Circuit Breakers & Electrical Fuses

In general, a circuit breaker refers to any device that can stop the flow of electricity by switching itself off. Most homeowners are familiar with circuit breakers in the context of their home’s breaker box or electrical panel, which manages power distribution to light fixtures, appliances, and electronics. The circuit breakers usually look like two columns of horizontal black switches. Each breaker may be labeled with a device or room to which it delivers power.

An overloaded circuit is usually what causes a circuit breaker to trip. When too many lights, electronics, or appliances are running at once, the breaker tries to draw more power than it can carry, and an internal sensor trips the breaker and shuts it off. To restore electrical power, the breaker simply needs to be switched back on. A breaker can also trip because of a:

• Short circuit
• Ground fault surge
• Arc fault

Sometimes, breakers can become loose or corroded after many years of use. This may cause them to trip by accident.

There are three main types of circuit breakers used in residential and commercial buildings:

• Standard
• Ground fault circuit interrupter (GFCI)
• Arc fault circuit interrupter (AFCI)

Each type serves a different function, discussed in more detail below.

• Standard, single-pole breaker: This is the most common type of circuit breaker found on an electrical panel board. These breakers monitor the electrical current flow in a single wire and trip if there is a surge or short circuit. Single-pole breakers handle 15-30 amps and are used with 120-volt circuits.
• Standard, double-pole breaker: This type of breaker works the same way as a single-pole breaker. However, a double-pole breaker monitors the flow of electricity in two wires instead of one. These breakers have two side-by-side switches. If one or both wires are overloaded or short out, the breaker will trip. Double-pole circuit breakers can accommodate 15-200 amps and work with either 120-volt or 240-volt circuits.
• Ground fault circuit interrupter (GFCI) breaker: These breakers trip in the event of a line-to-ground fault and provide overcurrent protection. Per the National Electrical Code (NEC), GFCI protection must be installed in any part of the home that is exposed to elements or has running water, such as a pool deck or a bathroom.
• Arc fault circuit interrupter (AFCI) breaker: Required in new construction, AFCI breakers protect against arc faults, which cause electricity to leave a circuit and jump to insulation, wood, and other materials. If arcing is detected in electrical wiring, an AFCI breaker will automatically shut off.
• AFCI/GFCI dual-function breaker: Also known as combination arc fault circuit interrupters (CAFCIs), this is a newer version of an AFCI breaker. Dual-function breakers can detect both parallel and series arcing.

A circuit breaker serves as a protection device. It can sense if there is a short circuit or electrical surge. If this happens, the breaker will disconnect automatically, cutting off the power supply to a specific part of the home. This is important for preventing electrical fires, as well as preventing damage to any device that gets plugged into an outlet, such as a computer or a microwave.

Circuit breakers are used to manage the flow of electrical power to different parts of a home. Most newer homes will have an electrical panel with a set of 20 to 40 breakers. However, an older home may have a fuse box that uses glass or ceramic knobs instead of circuit breaker switches. Once a fuse is blown, it must be replaced. Circuit breakers, in contrast, just need to be switched back on after they are tripped. Most circuit breaker switches will last for decades.

In most homes, the maximum voltage for a circuit is 120V. In a commercial building, a circuit breaker may be able to handle 240V.

Remember these electrical safety guidelines when working on or near a circuit breaker panel:

• Do not do any work on an electrical panel until you have shut off the main breaker.
• Call on a qualified electrician if you need a circuit breaker installed or replaced.
• Do not replace a circuit breaker with a breaker that has a higher amperage rating.
• Do not add a breaker unless you have an unused spot in the breaker box or load center.
• Always inspect new parts for damage before installing them.
• Be aware of product recalls and replace any recalled parts immediately.

Circuit breakers typically have a number marked on the end of the operating handle. This is the ampere rating and it specifies the maximum amount of electrical current that the breaker can carry. In most household breaker panels, the circuits will have a rating of 15 amps or 20 amps. Standard homes will have 100-amp or 150-amp power, while larger homes and commercial buildings may need higher amperage.

Since 2011, HomElectrical has been a reliable source of affordably priced products from electrical fuses to LED lighting to janitorial supplies. Serving contractors, professionals, and homeowners alike, HomElectrical has 30 warehouses across the United States to provide convenient same-day shipping on most items.

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