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Why Do Circuit Breakers Trip?

Master electrician Heath Eastman shows host Kevin O’Connor everything he needs to know about why and how breakers trip.

Heath Eastman talks about circuit breakers. Heath shows Kevin O’Connor that while resetting these breakers is simple, these are complex devices that monitor and protect circuits. First, the two talk about the different sizes of breakers before moving on to the different types. Finally, Heath shows Kevin how to test certain breakers to ensure they’re working properly.

Circuit breakers exist to protect people, appliances, and homes from dangerous electrical current. However, few people understand why the trip and how they operate. Master electrician Heath Eastman shows host Kevin O’Connor why this happens, and even explains a few different types of breakers.

Breakers Protect Circuits

When electricity comes into the house, it flows through the electrical service panel. From there, the electricity flows out through different branches in the house, each controlled by a circuit breaker. Should a branch begin to overload and overheat, the breaker will trip to prevent damage.

Breaker Sizes

There are two main sizes of breakers in a house: 15 amp and 20 amp. The amp rating explains how much current the breaker can handle before it will trip, and each requires a certain size of wire. Fifteen-amp breakers require a 14-gauge wire, while 20-amp breakers require a 12-gauge wire.

How They Work

A 15-amp breaker won’t necessarily trip the moment it experiences a spike above 15 amps. Many devices draw more amps upon start-up, and these breakers allow those temporary spikes. However, should the breaker sense elevated amperage for longer than is typical, it will trip to prevent the circuit from overheating.

GFCIs and AFCIs

Beyond circuit overload protection, there are other types of breakers that offer additional coverage. These include GFCI breakers and relatively-new AFCI breakers.

GFCI (ground fault circuit interrupter) breakers need to experience the same amount of current going out as coming back through the circuit. If the breaker experiences a drop in returning current, it assumes that the circuit is leaking, whether it be through a water source or a person. When this imbalance occurs, the GFCI trips immediately.

AFCI (arc fault circuit interrupter) breakers sense when the circuit, a device, or an appliance is arcing (the current is jumping from the circuit and onto something else or someone). When the breaker recognizes the arc signature, it trips immediately. These breakers are relatively new and look similar to GFCI breakers, but they’re becoming a code requirement in most locations.

How to Test Breakers

Homeowners, electricians, and inspectors can test their breakers. There are devices that users can plug into an outlet and replicate an error. These devices, known as AFCI/GFCI testers, can trip the breaker altogether or replicate a ground or arc fault, triggering the breaker. This is one of the best ways to ensure that a breaker is working properly.

When to Call a Professional

If a circuit is continuously tripping, or you know that it should be tripping and isn’t, be sure to call in a professional. An electrician will be able to determine the cause of the issue and make sure your circuit breakers and electrical system are safe.


Resources

Heath explains what a circuit breaker is, why they trip and how it protects a home. A circuit breaker is a device, installed in the electrical panel, that controls whether power can be sent from the panel through a circuit. Heath explains this ability is controlled by a switch that can be operated either manually—like when a person wants to interrupt power for service—or automatically, like a breaker trip.

He says power overloads, current “leaks”, and arcs are the three reasons that would cause a breaker to trip. A Power overload happens when a device is calling for more power than a receptacle, or a circuit is designed to provide. Current “leaks” are caused when current strays from the circuit for whatever reason, though it happens most commonly when moisture is present. Arcs can happen when the wire breaks down over time (due to overloads but also due to other factors, like animals chewing the wire and other decay) but what Heath sees the most is human error.

If a specific receptacle is consistently tripping the breaker, Heath advises to have a licensed electrician identify the problem to ensure the work is done safely.