A system for use in a facility, such as the home, equipped with a common power distribution system, for controlling, from a central location, the operation of a plurality of remote devices. The system includes a central control unit including a memory for storing user-entered command information, preset instructions, time-of-day information, and remote-device selection information. The time-of-day information is compared with the current time-of-day and, in the presence of a time match, the command information and the remote-device selection information is modulated in a serial binary format onto a carrier signal which is coupled directly to the electrical system. A receiver/demodulator unit coupled to the electrical system and to a remote device receives the information from the central control unit and, if the command information is intended for the remote device with which the receiver/demodulator unit is associated, acts on such command information for controlling the operation of the remote device. The system also includes a receiver/demodulator/transmitter unit coupled to the power distribution system and to a remote device including a sensor for receiving and demodulating interrogation signals from the central control unit, for transmitting to the central control unit a signal indicative of the status of the remote device, and for receiving and demodulating command signals for controlling the operation of the remote device; a portable control unit for transmitting command information to the central control unit; and a unit for converting speech to a signal modulated with command information for transmission to the central control unit.