MCCBs vs. ELCBs - Definition and Usage

MCCB is "Moulded Case Circuit Breaker" and it is used for Power Switching applications. It is available in a variety of continuous current ratings from 16A to 3200A and also with short circuit breaking capacities ranging from 10kA to 75kA. They are capable of Making, Carrying & Breaking Electric Currents in Circuits during Normal Conditions as well as during abnormal or faulty conditions. An MCCB normally will have over current & short circuit protection. Nowadays, MCCBs are also available with in-built earh fault protection.

An ELCB on the other hand is "Earth Leakage Circuit Breaker" and its purpose is to isolate the power supply to a circuit if the earth leakage current exceeds the set value. ELCBs are available with current ratings ranging from 10A to 125A and with Earth Leakage sensitivities from 10mA to 300mA. But, an ELCB cannot Make, Carry or Break Short circuit currents. An ELCB can never replace an MCCB.

You can use an MCCB instead of ELCB provided you have an external earth leakage relay whose contact is wired to the MCCB's shunt release so that in the event of an earth leakage, the MCCB is tripped.