Power line communication (PLC), also called Mains Communication, Power Line Telecoms (PLT), Powerband or Power Line Networking (PLN), is a term describing several different systems for using power distribution wires for simultaneous distribution of data. The carrier can communicate voice and data by superimposing an analog signal over the standard 50 or 60 Hz alternating current (AC). It includes Broadband over Power Lines (BPL) with data rates sometimes above 1 Mbit/s and Narrowband over Power Lines with much lower data rates. Traditionally electrical utilities used low-speed power-line carrier circuits for control of substations, voice communication, and protection of high-voltage transmission lines. High-speed data transmission has been developed using the lower voltage transmission lines used for power distribution. A short-range form of power-line carrier is used for home automation and intercoms.