Types of Circuit Breakers

The three main types of circuit breakers are standard, GFCI and AFCI. Some models have dual functionality. Each handles different amp capacities and operates in different locations in the home.

Standard circuit breakers monitor amp capacity of the devices they operate. Make sure to check the wattage and amperage of any device connected to a standard circuit breaker to make sure it can manage the load.

In the event of an overload or short circuit — caused when a hot wire touches a neutral wire, ground wire or another hot wire — the breaker will interrupt the current to prevent wires from overheating, diminishing the risk of electrical fires. Standard circuit breakers are either single- or double-pole.

Single-pole breakers

• The most common breakers used in homes.
• Protect one energized wire.
• Supply 120V to a circuit.
• Handle 15- to 30-amps.
• Available in three types: Full size (1-inch wide), half size (1/2-inch wide) and twin/tandem (1-inch wide with two switches and controls two circuits).

Double-pole breakers

• Occupy two slots on a breaker panel and protect two energized wires.
• Consist of two single-pole breakers with one handle and a shared trip mechanism.
• Supply 120V/240V or 240V to a circuit.
• Range in capacity from 15- to 200-amps.
• Are required for large appliances such as dryers and water heaters.

Ground fault circuit interrupter (GFCI) circuit breakers cut power to the entire circuit. They are tripped by an overload of current, a short circuit or a line-to-ground fault. This can occur when an unwanted path forms between an electrical current and a grounded element.

GFCI circuit breakers can be a good choice when a circuit and everything connected to it require ground-fault protection. They are required in all 125-volt, single-phase, 15- and 20-ampere receptacles in locations such as finished basements, hallways and closets, kitchens, laundry areas and bedrooms.

It is not necessary to have GFCI receptacles on a circuit that is protected by a GFCI circuit breaker.

Arc fault circuit interrupter (AFCI) circuit breakers protect against an unintentional electrical discharge in an electrical cord or wiring that could cause a fire. Once the breaker senses the electrical jump and abnormal path, it instantly disconnects the damaged circuit before the arc builds enough heat to catch fire.

Arcs generally occur due to worn or damaged electrical cords and wiring. Regular circuit breakers don’t always trip in these instances because standard breakers are designed to respond to a sustained amount of heat, not a quick surge.

When having a circuit breaker installed, check the latest National Electrical Code, section 210.12 (A) as requirements in most areas call for AFCI breakers in all rooms of the house under the 2017 code update. National building codes require AFCI breakers be used instead of standard breakers in new homes. 

Combination arc fault circuit interrupters (CAFCI) protect against the same arcs covered by AFCI as well as low-energy series arcing. They are becoming more common in homes as they protect downstream branch circuit wiring and power cords.

Dual function CAFCI/GFCI circuit breaker types protect against both arc faults and ground faults, which can save time and money while providing more safety than the other versions. CAFCI circuit breakers are required in all 15- and 20-amp circuits with the exception of locations where GFCI circuit breakers are required, including laundry rooms, kitchens, bathrooms, garages and unfinished basements.

The circuit load will determine the breaker size you need – and you’ll need to make sure to get the right brand, as all breakers are not interchangeable.

• Load capacity: Determine the amp size of the circuit breaker you need to install based on the total circuit load. Remember that the safety rating for circuit breakers is 80 percent of the maximum load. Most appliances have the amp rating listed on them. Permanently installed large appliances such as AC units, washing machines and ovens require their own dedicated circuit. Consult an electrician if you are unsure of your total circuit load.
• Brand: Always install the correct brand of breakers in your breaker panel. While some breakers are interchangeable, many are not, even if they look the same. Replacing one brand of breaker with another can be dangerous, may void your breaker or panel warranty, and may lead to a failed electrical inspection. Look on the breaker panel door for information about which breakers are compatible with your panel. Breakers continue to be manufactured for most panels, including older models.

• Always shut off the main breaker in the breaker box before beginning any work in an electrical panel.
• Be sure the device you choose matches the wiring, load requirements and type of breaker panel you have. The information should be on the breaker panel door.
• Never replace a circuit breaker with one of a higher amp rating.
• Only add an additional breaker if you have an open slot in your breaker panel.
• The bus bar in the electrical panel may still be energized even if the main power is off. It's always a good idea to work like everything is energized but if the bussing is energized after the main breaker is off please contact your local utility company because this should never happen.
• The feeder wires leading into the electrical panel are always energized and should never be touched.
• Always have new electrical work inspected by a licensed electrician or city/county inspector to ensure that it's properly installed and meets code requirements.
• Test AFCI and GFCI breakers every month to ensure they are in good working condition.