The present invention relates to the field of transferring information over the power line to and/or from the device or devices powered by said power line. Devices that may be powered by either alternating current (AC) or direct current (DC) their operation may be controlled by which type of power they are receiving, AC, +DC or −DC. Data may also transmitted by alternating the polarity of each half cycle of the power line, on a one half by one half cycle basis, in a controlled manner such that the powered device may receive such data to control its mode of operation. A method of reducing the heat in the switching devices and a system of encoding the data such that each powered device may have a different address and therefore may return data when requested is also disclosed.