Circuit Breaker Overview: Types and Functions of the Interrupter

Most times, when there is a power surge or circuit overload, the circuit breaker trips to prevent hazards.

Circuit breakers play a vital role in our homes, ranging from circuit protection to shielding from electric shock. It is a must-have relay in our homes.

In this article, you will get to know what a circuit breaker is, the types, and their functions.

But before moving further, let us understand the meaning of a circuit and circuit breaker.

A circuit is a path which current flows. With that at hand, you can easily define a circuit breaker as anything that breaks a circuit flow or path.

A circuit breaker is a protective device, designed to interrupt current flow when there is excess current or short circuit.

It does the same work with a fuse. Their only difference is that you can reset a circuit breaker to continue its function, while a fuse cannot.

Circuit breakers come in varying sizes, ranging from small devices that protect household appliances, to a large switchgear that protects high-voltage circuits.

Components of a circuit breaker.

Although we have different types of circuit breakers, some components are common in all. These components are in the breakers panel and they include:

  • Frame (breaker box): Protects the inner part of the breaker.
  • Contacts: Metallic materials that conduct currents when closed.
  • Operating mechanism: Assist in the opening and closing of a breaker
  • Arc extinguisher: Separates the arc when a breaker interrupts a faulty current
  • Trip unit: Opens the operating system when there is a high-voltage or short circuit.

Working principles of a circuit breaker.

A circuit breaker consists of a fixed and moving contact or relay that opens and closes the circuit. Under normal conditions, when the breaker is switched on, the current flows through it to the entire system.

But once it detects an overcurrent (faulty current), it trips to protect the electrical system from damage. The heat generated from the overcurrent causes the moving contact of the breaker to open. This leads to a power failure.

Once the circuit breaker has shut off, reset it. But before that, try to find out why the breaker tripped. Some may be due to circuit overload, ground fault, short circuit and even a bad breaker.

Here are the things that usually cause the circuit breakers to be tripping.

Qualities of a good circuit breaker

  • It must be an excellent conductor of electricity when closed (switched on).
  • It must also act as a good insulator while open.
  • Their operations must be reliable
  • Must be able to change from closed to open within the shortest time.
  • Must not cause overvoltage while switching


A circuit breaker is an overcurrent protection device, and their functions include

  • Protection of wires
  • Protect some appliances
  • Isolate loads
  • Protect us from electrocution
  • Allow shut down of power automatically and manually during maintenance.

Types of circuit breaker

Various types of circuit breakers exist, they are classified according to the voltage level, interrupting type, construction type and structure.

Under voltage level, we have

  • low-voltage circuit breakers,
  • Medium voltage
  • High-voltage circuit breakers.

Low-voltage circuit breakers

This breaker is rated for use at low voltage, between 0 and 1000V. They include:

Medium voltage circuit breakers

These breakers are rated for use on voltages from 1 to 72 kV (1000–72000 V). they include:

  • Air circuit breaker or interrupter: This breaker uses air as an extinguishing and interrupting medium.
  • Vacuum circuit interrupter: It uses vacuum as the interrupting medium.
  • Sulfur hexafluoride circuit breakers (sf6)

High-voltage circuit interrupters (72.5 kV and above)

High-voltage circuit breakers can either be live or dead tanks. In a live tank, the interrupter chamber (tank) is raised above the ground by an insulator, at a high potential, while in dead tanks, the enclosure is on the earth’s metal.

High-voltage circuit interrupters are used in substations to protect the distribution system from earth faults and overload. They are classified according to the medium they used to extinguish the arc. These include:

Other circuit breakers

These include breakers that protect against ground faults that are too small to trip an over-current device. They include:

  • Ground fault circuit interrupter (GFCI) or residual current device: A fast-acting circuit interrupter that shuts off current once it senses an imbalance current (leakage current). It is a ground fault protection device, mostly installed in the kitchen and bathrooms.
  • Earth leakage circuit breaker (ELCB): This breaker detects current in the earth wire immediately rather than detecting imbalance.
  • Arc-fault circuit interrupter: The breaker protects against loose connections. If it detects any, it trips to prevent electrical fires. The National Electrical Code recommends that every homeowner must have it.

Frequently Asked Questions

1. My circuit breaker tripped OFF. What could be wrong?

So many factors could be responsible. Some may be due to overload or short circuits.

If you experience such a power outage, check if they plug many appliances in the branch circuit and unplug them, if any. Or call an electrician for troubleshooting.

2. What is the importance of circuit breakers?

It helps protect your wires, appliances, and also regulates the effects of short circuits.

Prevent fire outbreaks that may arise from high voltage supply.

3. Are all circuit breakers the same?

Although they serve the same purpose, they are never the same. Several types of breakers exist, and the common ones include:

  • Domestic circuit breakers: This is the type we use in our home to protect our wires and appliances.
  • Ground fault circuit breakers or (Residual Current Device (RCD): This breaker shuts off the light when it senses an imbalance between the incoming and the outgoing light. They prevent shocks which may arise from ground faults when currents contact water.
  • Commercial circuit breakers: we use them on high-voltage circuits.

Fuse vs circuit breakers, any difference?

Fuse and breakers serve the same purpose, which is to open the circuit when there is a faulty current. However, they serve in unique ways.

While the breakers have an internal switch that goes off on exposure to a short circuit, the fuse has a metal that melts and once it blows, it will be replaced, unlike the breakers.

Take home

Circuit breakers are vital protective equipment that help safeguard our homes. When you install electricity in your homes, endeavour to add breakers too.

They act as a watchdog for the circuit and our electrical appliances. Don’t be the type that uses electricity without fuses or breakers, as the risk may be high.