The difference between the modes of operation of the essentially two different-types of 'RCD-unit' functionality, is that the operation for power-distribution purposes requires the internal 'Latch' to remain set within the 'RCD-unit' after any form of power-disconnection caused by either the user himself turning the power off, or after any power-outage attributable to the electricity service-provider; such arrangements are particularly applicable for connections to refrigerators & freezers.