Understanding Circuit Breakers: What They Are and How They Work

Woman checking bills for electricity at home
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Do you ever come out of your shower and then reach the outlet for the blow-dryer only to find yourself in total darkness without electricity, just because you plugged it in? Then, you go to the drawer stockpiled with heat, which is usually situated behind the door in your basement in most cases and find the one switch that you think is suspect and turn it and the magic light is back. So, next time you avoid getting a shock from that blow dryer while the whole circuit is plugged in together, you know why. As a result of such an immense current, the circuit breaker tripped.

Today you will find out what a circuit breaker is, why it is needed, and how this mechanism operates.

What is a Breaker?

There is a class of electrical switches called circuit breakers, designed to guard a circuit by using the mechanism of heating up when there is an abnormal amount of current and cutting power when current levels become more dangerous. By shifting some tasks to robots, you can for sure prevent these things, such as breaking, injury, and fire. There are different varieties of breakers with varying functions as per the peculiar needs of design. For example, you can find a load interrupter switch that ensures your safety in your home. Circuit breakers are used to protect the circuit and its components, which could occur as a result of a short circuit. Additionally, overload also provides an example of a functioning breaker system. Under such circumstances, a circuit overload unintentionally occurs if many appliances and power tools are plugged into one circuit. A short circuit may occur as a result of a circuit path directing electricity into an unintended location.

Function of the Circuit Breaker

It’s been mentioned what a circuit breaker is and now you are going to find out the basics before learning how circuit breakers operate.

Working of Electricity and What is Circuit

Lots of people rely on electricity and they won’t make it a day without it, except for the off-grid people. And despite that, we all know about electricity. All matter is made up of atoms, and electrons are one of the kinds of atoms in it. Electrical charge, the movement of electrons from one atom to another, is the backbone of electricity. Electricity is also an energy form like others, such as natural gas or coal, which our houses use. It is a secondary energy source.

Knowing some of the basic words in electricity comes in handy as you work on circuits. You have to use amperes to identify the strength of the electrical current running through the circuit. Overall, electricity can be transmitted through a considerable number of things, however, there is resistance to the rate of flow. When the resistance is diminished, it is done with the help of a particular unit of measurement called ohms. The power of an electric current is measured in watts.

A power source in an electrical circuit can always be attributed to a positive and negative terminal. The power shoves the electrons out through a material that permits the passage of electric current, and they move from the device’s positive end to the negative end. The current continuously flows in a closed circuit from the source to the load and back to the source during this cyclical process.

Fundamental Structure of a Circuit Breaker 

Circuit breakers cut off the flow of electricity when an overload occurs, so the ratings of circuit breakers are what play a determining role. Rated circuit breakers are those that are designed to carry current within a specified level and only safely interrupt that level. The main kinds of circuit breakers vary but a few have these common constituents.

Frame of a Circuit 

The frame is the usual appearance of a circuit breaker and normally it is made of plastic or synthetic resins. This way, if something dangerous arises, the components inside are shielded as well as the stuff on the outside of the breaker.


The bolt finishes on the underside of the terminal, outside of a metal block. The wires get electricity from the power supply, through the breaker, and to the device loader area.


This lever or switch permits a breaker to be flipped on and off. In addition, the position of the lever, in the middle of the trip, quickly points out which door has problems.


The link is, accordingly, the pull chain, which is made up of two pieces of metal that move to either open or close (interrupt) the circuit. The actuator is held in place with a pair of contact points, where one point holds the actuator mechanism and the other supports the main panel.

Actuator Mechanism

The element, in this case, is an iron arm in the circuit breaker. At the lever end, a new magnetic head is placed, and this head contains metal. The new head is at contract end. Pressing the lever turns on the actuator mechanism that drives the contacts closed or disconnects them.

Trip Unit

 A trip unit is an automatic disconnect part that indicates when the breaker should be tripped in the case of an overload, short circuit, or wiring fault.

What is Inside a Circuit Breaker?

Whenever the trip knob of a circuit breaker is moved to the “on” side, it allows electricity to flow from the power supply, passes through the trip unit, contracts, and then sends out the upper terminal to power the loads in the circuit. The thermal-magnetic trip unit may have its bi-metallic switch subjected to high temperatures in case of overload, which then bends and opens the circuit. During a problem, the electromagnetic forces are activated and separate the contacts inside the breaker and as a result, the breaker trips and shuts off the power to the circuit with the problem. 

Electrician measuring voltage
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Circuit breakers are built to avoid hazardous situations connected with high amounts of current, where overload is the most common example. The breakers should carry or interrupt the amount of current just within the safety range. There are various types of breakers in categories; however, any kind of breaker must have common components at its core. The fact that they help us to protect ourselves from accidental fires or injuries is the icing on the cake.

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