Circuit Breakers

Circuit breakers are safety devices that can switch off the electrical supply in a circuit when the current flowing is greater than its current rating. Without circuit breakers, a surge of current can actually damage home appliances or even cause a fire.
Two types
  • Miniature Circuit Breakers (MCB)
  • Earth Leakage Circuit Breakers (ELCB)
MCB ELCB
Deals with large current surge (between 5A to 20A) Deals with small current leakages (between 10mA and 30mA) from live wire to earth wire. Current in live wire will thus be greater than neutral wire.
Trip and cut off electrical supply to the part of house circuit Trip and cut off electrical supply to the whole house
Due to overloading or a short circuit has occurred somewhere in the system Due to poor insulation of old electrical appliances
Without ELCB, a person touching the metal case of an electrical appliance with current leakage will get electrical shock.
Points to take note

(1) Circuit breakers can be easily reset but it should be done only after the electric fault is corrected. If no, it will cause the circuit breakers to trip again. 

(2) Circuit breakers must be connected to live wire.

Reason:
When the current flowing exceeds the current rating, a circuit breaker on live wire will trip and cut off the electrical supply to the home circuit. 
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