How Do Circuit Breakers Work?

Electricity is ubiquitous these days. Virtually every home and business relies on electricity to operate to some extent. As useful as it is, electricity can also be incredibly dangerous. When harnessed incorrectly, it can lead to serious property damage, injury, and even death. Because of the danger electricity poses to those who interact with it, we’ve built safety components into our electrical systems to prevent those things from happening. A circuit breaker is one of those safety components. Do you know how circuit breakers work?

The Purpose of a Circuit Breaker

Most of the time electricity flows through an electrical system without any problems. Sometimes, however, the flow of electricity may be interrupted before starting up again or something may send electricity flowing back into the system. This causes power surges. Some power surges are small enough that they aren’t problematic. Others are big enough that they could damage electronics and property or even cause injuries. Circuit breakers protect electrical systems by cutting the power when it reaches a certain hazardous threshold. They have different ratings that dictate how much power the breaker can safely hold and interrupt. This is why it’s important to have the correct circuit breakers for any given electrical circuit.

Parts of a Circuit Breaker

There are a variety of circuit breakers out there, each with its own unique designs. While circuit breakers vary from breaker to breaker, most have the same main components.

Starting from the outside, circuit breakers have a frame that insulates and protects the internal components. The frame also protects anything outside of the breaker from damage if something goes wrong within the circuit breaker.

You’ll find terminals inside the frame. A terminal is a block of metal that has a bolt coming out of it. This is where the wires that carry the electrical current through the breaker are connected.

Circuit breakers also have a lever. This lever shows when a breaker has been tripped and is used to flip the breaker on and off. When a breaker has been tripped, the lever will be in the middle instead of to either side. That makes it easier to identify which breaker has tripped.

For a circuit breaker to work, it must have a way to close and open the electrical circuit. That’s what a circuit breaker’s contacts do. Contacts are two pieces of metal that move to interrupt the circuit. One is attached to the actuator mechanism and the other is attached to the main panel.

The actuator mechanism is a metal arm inside the circuit breaker that is connected to the lever on one end and a contact on the other end. It forces the contacts together or pulls them apart when the lever is flipped.

The last main part of a circuit breaker is the trip unit. The trip unit tells the breaker when to trip if there is an overload, fault, or short circuit.

How a Circuit Breaker Works

Each part of a circuit breaker is vital to its proper functioning. They all work together to interrupt the circuit if the amount of electrical charge is too high to be safe. So how does a circuit breaker work? If the circuit breaker is in the “on” position, electrical current is allowed to flow freely through the circuit starting. The current starts at the power supply and moves through the trip unit, contacts, and out the upper terminal.

A circuit breaker can interrupt the flow of power in two ways. The first way is through heat. If a thermal-magnetic trip unit’s bi-metallic strip overheats, it will bend and open the circuit, cutting off the power automatically. The second way is through an electromagnetic force, which can happen during a fault or short circuit. The electromagnetic force forces the circuit breaker’s contacts to separate. This also interrupts the flow of electricity and trips the breaker.

Circuit breakers play a critical role in allowing people to use electricity in their homes and businesses safely. Becoming familiar with the different parts that make up a circuit breaker makes it easier to understand how they work. When you understand how circuit breakers work and why they need to work properly, it’s easier to prioritize making sure they aren’t being overloaded and replacing them when the circuit breaker wears out. Circuit breakers are a vital part of any electrical system. Make sure they’re in good working order to keep everyone safe and prevent serious damage.

Are your circuit breakers tripping? Click here for insight from Connecticut Electric on some potential reasons for this.

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