A circuit breaker protects the home and its occupants from the effects of excessive electrical current in an electrical circuit.
Properly operating circuit breakers are important to prevent fires in the home.
The U.S. Fire Administration reports, “”During a typical year, home electrical problems account for 67,800 fires, 485 deaths, and $868 million in property losses.
Home electrical wiring causes twice as many fires as electrical appliances”.
The two purposes of the circuit breaker are:
• Prevent overload of the electrical circuit resulting from excessive current draw due to electrical appliances being plugged into the circuit that exceed the rated capacity of the circuit breaker.
• Prevent the occurrence of heat build-up in the home wiring system, which can heat up the wiring, melt the insulation on the wire and cause a fire
The circuit breaker is also a method to shut off the power to a circuit to work on the circuit.
A circuit breaker is designed to stop the flow of electricity through an electrical circuit when the circuit is overloaded, or when there is a short circuit.
The following conditions can cause an overload in the circuit:
• Amperage in the circuit exceeds the rated capacity of the circuit breaker due to devices of excessive wattage being plugged into the circuit
• Resistance increase in a circuit that raises the electrical current above the capacity of the circuit breaker, resulting from defective wiring or electrical appliances.
The following conditions can cause a short circuit:
• The hot wire and neutral wire of an electrical circuit contact each other
• An item that conducts electricity simultaneously contacts the hot wire and the neutral wire of an electrical circuit.
The following conditions cause a ground fault:
• The hot wire and the ground wire of a circuit contact each other
• An item that conducts electricity simultaneously contacts the hot wire and the ground wire of an electrical circuit.
Circuit breakers, unlike the fuses used in older homes, are reusable by resetting them after being tripped by excessive current flow and the cause of the problem is repaired.
Current rating and size
A circuit breaker’s capacity is rated by the safe number of amps at a certain maximum voltage that can flow safely through the circuit.
Amps and volts are electrical units. Circuit breakers are selected based on the rated safe capacity of the circuit that they are protecting.
They are available in different sizes to fit in different types and brands of circuit panels.
A circuit breaker operates by “tripping” (opening) when it is exposed to an electrical current that exceeds its rating.
When a circuit breaker “trips”, an internal device in the circuit breaker opens and stops the flow of electrical current to the circuit.
There are two types of mechanisms that operate circuit breakers.
One type of circuit breaker switch uses an electromagnet to open the circuit breaker when subjected to electrical current that exceeds its rated capacity.
A second type of circuit breaker switch uses a bi-metallic strip constructed of two dissimilar metals.
The bi-metallic strip opens the circuit by bending away from the electrical contact in the circuit breaker when subjected to electrical current that exceeds its rated capacity.
Combination type breakers
The 2008 National Electric Code requires that all new homes and homes being remodeled use a combination type circuit breaker in certain areas of the home.
A combination type circuit breaker combines the protection of a circuit breaker as described in this article and the protection of an AFCI (Arc fault circuit interrupter).
Hire an electrician
There is high voltage in the home’s electrical system that can seriously injure or kill a person who comes in contact with it.