Electric Circuit Breaker Types


Circuit breakers, whatever their type, share a common function---to protect an electrical circuit against overloading and to avert damage to the circuit and the appliances connected to it, and the possibility of fire. They achieve this by breaking the circuit with a gap wide enough that an electric current cannot bridge it, but which can later be closed again by resetting. They are, in other words, a kind of automated switch.


  • A circuit breaker interrupts an electrical circuit whenever the current in the circuit exceeds a safe level. Unlike a fuse, which has to be replaced once it has "blown," a circuit breaker can be reset an unlimited number of times.

How Circuit Breakers Work

  • The essential elements of a circuit breaker are a switch and a current-sensitive mechanism that will move the switch and break the circuit when the current exceeds the breaker's rated level. In domestic breakers, the force that drives this mechanism is provided either by a bimetallic strip or an electromagnet. In the case of a bimetallic strip, the higher current makes the strip bend to move the switch. In the case of the electromagnet, the increased current increases the magnet's force, enabling it to move the switch via a linkage.


  • Lower voltage circuit breakers---the kinds that are used domestically---are generally divided into three groups. The most common is the molded case, or MCCB, type; the next step up is the insulated case, or ICCB type; and for medium voltage and amperage, the metal clad breaker.


  • Circuit breakers are rated for the wire capacity and load of the circuit of which they are a part. This is expressed in amps and volts. Circuit breakers are available in a vast range of sizes, suitable for protecting anything from a 110-volt domestic lighting circuit to a high voltage circuit carrying enough power for an entire town. Common voltage ratings for low voltage circuit breakers are 120 volts, 240 volt, 277 and 480 volts AC. Typical breakers for domestic 120-volt circuits are 20 and 15 amp. Large appliances such as water heaters, ovens, air conditioners and clothes dryers are protected by larger breakers on dedicated circuits.

Typical domestic setup

  • Main household breakers are typically 100 amp, although recently, with the increase in domestic electrical consumption, 150 amp and 200 amp main circuits have become more common. Circuit breakers for 120-volt domestic circuits take up a single slot in the electrical panel, while those for 240-volt circuits take up two slots.

Breakers for wet locations

  • Because of the risk of electrocution from a wet appliance or switch, you should always use a ground-fault circuit interrupter (GFCI) to protect circuits---and people---in potentially wet situations such as outdoors, the kitchen and the bathroom.

Related Searches


Promoted By Zergnet


You May Also Like

  • About Neutrals Versus Grounds in House Wiring

    This article describes the difference between the functions of the neutral wire and ground wire in residential electrical circuits.

  • What Is the Function of a Circuit Breaker?

    A properly designed electrical system is very safe. However, when problems occur, electricity can generate dangerous heat and can be fatal to...

  • Types of Electrical Panels

    Existing as fuse boxes or circuit breaker panels, electrical panels provide large amounts of electricity to a building. Responsible for dividing up...

  • How to Test Electrical Domestic Circuits

    The circuits in a home or other domestic setting are quite complicated, and many advanced repairs must be performed by an electrician...

  • GE Circuit Breaker Types

    Circuit breakers perform the management, transportation and stopping of electrical currents. Under normal circumstances, the circuit breaker performs all three functions but...

  • Different Types of Circuit Breakers

    The most common type of household circuit breaker that people will see is the single pole breaker, which is a single switch....

Related Searches

Check It Out

22 DIY Ways to Update Your Home on a Small Budget

Is DIY in your DNA? Become part of our maker community.
Submit Your Work!