A control device and signaling are provided to operate selected numbers of
the ballasts in a multi-ballast, multi-lamp luminaire. The luminaire has a
control input for receiving a control signal from a wall switch, for
example. The number of ballasts operated by the luminaire increases or
decreases sequentially in response to one of consecutive pulses, signal
level transitions or interrupts in the control signal. The control device
can be programmable or hard-wired to the relays (e.g., a counter and
decoder) to allow for a more economical implementation. Different subsets
of the ballasts can be selected via the programmable integrated circuit to
distribute the burn times of the lamps.
