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The basic electrical requirements of an average home have increased steadily over the years. As a general rule, the older the building, the less electrical power it was supplied with. For this reason, most renovations involve some form of electrical work. This can range from a new electrical service and distribution system to merely adding a few outlets. We don't (and can't ) claim to be experts in this field. What we attempt to do in this section is to give you some background on electrical theory by explaining the system’s principal components. The aim is to help you to understand the basic criteria involved in the design of your house’s electrical system. While it may be inaccurate to say that electrical work is difficult, we can rightfully say that it's potentially hazardous. A faulty electrical installation could be the cause of fire or personal injury. We discourage anyone (other than a licensed electrician) from doing his own electrical work. We aren't alone in our advice. There are numerous areas in which the building code will not allow you to do your own electrical work. Furthermore, some insurance companies may charge you higher rates when they find out you were your own electrician. One way to solve this problem is to hire a licensed electrician to handle the overall job with you working as one of his helpers. Such an arrangement will offer the assurance that a qualified professional is in charge while still allowing you to be an integral part of the renovation crew. CORE COMPONENTS Electrical Circuits When you turn on a lamp, you trigger an intricate series of events. Electrical energy, composed of moving particles called electrons, starts flowing from the generator (at your local power company) to the lamp via a system of wires. The flow of electrons (current) from the source to the lamp constitutes a simple electrical circuit. This circuit may be compared to the water sup ply cycle in a plumbing system—with one important difference. Whereas in the plumbing system the water comes from the source through the pipes to the fixtures and is later drained and disposed of, in an electrical circuit two terminals are needed to induce the current flow. The electron flow must “return” to its source to complete an electric circuit. The reason for this is that electrons are negatively charged particles that flow or move because there is a higher positive electric charge at one terminal than at the other. The circuit therefore starts at the source, goes to the appliance, where the power is consumed, and ends at the source.* Switches The switching device you use to turn the lamp on is designed to open or close the circuit. When the switch is in the “off” or open position, the current flow is interrupted. The circuit is “broken” and there is a gap in the current path. No current is allowed to flow and the light will be out. When the switch is in the “on” or closed position, the reverse takes place. *To simplify matters, we will assume we are dealing with direct current (DC). Switch arrangements vary in their complexity. There are instances in which you may want to turn on the light at one location and turn it off later from another location. A “three-way” switch arrangement, designed to open or close the circuit from two different locations, can do this. “Four-way” switch arrangements are also available for control of a single light from several locations. Outlets Outlets are devices within the circuit where electric power is made available. They include receptacles, ceiling outlets, and sockets. In the simple circuit previously described, a floor lamp becomes part of the circuit by being plugged into a receptacle. It draws power from the circuit via the receptacle by contact between the wires in the plug and those in the receptacle. The receptacle itself consumes no power. Receptacles are most commonly seen in duplex form—that is, with provision to accommodate two plugs. Quad receptacles for four plugs are also available. [RECEPTACLES: Receptacles are rated according to the amperage and the voltage that they can handle. The minimum rating allowed by code is 180 VA (15 A, 120 V). Since quite a few appliances (range, water heater, etc.) are rated at more than 15A and operate at 230 V, 240 V, or more, there are special receptacles to meet these requirements. Care must be taken to provide the right receptacle for the right appliance, since plugs and receptacles are designed to fit each other. E.g., a plug from a range requiring 50A and 250 V will fit a receptacle of this rating but will not fit one with a higher or lower amperage or voltage (an exception is a 15 A plug, which will fit a 20 A receptacle of the same voltage). The NEC requires that a receptacle shall have an amperage rating of no less than the branch circuit it's part of.* * Many household appliances are presently rated at 115/230 V, others at 120/240 V. A house serviced by 120/240 V can handle a 230 V appliance, and vice versa. Such minor variations aren't a problem.] [SIZING THE SERVICE ENTRANCE: Sample calculations for a 3,000 sq. ft. house, for illustration purposes only. Available power: 115/230V
*Demand factor is a figure representing an estimate of how many appliances and fixtures may be in use at any given time. ] UNITS OF MEASURE Your monthly electric bill states the number of kilowatts (or thousand watts) consumed by the house’s electrical system. The monthly charge is based on a rate per kilowatt-hour. If you take a look at the appliances you presently own, you will see that they are also rated in watts: a light bulb may be 30, 60, or 100 watts, a toaster 1,200 watts, and a radio 150 watts. These ratings mean that these appliances need that specific number of watts to operate properly. Watts are a measure of electric power flowing through a circuit at a given time. They are a function of the current flowing in the circuit (measured in amps) and the “push” needed to get the current from the source to the appliance (measured in volts). Watts amps x volts, or W = A X V. E.g., let’s say you have a washing machine requiring 700 watts and 115 volts to operate. You will need W = V x A, or W ÷ V = A—that is, 700 ÷ 115 = 6.08 amps—for the washing machine to function properly. The utility company that serves you will determine the voltage you receive, be it 11 120/ 240, or 125/250. The amperage (the amount of current quantity) available to you is dependent on the capacity of the “service entrance” that you already have or that you request from the power company. As a general rule, the older the house, the less amperage is available to it. It isn't uncommon to find large turn-of-the-century houses which have a service entrance of 50 amps (some times even less) or an apartment with 35 amps. The service entrance is the place where the cables from the power company enter the building for distribution to the various circuits. The incoming power (or entrance capacity) from these wires and the related fuses or other safety devices must be sufficient to feed all the house fixtures and appliances with an adequate amount of electrical energy and allow room for growth. To plan the electrical capacity needed in your renovation, you must determine the amount of electrical power (watts) you need and divide by the available volt age. This gives you the desired amperage capacity. Compare this figure with the amperage at the service entrance. For a renovation, you will probably need more than you now have. *To find out the exact voltage in your area check with the power company. All areas are subject to periodic minor volt age variations, mostly voltage reductions, as a result of changes in current demand. These voltage reductions, if major or prolonged, are referred to as brownouts. Apartment buildings are more complicated to deal with. Each apartment is allocated a certain amperage as its total “service.” This, in turn, is tied to the main service entrance to the building. If you require additional power, you need to find out whether the building can make this power available to you. If not, you may have to bring a new service into your apartment by means of a new electrical “riser” or “feeder” from the cellar. People in upper-floor apartments and in pent houses will require the longest and therefore the costliest runs. THE THREE-WIRE SYSTEM The electrical devices in contemporary houses range from a clock, requiring 2 to S watts, to an electric range, which may consume up to 14,000 watts. Because the variation is so great and the demand for power has increased, a three-wire system has been devised. With this system, two different voltages are made available: one relatively low voltage (115, 120, or 125 volts) for de vices using little power and a higher one (230, 240, or 250 volts) for high-wattage appliances. The operation of a three-wire system isn't difficult to understand. Three cables from the power company are brought into the house and connected to a single meter. They are then brought into the service entrance panel for distribution to the various circuits. Either voltage can be obtained at the service entrance. The three incoming wires are generally black, red, and white. The black and red wires are called hot wires; the white one is the neutral. (Don’t be misled by the “hot” and “neutral” terminology; they are all equally dangerous.) The hot wires are each connected to a 115-volt generator, while the white neutral is connected to both generators.* When the wires in a circuit are connected to the neutral and one hot wire, they are hooked up to one generator (or one generator “winding”). The voltage being supplied is 115 V + 0 V = 115 V. When the circuit is connected to both hot wires, each of which is connected in turn to a separate generator (or to two separate generator “windings”), the resulting voltage is 115 V + 115 V = 230 V. Devices in the circuit connected to one hot wire and the neutral will receive 115 volts; those connected to both hot wires (and not to the neutral) will receive 230 volts. Thus, by a choice of wires either voltage can be obtained, according to the rated voltage of the appliance. Circuits handling the heavy-wattage equipment such as an electric stove will most likely be supplied at 230 volts, while those circuits feeding lamps and other small appliances will be supplied with 115 volts. Owners of older homes will probably find that the incoming service to their building is a two wire system. This provides only 115 volts, which isn't sufficient to operate high-voltage appliances such as air conditioners. Plan for a new three-wire system in your renovation. *We are discussing supplies of 115 and 230 volts in our examples throughout; 120 and 240 volts are also supplied by some utility companies. SAFETY DEVICES Overcurrent Protection: Fuses and Circuit Breakers At times we may inadvertently overload a circuit by connecting too many appliances and fixtures to it. Such an accidental overload will increase the heat in the wires and thus the possibility of fire. Safety devices—either fuses or circuit breakers— must be provided to limit the amperes to a predetermined number, in somewhat the same manner that safety valves keep in check the pressure and temperature in a plumbing system. You are undoubtedly familiar with the location of the fuse or circuit breaker box in your house or apartment. Most likely you have replaced a blown fuse or reset a circuit breaker at one time or another. A fuse consists of a short length of metal wire with a high resistance to current and a relatively low melting point. As long as the cur rent flowing through the circuit is below a predetermined amperage, the metal in the fuse will carry it with no problem. When the amperage exceeds the rated preset level, the metal will melt because of the heat generated by the excess amperage, thereby breaking the circuit. Some fuses combine a slow action for low overloads with instant action for high overloads. Whenever you try to draw more power from a circuit than it can deliver (for example, if you turn on a stereo, a color TV, a blower, an air conditioner, a type writer, an iron, and all the lights on one circuit all at the same time), you will blow a fuse. Fuses are rated according to the maximum amount of amperage they can carry—15 A, 20 A, 30 A, and so on. A circuit breaker operates as a switch. When ever more current flows than the breaker is designed for, it automatically opens up, breaking the circuit and stopping the current flow. Circuit breakers are preferred over fuses because they are safer and , unlike fuses, they can be reset and reused. A blown fuse must be replaced with a new one. It makes good planning sense to replace your present fuse box with circuit breakers. Overvoltage Protection: Grounding Grounding is the provision of an escape route for leakage of electrical current. It is a mandatory code requirement. When you install a lightning rod, its purpose is to direct the electric charge via a separate path away from the house to the surrounding earth. Similarly, when you ground the electrical system you are providing an alternate path by which the leakage of fault or “short circuit” current can be more safely discharged. This is customarily done by connecting one of the wires in the system (the neutral) to the earth by means of a wire leading to the metal water service entry pipe in the house or a metal rod driven in the ground .* The grounded neutral (white) wire is never interrupted by a switch, fuse, circuit breaker, or any other device. *The metal cold-water service is customarily used for the main building electrical ground connection. Where a plastic cold-water service is used, a ground rod is needed. In addition to grounding the entire system, all appliances should be grounded. The reason for this is that a defective appliance can have exposed live voltage on its metal parts. In other words, the electricity-carrying equipment within the appliance (normally insulated from the casing) can accidentally come in contact with the casing, establishing an electrical circuit and making the casing electrically “live” to the touch. Should you touch the casing, you may become part of the circuit, carrying current through your body to the ground. To avoid this danger, codes have traditionally specified that all devices with motors, as well as heavy electricity consumers, such as electric ranges, water heaters, clothes dryers, and bathroom heaters, be grounded by means of grounding-type receptacles. These receptacles have provision for an additional circular prong. This third prong connects the appliance casing to the grounded wire in the distribution wiring system.* Fixtures such as refrigerators, freezers, and dishwashers come equipped with a three-prong plug. Minor appliances like radios or televisions that don't have a three-prong plug can also be connected to three-prong receptacles, since they are designed for use with either receptacle. Grounding-type receptacles are now usually required by local codes throughout the entire installation. In addition to system grounding and special appliance grounding, the entire wiring system (regardless of type) must be continually grounded throughout. The purpose of this is to automatically ground fixtures when they are connected to the outlet. More on this follows in the section on wire types. Ground-Fault Protection: Ground-Fault Circuit Interrupters To further protect you from the danger of shock or fire, ground-fault circuit interrupters (GFCI or GFI) now must be included in your electrical system in selected locations such as bathrooms. A GFI is a device designed to open the circuit and stop the flow of current in the event of a fault or an unwanted flow of current to the ground from an exposed wire or “live” part. The latter may occur as the result of accidental contact between a hot wire and a grounded conduit, the armor of a flexible armored cable, a grounding wire, or the casing of a motor or appliance. The current flowing as a result of a ground fault is often too small to blow a fuse or trip a circuit breaker, but is large enough to give a shock or start a fire. *Older wiring systems did not provide the third-prong ground connection for every appliance. Newer systems, using three-prong plugs, do provide a ground connection for each appliance. Although three-prong plugs and three-wire cords properly installed to grounding receptacles should reduce these dangers, the possibility re mains that the cord or plug may be defective. Some GFI’s available offer protection to an en tire two-wire system, whereas others protect only a single receptacle. Keep in mind that the GFI’s maximum amperage rating has to be the same as that of the circuit or receptacle it protects, but unlike a fuse or a circuit breaker, it will trip on lower fault currents than its rated carrying capacity. *A GFI will not protect a two-wire circuit that's part of a three-wire supply system having two hot wires with a common neutral. The National Electrical Code (NEC) requires, among other things, the installation of GFI’s in all outdoor 115 V, 15 A, and 20 A outlets and in all 15 A and 20 A receptacles at construction sites. In addition to those locations, the code also requires GFI’s to be installed in garages and bathrooms where appliances are used close to grounded plumbing.* Countertop outlets closer than six feet to the kitchen sink must also be provided with GFI’s. It is likely that future NEC editions will require an even greater use of GFI’s. WIRES Wires provide the path through which electric current travels. They consist of a copper conductor (aluminum and copper-clad aluminum are also available but aren't recommended) wrapped in an insulating layer of plastic compound or rubber. Aluminum conductors have been forbidden by code in some localities. *The neutral (white) wire in the electrical system is grounded by connecting it to the earth via a wire leading to the metal water supply pipe in the plumbing system. In the event an exposed wire in an appliance causes the case or any exposed part to have “live” voltage on it, if you touch the case and a faucet or another part of the plumbing system, you’ll be completing the circuit from the fault to the plumbing and carrying current through your body. Wire Sizes: Ampacity Wires offer resistance to the flow of current. The energy lost by this resistance translates itself into heat. The greater the current flow (amperage) in the wire, the greater the resistance encountered and therefore the greater the heat that's generated. As the heat increases, the chances of the insulation breaking down, and consequently the possibility of fire, increase. For this reason, it's extremely important to limit the amount of amperage that a wire can carry. The ampacity, as the current-carrying capacity of a wire is called, is dependent on its size and on the type of insulation. The larger the wire, the more amperage it can carry with less resistance. A most peculiar aspect of wire sizing, leading to much confusion, is the fact that the smaller the circumference of the wire, the larger the number it's assigned. E.g., size 00 wire is approximately 3/s” in diameter, whereas size S wire is only about 1/s”. (This size represents the diameter of the copper conductor and does not include the insulating casing around the wire.) Wire sizes range from large ones, size 0000 (4/0), which is about 1/2” in diameter, to minuscule ones, size 40. Table A lists the ampacity of copper wires commonly used in residential work. According to the NEC, a circuit isn't rated exclusively according to the ampacity of its wires but is also rated according to the fuse or circuit breaker protecting the circuit. For instance, a no. 12 wire rated for an ampacity of 20 amps can carry that capacity only if the circuit it serves is protected by a 20 amp fuse or circuit breaker. Should the circuit have only a 15 amp fuse or breaker, the wire and the circuit ampacity will be reduced to 15 amps. *This table is included as an illustration of ampacities for preliminary design purposes. Since the NEC is periodically revised, check the most current edition for specific values. TABLE A* (to be used for preliminary selections only) Wire | Size | Ampacity 14 15 12 20 10 30 8 40 For ease of installation, two or three wires are grouped together to form a cable. Two-wire cables have one white neutral and one black hot wire. Three-wire cables have one white neutral and one black and one red hot wire. The two most commonly used types of cables for residential work are non-metallic-sheathed cable and flexible metal-armored cable, each with a different cost, method of installation, and acceptability by code. Conduit (both rigid and thin-walled) is yet another alternative but is usually not required for new residential construction (unless called for by code or it's to be used for surface wiring or some other special condition). Non-metallic - sheathed cable, generally referred to by its trade name, Romex (Rx), is available in type NM for use in dry locations and type NMC for damp (although not permanently wet) locations . (NM and NMC are National Electric Code designations.) This cable is cheaper than metal-armored cable and is easy to install, requiring no special tools. It is, however, more vulnerable to damage. Type NM consists of two or three wires covered with a flame-retardant and moisture-resistant plastic jacket. In addition to flame retardancy and moisture resistance, type NMC is fungus- and corrosion-resistant. Both its wires are embedded in solid plastic. An additional uninsulated wire is also present for grounding purposes. This wire is carried from outlet to outlet to provide a continuous ground. Although non metallic-sheathed cable is very popular, some codes don't allow its use, favoring armored cable instead. Flexible armored cable (usually referred to by its trade name, Bx) is most commonly available for residential work in type AC. (AC is the National Electrical Code designation.) This type, which is restricted to dry locations, consists of two wires, normally plastic-insulated, bound together with tape or braid. The wires, in turn, are covered with a spiral galvanized-steel armor. Like non-metallic-sheathed cable, it uses an uninsulated copper wire for grounding . The metal casing is grounded to every electrical de vice, metal box, or cabinet). Many codes prefer this type over nonmetallic- sheathed cable (Romex) because it offers greater protection against accidental grounds and against physical damage. It is, however, more difficult to install and generally more expensive. Neither nonmetallic-sheathed cable nor armored cable is suitable for underground installation. Check your local code for recommendations on cables to be installed in such special conditions. A few words on cable sizes. The size of a cable is referred to first by the size of the wire, say no. 12, then by the number of wires. E.g., a 12-3 cable will be one with three no. 12 wires. A 12-3 cable with ground will have in addition a grounding strip or wire. Conduit is still another wiring method which, although not generally used for residential construction, deserves special attention. Conduit is essentially a steel or plastic pipe (or tube). Wires aren't originally inside the conduit when you buy it; they are pulled through once the conduit has been installed. Metal conduit is available in rigid or thin-walled forms. It is hard to install, not necessarily because of cutting and connection work but because it's difficult to bend. It is, how ever, a very safe wiring system, and is generally required for large jobs (almost always required in commercial, industrial, or institutional work), in surface wiring of old installations, and certain other special conditions. MODIFYING THE EXISTING ELECTRICAL INSTALLATION Start by becoming thoroughly familiar with your local electrical code. Most likely, unless you are building in a heavily built-up area such as New York City, which has its own, quite strict code, you’ll be required to follow the National Electrical Code. Many localities have adopted the NEC as their guideline for construction. Others have amended it to incorporate local conditions. A few words about the NEC. The primary goal of this code is safety. We point this out for two reasons. The first is to emphasize that not following the code will lead to an unsafe installation; any deviation is both unwise and illegal. The second is to point out that its requirements are those needed for minimum safe conditions. Improving on minimum recommendations by providing larger service entrances and wire sizes and more circuits than required will give you a better installation with more room for expansion. Keep in mind that the use of electricity has increased drastically in the past and will probably continue to do so in the future. Evaluate the Condition of the Wiring Another recommended, although not essential step to take before designing the system is to contact the company that will provide you with fire insurance. Find out if any variation in the methods, materials, or design you are planning might make a difference in future insurance rates. The Size of the Service Entrance Find out the capacity of your present service en trance. In very old homes and apartment buildings, this isn't an easy job. The boxes aren't clearly marked and are often hazardous. It makes good sense to hire an electrician. He can take a look at the service entrance panel and advise you as to its capacity and condition. He should also check to make sure that the system is properly grounded. If the system isn't grounded, it has to be grounded. The older the building, the more likely the service entrance will need upgrading. If your service is presently a two-wire system, it will probably have to be brought up to a three-wire system to meet code. The NEC has traditionally specified a minimum service entrance of 100 amps and three-wire ser vice for a single-family house. Inevitably this requirement will be increased with future code revisions. Bear in mind that the NEC deals with minimum safety requirements; it does not take into account possible expansion of the house. Make sure that your service entrance has sufficient capacity not only to handle your present renovation but also for future growth. Some codes already require a minimum service entrance of 200 amps. We recommend a service of no less than 150 amps and preferably 200 amps (Inset II). The additional amperage will provide sufficient spare power to allow for growth, such as the installation of a central air-conditioning system at a later date. If you are planning to have electric heat, the minimum service will have to be 200 amps. (To enlarge the service of an existing residence, your electrician must work with and get approval from the utility company.) In the past, electrical wiring was insulated with paper, cloth, or rubber. This insulation will dry out and become brittle over the years, resulting in a hazardous electrical condition. All electrical wiring with dry or brittle insulation needs to be replaced. A licensed electrician is the person best qualified to evaluate the condition of the wiring. Determine an Adequate Number of Circuits Electrical outlets are grouped together into various circuits, each circuit protected by its own fuse or circuit breaker. Providing the premises with several different circuits decreases the possibility of overloading any one of them. Your local code will indicate the minimum number of circuits that may be installed. This figure is generally based on the floor area of the house. Start by determining how many circuits you presently have. One way to approach this is to make a diagrammatic sketch of every room or area of your house or apartment. Indicate every electrical device in each room. This includes light switches, outlets, lights, appliances, etc. (See “Drawing the Electrical Plans,” for the symbols and the procedure to follow.) Turn the switches on and off to determine which device they control, and draw a line between those on the same switch and on the same circuit. The next step is to go to the service panel and assign a number to each circuit (each fuse or circuit breaker represents a circuit). From this point on you will need the help of a friend with a good pair of lungs or a set of walkie-talkies. One per son will remove the fuses or flip the breakers while the other turns on lights and appliances and tests outlets to see whether they are on or off. Each electrical outlet should be given the number of the fuse or breaker that controls it. You should also note the number of outlets in any one circuit and whether they service small appliances, special appliances (such as electric ranges or air conditioners), or general outlets and receptacles. There are three types of circuits: the general (or lighting) circuit, the small-appliance circuit, and the special circuit. The general circuit includes not only permanently installed devices such as ceiling fixtures but also receptacles for floor and table lamps and other minor appliances like radios and vacuum cleaners. The figure used by the NEC to estimate the total load of the general circuit is 3 watts per square foot of floor area. To arrive at the number of general circuits, use the following calculation. A 2,500-square-foot house will require 2,500 X 3 or 7,500 watts as the total load to be carried by the general circuits. If the house is wired with no. 12 wire having an ampacity rating of 20 amps and a voltage of 115 volts, the load- carrying capacity of each set of wires will be W = A X V, or 20 amps X 115 volts = 2,300 watts. To find out how many circuits are needed to successfully deliver the required 7,500 watts, divide the total watt load (7,500) by the wattage that a pair of no. 12 wires can carry (2,300). It follows that 7,500 ÷ 2,300 = 3.26 required circuits. Since it's impossible to install a fraction of a circuit, four circuits will be provided. Keep in mind that the code is dealing with minimum safety figures. Together with the requirement of 3 watts per square foot, the NEC makes a recommendation (not a requirement) to install one circuit per 500 square feet of total floor area. Using this figure will give you five circuits for the same 2,500-square-foot house. Going one step further and providing one circuit per 400 square feet will give you even greater flexibility and make allowance for future needs. According to that figure the same house will be equipped with 6.2 or seven circuits. (Use an eight- or twelve-circuit panel.) Follow this procedure to determine the number of circuits that your house should have (including additional square footage that may be part of your renovation plans). Compare the result with the existing number of circuits. Most likely you will have to add or extend the present circuits. Some codes don't allow extending circuits from existing boxes. Be sure not to exceed the circuit’s capacity or the ampacity of the wire or of the circuit breaker. It is considered good practice to supply no more than six outlets per 15 A circuit and eight outlets per 20A circuit. Check the NEC and your local code to see if they offer different guidelines. Count the number of outlets serviced by each circuit. If they exceed the code requirements, take some off the circuit. General circuits can't handle the heavy loads required by small appliances such as toasters, blenders, coffee makers, and portable microwave ovens. Although not permanently installed, these appliances need a greater amount of electrical energy for their operation. Have you ever noticed how the lights dim when the toaster is in use? That is an indication that the circuit does not have as much capacity as it should have. Small- appliance circuits are designed to handle such loads. These circuits are strictly for portable appliances; no permanent appliances or lighting outlets may be installed on them. Look back at your survey to see if in fact you presently have any small-appliance circuits. Your renovation may involve extending or adding to them. Those who don’t have small-appliance circuits must include them in their renovation plans. The NEC calls for a minimum of two small- appliance circuits, each equipped with no. 12 wires and protected by a 20 amp fuse or circuit breaker. (Each of these circuits will have a capacity of 20 amps X 115 volts, or 2,300 watts.) When installing the outlets, it's wise to connect alternate outlets to alternate circuits. In other words, if you have four small-appliance outlets in a row, connect the first and the third to one circuit and the second and fourth to the other, further reducing the possibility of an overload. Do the same with two or more circuits in the same room. Check your local code for its specific requirements. Although not required by some codes, it's good practice to provide new installations with individual dedicated circuits for permanently in stalled appliances requiring heavy power loads such as electric ranges, water heaters, dishwashers, clothes dryers, or any appliance with a power rating over 1,000 watts. This will include permanently connected motors with a rating of ‘/8 horsepower or more (for an oil burner, furnace blowers, water pump, etc.). These circuits will be either 115 volts or 230 volts depending on the appliance voltage rating. Wiring of a sufficient amperage should be designed for each—30, 40, or 50 amps or as required. Determine the Locations Requiring GFI’s Take a look around. All outdoor and bathroom receptacles (existing or new) should be replaced with GFI’s. In addition, GFI’s should be installed in the garage and any location where appliances are used close to plumbing fixtures. GFI’s also must be installed in countertop outlets within 6’ of the kitchen sink. Check your local code for additional requirements. *We recommend no. 12 wire of 20 amp capacity as the mini mum wire size for general circuits. Drawing the Electrical Plans Take your plans (including both new and existing conditions) and trace onto a clean sheet of paper the walls and partitions of the house, including all openings for doors and windows. In addition, be sure to indicate the location of all special appliances in the kitchen, laundry room, workshop, utility room, and any other area requiring them. Draw the location of the service panel. To prepare a workable set of electrical plans, the following components, both new and existing, should be shown and identified:
SERVIC PANEL: The service panel should be located very close to the point of entry of the incoming cables from the power company. The reason for this is that until these conductors arrive at the main lugs or disconnect switch (in the ser vice panel), the service entrance cables are with out overcurrent protection. As a fire and safety precaution, the length of unprotected conductor must be kept to a minimum. Maximum allowable distances vary with the different codes, and sometimes they aren't even specified. In any case, make sure that the length of unprotected conductor is kept in accordance with the NEC. It is often illegal and may be hazardous for a service panel to be located in a highly combustible area. Ideally, service panels should be easily accessible and have plenty of working space around them. If your existing panel is in an illegal or hazardous location, it should be relocated. LOCATE THE WALL RECEPTACLES: Draw the location of the existing wall receptacles in your plans. Check your local code to see whether it includes maximum distance requirements between receptacles. The NEC states that no point along a floor line shall be more than 6’ from an outlet in that space. Few appliances or fixtures, however, come with 6’-long cords, so you should consider placing at least one receptacle and possibly two on each wall of each room. Look at the existing receptacles. If there are too few, or there is only one on a long wall, add more receptacles. Provide enough receptacles to allow for flexibility of furniture and appliance arrangement. For ex ample, locate wall outlets on each side of a bed. You may otherwise find yourself using an extension cord every time you change your favorite reading spot Extension cords, in addition to being a hassle, are unsafe and unsightly. At this point also include any weatherproof receptacles you may want to add to the exterior of the building. Make sure to indicate them as ground-fault circuit interrupters. While working on the exterior of the building, locate outlets for outdoor lights, motion/security light sensors, etc. LOCATE THE CEILING OUTLETS: Indicate in your plans the existing ceiling outlets (if any). Do they provide you with adequate light? Are you planning to replace some of the lights with ceiling fans? Perhaps the best approach to the lighting problem is to study the types of activities that are to take place in these areas. Is the present light source adequate to handle these activities? Do you need supplemental or task lighting? If you are planning a new room or redesigning an existing one, is it going to be lit by means of floor or wall lamps or from an overhead source? Would one light source, centrally located, be sufficient or do you need more lights to obtain proper illumination levels? Do you want a central outlet or would you rather highlight an area or element in the room such as a fireplace? Do you have a light switch at the entrance to give light when you come in? How about a high wall outlet for a favorite picture light? By answering these questions you can determine how many (if any) ceiling out lets you need. LOCATE THE SWITCHES: Examine each room or area and determine whether the existing switching is sufficient or whether you need more. There are areas that require switches from more than one location. Stairs, for example, should have a three-way switch at either end of the run. You already know your existing path of travel in order to turn lights on and off. Would you benefit from adding switches or converting some existing switches into three-way switches? Consider the possibility of having one or more wall outlets connected to a switch. This way, if the living room is lit exclusively by floor and table lamps, you don't have to move all around the room to turn them on and off; you can instead control them from a single switch. Check that each of your ceiling outlets is controlled by a switch. The most convenient location for switches is on the latch side of the door. • To indicate which outlets are connected to which switches, draw a dotted line between the outlet and the proper switch. In addition, indicate whether it's a one-pole or a three-way or four- way switch. LOCATE THE SPECIAL CIRCUITS: Kitchens, laundry rooms, workshops, utility rooms, etc., all deserve careful attention because of the concentration of appliances requiring special circuits. All such appliances (new and existing ones) should be shown in your drawing to remind yourself of the special outlets you need to provide. Give each one an outlet, noting next to it the exact power requirement. Consider installing a dedicated heavy-duty outlet for an air conditioner below or to the side of each living-room or bedroom window. LOCATE THE SMALL-APPLIANCE OUTLETS: Indicate in your plans any existing above- the-counter outlets in the kitchen and laundry room. The NEC requires a minimum of two small-appliance circuits. If you have only one, you need to add a second one. Assess if you have a sufficient number of outlets to service portable appliances such as blenders, coffee makers, irons, etc. INDICATE THE CIRCUITS: Indicate the existing circuitry by drawing a solid line between all the outlets connected to one circuit. Give each circuit a number. If you are adding or modifying a circuit, draw a slash line over the circuitry lines to be modified. With a solid line indicate the new circuits. Keep in mind each circuit’s maximum capacity; for example, a 15 A X 115 V circuit has a maximum capacity of 1,725 watts. If the wattages of the appliances to be installed in any one circuit exceed the circuit’s capacity, split it up into two or more circuits as needed. Check yourself by adding up the power required by each of these appliances and comparing it with the circuit’s maximum capacity. Splitting up circuits not only will prevent over loading but will give you usable outlets in each room should one of the circuits go dead. Provide the refrigerator and freezer with one circuit each. When they share a circuit with other appliances, you run the risk of being stuck with a lot of spoiled food if something in the circuit goes wrong and causes the circuit breaker to trip. Once the circuits are established, each one is given a number. The drawing of the room with all outlets, switches, and circuitry included should look something like Ill. 26. LOCATE MISCELLANEOUS DEVICES: It is at this point that the location of doorbells, the intercom system, and any other special electrical de vices should be included. Next: The Structural Floor: Its Design
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