John,
Check under BOCA mechanical code book. I don't have one here at home but I have one in the office. Also it may be a gas company rule. They want the lights there so that when they have to go up there in the middle of the night to relight a pilot light, they just want to see where to go. The worst part is that they leave the lights on and so that the next time they go up there the bulbs are all burnt out.
