Abstract: The a-c power distribution system used to energize various loads is also used to carry signals for controlling the operation of such various loads. A control station places an r-f pulse burst on the a-c power line to which is connected the controlled station. Each controlled station is represented by an individual time interval. Individual time intervals are timed at all stations by counters using clock inputs from a common source, such as the a-c power line cycles or from a clock pulse generator. The controlled station receives the first r-f pulse burst and begins counting pulses, either a-c line cycles or separate clock pulses, to time its individual timing interval. If a second r-f pulse burst produced by the controlled station coincides with the controlled station reaching the end of its individual time interval, an actuation signal is produced. The signal actuates a switch which controls energization of the load.