Answer / rvg

ELCB having protection against earth faults, but RCCB having
over current protection as well as earth fault protection.
So RCCB having higher degree of protection.

Answer / pillay

ELCB is voltage based sensing device.If the leakage voltage is above 40 v(usually) it will trip.
RCCB is current based sensing devise. If the leakage current is above the stated amount it will trip.(U CAN BUY DIFFERENT VALUES from 5 milliamps to 300 milliamps)
RCCB has a higher level of safety because even if the leakage current did not get to the earth by the normal circuit maybe because the earth wire was not connected or loose but passed through somebody and than to the ground the rccb will still trip if the current is above the milliamp rating.

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