle of the OFF position, then to the ON position.
SAFETY FIRST
Working with electricity is not hazardous as long as you obey strict safety rules. Always shut off or disconnect power before handling wires. If you are working on the electrical service panel, do not stand on a damp floor. Protect yourself by wearing rubber gloves and stand on a rubber mat or a piece of dry wood. Above all, if you are in any doubt about how to do any particular job, call in a licensed electrician.
FUSE BOX
The main Panel, usually called the fuse box in a household fuse system, is where all electrical circuits start and end. That is, electric power passes through a meter, then enters the house and is distributed by the main service panel.
Ordinarily, main and branch fuses are located in a metal fuse box that is equipped with a lever-type disconnect switch or a fusible pullout switch. The branch fuses have screw-in sockets.
Before working on your electrical system, shut off all power and make sure that a good continuous connection existst from the neutral or the service panel box to a ground rod driven into the earth or to a metal water pipe system. Also, make sure that the neutral is connected to the service panel box with a wire or bonding screw. If the main pullout switch(es) is in a separate box, these connections should be in that box instead. No ground connections should be made to white neutral wires anywhere else in your system, and no other neutral bar should be connected to the box in which it is mounted.
Some appliance circuits use fused receptacles. They can save you a trip to the panel. If you overload the circuit and blow the fuse, only this receptacle is out of order, and the bad fuse is at your fingetips.
There are just two types of fuses: plug and cartridge. But, within these two styles there are several variations.
PLUG FUSES
This style of fuse has a screw base that screws into a socket in the fuse box in the same way that a light bulb screws into a lamp socket. There are varying types of plug fuses: standard, time delay, type S, and minibreaker or circuit breaker fuses.
Standard Fuses
These plug fuses look similar to the bases of light bulbs. A metal strip runs through the center at the top of the fuse. You can see it through a tiny window. If the window looks black or discolored, the fuse usually is defective.
Time Delay Fuses
A time delay fuse allows temporary circuit overloading. In homes, time delay fuses are used in circuits that accommodate heavy appliances, such as air conditioners, that cause a temporary surge in power draw when they are turned on. The time delay fuse is made with a spring-loaded metal strip (link) that attaches to a plug of solder. As the power surge takes place, the fuse doesn't blow immediately, as would happen with a standad or type S fuse. Instead, the solder begins to melt. It must melt through completely before the fuse will blow. The delay allows for a limited period of power surge. However, if the overload continues beyond a certain point, the solder melts completely and the spring pulls the link free. The fuse then blows and interrupts the circuit.
Type S Fuses
Type S fuses are similar to standard fuses, except for one notable difference. A type Sfuse consists of two parts, the fuse itself and (in older homes originally using standard fuses) a socket adapter. The adapter screws into and locks in place as part of the socket in the fuse box. Do not remove the adapter unless it shows signs of being defective, such as cracking or discoloration. The other part, the fuse itself, screws into the adapter. Threads of a particular size (ampere) type S fuse are designed to be screwed all the way into threads of the same size adapter and no other. For example, a 15-ampere type S fuse fits only a 15-ampere type S fuse adapter; a 20-ampr type S fuse cannot be substituted for a 15-amp type fuse. A type S fuse assembly, therefore, prevents someone from replacing one size fuse with an incorrect size, either by accident or on purpose. Minibreakers or Circuit Breaker Fuses. THese fuses have apush button that pops out from the center of the face. When the minibreaker fuse blows, you simply push in on the push button to reset the fuse. It works like a pushbutton-type circuit breaker.
CARTRIDGE FUSES
Two types of cartridge fuses are used in homes. ONe type has round ends and a capacity of 15 to 60 amperes. It is used to protect a circuit on which there is a major electricity-drawing appliance, such as a kitchen range, clothes dryer, or air conditioner. Each circuit servicing a large appliance may be protected by a cartridge fuse. The toher type of cartridge fuse is used to protect the main power circuits. THis fuse has Knife-blade contacts on each end and is rated at a capacity of 60 to 600 amperes.
It is rare for cartridge fuses to fail, but if there is no other explanation for an inoperative appliance or for a power failure, it may be due to the particular cartridge fuse. The main reasons for cartridge fuse failure are the same as the reasons for plug fuse failure; that is, overload on the circuit or a short circuit. A cartridge fuse also may fail because of old age.
FUSE SIZES
As already noted, all fuses are rated in amperes. THey will be stamped with numbers or ratings from 15 to 60 or 60 to 600 amps. As a rule of thumb, a No. 14 wire (regular lamp circuit) takes a 15-amp fuse (1750-watt capacity); a No.12 wire circuit takes a 20-amp fuse (2300-watt capacity); a No. 10 wire takes a 30-amp fuse (3500-watt capacity). The (following) chart gives the recommended (minimum) fuse amperage size for typical household circuits. It is wise to keep sapre fuses handy near the fuse box.
Fuse Amperage
Branch Circuit 120V 15
Doorbell Transformer 120V 15
Motors (single phase) (up to 1/2 hp) 120v 15
Range hood 120V 15
Sump pump 15
Air conditioner: 120V up to 11,000 BTU 20
240V up to 23,000 BTU 20
Kitchen branch circuit 120V 20
Dishwasher 120V 20
Electric heat 12 (up to 1650 watts) 20
Electric range 240V (up to 5kW) 20
Motors (single phase) (1/2 to 1 hp) 120V 20
Air conditioner 240V up to 36,000 BTU 30
Clothes dryer 240V 30
Electric range 240V (5kW to 8kW) 30
Hot water heater 240V (up to 6kW) 30
Well pump (up to 1/2 hp) 120V up to 200 ft. 30
Electric range 240V (8kW to 10kW) 40
Well pump (up to 1/2 hp) 120V, 201-300ft. 40
Electric range 240V (10kW to 20kW) 50
Follow directions on appliance nameplate for branch circuit amperage if given. Under no circumstances should you increase fuse size when replacing an appliance, unless you have confirmed that circuit wiring is sized appropriately for the new wire size.
FUSE FAILURES
When a fuse blows and the power goes off, the most likely cause is an overloaded circuit. An overloaded circuit is when too many appliances or lights are plugged into a circuit. When overload occurs, the small wire in the fuse breaks without heating excessively. The window on the fuse should be clean so you can see the broken wire.
Fuses that continually blow usually can be traced to an overlaoded circuit. So, before you replace a blown fuse, check along the circuit for the overload: too many lights and appliances? Correct this situation and replace the fuse. Another cause of fuse failure is a short circuit, which is one bare electrical wire touching another bare wire or piece of metal. The rate of flow of the electric current is excessive when a short circuit occurs. The fuse wire vaporizes, spraying and discoloring the fuse window.
Checking for a short circuit:
1. Turn off the power (main fuse) at the service panel.
2. Unplug all lamps, overhead fixture light bulbs, and any appliances on the failed circuit. Check the wire plugs. If a plug is cracked, has melted from heat, or has broken prongs, do not reconnect the plug until it has been either repaired or replaced. If you spot a worn or frayed wire on a lamp or appliance cord, replace or repair it.
3. Replace the blown fuse on the circuit with all appliances, lamps and other electrical devices disconnected. Wait one minute. If the fuse blows again, the problem is the house wiring. Call a professional electrician. If the new fuse doesn't blow, the wiring is not the problem.
4. Remove the new fuse and reconnect one of the disconnected items. Replace the fuse. If the fuse doesn't blow, this lamp or appliance is not the problem. Continue plugging in all items on the circuit one at a time. Always remove the fuse, plug in the device then replace the fuse. The device with the short circuit will blow the fuse. Repair device before you replace the fuse.
REPLACING BLOWN PLUG FUSES
The first step is to turn off all lights and appliances on the circuit controlled by the fuse. Then turn off the main power. In some houses, the main power is controlled by one to six fuse blocks. These square or rectangular fuseholders have handles that allow you to pull them out and gain access to the actual to pull them out and gain access to the actual cartridge fuses they hold inside. To shut off the main power so you can safely remove the blown fuse, grasp the handles of the fuse blocks one at a time, and pull them out. In other houses, the main power is controlled by a lever-type switch on the side of thefuse box. To cut the power, pull this switch downward. Actual fuse replacement is simple, but use care when working at the panel.
1. Select a fuse rated for the same amperage as the one you are replacing.
2. Turn the blown fuse counterclockwise to remove it from the fuse box.
3. Install the new fuse by screwing clockwise into the socket.
4. Replace the main fuse blocks or turn the main power on.
REPLACING FAULTY CARTRIDGE FUSES
To determine if a cartridge fuse has failed, proceed as follows:
1. Turn off the main power and open the service panel of the fuse box.
2. Using a fuse puller, grasp the middle of the fuse and pull it out of the spring clips that hold it in place. If the fuse has knife-blade ends, don't bend them.
3. Some cartridge fuses are mounted in a compartment-type housing. To remove the fuses, grasp the wire-loop handle and pull the compartment straight out of the panel.
4. To test the fuse, touch one probe of a continuity tester to one end of the fuse and the other probe to the other end. If the tester lights, the fuse is okay. If the tester does not light, replace the fuse.
CAUTION: Never test a fuse while it is in the service panel. Always remove it from the service panel.
5. To install a cartridge fuse, push it into the spring clips by hand. If a new fuse fails, the problem is in the circuit wiring or there is a short circuit in an appliance.
*Creative Homeowner Press, 24 Park Way, P.O. Box 38, Upper Saddle River, NJ 07458. How-To-Booklet #1. Fred Meyer. Consult State & Local Codes. Observe safety precautions.
Follow thes tips and instrucitons on how to replace or install electric sweitches, to save you time and effort. Before beginning any electrical repairs, turn off the power at your service panel, fuse box or breaker box. If you know which fuse or breaker controls the circuit you will be working on, remove that fuse or trip that breaker. If there is any doubt, you can remove the main fuse or trip the main breaker. CAUTION: tripping the main breaker or removing the main fuse will ususally shut off all power to the house. Thke the time to read the directions thoroughly to hlep ensure a satisfactory job.
THREE BASIC TYPES OF WALL SWITCHES
The popular toggle switch has an arrow-shaped armature that floats between the contact points when the switch is in the off position. This armature comes in contact with both terminals when the switch is flipped to the on position, thus providing a continuous flow of electrical current to the light or appliance. The mercury switch has a small hollow cylinder, partially filled with mercury. In the off position, the small contact point is above the mercury level. When flipped to the on position, the contact point is immersed in mercury. This establishes contact between the two terminals and provides power to the light or appliance.
The silent switch has a steel spring armature that is pressed away from the bottom terminal when the switch is turned off. Flipping the switch lever to the on position moves the steel spring back against the contact point, thus establishing contact in the circuit.
The silent and mercury switches make almost no noise when operated. The toggle switch makes a distainct "click" when flipped on or off.
For installation purposes, all three types of switches can be used interchangeably.
THE SINGLE-POLE TOGGLE SWITCH
The simplest switch system is the single-pole toggle switch . The ordinary single-pole toggle switch porvides a means for breaking or feeding electrical current to a light, appliance, etc. The single-pole toggle switch has two brass terminal screws. One wire (usually the black) is cut, then is connected to the two brass terminals. The other wire (white) is uninterrupted from the power source to the light or fixture. When connecting a wire to the terminal screw of a switch, always turn the loop on the end of the wire in the same direction as the screw threads. If the loop is turned in the opposite direction, tightening the screw will lossen the loop. If the wire connects to the terminal screw and then runs on, cut and strip the wire on both sides of the cut. Using a 6" piece of wire with both ends stripped, sometimes called a pigtail, and a wirenut, fasten the three wires together. Connect the pigtail to the terminal.
Use wirenuts or screw-on connectors to save time and effort when you must make a splice in any electrical wire. Always cover any soldered connection with insulating tape. If soldered sections are rough, apply an extra layer of tape. Insulate the wire an additional inch or two beyond the soldered connection in each direction.
White wires should generally be attached to light colored terminal screws such as silver. Black wires should generally be attached to dark colored screws such as brass colored. If the terminal screws are the same color, either wire can generally be attached to either terminal. Green terminal screws are for grounding wires.
INSTALLING SWITCH OUTSIDE MAIN WIRING RUN
Use an ordinary toggle switch for installations outside the main wiring run. Shut off all current at the main service panel. At the light fixture, connnect the black wire from the switch to the black wire from the light fixture. Connect the white wire from the switch to the black wire from the power source. CAUTION: Anytime it is necessary to connect a white and black wire together, take the time to paint the white wire black at both ends to indicate that the white wire is attached to a power source. Connect the white wire from the light fixture to the white wire from the power source. At the light switch, connect the black wire to one terminal and the white wire to the other. Remember, a green screw is always for the ground wire.
IN-LINE SWITCH FOR CONTROL OF ONE LIGHT
Shut off all current at the main service panel. A third wire must be added to the power cable for this switch arrangement. The red wire serves as a black wire from the switch to the light or outlet which is to be controlled. The white wire feeds continuaously from the power source to all fixtures. The black wire is pigtailed on one terminal of the switch, while the red wire attaches to the other terminal. The black wire then runs continuously through to the light or outlet which is not controlled, while th ered wire runs from the switch terminal to connect twith the black wire on the controlled light or outlet. This arrangement allows the switch to control the first light or outlet while power continues uninterrupted to the second fixture.
INSTALLING SWITCH AND CONVENIENCE OUTLET IN SAME BOX
Shut off all current a the main service panel. At the double-switch box, connect a pigtail to the brass terminal on the outlet and another pigtail to either of the terminals on the switch. Wirenut these two pigtails and the black wire from the light fixture together. Connect the white wire from the light fixture to the silver terminal on the outlet. Connect the red wire from the light fixture to the other terminal on the switch. At the light fixture, wirenut the white wires from the power source, the light fixture and the switch together. Wirenut the black wires from the power source and the switch together. Wirenut the red wire from the switch and the black wire from the light fixture together.
TWO PARALLEL SWITCHES FOR CONTROL OF TWO SEPARATE LIGHTS
Shut off all current at the main service panel. At the switch box, attach a pigtail to one of the terminals on switch
1. Connect a second pigtail to one of th terminals on the switch
2. Wirenut these two pigtails and the black wire from the light fixture together. Connect the red wire from the light fixture to the other terminal on switch
1. Connect the white wire from the light fixture to the other terminal on switch
2. Be sure and paint the white wire black.
At light fixture1, wirenut the black wire from the power source and the black wire leading to light fixture
2 together. Wirenut the white wires from the power source, light fixture
1 and light fixture 2 together. Wirenut the black wire from light fixture 1 and the red wire to light fixture 2 together.
At light fixture 2, wirenut the black wires from light fixutre 1 and the switches together. Wirenut the white wires from light fixture 1 and light fixture 2 together. Wirenut the red wires from switch 1 and light fixture 1 together. Wirenut the white wire from switch 2 and the black wire from light fixture2 together. Be sure to paint the white wire black.
HOW A THREE-WAY SWITCH WORKS REQUIRES ILLUSTRATION
THREE-WAY SWITCHES FOR LIGHT CONTROL BEYOND SWITCHES
Shut off all current at the main service panel. At the light fixture, wirenut the white wires from the power source and the light fixture together. Wirenut the black wires from the power source and the switches together. Wirenut the black wire from the light fixture and the white wire from the switches together. Paint the end of the white wire black. At switch1, locate the terminal on the three-way switch that is marked as common and attach the red wire. Attach the black wire to either of the two remaining terminals. Attach the white wire to the last terminal.
At switch 2, locate the terminal on the three-way switch that is marked as common and attach the red wire. Attach the white wire from switch 1 either of the two remaining terminals. Paint the end of the wire black. Attach the black wire from the light fixture to the last terminal. WIre the black wire from switch 1 and the white wire from the light fixture together. Paint the end of the white wire black.
THREE-WAY SWITCHES FOR LIGHT CONTROL BETWEEN SWITCHES
Shut off all power at the main service panel. At switch 1, find the terminal marked as common and attach the red wire. Attach the white wire to either of the two remaining terminals. Attach the black wire to the last terminal. At switch 2, find the terminal marked as common and attach the red wire. Attach the white wire to either of the two remaining terminals. Attach the black wire to the last terminal. At the light fixture, wirenut the two red wires from the switches together. Wirenut the two white wires from the switches together. Wirenut the black wires from the power source and switch 1 together. Wirenut the white wires from the power source and the light fixture together. Wirenut the black wires from the light fixture and switch 2 together. *1991 Home Center Institute/National Hardware Association. Informational pamphlet # 8. Home Depot. Check your state and local codes before starting any project. Follow all safety precautions. Information in this brochure has been furnished by the National Retail Harware Association. Every effort has been made to ensure accuracy and safety. Neither the N.H.R.A. nor the retailer can be held responsible for damages or injuries resulting from the use of the information in this booklet.
