An apparatus for communicating with a ballast or driver through power connections in a lighting system, comprising: a first terminal coupled with a first output of an AC power source; a second terminal coupled with a first power connection, the first power connection being coupled with at least one lighting ballast or driver; a third terminal coupled with a second output of the AC power source; a first switching device coupled between the first terminal and the second terminal, the first switching device operable according to a first switching control signal to selectively couple the first terminal to the second terminal in a first state and to decouple the first terminal from the second terminal in a second state; and characterised by further comprising: a communications system coupled with the first terminal and the third terminal, the communications system comprising a secondary power output operatively coupled with the second terminal, a secondary power circuit operative to convert power from the first and third terminals to selectively provide secondary power to the secondary power output, and a transceiver circuit operative to selectively provide a communication signal to the secondary power output; and a control circuit operative in a first mode to provide the first switching control signal to place the first switching device in the first state to provide power from the AC power source through the first switching device to the at least one lighting ballast or driver, the control circuit being operative in a second mode to provide the first switching control signal to place the first switching device in the second state and to cause the communications system to provide the secondary power and the communication signal through the second terminal to the at least one lighting ballast or driver. a first terminal coupled with a first output of an AC power source; a second terminal coupled with a first power connection, the first power connection being coupled with at least one lighting ballast or driver; a third terminal coupled with a second output of the AC power source; a first switching device coupled between the first terminal and the second terminal, the first switching device operable according to a first switching control signal to selectively couple the first terminal to the second terminal in a first state and to decouple the first terminal from the second terminal in a second state; a communications system coupled with the first terminal and the third terminal, the communications system comprising a secondary power output operatively coupled with the second terminal, a secondary power circuit operative to convert power from the first and third terminals to selectively provide secondary power to the secondary power output, and a transceiver circuit operative to selectively provide a communication signal to the secondary power output; and a control circuit operative in a first mode to provide the first switching control signal to place the first switching device in the first state to provide power from the AC power source through the first switching device to the at least one lighting ballast or driver, the control circuit being operative in a second mode to provide the first switching control signal to place the first switching device in the second state and to cause the communications system to provide the secondary power and the communication signal through the second terminal to the at least one lighting ballast or driver.