Ripple Relay
ANSWER
Power companys will offer you cheaper power if they can control or switch off the load when they need to. This load is generally your electric Hot Water Cylinder and other fixed agreed loads.
Switching off can happen when there is high load on the National Power Network and when there is a high charge for this power from the National Grid to your Power Supply Company.
This can be during breakfast, when everyone is cooking, and in the evening when consumers arrive home or this can even happen during breaks in popular television programs (everyone turns on their electric jug for Coffee or Tea). In Britain during the wedding of the William Prince of Wales and Catherine Middleton the power "spiked a further 2400MW after the vows.
"Ripple Relays" are controlled through an imposed frequencies over the mains supply. Often you'll hear the Ripple Relays switching on and off frequently usually at night.
Contact us through our "Ask a Question" page if you'd like to know more.