Multi-zone lighting control system

Diagnostic apparatus adapted for use in a light dimming circuit of the type which selectively controls the current flow through a lighting load to adjust the luminous output thereof, such light dimming circuit comprising (i) a controllably conductive device (e.g. a triac) connectable in series between an A.C. power source and a lighting load, and (ii) a control circuit which responds to a dimming level control signal provided by a light control unit to selectively apply a selected portion of an A.C. voltage waveform produced by the A.C. power source to the lighting load to adjust the RMS voltage across the lighting load, such selected portion being determined by a firing angle at which the control circuit causes the controllably conductive device to conduct power during each half cycle of the A.C. waveform, said diagnostic apparatus comprising:

• (a) means for sensing the operating status of a component of the dimming circuit and/or the presence of the dimming level control signal;
• (b) logic and control means for comparing an output of the sensing means indicating the present operating status of the component and/or the presence of the dimming level control signal with a stored value;
• and
• (c) a status indicator which responds to an output of the logic and control means to provide a visual indication of a change in status of the component and/or the presence of the control signal.