"Dedicated" circuit for dry system air compressor- can light be on it?

[lectrical1]

I'd like some opinions regarding what constitutes a "dedicated circuit" for the air compressor on a dry system. The "closet" where the sprinkler equipment is located is about 3' by 4' and houses only the compressor and valves for the sprinkler system. The dedicated circuit for the compressor also serves the single lightbulb in the ceiling, and a receptacle for use when working on the equipment. I have never had an AHJ refuse "ANYTHING" else to be on the circuit as long as it only serves the equipment being served. This installation hasn't had a problem until the compressor froze up and blew the circuit. When the tech came to instal the new compressor(and the light wouldn't work), he made a big issue of it and said a new circuit had to be run to only serve the compressor. I'd like some opinions, and other experiences. Doug