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Electrical Safety
Each year the Chula Vista Fire Department responds to a significant
number of fires and medical emergencies caused by electrical malfunction.
Every year in the United States, more than 1,000 people are killed
and thousands more injured in electrical fire or shock incidents.
It is important to know how to use electrical appliances safely
and how to recognize electrical hazards.
The Nature of Electricity
Most homes have two incoming voltages: 120 volts for lighting and
appliance circuits and 240 volts for larger air conditioning and
electric dryer circuits. When an appliance switch is turned on,
electrical current flows through the wire, completing the electrical
"circuit" and causing the appliance to operate.
The amount of flowing current is called "amperage". Most lighting
circuits in the home are 15 amp circuits. Most electric dryers and
air conditioners require larger 30 amp circuits. The amount of electrical
power needed to make an appliance operate is called "wattage" and
is a function of the amount of current flowing through the wire
(amperage), and the pressure in the system (voltage).
Mathematically speaking, volts x amps = watts. So, with a 120-volt
system and a 15-amp current, a maximum of 120 x 15 or 1,800 watts
can flow on a typical lighting or appliance circuit. When too may
lights or appliances are attached to the electrical system, it will
overload and overheat. This can cause the wire insulation to melt
and ignite, resulting in an electrical fire. Resistance affects
the amount of electrical current flowing through wire. This is known
as "ohms". Resistance causes increased heat in the wire. Heat is
the byproduct that makes some appliances work, such as an iron,
toaster, stove or furnace. Large current faces high resistance when
moving through a small wire. This generates lots of heat. That's
how an incandescent light bulb works. Resistance through the light
filament causes it to heat up which gives off a bright light. The
length of a wire also affects electrical resistance. Operating an
electrical hedge clipper with a long extension cord increases resistance
and might cause the cord to overheat, melt or ignite. The same occurs
if too many strands of holiday lights are connected together.
The size of electrical wire is dependent upon the amount of current
required to operate a particular appliance. Wiring to the air conditioner,
electric stove and electric dryer is much larger to handle the increased
voltage (240 volts) and amperage (30 amps). Wiring is covered with
a protective material called "insulation".
Electrical circuits in homes are designed so that all components
are compatible. The size of the wire, outlets and circuit breakers
are designed for an anticipated electrical load. A circuit is said
to be overloaded when too much current flows causing heat build
up or wiring to break down. When two bare wires touch, a "short
circuit" is said to occur. This can lead to sparks and fire. Deteriorated
insulation is one of the most frequent causes of short circuits.
A "circuit breaker" or "fuse" is a safety device designed to prevent
accidental overloading of electrical circuits. They are set at specific
amperage. When that amperage is exceeded, it trips and shuts off
the flow of electricity, stopping the circuit from continued overheating.
When a fuse or circuit breaker trips, it is important to find the
cause and correct it. Often, people will just reset the breaker
or put in larger fuse.
NEVER USE OVERSIZED FUSES ON CIRCUIT BREAKERS. NEVER SUBSTITUTE
A PENNY OR FOIL WRAPPED FUSE. This could cause a fire!
General Electrical Safety
Only licensed electricians are permitted to install electrical
systems. During home remodeling, when electrical circuits are added
or changed, make sure to use a licensed electrician whose work complies
with the electrical code.
When choosing an electrical appliance, be sure a safety-testing
laboratory approves it. This insures that it has been constructed
in accordance with nationally accepted electrical standards and
has been evaluated for safety.
Touching an electrical appliance, wall switch or electrical cord
while wet or standing in water, will increase the chance of electrical
shock.
When using an extension cord, be sure it is designed to carry the
intended load. Most cannot carry as much current as permanent wiring
and tend to overheat. Do not use an extension cord in place of permanent
wiring, especially if a tripping hazard exists or where there is
high physical abuse, such as under a carpet. Keep electrical cords
away from infants and toddlers and use tamperproof inserts on wall
outlets to prevent them from sticking objects into the outlets.
The cord must be protected from damage. Do not run it around objects
or hang on a nail. Inspect it periodically for worn insulation and
overall condition.
Safety with Electrical Appliances
The potential for electrical shock or fire from an electrical appliance
is very real, especially when safety recommendations are not followed.
Before buying an appliance, look for the label of a recognized testing
laboratory such as Underwriters Laboratory or Factory Mutual.
Keep space heaters, stoves, irons and other heat-producing appliances
away from furniture, curtains, bedding or towels. Also, give televisions,
stereos and computers plenty of air space so they won't overheat.
Never use an appliance with a damaged cord, and be sure to use
three-pronged electrical devices in three-pronged outlets. These
outlets may not be available in older homes, so use a three-pronged
adapter, and screw the tab onto the grounded outlet box cover. Never
cut off or bend the grounding pin of the plug. When using a polarized
plug (with one side wider than the other), never file it down or
try to make it reversible.
Keep electrical cords out of the path of traffic. Don't put cords
under carpets or rugs, wires can be damaged and might result in
fire. Protect young children by putting plastic inserts in receptacle
outlets not in use to keep them from putting anything into outlets.
An electrical cord should never be wrapped around an appliance
until the appliance has cooled. Because hair care equipment is often
used in bathrooms near sinks and bathtubs, it is extremely important
to be especially careful that the appliances do not come in contact
with water. If one drops into water, do not touch it until the wall
plug has been pulled.
Never put a kitchen knife or other metal object in a toaster to
remove stuck bread or bagels unless it is unplugged and cooled.
Install television and radio antennas where they cannot fall across
power lines. Use caution when operating a tree-pruning device or
using a metal ladder around power lines.
Inspect appliances regularly to make sure they operate properly.
If an appliance smells funny when in use, makes unusual sounds or
the cord feels warm to touch, repair or replace the unit. Don't
repair it yourself unless you are qualified. Keep appliances in
a cool, dry place to prevent rusting.
Electrical Emergencies
When an electrical emergency occurs, there are several survival
actions that can be taken. Learn how to trip the main circuit breaker
at the electrical panel to turn off all power to the house. If an
appliance smells funny or operates improperly, pull the plug if
it can be done safety. If arcing, burning or smoking from an appliance
occurs, turn off the power at the circuit breaker.
Winds accompanying thunderstorms may knock down power lines or
utility poles. Keep people away from the area, and call the fire
department. If power lines come in contact with a vehicle, do not
touch it or the vehicle. If people are inside, tell them to stay
inside. If they try to exit, they may complete a grounded electrical
circuit and be instantly killed. They must stay inside until the
utility company shuts off the power.
If a serious electrical malfunction occurs in the home, school
or workplace, it is the same as a fire. Notify others, activate
the fire alarm and exit promptly.
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