You gentlemen are confusing me. The original question says "Service Garage" which I think needs more explanation of exactly what this is. If this is the same as a Commercial Garage (Article 511) then the Class 1 location only goes up to 18 above the floor (not counting any pits or depressions). The Class 1 area also changes depending on the ventilation system.
Say it was a service garage with ventilation fans and offices were attached to this garage. The devices in there would not be affected in anyway or would they