A friend of mine that owns a shop had a fire in one of his booths about 7 years ago. They managed to get the car out of the booth, but the booth was destroyed, and the smoke/water damage in that part of the shop created huge problems for him for a while.
I am really curious. Do you recall what part of the booth caught on fire? My building official is claiming that the discharge filters, the discharge plenum, the fan, and the discharge ductwork, in addition to the booth itself, are all potential fire sources due to paint deposition.
My booth suppression system had 2 nozzles in the fan plenum and 2 nozzles upstream from that in the stack, plus 6 in the booth spray area.
When I first went into business, the local FD gave me the requirements for a system, and once it was installed, I never saw them again.
I did see the supplier twice a year for inspection/maintenance, though. Once, I questioned him about the need for twice-yearly visits. He said "Before you ask me that, call your insurance company and ask if you're covered in the event of a fire and skipped inspections." The Insurance company said "Sorry. If you skip an inspection and have a fire in the booth, you're on your own." I kept paying for the twice a year inspections...