A circuit breaker is an electrical safety device designed to protect an electrical circuit from damage caused by an overcurrent or short circuit. Its basic function is to interrupt current flow to protect equipment and to prevent the risk of fire. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation.
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.In a normal scenario, the breaker sits in the circuit like an open gate, allowing current to circulate in the wires, going out to where it’s needed and back again to the panel. When a circuit gets overloaded or experiences a sudden surge called a fault, the gate shuts, stopping the flow of electricity in the circuit.The breaker can be reset and used again, but only if you resolve the overcurrent situation.
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 can’t run on a regular 120-volt circuit, which uses one hot wire to deliver current. A big 50-amp air conditioner uses two hot wires to deliver enough current for the appliance to operate.
GFCIs protect people from a specific source of electrical shock, the ground fault. That occurs when electricity from a hot wire takes an unintentional path to ground 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.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.
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.
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