The Beginner’s Guide to Circuit Breaker Types

Circuit breakers are an essential part of the modern-day world but not much is known about them by the public. Circuit breakers are one of the most important safety devices in your home, as they regulate the flow of electricity through your house.

Circuit Breaker Function

When electricity enters your home from a power distribution grid, it goes into a circuit breaker box. From there, the current is divided into several circuits, each of which is protected by a fuse or a breaker. The circuits provide power to different parts of your home while the breakers regulate the currents. There are a switch and a moving conductive plate within the circuit breaker, and, when electricity comes into play, the switch is moved by the plate.

These breakers and switches have limits; if you try to push too much power through a circuit, the breaker can shut it off before damage can occur. When this occurs, the contact plate forces the switch to flip, and it breaks the current flow. Without this system, wire insulation can melt and result in fires.


Types of Circuit Breakers

There are three main types of circuit breakers you will see in your home and in commercial applications.

Magnetic Circuit Breaker

These types of breakers use an electromagnet, also referred to as a solenoid. The solenoid generates a magnetic field to gauge the strength of the current, which increases with the increasing current. The strength of the magnet, therefore, increases with the force of the current. The magnetic field pulls on a lever within the breaker and, when the current exceeds acceptable limits, the lever forces the switch to flip and cuts the electricity.

Magnetic circuit breakers are most useful when dealing with spikes from short circuits or large power surges. However, in cases where there is a power surge but it does not quite exceed the breaker’s limit, these prolonged low-level surges can damage the circuitry and cause overheating. This can cause damage to the circuit breaker and even start fires.

Thermal Circuit Breaker

As the name would suggest, thermal circuit breakers use heat to break a circuit. These are found mostly in distribution boards. This breaker employs the use of a bimetallic strip. This strip is made of two different types of metal running side by side that react to heat by expanding and bending. This bending increases with stronger currents and, eventually, the strip bends at an angle and breaks the circuit.

Thermal circuit breakers are especially useful in prolonged low-level surges where magnetic circuit breakers are lacking.


Hybrid Circuit Breaker

The third common circuit breaker is a hybrid. This breaker uses both electromagnetism and heat to detect and regulate currents. This configuration employs both a bimetal switch and electromagnet. The bimetallic strip handles overcurrents and long-lasting power surges. The magnetic component handles the short-circuit currents. This type of circuit breaker is configured to combat quick surges, as well as detect and cut long-term overcurrents.

These breakers are convenient because they can react to both short-circuit power surges as well as low-voltage power surges.

Circuit Breakers Are Also Defined by Voltage Limits

Circuit breakers can also be broken up into categories based on the voltage limits of the breaker. There are low-voltage circuit breakers that are primarily used in residential and commercial applications. Medium-voltage circuit breakers are used in industrial settings, and high-voltage circuit breakers are used in power grids. Each of these breakers has a different voltage limit.


Circuit Breakers in Residential Homes

In most residential homes, there are several types of breakers in use:

  • Single Pole Breaker: Out of the 240-volt service provided, these control a 120-volt branch circuit and are used most often for outlets and lights. They control one side of the volts and can also be used in circuits that require 120 volts, like furnaces and washing machines.
  • Double Pole Breaker: This type of breaker picks up both sides, or poles, of the 240-volt service. These are generally used for ovens, dryers, and water heaters.
  • GFCI BreakersShort for Ground Fault Circuit Interrupters, these are for circuits that reach areas in the home where water is present. Bathrooms and kitchens require GFCI protection.
  • AFCI BreakersArc Fault Circuit Interrupters prevent fire-causing arcs. While other circuit breakers trip the circuit, they do not always have features that prevent or stop fires. These arcs can even occur in the wall before the breakers can stop the circuit and before AFCI breakers were introduced.
  • Half/Mini Breakers: Single pole and double pole breakers are available in half sizes and are used when adding circuits.

Final Thoughts

In selecting a breaker, keep in mind the end location. Consider what kind of environment your breaker will be exposed to or what kind of electrical appliances will need to be powered with this circuit breaker. Consider temperature, altitude, and moisture when deciding on a breaker.