Abstract: A system for lowering electrical energy peak demand while minimizing service disruption allows instantaneous dropping of a plurality of interruptible thermal storage devices with predictable reserve capacity. At the time the loads are dropped, a central computer establishes a plurality of permissible off-times for corresponding mutually exclusive groups of loads in similar installations based on characteristic projected energy consumption profiles predicted from past statistical history for the groups. At the end of each off-time interval, a central transmitter transmits reconnect signals to which the devices in the corresponding group are responsive. The groups of units are thus reconnected sequentially avoiding the possibility of generating a secondary peak by indiscriminate, simultaneous reconnection. The reconnection sequence is determined according to changing priorities which take into account the customer's needs at the time of disconnection.