My firehouse wants to put a 5kw generator in the truck bay area for use on the garage doors only. I told them NG. You can,t put a generator inside the bay. Must have a special room for the unit. Plumber want's to connect it to the gas line inside and vent out-NG,NG! Where will I find the codes for this applaction needed to do this job correctly? Building codes & NEC codes
If he can vent out the combustion exhaust, I don't know of a code violation.
The trick is venting out the exhaust. No 5kW unit that I have ever seen is capable of having its exhaust piped remotely. You could basterdize the exhaust, then Ryan's code section would apply.
The process is similar to having a gas fireplace in the building, if it is piped out properly, then flame away.
You need NFPA 110, and (I think) 54 Fuel gas code. There is nothing preventing running the exhaust outside and placing genset inside, it's done all the time, usually with schedule 40 or 80 black pipe.
The fire truck engines run inside, so can the genset, but just like you put the exhaust tubes on the trucks to work on them, be careful with the exhaust. You do need a drain at the low point, and must consider any windows, etc.