• Before circuit breakers,
we had fuses.
• Fuses are single-use
devices that interrupt a
• If a current grows too
large, the metal in the
fuse melts and the
circuit is left unharmed.
• Fuses consist of thin
wire encased in heatresistant glass.
• Fuses are like bridges
that let electricity flow
• Fuses burn out if too
much electricity flows
Pictured: A fuse at work with an electricity shark
• But fuses need to be replaced every time one
• Since fuses are cheap, they continue to be
used in the systems of cars and other vehicles
on both land and sea.
• However, electrical panels use more advance
components, such as switches, relays, and
• Circuit breakers are like the reusable versions
of fuses and work in much the same way.
• Circuit breakers are part of a larger structure
called the electrical panel and prevent fires by
creating gaps in the circuit.
• But how do electrical fires begin anyway?
• Well, each circuit is composed of a hot wire and a neutral, or ground, wire.
• The hot wire is connected to the power source. Leave this wire alone or
you’ll find yourself in the hospital or morgue.
• The ground is connected to the, you guessed it, ground underneath a
• These two wires never touch so the current passes through a load, or
• In the US, power is delivered at 120-240 volts, but current resistance
varies from home to home.
• Occasionally, something random and unfortunate happens which causes
the hot wire to touch the neutral.
• This causes a tsunami surge of electricity, leading to a fire.
• Single Pole – 120 volts with a rating of 15-20 amps. The most
• Double Pole – 240 volts with a rating of 15-50 amps. Often
serve large appliances, ovens, etc.
• Ground Fault Circuit Interrupter (GFCI) – protects circuits and
multiple outlets. Used in rooms with high risks of
• Arc Fault Circuit Interrupter – designed to turn off power
when electricity arcs are detected.
• All circuit breakers feed into a central circuit breaker panel,
otherwise known as the electrical panel.
• Electrical panels are found in basements or side closets. When
a circuit breaker does its job, it can be reset here.
• Circuit breakers are stacked and controlled by little levers
marked “On” or “Off”.
• Most breaker panels feature a neutral bus and grounding bar
and is sealed off by a metallic panel giving access to the circuit
breakers without letting loose any wires.
• Main breaker – usually a large double-pole circuit
breaker limiting outside electricity.
• Circuit breakers – stacked like building blocks in rows
• Bus bars – feeds home circuits with power from
• Neutral bus – connects to main circuit’s neutral wire.
• Grounding bus bar – unites all ground wires and is
connected to grounding connector.
• Main breaker panel – installed meter and
feeder cable are within range of the panel
• Main lug panel – runs wires to lugs and can be
used as a sub-panel.
• Sub-panel – separate breaker panel for new
circuits separate from pre-installed circuits.
• For more information,
– Visit us at bkelectricservices.com
– Call us at 310-430-2300