Standard circuit breakers monitor the flow of electricity as it enters your home and makes its way through your electrical wiring system to outlets, light fixtures, appliances and electronics. As long as the electrical current operates within levels determined by the breaker’s ratings, the flow of electricity continues unhindered. However, 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 trips and breaks the current to prevent wires from overheating and diminish the potential for electrical fires.
• Single-pole breakers protect one energized wire and supply 120V to a circuit.
- Standard single-pole breakers are generally 15 or 20 amps.
- Single-pole units, which occupy one slot on a breaker panel, are the most common breakers
- Three types of single-pole breakers are available:
- Supply 120V/240V or 240V to a circuit;
- Protect two energized wires;
- Range in capacity from 15 to 200 amps; and
- Are required for large appliances like dryers and water heaters.
Ground fault circuit interrupter (GFCI) circuit breakers cut power to the circuit when they are tripped by an overload of current, a short circuit or a line-to-ground fault, which occurs when an unwanted path forms between an electrical current and a grounded element. All GFCI breakers have test buttons on the front and coiled wires. They function in the same way as GFCI receptacles, but protect an entire circuit, eliminating the need for GFCI receptacles on that circuit. Both GFCI circuits and receptacles should be installed as recommended by the National Electrical Code (NEC). GFCIs are:
AFCI 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. In new construction or renovation, the 2008 NEC requires an AFCI breaker for any 15 or 20 amp 120V circuit that includes a receptacle or light fixture, other than GFCI protected outlets in kitchens, bathrooms, unfinished basements and outdoors. Check 2011 NEC codes, as requirements in most areas call for AFCI breakers in all rooms of the house under this code update.
Arc faults occur most often in one of two situations:
• In older homes where the insulation around the wiring becomes cracked or
Arc-fault circuit-interrupter (AFCI) breakers look very much like GFCI breakers, right down to the test buttons and coiled wires. In fact, often the only way to tell them apart is to read the fine print on the breaker. Because the two function in different ways, be sure to read the fine print on the breaker to ensure you’re buying the correct breaker for the correct application.
• Circuit breakers are designed to protect home and building wiring, not appliances. They generally
will not trip if a short or fire occurs in an appliance, or if an appliance or fixture overheats.
• Standard breakers do not protect against surges, such as from lightning, which can damage
electronics. To learn how to protect against surges, see our Surge Protector Buying Guide
• Always shut off the main breaker in the breaker box before beginning any work in a
• 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 amperage 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 hot even if the main power is off
• The wires leading into the electrical panel are always energized and should never be touched.
• Always have new electrical work inspected to ensure that it's properly installed and meets code
• Test AFCI and GFCI breakers every month to ensure they are in good working condition.