National Electrical Code Articles and Information

National Electrical Code Top Ten Tips: Article 513 -- Aircraft Hangers

1. Article 513 covers any structure used for storing or servicing aircraft containing Class I (flammable) or Class II (combustible) liquids whose temperatures are above their flashpoints [513.1]. Basically, if it's an engine-powered aircraft then you need to follow Article 513.
    
2. Article 513 does not cover facilities used exclusively for unfueled aircraft [513.1].
    
3. Article 513 provides four classifications of locations: Below floor level, Areas not cut off or ventilated, Vicinity of aircraft, and Areas suitably cut off and ventilated [513.3]. With the 2020 revision, 513.3 has been extensively rewritten. Be sure to read the Informational Note that is new with this revision.
    
4. When installing equipment in a location that is in, may be in, or may be operated in, a Class I location, comply with the applicable provisions of Articles 501 and 505 [513.4(A)]. If you're not sure, ask someone such as the facilities manager.
    
5. If the location isn't Class I but is a hanger, then you must install fixed wiring in metal raceways unless the area is "suitably cut off and ventilated." Alternatively, you can use Type MI, TC, or MC cable [513.7(A)]. The key is that the raceway must be metallic (to serve as an EGC), not that it be conduit. So you can use metallic tubing (e.g., EMT) but you cannot use PVC conduit.
   
6. You can't use standard cords for pendants. The flexible cord must be identified for hard usage or extra-hard usage. And it must have a separate equipment grounding conductor [513.7(B)]. Make sure you correctly use the proper strain relief(s) and support(s) for the cord and the application.
    
7. If wiring runs under or in the hangar floor, it must comply with Class I, Division 1 requirements [513.8(A)].
    
8. If a receptacle is in an area where it might be used for electrical diagnostic equipment, electrical hand tools, or portable lighting equipment, it must be GFCI-protected [513.12]. Pay attention to how you wire a GFCI, because if it's wired incorrectly there is no GFCI protection. Start by identifying the line wires (incoming power). Label these as such, to reduce confusion and error if a replacement is needed. That leaves the other wires as the load wires. No pig tails. Connect the line wires to the line terminals. Connect the load wires (if any) to the load terminals. Always test a GFCI after installing it. For improved safety, purchase GFCI receptacles that have an indicating LED; it will be green if the unit is properly wired and red if it is not or red if there is a problem.
    
9. 513.16(A) contained confusing language with the 2017 revision, and this was not corrected with the 2020 revision. The subtitle of 513 refers to grounding and bonding. What it means is bonding (see Article 100 definition). Nothing in this passage has anything to do with grounding. You accomplish nothing by grounding a raceway. What you want to do is bond it. Ensure that any bonding connections are mechanically sound; use the correct connectors and torque them appropriately.
    
10. Maintain the continuity of the bonding conductor (which, in the NEC, is incorrectly referred to as the equipment grounding conductor or EGC in direct conflict with Article 100 definitions) [513.16(B)(2)]. It's not specified here what is meant by "approved means" but it's really a reference to 110.2.