Circuit Breaker Types – Standard, GFCI, AFCI, Combination, Dual Function

There are a few different types of circuit breakers you will find in modern electrical panels. These are:

  • Standard original-style breakers
  • GFCI Breakers
  • AFCI Breakers
  • Combination GFCI/AFCI breakers

Standard Original-Style Circuit Breakers

Standard circuit breakers are what you will see in most electrical panels in homes built before the early 2000s unless the home has been updated or breakers added or replace since the early 2000s. When a panel is replaced or breakers are replaced building codes in force at the time of the upgrade must be followed. However older electrical work that has not been modified does not usually need to be updated to current code.

For a discussion on how standard circuit breakers work please see: Circuit Breakers and Fuses – Over-Current Protection.

GFCI Breakers

GFCI, or Ground Fault Circuit Interrupter, breakers trip when a ground fault is detected. A ground fault is when all the electricity that leaves the hot wire in the circuit is not returned on the neutral side of the circuit. If the same amount of electricity isn’t flowing through both wires the electricity is leaking out of the circuit through something, or somebody. Ground faults are a dangerous condition because that leaking electricity may be flowing through a person’s body which may injure or kill them.

GFCI breakers were developed to monitor the difference in the flow of electricity between the hot and neutral sides of a circuit. These breakers will trip if a difference of around 5 milliamps is detected in the flow between the hot and neutral sides. This is a very small leakage that is required to trip these breakers. It’s 75,000 times smaller than the maximum current allowed through the smallest breakers we find in our homes, which is 15 amps.

Note that GFCI protection does not have to exist at the electrical panels themselves. GFCI protection often happens at outlets instead. If you see an outlet that has test and reset buttons, it’s a GFCI outlet.

GFCI breakers are supposed to be installed such that they protect outlets where the possibility of someone contacting earth (dirt, concrete, etc.) or water while handling an electrical device is possible. These locations include: kitchen counters (all of them, not just within 6′ of a sink), bathrooms, exteriors of homes, basements, garages and hot tubs.

To test a GFCI breaker the best thing to do is to press the test button on the breaker itself. Alternatively you can use an outlet tester. When the test button is pressed the GFCI outlet should disengage.

AFCI Breakers

AFCI or Arc-Fault Circuit Interrupters are a bit like GFCI’s but they detect arcing instead of ground faults. An arc fault occurs when a connection in the circuit is poor and arcing begins occurring. One example is if someone in a rocking chair was rocking and there was an extension cord under the rocker. Eventually this wire gets cut but the ends are still close enough for electricity to jump from one side of the broken wire to the other. When the electricity jumps this gap an arc is produced. These arcs are extremely hot because the air is a lousy conductor and the resistance to electricity flowing is high. So when it does flow there’s a lot of heat. It’s essentially a small lightning bolt. So with this kind of heat there’s the potential for fire.

Other ways arc faults occur are: A screw is loose on the terminal of an outlet or switch, a wire nut joining two wires is loose, someone runs over an extension cord with a lawn mower, or cuts it with a hedge trimmer, a plug doesn’t fit into an outlet tightly, someone hammering a nail into a wall and striking a wire.

You might wonder why a regular breaker doesn’t trip during an arc fault. The answer is simple. There’s not enough current flowing to trip the breaker. So you don’t need that much current to create an arc which can then lead to a fire.

AFCI breakers are now required on any circuit that has outlets or devices in kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sun-rooms, recreation rooms, closets, hallways, laundry areas and similar areas. However, you don’t have to run out and replace your breakers or electrical panels. These requirements are only for new or updated work.

To test AFCI breakers you should first disconnect all appliances from the outlets that the breaker serves. This is because testing an AFCI breaker can damage sensitive electronic equipment like TVs, computers, etc. This is why we generally don’t test AFCI breakers in homes during a home inspection. We don’t know what is plugged into the circuit. After pressing the test button the breaker should disengage. There are devices made to test AFCI breakers but manufacturers generally recommend only using the test button on the breakers.

Combination AFCI Breakers

Originally AFCI breakers were designed to only catch arcing between a hot wire and a neutral or ground wire. This didn’t protect from extension cords having cut wires where arcs occurred. To fix this combination type AFCI’s were designed and introduced. Now the combination AFCI breaker is all that is produced.

Dual Function AFCI/GFCI Breakers

On some circuits both GFCI protection and AFCI protection is now required. To meet this need dual function breakers were developed that do protect against both.

Can you upgrade your breakers to AFCI breakers from regular breakers?

The answer to this question will depend on the panel. Older panels weren’t specifically designed to accept AFCI breakers. AFCI breakers are larger than regular breakers. If your home was built in the early 2000’s and beyond you may be able to upgrade to AFCI breakers because that’s when they started being required on a couple circuits in the home. To answer this question for your electrical panel, the best thing to do is to check with the manufacturer or an electrician.

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