Earth Leakage Detection and Circuit Termination Units.

Earth leakage circuit breaker in short is ELCB which is an electrical device that will open its contacts and terminate the circuit through it upon detection of an earth leakage event, various methods of detection can be employed. In the case of this device it isn't neccessarry for the leakage to be present for longer than duration Xsec. it is only neccessarry for the leakage current to get within 2% or above the stippulated value of the unit to trigger its function. RCD units does take the duration of the leakage current into account where an elcb doesn't.

Residual current devise that includes a circuit breaker bears the acronym:RCBO where the RCD that doesn't incorporate a CB gets called RCCB?

WHY incorporate the letters CB in RCCB if it hasn't got a CB in it, and why have an acronym RCBO apparantly stating with overload protection, SHOULDN't THIS UNIT BE CALLED An RCCB?