Aircraft Hangars

A hangar looks like a big empty box but the fuel changes everything. The floor to a defined height is classified, pits and depressions are treated more severely, and areas near fueling operations tighten up further. Portable lighting and cords used around the aircraft have to be rated for the classified zone, not just grabbed off a shelf.

What people forget is the aircraft itself and any powered mobile stands need bonding and grounding so static does not build and discharge into a vapor. In a hangar I think about static electricity as seriously as I think about my wiring, because the spark that lights the room may not come from a wire at all.

When it applies

Article 513 classifies aircraft hangars, where residual aviation fuel can give off vapor. The floor area near aircraft and any pits or depressions get treated as classified space, because heavy vapor settles low. That drives the wiring methods, the height at which ordinary equipment is allowed, and the bonding of aircraft being serviced.

Common mistakes

• Installing ordinary receptacles or equipment below the height where the classified zone ends.
• Forgetting that pits and trenches in the floor are among the most hazardous spots and need the strictest methods.
• Skipping the static bonding of the aircraft during fueling or service.

In the field

In a hangar I pay closest attention to anything low, floor boxes, pits, trenches. Fuel vapor pools down there, so that is where the classified wiring methods matter most and where shortcuts do the most harm.