Electrical Circuit Breakers

Types of Circuit Breakers

How to determine which circuit breaker should be used for an electrical circuit.

Single Pole 120Volt Breaker

This is a full size 15 amp circuit breaker which is most commonly used for lighting circuits and some outlet circuits. Full size 20 amp circuit breakers are typically used for outlet circuits such as in the kitchen.

Twin or Tandem Breaker

These two single circuit breakers are shown to describe how the full size circuit breaker shown above can only serve one circuit once the breaker has been installed into the electrical panel. The breaker shown below the full sized breaker is designed so that two circuits may be attached and protected instead on only one. This can be very helpful when an electrical panel has run out of room for an additional circuit to be installed.

Two Pole 240Volt Breaker

This full size two pole circuit breaker is just like having two single pole circuit breakers mounted side by side, in fact that is essentially how this circuit breaker is put together, but with one exception. You will notice that the two on and off switch handles are joined together with a tie bar which enables both sides of the circuit breaker to turn off even if only one side of a 240 volt circuit overloads or encounters a fault.

AFCI Arc Fault Breaker

The AFCI, or Arc Faulty Circuit Interrupter circuit breaker is required by code to be installed in areas such as bedrooms. The purpose of the AFCI circuit breaker is to sense and turn off the circuit if an arc has been detected. An arc can be cause by a short cir suit in the circuit wiring or arc can be from an object being inserted into an outlet and shorting together. Arc fault circuit breakers help reduce the risk of home fires and shock hazards.

Circuit Breaker Panel

A typical modern home electrical circuit breaker panel will have one or two rows of circuit breakers that have been installed to protect all of the electrical circuit wiring of the home electrical system.

Circuit Breakers and Electrical Wiring

Question: Are the new AFCI's really essential when a house is newly wired with romex.

I can understand the importance with the old knob and tube but it seems a bit redundant with today\'s wiring techniques and materials. Do regular circuit breakers not detect arc faults?

If they are that effective why are non-living areas not required to have them?ask-the-electrician.com Hi Ben - Great Question!Absolutely - AFCI's are now required in all new and remodeled homes.

Answer: A normal circuit breaker will not sense the arc at all, and the safety features of the AFCI will surely prevent a lot of fires from occurring, and yes - they will soon be required is most all areas of the home with the exception of the kitchen and probably the garage due to small appliance motors which produce an arc with normal operation between the brushes and the armature of these types of motorized devices. The AFCIs' will still be improved to prevent nuisance tripping because of motorized devices such as vacuum cleaners etc. In the beginning of the AFCI era, these breakers would trip off when using higher wattage incandescent lamps connected onto the same circuit, but they are much better now.