Electricity 101

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Electricity
n. Electric current used or regarded as a source of power.
n. Intense, contagious emotional excitement.


Circuit breaker
n. An automatic switch that stops the flow of electric current in a
suddenly overloaded or otherwise abnormally stressed electric circuit.




E-L-E-C-T-R-I-C-I-T-Y is one of those 4 letter words we dare to
mutter (ok, so its 11 letters, but work with us here). Yes,
electricity can be scary for those of us who have yet to tackle an
electrical project, but just like a woman - electricity just needs
a little respect!


Projects can range from the simple install-a-dimmer-switch to the
more laborious "I'm going to re-wire my entire 1940's
bungalow and bring it up to code".If you're just starting
out, below are a few great starter projects you can do TODAY.

And here's a BE JANE TIP: Dimmers add value to
your home with little cost!

SAFETY TIP:We think you can do it, but if
you aren't 100% confident that you can turn off the
power to your home before starting your project -
then STOP and call either a professional electrician, or
your friendly neighborhood handywoman.

Wires: Past & Present

From the circuit breakers or fuses in your main service panel, a
network of wires and cables brings power to each receptacle, light
fixture and electrical appliance in your home. Unless you are
repairing or replacing an appliance or device, these wires remain
hidden.

The appearance of the wiring in a home can vary dramatically,
depending on the age of the system.



  • Wiring installed in the early part of this century, until about
    1940, was covered with a layer of rubberized cloth fabric called
    "loom", but it had no sheath for additional protection. This
    wiring was commonly strung along porcelain insulators, which
    gave it the name of "knob and tube" wiring.

  • Starting in the 1920's, some wiring was manufactured in flexible
    metal cable. This "Greenfield" or "BX" wiring proved much better
    than the knob and tube wiring because it shielded the wires from
    damage. The armored cable on Greenfield wiring lacked a
    grounding wire; the metal coils of the cable provided the
    ground.

  • Metal conduit has been installed in many homes since the 1940's.
    Like Greenfield cable, the metal conduit shell protected wiring
    and provided a ground. Metal conduit is still recommended by
    code in some installations, such as exposed wiring in a basement
    or garage, but modern conduit will use a ground wire.

  • Early NM (nonmetallic) cable was installed from 1930 to about
    1965. Early NM, which has no ground wire, has flexible
    rubberized fabric protecting the wires. Electricians loved it
    because they did not have to snake individual wires through
    conduit.

  • Modern NM (nonmetallic) cable, which includes a bare grounding
    wire, was introduced in 1965. The wire insulation and the outer
    sheathing is made of plastic vinyl; the gauge of the wire is
    printed on the sheathing. A "12-2" cable, for example, has two
    12 gauge insulated conducting wires. Today almost all home
    wiring is NM, except where otherwise prohibited by code.

  • UF (underground feeder) cable is designed to be installed in
    damp conditions. Its wires are embedded I solid-core vinyl
    sheathing. Like NM cable, it too contains a bare copper
    grounding wire.


Inside the protective sheathing and insulation, the metal wire used
to carry current is usually made of copper. In some houses,
however, the wire conductors are aluminum-sometimes clad with
copper or nickel. Aluminum or clad-aluminum wires have special
safety concerns.

Wires in home circuitry can range from thick, #6 gauge cables, used
for large appliances, to very thin #22 gauge wires, used only for
low voltage applications, like doorbells.

Wires must be large enough for the amperage rating of the circuit.
A wire that is too small and is overloaded can become hot enough to
melt its insulation and start a fire. The "ampacity" of wire refers
to how much current it can safely carry.

Ampacit varies according to the size of wire and the material used.
The chart shown below shows the ampacity of copper wire. Check your
home to make certain the gauges of the circuit wires match the
circuit ratings, stamped on the circuit breaker or fuse. If not,
have an electrician correct the situation immediately. In addition,
make sure the total wattage load likely to be placed on the circuit
at any one time does not exceed the ratings shown in the third
column. The Electrical Code states that the wattage load should
never exceed 80% of the full wattage capacity of the circuit. A
15-amp 120volt circuit, for example, has a maximum capacity of 1800
watts (15 x 120), but the load placed on it should be no more than
1440 ( 80% of 1800). Although the wires can safely carry the
maximum wattage load, these high loads may eventually cause a
circuit breaker to malfunction.








































WIRE GAUGEAMPERAGEMAXIMUM WATTAGETYPICAL USE
#1415 amps1440 (120 V)
2880 (240 V)
Light fixtures, outlets
Room air conditioner, large tools
#1220 amps1920 (120 V)
3840 (240 v)
Light fixtures, outlets, room air conditioner,
appliances
Room Air conditioner, large tools
#1030 amps2880 (120V)
5760 (240 V)
Commercial equipment
Clothes dryer
#840 amps7680 (240 V)Electric range, central air conditioning
#655 amps10560 (240V)Central air conditioning, electric furnace

Important Note About Aluminum Wire
If you find aluminum wire in your home, you need to take special
precautions. Aluminum wire is identified by its silver color and by
the AL stamp on cable sheathing. Two variations, copper-clad
aluminum wire and nickel-clad aluminum wire, have a thin coating of
copper or nickel bonded to a solid aluminum core.

During the 1960's and the early 1970's, aluminum wire was installed
in many houses, but by the early 1970's, all-aluminum wire was
found to be a safety hazard if connected to devices with brass or
copper screw terminals. The problem arose because aluminum expands
and contracts at a different rate than copper or brass, and can
gradually work loose from connections.

For a short while, switches and receptacles with an Underwriters
Laboratories (UL) wire compatibility rating of AL-CU were used with
both aluminum and copper wiring. Unfortunately, these AL-CU devices
also proved to be hazardous. When connected to aluminum wire and
copper-clad or nickel-clad aluminum wire.

Since 1971, switches and receptacles designed for use with aluminum
wiring were introduced with making CO/ALR. Today this is the only
approved device for aluminum wiring.

IMPORTANT: If you have aluminum wiring, you need
to replace any switch or receptacle that does not bear the CO/ALR
rating stamp. Aluminum wire or clad-aluminum wire is considered
safe if proper installation methods are followed, and if the wires
are connected to special switches and receptacles designed to be
used with aluminum wire. A switch or receptacle that has no wire
compatibility rating printed on the mounting strap is designed for
use with copper wires only. (If you have copper-clad or nickel-clad
aluminum wiring, see an electrician or consult a detailed
description of the National Electrical Code for more information.)

But all parts of the system must be up to Code to be safe. If you
have any doubts, have a qualified electrical inspector review your
system.

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2 comments

12
Apr

I recently purchased a new dryer everything was fine for about 3 weeks then it stopped heating. I followed the troubleshooting tips and replaced the dryer plug and fuses nothing worked. The workmen suggested calling an electrician since they believed the problem was with the wall outlet itself how would I test that?
13
Apr

did u happen to get a 30 day guarantee w/ the dryer? also I had the same problem with my new dryer and it turned out to be the metallic tube exhaust hose in the back of the dryer. We bought a new one at home depot like for 12.00 or something like that and cut it short so it wouldnt bunch up and not release heat. It was a lot simpler than we thought. Are the coils heating up in the back (red glow from back of dryer) or just no heat because it could be a heating element also. Call local appliance store for parts and they may be able to check them for you. If the dryer turns on and there is no heat it's not the outlet because its getting power just not heating. I hope this helps Juli