Abstract: To enable a consumer of electrical energy to effect control of total energy consumption by various individual appliances and loads, each individual load has a control unit, conveniently in a plug top, which responds to pulses broadcast on the power supply wiring in the form of short duration interruptions of the waveform. At each appliance a microprocessor unit counts the number of successive pulses in a predetermined time interval and operates an electronic switch if the received count reaches a predetermined number, which may be different for different loads thereby enabling selective control of the loads. Provision is made for automatic restoration of supply if the overall energy consumption falls. Provision can also be made for automatic resumption of supply after a predetermined time interval.