Residential Electrical Contractor | Residential Electrician Service
Have you ever had to use an adaptor in order to plug an appliance or tool into an old 2 wire non-polarized outlet? Or even worse, have you ever used a tool that was missing the grounding prong because someone had hacked it off in order to use a two wire outlet? Or worse yet, has someone installed regular three wire outlets into your 2 wire system, thus allowing grounded appliances to be plugged in while giving a false sense of security? All of these situations are potentially life threatening, and should be corrected.
Many houses which were built before 1941 still have two wire electrical systems, which can't safely accommodate many modern appliances. If your home is in this category, then there is a safe, economical way for you to upgrade your outlets to a three wire system, by installing Ground Fault Circuit Interrupter outlets (commonly called GFI or GFCI receptacles).
The third wire of a three wire system is designed primarily to protect people from being shocked. It accomplishes this by providing a path for the current which is caused by a "Ground Fault" (also known as a "short") to go to "ground". If the current is at all substantial, this will cause the breaker to trip (or the fuse to blow), preventing the faulty equipment from being used, and thus protecting the user from being shocked. Nothing is completely fool proof though, and one of the shortcomings of a regular grounded system is that there could be a ground fault without sufficient current to trip the breaker, but would still allow a person to be shocked under certain circumstances, especially if the person is a better path to ground than the system ground (if you were standing in water for example).
A GFI device actually provides better protection than a grounded 3 wire system does, but in a different way. The GFCI electronically detects even a very small ground fault and very quickly interrupts the current to the device. This provides protection even if you are standing in water, that is if everything is working correctly, but don't tempt fate by unnecessarily gambling on technology. Never use electricity when you are standing on wet ground.
Warning: Some appliances, such as microwave ovens can hold a high voltage charge on internal parts (like a capacitor) which could conceivably energize the appliance frame, so you should not rely on a GFCI connected to a two wire system to safely power a microwave oven. You should have an actual grounded receptacle installed by a qualified person instead.
Note: Even though a GFIC receptacle will be able to accommodate grounded 3 wire plugs, and will usually protect people from shocks due to ground faults it still won't actually be grounded if installed on a two wire system. Because of this fact certain devices won't work correctly if plugged into such an outlet - especially surge suppressors which work by directing excess current to ground. So, don't plug delicate electronics into a GFIC outlet that is connected to a 2 wire systems. Surge suppressors and delicate electronics need an actual ground!
Replacing a two wire outlet with a three wire GFI receptacle is a safe, easy do it yourself upgrade that will make your home safer and more convenient.
For most areas of a house, receptacles must be no more than 12 feet apart and no more than 6 feet from a door or entryway - IE, every point on almost all walls should be no farther than 6 horizontal feet from a receptacle. The wall spaces formed by fixed room dividers, such as freestanding counters, or railings, are included in the six-foot measurement. Receptacles installed in the floor within 18" of the wall may be used in place of wall-mounted receptacles. Receptacles installed in the floor must use a box-receptacle combination designed specifically for that purpose.
Every hallway over 10 feet long must have at least one receptacle - other than this, hallways are exempt from the 6 foot rule.
No outlets may be installed over an electric baseboard heater.
Plugs which are located behind a stationary appliance such as a refrigerator or washing machine do not count when considering plug spacing.
Any wall space that is 2 feet or more in width must have a receptacle.Every basement and garage must have at least one receptacle, and all must be GFI protected. At least one receptacle must be installed in the each unfinished portion of a basement. This receptacle is in addition to any receptacles that may be installed for laundry or other specific purposes.
One 20-amp branch circuit must be provided for the laundry. This circuit is limited to receptacles within the laundry room. No other outlets are permitted on this circuit.
There must be at least two GFI plug on the outside of the house located near the front and back doors, and all exterior plugs must be GFI protected. Note: Outdoor outlets installed in wet locations shall have an enclosure that is weatherproof whether or not it is in use. An accessible 15 or 20 amp plug must be within 25 feet of all HVAC equipment.
As a general rule you may have up to 10 receptacles on a single circuit, but this is a gray area which is subject to the discretion of the codes official.
Dining room plugs must be on a separate circuit
At least one 20-amp circuit for bathroom receptacles must be supplied. Each bathroom must have its own GFI plug circuit with a plug near the wash basin, and no lights or other plugs or appliances on these circuits. Where a 20-ampere circuit supplies a single bathroom, outlets for other equipment within the same bathroom shall be permitted to be supplied in accordance with 210.23(A). This circuit shall NOT be used to supply a major fixture such as a whirlpool or hot tub!
At least one 15 or 20 amp, 120 volt GFCI protected receptacle must be installed at an indoor spa or hot tub location - not closer than five feet from the inside wall of the unit and not more than ten feet away from it. Light fixtures, outlets and ceiling fans over spas and hot tubs shall be a minimum of 7'6" above the maximum water level. Note - pump motors and other spa related electrical equipment must remain accessible for service after all finishes are in place.
Outdoors spa or hot tubs have the same requirements as a swimming pool. Check in section 680 of the NEC for those requirements.
Replacing a 2 prong outlet with a 3 prong GFCI outlet greatly improves the safety of an ungrounded electrical system
Subjects in this article are covered by the National Electric Code - NEC 2005 section 406.3(D)(b),(c)
In the kitchen and eating areas every counter space wider than 12 inches must have a GFI protected plug, in general all kitchen counter top plugs should be GFI protected. Countertop receptacles shall be installed so that no point along the wall is more than 24" measured horizontally from a receptacle outlet in that space. Peninsular bars and islands 12" or wider shall have at least one receptacle. Exception: Tennessee Code in dwelling unit's section states, "The installation of receptacles for island counter spaces and peninsular counter spaces below the countertop shall be optional.
At least two 20-ampere branch circuits are required to feed receptacle outlets for small appliance loads, including refrigeration equipment in the kitchen, pantry, breakfast room, and dining room. These circuits, whether two or more are used, shall NOT supply anything other than receptacles in these areas. Lighting outlets and built-in appliances such as garbage disposals, hood fans, dishwashers, and trash compactors are NOT permitted on these circuits.
Kitchen counter top receptacles must be supplied by at least two small appliance branch circuits.
Kitchen appliance and convenience receptacles must be on 20 amp breakers, and wired with 12 gauge wire. Required Ground Fault Protection A ground fault circuit interrupter must protect ALL receptacles listed below:
Kitchen receptacles that serve counter top surfaces
Counter top receptacles within 6 feet of a wet bar sink.
All receptacles in an unfinished basement:
Crawl spaces at or below grade.
Spas, Hydro massage, Hot tubs and associated electrical components.
Pretty much any location where water and electricity might mix.
Required Arc Fault Circuit Interuptor protection - 208 NEC 210.12 (A)An arc fault circuit interuper - AFCI is a device (usually if not always a breaker) designed to give protection from arc faults. An AFCI breaker will trip whenver an arc is detected. In all dwellings an arc fault circuit interrupter must protect ALL 120 volt 15 and 20 amp single phase receptacles in family rooms, living rooms, parlors, recreation rooms, dining rooms, libraries, dens, sunrooms, recreation rooms, closets, hallway or similar rooms. In other words pretty much all receptacles inside of a dwelling except the bathrooms, kitchen, laundry and garage must be AFCI protected.
Note that all bedrooms outlets must be protected by an arc-fault circuit interrupter listed to provide protection of the entire branch circuit. This includes wiring to the smoke detector outlets.210.12, NEC
Appliance Branch Circuits
The following Appliances must be on a separate 20-amp circuit: Dishwasher, Garbage disposal, Washing machine.
As a general rule All 240-volt appliances must be on their own circuit.
Hot tubs, garden tubs, Jacuzzis and the like must be GFI protected and wired as required for the particular model and local codes.
The service areas of all appliances must be accessible after the final finish is complete.
Required Light Fixtures
General Lighting Branch Circuits shall be computed on a three watts per square foot basis. You may wire up to 600 square feet of living area on a 15 ampere branch circuit or up to 800 square feet on a 20-ampere circuit. These branch circuits may supply lighting outlets in all areas of the dwelling and convenience receptacles, other than Small Appliances, Laundry, Bathroom, or HVAC - as outlined above.
Every room, hallway, stair way, attached garage, and outdoor entrance must have at least one light fixture controlled by a wall switch. However, in most rooms other than kitchens and bathrooms, the wall switch may control one or more plugs into which lamps may be plugged instead of a ceiling or wall mounted fixture."
There must be at least one wall switch controlled light in a utility room, attic, basement or under floor space used for storage or which contains equipment such as heat and air, water heaters, sump pumps, etc. which may ever require service. The switch must be located at the entry point to these areas.
Hallways and stairs with more than six steps require the lights to be controlled by a switch at each end.
In closets, fluorescent fixtures must have at least 6 inches of clearance away from shelves or storables. In a typical two foot deep (approx.) closet, the fixture will be mounted on the wall just over the door.
In summary, put a light in every room or large closet, outside of every exterior door, and under the floor and in the attic if there is electrical equipment in these spaces or if they are suitable for storage.
Switch the room lights at every door entering the room, switch a hall or stairway at both ends, and switch exterior lights at the doors which they service.
As a rule of thumb you can put up to ten average light fixtures on a single circuit, unless this will add up to excessive wattage for the circuit (note, a ceiling fan and light kit qualify as one fixture).
Notable exceptions would be floodlights, which are high wattage fixtures. Four double bulb floodlights would pretty well fill up a circuit by themselves.
The actual rule for this is to not exceed 80% of the calculated wattage capacity of the circuit.
Wattage capacity of the circuit equals the amp rating of the breaker times the voltage (120), so for a typical 15 amp light circuit add up all of the maximum wattage's and make sure that they are less than 80% of 15x120 (1440 watts max). Keep in mind that the inspectors may be looking for no more than 10 fixtures (more or less according to local variances) per circuit, your calculations notwithstanding.
There must be a 120-volt battery back up smoke detector on the ceiling, or on the wall close to the ceiling in the area outside of every bedroom, and inside of each bedroom. All smoke detectors must be tied together so that if one goes off they all do. Smoke detectors must be protected by an arc fault breaker. When you are roughing in for smoke detectors daisy-chain them with 14-3 WG and the extra (red) wire will interconnect the system.
Note that all bedrooms outlets must be protected by an arc-fault circuit interrupter listed to provide protection of the entire branch circuit. This includes wiring to the smoke detector outlets.210.12, NEC Ground Conductor Make Up All equipment grounding conductors must be connected together with solderless pressure connectors such as wire nuts or crimp sleeves, leaving sufficient extra conductor for attachment to the metal box and/or device. When crimp type connectors are used, they must be crimped using the tool recommended by the manufacturer. Please note that ALL metal junction and outlet boxes must be grounded by attaching the equipment grounding conductor out of the NM cable to the metal box using an approved screw or grounding clip. When circuit conductors are made up, six inches of free conductor must be left for use in make-up and for the attachment of devices.
Wire Size Application GuideWire Size and type
14-3 wg 15 amps max, Switch circuits
14-2 wg 15 amps max, Standard 120 volt 15 amp general purpose branch circuits. With all of the electronics equipment that families have (and are likely to have in the future) in the interest of doing a good job it is worth considering to just not use any wire smaller than 12 gauge so that 20 amp breakers can safely be used on all circuits - Even if the local codes would allow 14 gauge wire. Using one less wire size on the job also helps to decrease waste.
12-3 wg 20 amps max, switch circuits and (rarely) 240 volt 20 amp equipment
12-2 wg 20 amps max, branch circuits, kitchen receptacles, and other 120 volt 20 amp small appliance circuits
10-2 wg 30 amps max, Water heaters, AC units, and (rarely) other straight 240 volt 30 amp appliances
10-3 wg 30 amps, Electric clothes dryer, and other 220/110 volt 30 amp combo appliances
8-3 wg 50 amps max, Oven or cook top, and other 220/110 volt 50 amp combo appliances
6-3 wg 65 amps max, Range or oven/cook top combo, other 220/110 volt 60 amp combo appliances
InspectionsSeveral inspections (AKA permits) are required for most residential construction projects:
Temporary Service Inspection (if a temporary service will be used)
Rough in inspection
HVAC system electrical inspection
In addition to these, any electrical work done by a subcontractor other than the electrician will have to be inspected (usually both rough in an finals) for example - well pumps, or external wood fired furnaces.
In some cases you may be able to get a service release between rough in and final inspections so that you can more easily run HVAC and other high current services during construction. If so you will usually have to get an inspection for the service release.
If any inspection is failed then the codes official will usually leave a brief (and often cryptic) note outlining the reasons for the failure, and an additional inspection permit will have to be purchased. Note that all subcontractors who do wiring work must pull their own permits using their own contractors license. It is not permitted to have work which was done by other subcontractors inspected under any license other than their own. If you are a homeowner who is wiring your own house under a licensing exemption, you are not allowed to pull permits for subcontractors.
Rough in Inspection
At the time you call for your rough in inspection, you should have all wires pulled, stapled properly, installed in ditches, and splices made up and ready to accept devices and fixtures. DO NOT cover any wires with insulation / wall coverings, install any devices / fixtures, or cover any wiring which is to be buried . Note: Temporary address numbers should be installed prior to the rough in or temporary service inspections.
All permits must be on site. The electrical installation should be complete at the time of request. All devices and fixtures installed, service equipment complete, and labeled properly. All wiring shall be free from short circuits, ground faults and open circuits. All light fixtures are required to be grounded along with light switches that are within five feet of a grounded object.
Note: Permanent address numbers should be installed prior to the Final inspection.
Subjects in this article are covered by the National Electric Code - NEC 2005 sections 314.23, 314.27(D) and 422.18(a)
Whenever you are replacing an existing light fixture with a ceiling fan it is safe to assume that the work box that the light was installed on will not be sufficient in itself to safely and legally support a ceiling fan. Fortunately, there are several ways to remedy the situation. The National Electric Code article 314.27(D) states that a box cannot be the sole means of support for a ceiling fan unless it is listed and designated by the manufacturer as such.
If you choose a fan with a large diameter base, then you can support the fan by fastening it directly to the ceiling joist that usually adjoins the box, thus not relying on the box to support the fan at all. You can't do this unless the base is at least 6 1/2" in diameter more or less, because the screws that you use to mount it need to go through the fan bracket as near as possible to the center line, and you want the finished installation to cover the work box. This is very similar to what happens with a fan rated plastic "saddle" box.
Understanding 220 or 240 volt Electrical Circuits
To understand how a 240 volt (also known as 220 volt) household circuit works you should first know a little bit about how a regular 120 / 110 volt circuit works. If you are at all familiar with residential electrical wiring then you probably already know that in most cases appliances, and fixtures connect to three wires:
1) A black wire which is often known as the "hot" wire, which carries the current in to the fixture.
2) A white wire called the neutral which completes the electrical circuit.
3) A bare copper wire called the ground, the sole function of which is to enhance user safety.
When the circuit is in use current is "pushed" through the fixture by way of the "hot" wire and then to ground by way of the neutral, and unless something goes wrong the bare ground wire doesn't do anything except to remain ever vigilant in case of a problem.
Since house current is alternating current the actual direction that the electrons flow reverses direction 60 times per second (60 cycles). Put another way, the hot wire has a negative charge alternating with an equal positive charge, and the polarity of the hot wire reverses 60 times per second.
Now for the quick explanation of 240 / 220 volt house current; Appliances which use straight 240 current (such as electric water heaters, or (rotary phase converters) also have three wires:
1) A black wire which is often known as the "hot" wire, which carries the current in to the fixture.
2) Another "hot" wire which may be blue, red or white (if it is white the code actually requires it to painted or otherwise marked one of the other colors, but often it is not) which also carries current in to the fixture.
3) A bare copper wire called the ground, the sole function of which is to enhance user safety.
That's it, no neutral. Now, if you are paying attention, then you are probably wondering "If there isn't a neutral wire then how is the circuit completed?" The answer is that when one hot wire is negative, then the other is positive, so the two hot wires complete the circuit together because they are "out of phase". This is why 240 volt circuits connect to double pole breakers that are essentially two single pole breakers tied together. In the main panel, every other breaker is out of phase with the adjoining breakers. So, in essence 240 volt wiring is powered by 2 - 120 volt hot wires that are 180 degrees out of phase.
Previously mentioned, "straight" 240 volt appliances, but there is another class of 240 volt equipment; some appliances (such as clothes dryers and ranges) use 240 volt current to power their main function (drying clothes or cooking food) but use 120 volt current to power accessories such as the clock on your stove or the light inside the oven, or the digital readout on your dryer controls. That is why some 240 volt circuits have four wires:
1) A black wire which is often known as the "hot" wire, which carries the current in to the fixture.
2) Another "hot" wire which is red, which also carries current in to the fixture.
3) A white wire called the neutral which completes the electrical circuit for the 120 volt accessories only.
4) A bare copper wire called the ground, the sole function of which is to enhance user safety.
At one time, the code allowed for one insulated wire to function as both ground and neutral in 120 / 240 volt combo circuits, but now all such circuits must use the 4 wire scheme. This is why your new dryer (or electric range) might have 4 prongs on its plug and your old dryer receptacle only has 3 holes. In which case article 250.140 of the 2005 N.E.C. (National Electric Code) allows for the "pigtail" (the cord and plug assembly) to be changed to match the old 3 wire receptacle as long as certain conditions are met. The National Electric Code allows that, but your local code might not, so check first, or even better yet make a deal with the appliance dealer to do it for you.
Basic 220 Volt Circuits
220 volt circuits (AKA 230 volt, or 240 volt) are used to supply power to appliances which draw high currents such as clothes dryers, ranges, ovens, cook-tops, heaters, air conditioners, rotary phase converters, and water heaters. Parts of a 220 Circuit
No matter what appliance you are wiring for, any 220 circuit has three elements:
1) The breaker panel connections.
2) The supply wire.
3) The terminal connection, which can be either a special receptacle or a direct connection to an appliance.
For any appliances rated over 300 Volt-Amps (which includes almost everything 220) there must be either a means of disconnect at the appliance or a breaker lock permanently installed in the panel so that a service man can insure his own safety. (NEC article 422.31) "Means of disconnect" can include a pigtail which can be unplugged from a receptacle, a disconnect device (often used for HVAC equipment) or a unit mounted switch which has a clearly labeled off position. Appliances which are in a direct line of site of and in the same room as the breaker panel are exempt from this requirement. Any time that you are working with aluminum wire, you must coat all connections with conductive grease such as Ideal brand Noalox. Failure to do so will result in a connection failure due to corrosion, and a hazardous condition which could result in fire or electrical shock.
Breaker Panel Connections
Important safety note: Main panels cannot usually be de-energized by turning off breakers. Only qualified personnel should work on main electrical panels. A simple mistake can result in death or injury.
All 220 circuits connect to the breaker panel through a double pole breaker (or equivalent fuse). Double pole breakers often look like a pair of single pole breakers that are stuck together - because that is exactly what they are. 220 equipment will actually function if it is connected by way of two single pole breakers, but it wouldn't be safe or up to code, because in the event of a fault one breaker might trip causing the appliance to stop working, but it would still be energized by the other breaker. So double pole breakers are designed to trip both sides simultaneously. The amp ratings of breakers should never exceed the amp rating of either the wire, appliance, receptacle, or disconnect used in the circuit. Power Connections
The 2 line voltage wires which are feeding the 220 circuit connect to the double pole breaker in the panel. Both of these wires should be either black or red for their entire exposed length inside of the breaker panel. These wires can be colored with paint, tape, or perm marker to comply with this code.
Ground and Neutral Connections
All modern 220 circuits will also have a ground wire which is identified by either green insulation or by being bare metal with no insulation. The ground wire connects to the ground bar. Some 220 circuits will also have a white insulated neutral wire which connects to the neutral bar, or to the combined neutral / ground bar.
Wire for 220 Circuits
The wire requirements for 220 volt circuits are pretty much the same as for any other circuit - it must be of the proper type for the place that it is being used, it must have sufficient volt - amp capacity, and it must have the correct number of conductors. Proper color coding would also be nice, but isn't a big deal because the exposed lengths of the conductors (in the main panel and in the terminal device) can be colored with paint, tape, or permanent marker. If you are wiring for a dryer, range, or any other 220-110 combo appliance you must use a four conductor wire with an insulated neutral and a separate ground such as X-3-WG. If you are wiring for straight 220 equipment such as a water heater then you can use a three conductor wire such as X-2-WG. The amp rating of the wire should never be less than that of the circuit breaker that is used. You can find a handy wire application / amp rating charton this page.
Note: You can no longer install 3 wire range or dryer circuits - you must install 4 wire systems for ranges and dryers. If you already have a 3 wire range or dryer then don't worry, your old appliance can be made compatible with a 4 wire system by installing a 4 wire pigtail on it. Then when you buy a new appliance it will plug right in to your new 4 wire system.
Terminal Connections Connecting the terminal connections on a 220 system aren't all that different than installing any other appliance, fixture or receptacle except that the wire and connection hardware is usually bigger (and a little bit harder to work with) and there is an extra "hot" wire. Because of the bigger stiffer wire it is also more important to cut the conductors to the correct length as you won't be able to stuff extra wire into a box like you can with most fixtures.
AFCI - Arc Fault Circuit Interrupter
AFCI Breakers are designed to protect your home from fires which are cause by arcing as well as over current conditions. Normal breakers are only effective against over current conditions. Arc Fault Breakers are now required by new construction codes to protect receptacles which are located in bedrooms (and possibly other locations according to local codes variants). Arc Fault breakers may not be 100% effective against all fires caused by arcing because there is a certain amount of arcing which is normal, and the arc fault breaker would be unusable if it tripped every time that a normal arc were detected. For example if you ever noticed a spark when you unplug an appliance or flipped a wall switch, then that is normal arcing. Abnormal (and Dangerous) arcing often is caused by a poor connection, or damaged wire. Unfortunately, dangerous arcing "looks" an awful lot like normal arcing to the breaker, so it is possible for a fire to be started without tripping the breaker. Nonetheless an arc fault breaker, even if less than perfect, is a lot better than no protection at all. By the way, arc faults are one of the big reasons that electrical connections should never be made outside of an approved wiring device. Arc Fault Breakers like GFI devices have "test" and "reset" buttons and should be tested periodically according to the manufacturer's specifications (usually once a month).
GFI or GFCI (Ground Fault Circuit Interrupter) devices help to protect people from being shocked or electrocuted. They work by very quickly detecting a "Ground Fault" (for example the ground fault that happens when a person is being shocked, one caused by a short, or a voltage "leak" caused by dampness in and around electrical equipment) and interrupting the current. GFI devices are usually either in the form of a receptacle or a breaker, although some equipment (hot tubs for example) may sometimes have GFI protection built in, but not usually. A single GFI receptacle or breaker often protects many additional receptacles or fixtures, which sometimes causes confusion because a homeowner doesn't know that a tripped GFI receptacle in another part of the house could be interrupting the current to a regular receptacle. In many codes jurisdictions an old fashioned two prong outlet can be replaced with a three pronged GFI receptacle in order to safely allow the use of modern appliances with three pronged plugs. GFI protected circuits and devices are usually found (and required by codes) outside, and in damp locations such as bathrooms, kitchens, and basements. Wet conditions around a GFI protected device may trigger the GFI and prevent it from being reset able. All GFI devices have "Test" and "Reset" buttons on them. The test button causes a ground fault within the device and trips the reset button causing it to pop out and protrude slightly, thus interrupting the current to any devices which are protected by the GFI in question. Pushing the reset button in until it catches will restore current to the circuit. If the "test" button fails to function as described then the GFI device must be replaced. As mentioned previously, a continuous ground fault (like one cause by excessive water around the electrical equipment) will prevent the GFI from being reset able, and must be remedied before the circuit will be usable. A nonfunctioning GFI device is an extremely dangerous situation, which must be remedied immediately.
All residential electrical systems should have a single point ground. Grounding to multiple places will cause all kinds of problems with noise, hum, snow, and generally bad audio video signals. Intuitively it would seem that having redundant grounds would be a good thing, but it is not, because voltage is a relative value. If you did an experiment where you connected a long conductor to your house current, and then checked the voltage to ground at different locations (different places in the yard, water pipes, the ground rod, etc..) you would find that there would be different voltage potentials at different spots. In fact if you measured the voltage potential between two spots of earth in the yard you might find that current would actually flow through a conductor between two spots of earth. Those different voltage potentials and the current they cause are why ground loops are bad. Especially troublesome ground loops can be cause when a length of coaxial wire connects two pieces of audio video equipment (cable box, TV, etc…) which are plugged into different outlets. One great way to fix this problem is to use surge protectors which incorporate coax protection.
An electrical term which is short for "line voltage" and indicates wires which bring power into a device, and the terminals that such wires connect to. Incoming Power.
An electrical term which indicates an additional electrical load, the wires that carry current from a device to the load, and the terminals on a device that such wires connect to. Outgoing power.
Wild-wire or red-leg delta properly referred to as high leg delta is a type of three phase transformer winding connection sometimes found in older electrical installations. A transformer wound in this fashion will have four wires coming out of the secondary: the three phases, plus a neutral that is a center-tap of one of the windings. The voltages between the three phases are relatively the same; however the voltage magnitudes between a particular phase and the neutral vary. The phase-to-neutral voltage of two of the phases will be half of the phase-to-phase voltage. The remaining phase-to-neutral voltage will be 1.7 times the phase-to-phase voltage. Typically, the transformer is designed such that the 'B' phase is the 'high' leg. According to Article 110.15 of the 2005 National Electrical Code, panel boards connected to this type of transformer must explicitly identify as the high leg, preferably by coloring it orange. Generally the high-leg can not be used for loads requiring a neutral such as lighting because of the high voltage potential. In other cases such as three phase motors which do not utilize a neutral the wild-leg is irrelevant because it has the same phase to phase voltage potential as the other two legs.
Do You Need To Upgrade Your Electrical Service?
Not having enough power isn't just an inconvenience - voltage drop-offs may actually damage sensitive electronics, so having plenty power is important to electrical home safety. Even with enough power, you may need additional outlets to avoid relying on a tangle of power strips and extension cords - a potential safety hazard. The standard for household power used to be 60 amps. But modern homes may need as many as 200 amps to run air conditioners, computer equipment, high-definition televisions, and high-tech home automation devices. To handle increased electrical loads, it's likely you'll also need to upgrade electrical wiring, especially if your house is more than 40 years old.
Rewire when the time is right and save Rewiring can be a messy and expensive proposition, but with a little upfront planning you can minimize the disruptions and even turn the job into an opportunity to add features that will increase the value of your home.
The best time to rewire is during a remodeling project, such as renovating your kitchen or adding a family room, when subcontractors are opening up your walls anyway. That way, your electrician has easy access to the walls, and refinishing walls will be part of the larger remodeling project-not just the rewiring.
Plan ahead for your future power needs Structured wiring is a smart investment and may be a marketing advantage if you should decide to sell your home. Structured wiring is a generic term for any heavy-duty electrical and data cables designed to handle the latest entertainment and communication devices-and those yet to be invented-including phones, Internet, and household heating and lighting systems.
While a standard electrical upgrade essentially maintains the value of your home, adding structured wiring can increase it. According to a 2009 study by the Consumer Electronics Association and the National Association of Home Builders Research Center, almost 50% of homes built in 2008 included structured wiring, a sure sign of its growing value to home owners.
Find and Prevent Electrical Fire Dangers in Your Home
Most homeowners know that overloading circuits and using frayed extension cords can lead to electrical fires. But there are other electrical fire dangers in your home that, while they may not be as obvious, are no less dangerous. According to the most recent data from the National Fire Protection Association, electrical failure or malfunction caused an estimated 52,500 fires in U.S. homes in 2006, resulting in 340 deaths, 1,400 injuries, and nearly $1.5 billion in property damage.
Electrical home safety warning signs Here are warning signs of four potential hazards that you may not know about. If any of them sound familiar, consider hiring a licensed electrician to conduct a wiring inspection ($200 to $300).
Hidden danger #1: Old wiring The lifespan of an electrical system is 30 to 40 years. But more than 30% of the nation's houses-some 30 million homes-are more than 50 years old. Older homes with fuses were set up for about 30 amps of power; many homes now have 100, 150, even 200 amps of power.
Warning signs of inadequate power include circuit breakers that trip or fuses that blow repeatedly, and an over-reliance on extension cords. They're meant to be temporary. If you have extension cords routed all over, it's time to get an electrician out there. Your home would not comply with the National Electrical Code.
Hidden danger #2: Aluminum wiring Many houses built in the 1960s and early 1970s have aluminum wiring, which oxidizes and corrodes more easily than copper and has been linked by the Consumer Product Safety Commission to electrical fires. It's okay for a while, but it doesn't have the life that copper does, particularly where wires terminate. The terminals and splices are known for overheating. Short of a whole-house wiring upgrade, an electrician may be able to head off potential problems by installing copper connectors called pigtails at receptacles and breakers. "It's time-consuming," Boyell says, "but there's no big equipment involved."
Hidden danger #3: Arc faults An arc fault-which occurs when electrical current veers off its intended path, often through a breach in wiring-is a leading cause of electrical fires, according to the National Fire Protection Association. It doesn't take much to cause an arc fault. You could damage wiring inside the wall when hanging a cabinet, a piece of furniture could cut through a cord, or there may be a loose connection in an outlet. The resulting arc, capable of producing heat in excess of 10,000 degrees F, can be nearly impossible to detect. But arc faults are preventable. A device called an arc-fault circuit interrupter (AFCI) senses these dangerous abnormalities in wiring or appliances and shuts down the circuit before it overheats. The Electrical Safety Foundation International estimates that the use of AFCIs could prevent 50% to 75% of fires caused by arc faults. AFCIs are now required on circuits covering most general living areas in new houses. (Note: These are not the same as ground-fault circuit interrupters, or GFCIs, which are used in kitchens, baths, and other wet areas to prevent electrical shocks.) But they're even more valuable in older houses, where connections may have degraded over the years. It's an easy job for an electrician to upgrade standard circuit breakers, which don't protect against arc faults, to AFCIs. At $30 to $50 per breaker, it could cost a few hundred dollars to retrofit every circuit. Still, weighed against the potential tragedy of a house fire, it's money well spent.
Hidden danger #4: Counterfeit electrical products If you've ever gone to a flea market and seen vendors hawking extension cords, power strips, night lights, batteries, even circuit breakers for ridiculously low prices, there's a reason. They're probably counterfeits, and they're incredibly dangerous. Your best bet is to buy electrical products only from reputable retailers who will take things back if they don't work. And look for the Underwriters Laboratories seal. On low-cost items that are ripe for counterfeits, UL puts its logo in a holographic label that's much more difficult to reproduce.
When It's Time for an Electrical Wiring Upgrade
The lights come on when you flip the switch, the TV works, and the refrigerator keeps food cold. That means the electrical wiring must be fine, right? Not necessarily. There may be times, especially if your house is more than 40 years old, when you need to upgrade electrical wiring for safety, or because the existing wiring no longer meets your family's power needs. Rewiring can be a messy and expensive proposition, but with a little upfront planning you can minimize the disruptions and even turn the job into an opportunity to add features that will increase the value of your home.
Safety issues with older wiring
Faulty wiring is the leading cause of residential fires, according to a 2009 study by the National Fire Prevention Association. And the older your house is, the greater the chances that the wiring might be outdated or unsafe. Old wiring-even knob and tube wiring that dates back to the early 20th century-isn't inherently dangerous, but unless you were around when the house was built, you can't be sure the electrical system is up to code. Plus, materials such as wire insulation can deteriorate over time.
If you don't know when your wiring was last inspected, it's worth paying a licensed electrician to give it a once-over, especially if you have any of these warning signs:
Breakers that trip or fuses that blow repeatedly
A tingling sensation when you touch an appliance
Flickering or dimming lights
A persistent burning smell from a room or appliance
Warm, discolored, or sparking outlets
Two-prong ungrounded outlets throughout the house
No ground fault circuit interrupter (GFCI) outlets in kitchens, baths, and other areas exposed to moisture.
Another reason to consider upgrading is that some carriers refuse to insure houses with older wiring, or charge owners higher premiums.
Be on the lookout for aluminum wiring Instead of the standard copper wire, many houses built in the 1960s and early 1970s have aluminum wiring, which is considered a safety hazard. Aluminum wiring connections often loosen up over time. An inspection can determine whether it's safe to leave the wiring in place. Sometimes the addition of copper connectors, called pigtails, at receptacles and circuit breakers can resolve potential problems.
When you need more power Sixty amps used to be the standard for household power. Today, houses often need 200 amps to run air conditioners, flat-screen TVs, computer equipment, and all the other gadgets our parents and grandparents hardly imagined. Not having enough power isn't just an inconvenience; it can actually damage sensitive electronics. Even with adequate power, you may need to add outlets to avoid relying on power strips and extension cords, an inconvenience and a potential safety hazard.
Prepare to open your walls-and your wallet Upgrading electrical wiring is a big job, for one simple reason: All the wires are behind the walls. Every house is different and prices vary by market, but for a whole-house rewiring job, you're easily looking at a bill of several thousand dollars. The vast majority of that is the labor involved to get to the wires, run new ones, connect them to every switch and outlet, close up the holes, and clean up the mess.
The easiest time to tackle this work is during a larger remodeling project, such as redoing a kitchen or building an addition, when contractors are knocking holes in the walls anyway. That speeds the process, which can take anywhere from five days to two weeks for an entire house.. Examples are when you need to add circuits to run a new appliance or power an addition like a swimming pool. In those situations, the expense and disruption could be reduced.
Plan ahead for future power needs If you're going to spend the money and cut holes in the walls, you might as well run all the wires you can. That way, you'll be ready for any possible future power needs. One smart investment is structured wiring. These are heavy-duty data cables that enable the latest features of TVs, stereo equipment, computers, game consoles, phones, security systems-even Internet-based remote control of house systems like heating and lighting. While a standard electrical upgrade essentially maintains the value of your home, adding structured wiring can increase it. According to a 2009 study by the Consumer Electronics Association and the National Association of Home Builders Research Center, almost 50% of homes built in 2008 included structured wiring, a sure sign of its growing value to home owners.
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