Identifying the Different Types of Circuit Breakers

We’ve all been annoyed by a tripped circuit breaker. Whether you’re getting ready for a night out or cooking dinner on a major holiday, it usually happens at the worst possible time. To get on with your life, you probably just walk over to your electrical panel and reset the breaker. I’m an experienced electrician, and I do the same.

But how much do you know about these ubiquitous safety devices? Circuit breakers protect electrical circuits by stopping the flow of electricity when they detect too much current on the circuit. This “overcurrent” can be caused by having too many things plugged in at once, called an overload, or by sudden surges of electricity caused by electrical arcs and short circuits.

“When a circuit is overloaded, it can no longer safely handle the amount of electricity flowing through it,” says George Talbot, a licensed electrician with Mister Sparky in Georgia and Tennessee. When that happens, wires, insulation and even your devices can overheat, causing them to melt or catch fire.

Electrical fires can be particularly devastating because they can smolder undetected for a long time and it often happens when we’re least prepared. According to the National Fire Protection Association (NFPA), which publishes the National Electrical Code (NEC), over half of all deaths from electrical fires occur between midnight and 8 a.m. That’s why it’s so critical to have functioning circuit breakers.

Here are the most common circuit breakers found in your home.

Standard, Single-Pole Circuit Breaker

A single-pole breaker protects a single circuit in your home’s electrical system. This single circuit might power the lights in your living room or feed receptacles in your kitchen. Single-pole breakers take up one slot in your home’s electrical panel and typically protect 15-amp and 20-amp circuits.

Like other breakers, single-pole circuit breakers have a handle with three possible positions: On, Off and Tripped. When the circuit is on, the breaker allows electrical current to move through the circuit conductors from the outside transformer to the device or appliance, then back again in an endless loop. Electricity always wants to return to its source, so as long as the breaker doesn’t sense a problem or you don’t manually stop it, this cycle will continue indefinitely.

But let’s say you have a 20-amp circuit in your bathroom. It’s chilly in the morning, so you turn on your 1500-watt bathroom space heater, which draws about 12.5 amps. You step out of the shower and start to dry your hair with a standard 1875-watt hair dryer, which draws more than 15 amps. Your single-pole breaker trips, because you put more than 28 amps of electricity on a circuit designed for 20 amps.

If that happens occasionally, you can just go to the panel and reset the breaker. Unlike fuses, which were once common in older homes, breakers can be reset repeatedly. But don’t ignore breakers that constantly trip, especially if you don’t know what’s causing the trip (unlike the hair dryer overload). Call a licensed electrician for help.

Standard, Double-Pole Circuit Breaker

Double-pole breakers work the same way as single-pole breakers, but they protect circuits that power larger equipment, like air conditioners, ranges and dryers. These appliances need two hot wires to deliver enough current to run, so double-pole breakers have two wire terminals, and they take up two slots in your electrical panel.

When a double-pole breaker trips, it must sever electricity to both hot wires at the same time. Likewise, when you go to reset a tripped double-pole breaker, the handle allows you to reset both hots simultaneously. That’s actually an NEC requirement; if something goes wrong, the last thing you need to worry about is a half-hot circuit.

In addition to the two-pole breakers protecting your large appliances, your main breaker is also a double-pole breaker. “This is usually a larger switch located at the bottom or top of your breaker’s service panel,” Talbot says. It’s vitally important to turn off breakers before doing any work on your electrical panel. “Turning off the breaker is a crucial step before doing any type of electrical maintenance,” Talbot says.

Ground Fault Circuit Interrupter Breaker

You’ve used ground-fault circuit interrupter (GFCI) receptacles in your kitchen and bathrooms, but what about GFCI circuit breakers? It’s perfectly acceptable to protect circuits with GFCI breakers instead of relying on individual receptacles. When you need full-circuit protection, breakers are often the most economical and easiest way to go.

GFCIs protect people from a specific source of electrical shock: ground faults. Ground faults occur when electricity from a hot wire takes an unintentional path through conductive things that don’t normally carry electricity. This path could be a metal pipe in the wall, the outside of an appliance—or you.

To combat this danger, electricians like me install a deliberate path, colloquially called a “ground path,” to redirect this stray current back to the source. “When an outlet or device is grounded, it means there is a ground wire that is linked from the outlet to the electrical panel in order to act as a safety valve” for these stray currents, Talbot says.

GFCIs detect the amount of current going out to the load (what you’re powering) and compare it to the current coming back to the panel. If the difference between the two paths is more than six milliamps, the GFCI opens the circuit, stopping the flow of electricity. This happens in as little as 1/40 of a second.

The NEC requires GFCIs in places where water is a common hazard. Bathrooms, kitchens, garages, crawl spaces, outdoor receptacles and more must be GFCI-protected in new construction, remodels and repairs. Check with your local code authority for specifics.

Arc Fault Circuit Interrupter (AFCI) Breaker

Arc fault protection is a relatively new requirement in the NEC, first made mandatory for bedrooms in 2002. Since then, the NEC has expanded AFCI protection requirements to include nearly every room in your house, except bathrooms and basements. In new construction and remodels, AFCIs are replacing standard breakers as the most common breakers in your panel.

AFCIs protect your home from fires by monitoring circuits for dangerous electrical arcs. What’s an electrical arc? Imagine two wires connected under a wire nut. As long as the connection is tight, the current flows seamlessly through the splice. If that connection comes loose, the electricity will try to “jump” from one wire to the other to continue its path, creating an arc between the conductors.

This arc can happen anywhere there’s a loose connection, but if that arc happens in an old lamp cord behind the living room curtains or under your bed, for example, you could be looking at a dangerous situation. Any combustible material in the vicinity of that arc has the potential to catch fire.

An AFCI breaker detects these unintentional arcing events wherever they occur and immediately severs the flow of electricity to the circuit.

AFCI/GFCI Dual-Function Breaker

Kitchens and laundry rooms require GFCI and AFCI protection, so the dual-function breaker combines both levels of protection into one device. Before these breakers came about, a homeowner would have to use an AFCI breaker and a GFCI receptacle to achieve both levels of protection on one circuit.

If your house is newer, or if you’ve updated your electrical panel in the last few years, you may see these dual-function breakers in your panel instead of standard, GFCI or AFCI breakers.

About the Expert

• Gerald Talbot is a licensed electrician with Mister Sparky. Talbot has electrical contracting licenses in Georgia and Tennessee and is the owner-operator of Mister Sparky in Chattanooga, Tennessee.

Sources

• Campbell, Richard. National Fire Protections Association: Home Electrical Fires (Jan. 31, 2022)