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 The
circuit breaker, an essential part for electrical safety in
your home. A typical electrical service coming into your
home will be 150-200 amps. This allows adequately available
electricity to run branch circuits, small appliances, heat
pumps, refrigerators, water heaters etc. The electrical
service coming into your home is split into several smaller
branch circuits inside the electrical panel by circuit
breakers. Some appliances like the clothes dryer or water
heater have dedicated circuits, this means that the wire
goes from the circuit breaker to that particular appliance
and nowhere else. |
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Basic circuit breakers in your home work on
three different principles, magnetic trip, bimetallic trip
and electronic trip. Lets look at these three devices in
detail.
Magnetic Trip -
Current flow through the breaker electrically magnetizes a
built in electromagnet. The higher the current flow the
stronger the magnet pulls, eventually tripping the breaker
and opening the circuit.
Bimetallic Trip - This breaker
works in the same manner as the magnetic trip except a
bimetallic strip bends and opens the circuit.
Electronic Trip - This type breaker
has an electronic module inside the housing that opens the
circuit. These breakers are Ground Fault, Arc Fault and
Shunt Trip. Further descriptions on these breakers are
below.
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Circuit breakers are safety devices. The wire
going from the circuit breaker throughout your home is rate
to carry a certain amount of current. For instance a 14
gauge copper wire is rated at 15 amps therefore, it is
connected to a 15 amp circuit breaker. A 12 gauge wire is
rated at 20 amps therefore a 20 amp circuit breaker. If an
appliance such as a portable heater is connected to a wall
receptacle the load is pulled through the copper wire from
the electrical panel. If the heater was rated at 1500 watts
it will pull 12.5 amps. As you can see the current draw from
the heater is over 80% of the current that can safely pass
through the copper wire. If something else happens to be
plugged into that same circuit lets say a computer or your
stereo equipment, you may exceed the rating of the wire.
Then the breaker trips. The breaker just protected the
copper wire from getting too hot and melting the insulation
covering it and possibly causing a fire. |
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Single Pole & Double
Pole |
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The two most common types of
circuit breakers are single pole and double pole. The single
pole breaker connects to a single side of the panelboard bus
therefore supplying 120v circuits. The double pole connects
to both busses in the panel supplying 240v circuits.
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Ground Fault Circuit
Breakers |
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Ground fault circuit breakers
are generally installed where using a ground fault
receptacle is impractical or where the entire circuit must
be protected. You will find these breakers feeding outdoor
circuits, Jacuzzi or hot tubs or lighting circuits above
tubs or showers. You can learn more about the GFCI breaker
by reading our GFCI Article HERE. |
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Arc Fault Circuit
Breakers |
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Arc Fault Circuit Breakers
detect arcing characteristics on the circuit they are
attached to. These are required by the National Electric
Code to be installed on all bedroom circuits. These breakers
look very similar to the ground fault type. You can learn
more about the AFCI breaker by reading our AFCI Article
HERE. |
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Quad Circuit Breakers |
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Quad breakers can be
confusing to the homeowner. These breakers are used when
space is limited. This breaker allows two 2-pole circuits to
be installed in the space of a single 2-pole breaker.
Referring to the picture to the left there are two 2-pole
20 amp breakers. The two breakers on the inside are tied
together to make a 2-pole 20 amp and the outside two
breakers are tied together to make another 2-pole 20 amp.
this breaker is essentially four half size breakers combined
into one unit than fits in a standard 2-pole space. |
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Half Size Circuit
Breakers |
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Half sized circuit breakers
are used when space is limited. They work exactly the same
as a full size breaker but take up half the space. You
cannot put two of these half size breakers side by side and
make a 240v circuit since the side by side breakers clip
onto the same buss in the panel, they would both be 120v. |
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Twin Circuit Breakers |
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Twin circuit breakers are
simply two half size breakers tied together to occupy one
full size space. This breaker supplies two 120v circuits and
cannot be used for 240v applications since both circuits are
on the same phase in the electrical panel. These are
available in 15 & 20 amp versions. |
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Shunt Trip Circuit
Breakers |
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Not usually found in the home
a shunt trip breaker opens the circuit when a contact is
made from an outside source. For instance an exhaust hood in
a restaurant can be shut off when the fire alarm system goes
into alarm. Shunt trip breakers are remotely opened but must
be reset at the breaker location. |
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HACR Circuit
Breakers |
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HACR circuit
breakers are approved to be installed on Heating, Air
Conditioning and Refrigeration equipment. They can be used
on any other circuit. |
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Bolt-in &
Snap-in Circuit
Breakers |
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This is
dependant on the manufacturer of the electrical panel. The
circuit breaker either snaps in or requires a bolt to attach
the breaker to the panelboard buss. Residential panels are
snap in type, commercial panels can be snap-in but are
usually
bolt-in. |
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See the internal components
of a circuit breaker in our article.
"How Circuit Breakers Work"
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