Have an underground rigid feeder to a 30-amp explosion proof disconnect, mounted at 48" AFF, seal off 1st fitting out of slab, then exp proof union into bottom of disconnect. 6" nipple out of top of disconnect with seal off then 10' rigid pipe stub to approximately 14' 8" AFF. Question being do I need a 3rd seal off at that point to change over to EMT and wire a garage door opener motor mounted at 18'?
Is this just a storage hangar? (a place to store the plane).
Entire area from 18" above the floor and below is classified locations. Only other classified locations would involve being within 5 feet of the aircraft power plant or fuel tanks, I would presume they mean it's usual position while stored in the hanger, that is what we went by when I have been involved with a hanger, but it's been a long time since I worked in one.
So if you are not placing anything in a zone effected by the plane itself all you should really need is a seal near but above that boundary at 18" from the floor on the supply line and shouldn't even need explosion proof disconnect.
Biggest thing we usually had to watch for was to not place luminaires too close to a classified location or it would need to be classified wiring and luminaire in those areas. Many planes have fuel tanks in the wings.
