Residential MCBs (miniature circuit breakers) are used in domestic consumer units and switch fuses to break the circuit in case of a fault. They are usually used to protect small appliances or control circuits, and have a fixed trip setting.
Residential MCBs are a very low voltage type of circuit breaker. When a current or voltage is interrupted, an arc is generated, which must be controlled and extinguished so that the circuit can function again.
MCBs utilise air alone to break the arc by dividing it into smaller arcs using a series of insulated parallel metal plates known as arc chutes to cool each section down separately. Once the fault is fixed, the contacts are closed once more to restore power to the circuit.
Residential MCBs can have differing current and voltage ratings, lead times and numbers of poles. Their dimensions can also vary, though all are relatively small.