Electrical FAQ's

ONLY CONNECT answers some of your basic electrical questions-both practical and theoretical. We strongly recommend that you seek trained and qualified help when you need electrical repairs or improvements. Please let us know which answers are helpful. Contact us for more details or with other questions at projects-and-repairs@onlyconnectelectricricians.com or at 617-484-2828. And, of course, call us to explore solutions to your electrical problems and set up an appointment for the work.

Knob-and-Tube Wiring: What's the Big Deal?

  • What is Knob-and-Tube ?

    The oldest wiring system you're likely to encounter is called "knob-and-tube". Knob-and-tube uses individual wires supported by porcelain insulators (knobs) and run inside porcelain cylinders (tubes) when going through wood beams. Until the mid-1930s, knob-and-tube wiring was installed in many homes. It required real skill to install. Most installations that we see are high quality work.
  • Insurance and Insulation

    At ONLY CONNECT, we have been replacing larger amounts of knob-and-tube wiring than ever before, and none of these projects were impulse buys. Homeowners did not really have much choice.

    Understanding the issues is key. For many sellers, buyers, and other homeowners, replacing knob-and-tube wiring is not an option or a choice. Here's why..

    Insurers are driving the change. Nearly all insurance companies refuse to insure knob-and-tube wiring. In our experience, insurers require a home to be free of knob-and-tube wiring before a sale or very soon afterwards. They ask about knob-and-tube wiring in the application form. Insurers may see knob-and-tube wiring during a claim inspection and ask about it. And they can ask at yearly policy renewal time. Knowing the issues can prevent a big surprise.

    Planning to insulate to save on heating costs? Insulation contractors cannot insulate near live knob-and-tube wiring. Utility companies offering insulation rebates require a licensed electrician to certify that there is no live knob-and-tube wiring. Over-heated wires can cause fires, so the Mass. Electrical Code prohibits covering live knob-and-wiring. Replacing knob-and-tube is the only real solution.

    What to do? We test a home's wiring to determine if any live knob-and-tube requires action. We look for hidden knob-and-tube that may have been only partially replaced. We offer solutions that meet your deadlines. We have worked on small and large knob-and-tube projects, but they are never a quick and simple day's work.
  • Is Knob-and-Tube Safe?

    Like other electricians we know, we believe that knob-and-tube wiring properly installed and in good condition is both reliable and safe. As with any type of wiring, damage or illegal modifications can create safety hazards. We do see installations where modern wiring has been added to knob-and-tube in unsafe ways. This is a problem.

    Dangers. The biggest danger that we have heard about starts at the connections between wires in a knob-and-tube system. Knob-and-tube splices are not contained inside an electrical box. If the insulating tape that covers splices loses its stickiness, it may not cover the splice well. If the splice loosens up over the years, it may heat up and create a fire hazard.

    To date, we have been unable to locate any data about how often knob-and-tube wiring is actually implicated in causing fires.

    Appropriate Uses. Knob-and-tube has no ground wire and is not appropriate for electrical equipment that requires grounding (e.g., appliances like washers, microwaves, refrigerators or electronic equipment like TVs, computers, music systems). Installing a new modern circuit can solve this problem for a specific piece of equipment. On the other hand, lamps, like many items, typically have 2-pronged plugs and do not utilize a ground.

    For more about knob-and-tube wiring, go to Cables and Wires below.

  • Electrical Project Strategy
  • How can I keep the cost of electrical work down?

    Planning. Any time you are going to paint a room, it's time to think about electrical repairs and any new receptacles, switches, networks you may want. When an electrician works just before the painter or plasterer comes, the work goes a bit faster and therefore costs less. Professional painters and plasterers can repair the unavoidable holes needed for pulling new wires into your walls and the crumbling of old plaster around a new outlet. A slightly larger hole or an extra hole goes quickly for them. Going to extremes to minimize holes in your walls can slow the electrician dramatically. Get the electrician in just before the painting.

    Circuit Breaker Panel Schedules. Having a complete list of which receptacles and lights are controlled by each circuit breaker saves the electrician time-and you money.
  • Is upgrading my Electric Service to 200 Amps worthwhile?

    In classic form, we'll give you a "definite maybe" on this one. Our experience shows that upgrading a service to 200 Amperes is rarely particularly useful to customers. If you are having trouble with individual circuit breakers tripping, a new service is probably not the answer. Most often, we find, that adding new circuits and circuit breakers provides the needed improvement. For example, a toaster over and a microwave may be too large for a single circuit. A treadmill may require its own 20 Ampere circuit. A portable electric heater added to a circuit with other things running make push the current draw over the limit. A new, upgraded service will not correct any of these problems. Most often, we find that adding new circuits in key locations in your home is the most effective and cost-effective solution for many situations like these.

    We believe that service upgrades are sometimes justified, usually by major renovations or additions to a home or by additions of major new pieces of electrically powered equipment like central air conditioning or large installations of electric heat. If your current services is 30 or 60 Amperes, it is more common that an upgrade can be useful. Ask yourself this question, "Have we ever tripped the main circuit breaker?" If the answer is yes, the likelihood is higher that a service upgrade will be beneficial.

    In thinking about a service upgrade, consider the following: A 200 Ampere service, fully loaded draws 48,000 Watts or 48 Kilowatts. Depending on your power company, this electricity will cost you 50¢ to 70¢ per hour. For 4 hours a day, 48 KW will cost you about $75 a month. Most people don't use that much electricity in 4 hours-ever. There are, of course, exceptions to every generalization.

  • Useful Terms for Educated Consumers

    Three Way Switch: a switch used when you want to be able to turn lights on and off from two or more locations.

    Ground Fault Outlet: a receptacle designed protect human life by detecting small amounts of electricity leaking from its normal path and creating a safety hazard.

    Ampere. measures the amount of electricity that flows past a given point on a circuit (each second).

    Breaker Box (breaker panel): houses the circuit breakers or fuses that protect and distribute power to various parts of your house.

    Circuit: all wiring controlled by one a single fuse or circuit breaker.

    Circuit breaker: a protective device for each circuit that automatically cuts off power from the main breaker to the circuit in the event of an overload or short. The ampere rating of the breaker tells how much current can pass through the breaker before it will "trip."

    Main breaker: protects your entire house by turning the power entering your home through the breaker box on or off. The "main" is sometimes found in the breaker box, or it may be in a separate box and at another location.

    Volt: measures the current pressure at receptacles and lights. Think of it as analogous to water pressure at a faucet. Average household voltage is 120.

    Watt: the rate at which an electrical device (light bulb, appliance, etc.) consumes energy. Watts = Volts x Amperes. Watts measure power for electricity. Horsepower, on the other hand, measures power for automobiles. 550 watts = 1 horsepower.

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  • So what is grounding anyway?

    When we "ground" a box or a piece of equipment, we are actually connecting its potentially dangerous pieces of metal to the ground, the earth. The grounding electrode system is a method to connect the neutral and grounding conductors to the earth. The connection from the electrical system to the grounding system is made in only one place to avoid ground loops. Ground fault electric currents (hot wire to grounded case shorts) are conducted down the ground wire to where it is interconnected with the neutral and to the earth. Enough current should flow to trip the circuit breaker or blow the fuse.
  • What is the receptacle with the buttons in my bathroom? Why do I need it? And how does it work?

    Ground fault receptacles (Ground Fault Circuit Interrupters or GFCIs) help protect you against shocks that may kill you. Whenever there is a short-circuit in hair dryer or any other piece of equipment, electricity may flow to its case. If you are holding the equipment and touch a faucet or pipe, electric currents can cross your heart on the way to the faucet and ultimately to the ground. Only a few milliamperes of electricity can cause your heart to malfunction.

    To protect people from this danger, the Massachusetts Electrical Code (the law), requires GFCIs in renovations, new construction, and when replacing certain receptacles. Receptacles near sinks in bathrooms and kitchens, in unfinished basements, and near pools or outdoors must be GFCI-protected.

    GFCIs can shut off the electricity to the receptacle much more quickly than a circuit breaker, typically within a few cycles. The electronics in the GFCI compare the electric current on the two main wires to the outlet (the hot and neutral). If the currents are not the same, the GFCI trips and turns off the power.

  • What should grounding look like in a properly installed switch, receptacle, or lighting box?

    Every switch or receptacle should have a grounding wire. Every metal box should have a grounding wire. All the ground wires should be connected together and connected to a grounding wire going back to the circuit breaker panel or fuse box. Any metal part that might accidentally be touched by a live wire-due to insulation failure, deterioration, or a loose wire-should be grounded.

    Metal boxes. Both the metal box and the switch, receptacle, or light fixture attached to the box must be grounded. It is good practice never to rely on the mounting screws to ground the switch, receptacle, or light fixture to the box.

    Plastic boxes. Plastic is mostly and insulator; the plastic box itself does not need to be grounded. The switch, receptacle, or light fixture attached to the box does need to be grounded. Here are three ways to do it correctly.

  • How does grounding work when a lamp has a 2-prong plug?

    This is a great question because most electric things we have in our houses to day have 2-prong plugs. The answer is: 2-prong plugs and 2-hole receptacles provide NO GROUNDING PROTECTION. Many pieces of electrical equipment manufactured today have no exposed metal parts and are constructed to prevent users from touching live parts.

    Properly constructed table lamps and the like should have "polarized" plugs. The larger prong is inserted into the larger hole in the receptacle and connects with the "neutral" wire. The smaller prong connects to the "hot" wire. Inside the lamp, the neutral connects to the threaded shell that you screw your lightbulb into. The hot connects to the little tab in the bottom of the lightbulb socket and is harder to reach with a finger. This arrangement lessens the chance that you will touch a hot part of the lamp and risk getting shocked.

    Whenever any electrical equipment, from a vacuum cleaner to a drill or a lamp, has a 3-prong plug, you need a 3-hole, grounded outlet to plug it in safely.

  • What is 2-wire Romex? And what is it for?

    Two-wire Romex cable is old and does not have a ground. It is no longer installed. It should be replaced if you need a ground. Replace it when you need a ground.

  • I know what a "hot" wire is. I found out the hard way. What is the difference between a neutral and a ground wire?

    Let's start at the beginning. Three wires connect to the receptacle in your living room, where a computer with a 3-prong plug is attached. Technically speaker, these three wires are the hot wire (black), grounded wire which is commonly called the neutral (white), and the grounding wire commonly call the ground wire (bare, green, or green with yellow stripe).

    When your computer is running, electricity flows through the hot and the neutral. Back at the circuit breaker panel, the neutral is attached to a wire to the earth or to a water pipe going into the earth. DON'T TRY THIS-AT HOME OR ELSEWHERE. If everything is perfect, you can attach a wire from the neutral hole at the outlet to the earth and no electricity will flow. ESPECIALLY DON'T TRY THIS. In fact, if you touch the neutral and touch the earth, you should not get a shock. Creating this safe situation is a major reason for the grounded neutral. But remember, everything is rarely perfect. Do not experiment with the neutral or any live wire.

    Even when your computer is running, no electricity should flow through the grounding wire. The grounding wire is there for the occasional times that something goes wrong and a hot wire connects with the case of equipment or a outlet box. It then provides a path to complete the circuit and trip the breaker. It is an important safety device. NEVER USE THE GROUNDING WIRE FOR ANY OTHER PURPOSE.

  • Does knob-and-tube wiring or 2-wire cloth-covered cable have a grounding wire?


  • What do banks think about knob-and-tube?

    Some banks get nervous about knob-and-tube. They may insist that you replace it before they give you a mortgage.

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Computers and Networks

  • How important are surge suppressors/protectors? Are they worth the money?

    In two words: very and yes.

    Surge suppressors protect the delicate electronics in everything from refrigerators to computers. In normal circumstances, the voltage in your house can vary enough to destroy electronics. During lightning storms, the risk is higher and more immediate.

    You've seen the snow on your television when you run an old vacuum cleaner. Computers and anything with a computer in it can be affected by motors turning on or off in your house. Plugging your computer into a surge suppressor plugged into the wall can protect against the snow (noise) and help protect against voltage surges from outside your house.

    Whole house surge suppressors (installed at your circuit breaker panel) help protect everything against voltage surges from outside but don't stop the noise generated inside the house. Depending on your situation, you may want one or both.

    Surge suppressors are absolutely worth the money. We know people who've lost computers, televisions, hifi equipment, and refrigerators during storms. Even though surge suppressors won't protect against huge voltage surges, they are cost-effective insurance.

  • I need a computer network in my house. Should we run wires or go wireless?

    We did a back of the envelope calculation and decided that new wireless equipment can support High Definition Television signals. That's enough speed for almost everybody. And wireless will only get better.

    At this point in history, wired networks are for special situations. Wireless networks are getting faster and more reliable every week. If you are running a data-intensive business from your home, you may need the speed of CAT6 cable or Gigabit Ethernet. But even if your teenager plays graphics-intensive games online or you download massive amounts of data from work each night, wireless will probably do just fine. After all, a wireless network at home is faster than any Internet connection you can afford.

    Some houses interfere with wireless network signals to the point where you cannot go this way. Often the problem is plaster with wire mesh lathe (after wood lathe, but before wallboard). In these cases, it is worth explore powerline and phoneline networks, which both use wires already in your walls. As a last resort, there's installing Ethernet wiring in your walls.

    Why do we try to avoid wired networks? Simply because it can get expensive, and you often don't get much extra value for your investment. Do you need the speed or copper wires? (usually not). Are wires more convenient? (absolutely the opposite). Installing wires of any kind in the walls of an existing house is one of the most expensive parts of any electrical or network project. The wire itself is cheap, but it takes a lot of time.

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Extension Cords

  • Extension cords and over-stuffed outlets: Are they safe? What should I do? Do I need extra outlets or extra circuits?

    Extension cords are really for temporary use. The equipment cord should be long enough, and an outlet close enough, to plug it in directly. Surge protectors seem to contradict this, but they are not extension cords, they are safety devices to protect your equipment. Note they don't have very long cords.

    An additional outlet may solve the problem.

    If the problem is overloading a specific outlet, you may need an additional circuit - not a new service.

  • Extension Cord "Do's and Don'ts"

    Never run an extension cord under a rug.

    Never cover an extension cord with carpet, pillows, or other material.

    Never connect an extension cord to the house or furniture with tape, staples or nails.

    Never connect one extension cord to another unless you know how to calculate electrical loads.

    Never use extension cords to "solve" the shortcomings of a house with one or two receptacles per room.

    Never use a long cord before uncoiling it.

    Use an extension cord ONLY as a temporary measure and install and CONNECT a permanent solution SOON. The Massachusetts Electric Code helps reduce or eliminate the need for extension cords by specifying requirements for how many outlets belong in a room and where they should be located.

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Cables and Wires

  • What do the different colors on wire insulation mean?

    The colors are for safety. They indicate the purpose of the wire and the voltage that should run through the wire. Observing the colors-and then testing to be certain the color-coding is correct-helps keep human fingers out of places they don't belong also help speed the electrician's work.

    In houses, apartments, and condos with 120 and 240 power, all the wire insulation is black, red, blue, white, or green. Sometimes, the wires are marked with colored tape. The blacks, reds, and blues are the "hot" wires; the whites are grounded or "neutral" wires, and the greens are grounding wires.

    To confuse you a bit more, the color of wires going to switches may be different.. Plastic covered cables (leading brand name: Romex™) come with two insulator wires (black and white) and one uninsulated wire (the grounding wire). In the diagram below, a cable from the circuit breaker panel brings power to a ceiling light. Another cable (the switch leg) connects the ceiling light with a wall switch. Correct color-coding is shown below. Talk with your electrician for a more detailed explanation.

  • Knob-and-tube, Romex™, BX, UF cables: What is 2-wire Romex, and what is it for?

    The oldest wiring system you're likely to encounter is called "knob-and-tube" (K&T). It was installed as recently as the mid-1930s. Individual wires are mounted on ceramic posts (knobs) and run along joists or studs. When the wires run through a joist or stud, ceramic tubes (tubes) protect the insulation from the wood. Wires are connected or spliced by twisting them together, soldering, and wrapping with tape. When K&T isn't color-coded, a tester is required to identify "hot" and "neutral" wires.

    In general, electricians installing knob-and-tube were careful; the workmanship tends to be pretty good. The wire, insulation and insulators tend to stand up very well. Most K&T I've seen, for example, is in quite good condition. The distance between the wires added another safety factor: squirrels gnawing cables in your attic or basement cannot chew through the insulation in one bite and short out the hot and neutral.

    Since it tends to be in pretty good condition, knob-and-tube does not need to be replaced merely because it is knob-and-tube. Renovations that may have damaged it are a cause for concern and replacement. If your insurance company insists that you remove the knob-and-tube or you want to insulate walls that contain knob-and-tube, you many not have much choice.

    There are two major shortcomins to knob-and-tube wiring. First, there is no ground, and it is difficult and usually impractical to install grounding for a knob-and-tube circuit. It is typically more cost-effective to replace the K&T with modern wiring. See the section on grounding for a discussion of when grounding is valuable.

    The second problem with K&T has to do with building insulation. It is both unsafe and a violation of the National Electrical Code to run K&T wiring where building insulation surrounds the wires. While the insulation keeps you warm by trapping heat in your home, it also traps heat generated in the wire; this extra heat can cause the wire insulation to deteriorate more quickly and create electrical and fire hazards. Because splices between wires are not contained inside boxes, faulty splices that may heat up can ignite the building insulation.

    Replacing knob-and-tube wiring typically involves installing new cables in the walls and ceilings of your home. This can be time consuming and expensive. When you are painting or replastering, or better yet renovating a section of your house, it is much easier and faster to install cable in the walls. It is the most economical time to consider replacing knob-and-tube. Talk with your electrician or municipal wiring inspector about the best course of action for each individual situation.

    Multi-conductor cables
    In the 1940s and 1950s, 2-wire cables, sheathed in a cloth and varnish insulation were used. These cables look similar to the plastic sheathed cable used today. Like knob-and-tube, they have no grounding conductor. Major problems are brittle insulation that crumbles when touched and the lack of a ground wire. Not infrequently, cables that look like modern Romex™ (a brand name) are actually 2-wire cables with no ground. They often cause extra work when re-wiring or changing 2-hole receptacles to 3-hole grounding receptacles.

    BX Cable
    BX, properly called armored cable or Type AC cable, has a flexib le, spiral steel or aluminum jacket. Much of it is very old, but BX and similar types of cables are still installed today to provide physical protection to the wires. The metal jacket acts as the grounding wire. Sometimes, old BX cable also has crumbling insulation problems, especially in boxes above ceiling lights, where it can get over heated. It is not unusual for vibrations in a building to loosen the insulation and cause the hot wire to short circuit to the cable jacket or wiring boxes. If the jacket is rusted, it the jacket is rusted or the fittings are loose, BX may not provide a good grounding connection and may pose a fire hazard.

    Because the insulation may be brittle, replacing a receptacle or switch fed by BX can turn into a several hour effort to re-insulate the exposed wires with electrical tape or heat-shrink tubing. http://www.nexans.ca/egy/images/AC90BX.jpg

    Non-metallic Sheated Cable
    Often called Romex™, a popular brand, this is the cable most commonly used in homes today. Except for wet locations and areas where physical damage is a danger, non-metall sheathed cable is suitable for most residential uses.

    UF Cable
    Underground feeder cable is rated for dry, damp, wet or corrosive locations, and for direct burial in the earth. The sheathing on UF cable is also designed to resist deterioration from the ultra-violet light in sunlight. UF cable is a necessity for outdoor wiring. When buried, it must meet depth requirements to protect it from accidental damage from shovels, roto-tillers, and the like.

  • Why does it take so much time to "snake" new cables into walls?

    Getting wire into walls when there's no plaster or sheetrock is pretty fast and easy. When electricians want to limit the number and size of holes in the walls of your intact house, the situation is different. Some small holes are usually unavoidable, but getting wire from one hole to another requires wiggling a spring steel "snake" into the wall and aiming for the next hole. Sometimes, all to rarely, it flies right in and pops out the next hole. Usually, it's more art than science, putting one snake in and then working to "catch" it with another snake at the next hole.

    On top of this, electricians discover wood supports hidden inside the walls when snaking. In old houses, lots of wood substituted wood for engineering: keeping adding wood until it feels safe and strong. Hidden wood means more holes in the walls and more drilling to allow the wire through. At the same time, it is important to keep the holes small and easily patchable.

    The best way to speed the snaking process is to do electrical work before the painters come. That way there can be more, larger holes-made with less care and more speed. When the professional prepare the walls for painting, they can patch the holes quickly and more economically.

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Circuit Breakers and Fuses

  • What's the difference between 110 volt, 115 volt, and 120 volt circuits?

    Simply put, they are all the same. The actual voltage is typically between 117 volts and 124 volts; 110, 115, and 120 (and 220, 230, and 240) are just names that come out of history.

  • One of my circuit breakers tripped, but I could not reset it. What's the problem?

    The first thing to check is whether you have removed the problem that tripped the breaker. If you were doing something, like plugging something into an outlet on the circuit, remove it. Then reset the breaker.

    Resetting the breaker: Most circuit breakers move to a middle position when they trip-not "on" but not fully "off." First, push the handle all the way to off; it should stay there. Then, reset the handle to the "on" position. If the breaker won't stay in the "on" position now, you may need help locating the problem.
  • What is a circuit breaker panel schedule, and why do I need one?

    A circuit breaker panel schedule is simply a list of which receptacles and lights are controlled by each circuit breaker. They are often posted on the inside of the panel cover. They are most often either blank or scribbled over and illegible. It is worth making a complete, easy to read list: it will save you time and energy when a circuit breaker trips, and it will save an electrician time-and you money. You probably have better things to do with your money than pay an electrician to map out the circuits in your house. And it puts most electricians in a better mood.

  • Are circuit breakers better than fuses? Should we replace our fuse box?

    If you still have fuses, it may mean you have old wiring-that may have crumbling insulation or may just not be good enough for modern demands. But the fuses themselves are pretty good for many situations. Unless there is a particular problem with your fuses, allocate your money to electrical work that will make your house safer, more comfortable, more convenient, or more fun.

    Old may mean worn out for many things, but fuse technology lives almost forever. Fuses break an electrical circuit when a metal link gets hot and melts. It's low tech; there are no moving parts; there's nothing to jam or fail: metal melts when it gets hot enough. Period. It may be inconvenient because you need to keep a supply of fuses on hand and change them. But fuses are reliable.

    We have heard claims that statistics show that fuse panels have a significantly higher risk of causing a fire than breaker panels, usually because a fuse is not screwed in properly, or because the contacts have corroded, or because the wrong size fuse has been installed. A penny or aluminum foil under the fuse is a dangerous trick. We have not seen the research ourselves.

  • What's the difference between and overloaded circuit and a short? Does it matter?

    Plug a 2000 watt toaster oven into a 15 Amp circuit and the a fuse takes a little time to blow, a circuit breaker takes some time to trip. It's drawing 16-2/3 Amps, just a little too much current, which takes time to heat up and melt the fuse or set off the breaker.

    Drop a big kitchen knife on the counter and cut through the cord. When the knife blade connects the two wires in the cord, you get a spark. It draws a lot of current and melts the fuse or trips the circuit breaker immediately.

    In both cases, the circuit breaker or the fuse does its job; it acts as an over-current protection device and shuts down the electricity.

  • I've heard about a new kind of breaker, Arc Fault Circuit Interrupters. What are they and do I need them?

    Arc Fault Circuit Interrupters (AFCI) are designed to detect early signs of trouble in a circuit and turn off the circuit to prevent possible fires. They are required by the Massachusetts Electrical Code in some situations, like newly constructed bedrooms.

    If there is a loose connection in a wire in your wall or in something you've plugged in, there may be small sparks that could start a fire. The sparks affect the shape of the 60 cycle waves in your electricity in very specific ways. AFCIs have electronics to detect this change, the signature of sparking (or arcing) and turn off the power more quickly than circuit breakers.

  • Why are some of the handles of circuit breakers in my panel connected together?

    Equipment like electric baseboard heaters require 240 volts (also called 220 volts, 215 volts, and 210 volts, but don't worry about that) to operate. The circuit feeding 240 volt equipment requires two circuit breakers. To assure that all power to the equipment is turned off at the same time, the handles are tied together; if one goes, they both go.

    Also, often two separate circuits in the same part of your house are fed by a single cable with 3 wires and a ground. One "hot" wire for each circuit, a shared "neutral," and a shared "ground." Say, for instance, that the two receptacles in a box are on different circuits. Most often, only one of the circuits might have trouble at any given time. When the circuit breaker for that circuit trips, you might think that it's safe to open the box and fix something. If the breaker handles for the two circuits were not tied together, there would still be electric power in the box. The "handle tie" is to keep you alive.

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Fans and Fixtures of all Sorts

  • What does it take to repair or replace an old, noisy bathroom fan?

    Bathroom fans get old. Sometimes they stop running altogether, which can sometimes be an enormous relief from the noise. Typically, bathroom fans have two parts: 1) the case that mounts in a hole cut in the ceiling (the rough), and 2) the fan and motor that attach to the case, and the cover.

    If replacement fans were the same size as the originals, it would be easy to remove the cover, unplug and unbolt the fan or light, and replace them. Unfortunately, and we are suspicious that this is no accident, new models rarely fit exactly. Sometimes you can obtain replacement parts direct from the manufacturer, often at higher prices than an entire brand new. Unit. It work out cheaper because, with a little handiness, some scraped knuckles, and a knowledge of electrical safety procedures, you may be able to replace the part yourself.

    If replacement parts are not available, you may find a new fan unit that has fits the existing hole in the ceiling, but avoiding real damage to the ceiling will require careful carpentry-and there is still rewiring to do. Most often, new fans are a different size and require electrical work, patching, and painting. Replacing a bathroom fan is rarely a project that fits into a ½-hour home improvement TV show.

  • I've seen ceiling fans from $100 to $500 or more. What's the difference, and what does it take to install them?

    Cheap to expensive: style, reliability, convenience. Getting a lot of choice on what it looks like costs money. More expensive fans allow controlling the fan a light over the 2 switch wires that are already there. Cheaper models often require a third wire, which requires getting new wires in the wall (A more expensive fan is often cheaper.)

    Convenience: more expensive fans have more elaborate controls: speed, forward-reverse, dimming; and hand held remotes (hand-held remotes also eliminate the need for extra wires.

  • Fixtures: why do they specify maximum wattage for the bulbs? (which electricians call lamps)

    Lights generate heat. The wattage limit is to avoid damaging the lamp socket or the wiring and risking a fire. If you've ever looked at old wires when a ceiling fixture is removed, the insulation is often crumbling. It's gotten too hot for too long, dried out, and become brittle. New fixtures have fiberglass insulation that is supposed to protect the wires up to the maximum wattage on the label. Over time, they will still become brittle, but more slowly. Nothing is forever. Obey the label. Low wattage compact fluorescents, if they fit, are sometimes a good solution to getting more light.

  • What are the good and bad points of compact fluorescents?

    Compact fluorescents are miniature fluorescent lamps, with all the electronics attached. The common, garden variety compact fluorescent is designed to be screwed into a regular light bulb socket. The advantages are that they use less electricity to run, they last longer and have to be replaced less often, and they generate less heat. The disadvantages are that you cannot use a dimmer with them and that some people do not like the color of the light. But color choices are getting better every year.

  • How do I tell which is the hot wire and which is the neutral in a table lamp?

    The Plug: On newer table lamps, the prongs on the plug are different sizes. The larger prong is (should be) the neutral. The receptacle i
    n the wall has different sized slots; the longer slot is (should be) the neutral. For safety, the plug should fit in only one way.

    The cord: If you rub your fingers along the two sides of the cord, one should be smooth while the other has little ridges. The ridges are (should be) on the neutral wire side.

    Strictly speaking, the neutral wire is called the identified conductor. That's why the neutral has the larger prong and the ridged side of the cord.

    The lamp socket: The shell of the socket, the threaded part where you screw the light bulb in, is (should be) attached to the neutral. The tab in the center of the bottom of the socket, is (should be) attached to the hot wire. This arrangement makes the part that can give you a shock harder to reach with your fingers.

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  • Always wear safety goggles or glasses when working on your house. They protect against flying pieces when cutting wire, against sparks and hot flying metal, and against chips and plaster when you drill or cut. Whenever you are not absolutely certain that you know how to do something safely and are capable of doing it safely, don't do it.

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Although we've done a fair bit of wiring, these eFAQ comments are necessarily limited and incomplete. We cannot and will not be responsible for what you do. We do not recommend that you perform any work for which you are not adequately trained and skilled. If you are at all uncertain about what is correct or safe, don't do it. Contact someone qualified -- a licensed electrician or your local electrical inspector. Electricity is no joke; mistakes can result in shocks, fires, mutilation, or death.

Our comments are based on the U.S. National Electrical Code (NEC) and our own experience. Our explanations are intended to provide general background information as a starting point for further study. We want you to be an informed, educated consumer of electrical services. Know what you want, and know what you are buying. If you have questions or doubts about what we say, please let us know.

The NEC has the force of law only when local or state governments adopt it. Massachusetts has adopted the National Electrical Code as the law, with some significant changes and additions. Remember that the Massachusetts Electrical Code is a set of minimal standards; it is not a project design guide. Meeting Code requirements will not necessarily provide the convenience you desire. It is often smart to go beyond its minimal requirements.

Contact us for more details or with other questions at eFAQs@onlyconnectelectricians.com or at 617-484-2828. And, of course, call us to explore solutions to your electrical problems and set up an appointment for the work.

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