What Size Breaker Do I Need for a Camper?

Turning off the Power

• Every time you work around electricity, the first step is to turn off the power for the trailer by opening its main breaker. Confirm the power is off by touching a non-contact voltage detector to the wire's insulation. Double-check that there is no power by making sure there is no power in the trailer. It only takes a few amps to stop the human heart, so be extremely careful around electricity and wires.

Identifing Wire Type

• Look at the wire to which you wish to connect the breaker to see what type of metal it's made of. If it is copper-colored, it's a copper wire; if it is a dull silver color it's aluminum. This is important as different metals melt at different temperatures; aluminum wires typically require lower amperage breakers.

Identifing Wire Gauge

• The wire gauge is the diameter of the conductor printed on the insulating cover of the wire; it will look something like "14/2" or "12/2". The first number represents the gauge, or diameter, of the conductor. The second number indicates the number of conductors in the wire. A 120-volt circuit needs two conductors to operate properly, while a 240-volt circuit requires three conductors to work. Both types of circuits will also have a green or bare ground wire intended to provide a backup safety system.

Select Breaker Size

• Choose your breaker size cross-referencing the above information with the table below:

  Use a 15-amp breaker for copper 14-gauge or aluminum 12-gauge wires.

  Use a 20-amp breaker for copper 12-gauge or aluminum 10-gauge wires.

  Use a 30-amp breaker for copper 10-gauge or aluminum 8-gauge wires.

  Use a 40-amp breaker for copper 8-gauge or aluminum 6-gauge wires.