NEWS & KNOWLEDGE

Circuit Breakers Breaker Design: Advanced

More advanced circuit breakers use electronic components (semiconductor devices) to monitor current levels rather than simple electrical devices. These elements are a lot more precise, and they shut down the circuit more quickly, but they are also a lot more expensive. For this reason, most houses still use conventional electric circuit breakers.

One type that can be found built directly into outlets, particularly near bathroom sinks, is the ground fault circuit interrupter, or GFCI. These sophisticated breakers are designed to protect people from electrical shock, rather than prevent damage to a building's wiring. The GFCI constantly monitors the current in a circuit's neutral wire and hot wire. When everything is working correctly, the current in both wires should be exactly the same. As soon as the hot wire connects directly to ground (if somebody accidentally touches the hot wire, for example), the current level surges in the hot wire, but not in the neutral wire. The GFCI breaks the circuit as soon as this happens, preventing electrocution. Since it doesn't have to wait for current to climb to unsafe levels, the GFCI reacts much more quickly than a conventional breaker.

All the wiring in a house runs through a central circuit breaker panel (or fuse box panel), usually in the basement or a closet. A typical central panel includes about a dozen circuit breaker switches leading to various circuits in the house. This box uses two sub-types of breakers, known as single-pole and double-pole. A single-pole breaker carries 120 volts of current and handles most home devices. A double-pole breaker features two switches fused into one and carries 240-volt current to supply specialized outlets for more demanding things like ovens and clothes dryers. One circuit might include all of the outlets in the living room, and another might include all of the downstairs lighting. Larger appliances, such as a central air conditioning system or a refrigerator, are typically on their own circuit.

Another type being introduced into homes is called an arc fault circuit interrupter, or AFCI. These breakers electronically monitor the home's power grid for arc faults that older styles of breaker can miss, but can nonetheless lead to extreme heat in wiring, and fire hazards in some cases. AFCIs are being installed in conjunction with typical central breakers in order to provide a wide range of protection.

For more information about circuit breakers and other electrical systems, check out the links that follow.