A powerline communication control system for controlling a lighting fixture, comprising: a master controller, comprising: a configurable interface adapted to interconnect to at least one of a plurality of different conventional dimmer controllers, wherein the configurable interface is arranged to provide a stimulus to produce a response from the at least one conventional dimmer controller configured to determine a user-adjusted setting of the at least one conventional dimmer controller; a lighting control processor in communication with the configurable interface, the lighting control processor adapted to generate a lighting unit command output in a lighting unit system command format in response to an indication of a user-adjusted setting of an interconnected one of the plurality of different conventional dimmer controllers received from the configurable interface; and a power distribution system interface in communication with the lighting control and adapted for interconnection to a power distribution system, the power distribution system interface adapted to superimpose the lighting unit system command output onto the power distribution system; and at least one lighting fixture controller, comprising: a command receiving interface adapted for interconnection to the power distribution system, the command receiving interface further adapted to separate the lighting unit system command output from the power distribution system; a slave control processor in communication with the command receiving interface and adapted to convert the received lighting unit system command output into a corresponding lighting unit control command; and a lighting unit interface for providing the lighting unit control command to at least one lighting unit to control the at least one lighting unit in response to the user- adjusted setting of the interconnected one of the conventional dimmers, characterised in that the master controller and the lighting fixture controller are electrically in parallel in the power distribution system. a configurable interface adapted to interconnect to at least one of a plurality of different conventional dimmer controllers, wherein the configurable interface is arranged to provide a stimulus to produce a response from the at least one conventional dimmer controller configured to determine a user-adjusted setting of the at least one conventional dimmer controller; a lighting control processor in communication with the configurable interface, the lighting control processor adapted to generate a lighting unit command output in a lighting unit system command format in response to an indication of a user-adjusted setting of an interconnected one of the plurality of different conventional dimmer controllers received from the configurable interface; and a power distribution system interface in communication with the lighting control and adapted for interconnection to a power distribution system, the power distribution system interface adapted to superimpose the lighting unit system command output onto the power distribution system; and at least one lighting fixture controller, comprising: a command receiving interface adapted for interconnection to the power distribution system, the command receiving interface further adapted to separate the lighting unit system command output from the power distribution system; a slave control processor in communication with the command receiving interface and adapted to convert the received lighting unit system command output into a corresponding lighting unit control command; and a lighting unit interface for providing the lighting unit control command to at least one lighting unit to control the at least one lighting unit in response to the user- adjusted setting of the interconnected one of the conventional dimmers, characterised in that the master controller and the lighting fixture controller are electrically in parallel in the power distribution system. a command receiving interface adapted for interconnection to the power distribution system, the command receiving interface further adapted to separate the lighting unit system command output from the power distribution system; a slave control processor in communication with the command receiving interface and adapted to convert the received lighting unit system command output into a corresponding lighting unit control command; and a lighting unit interface for providing the lighting unit control command to at least one lighting unit to control the at least one lighting unit in response to the user- adjusted setting of the interconnected one of the conventional dimmers, characterised in that the master controller and the lighting fixture controller are electrically in parallel in the power distribution system.