ELCB

Not the neutral current sir, As,

_ _ _

I1 +I2 +I3 = 0 in neutral. They use core balanced CTs , insert in the neutral.

ELCB means earth leakage circuit breaker.Years back there were two types-voltage operated and current operated type but now only current operated type(RCD) is in use. Both have advantages and disadvantages.

Why did you not try an internet search for such a simple question?

Putting 'ELCB' into a search engine produced the answer in the first hit.

Come on people (and this is not just directed at you shahzaib85), please perform simple internet searches for your answers first. This is an engineering forum with literally centuries of combined experience at your disposal, not an automated search engine for the lazy. I worked for a NASA sub-contractor for one of the Mars rover missions for crying out loud!

_{Jack - Every time someone asks about bus bar current ratings a little piece of me dies.}