NEC Article 513.1 - Scope

Hawk55

Member
I'm not sure if you can answer this question - we bought four 70' 12/3 extension cord reels to be installed in a new corporate jet hangar. We asked the electricians to install them attached to GFI outlets about 48" high around the hangar, however they refused saying that they had to be explosion proof reels because they would be used below 18" above the floor, per NEC Article 13. I have never seen an explosion proof extension cord in any hangar that I've ever been in and I've run a large corporate aviation department for years. The problem is the prices for explosion proof reels for a 50' length start at about $5,000 (and can go way higher from there) vs. $800 for a conventional reel.

"NEC 513.1 Scope. This article shall apply to buildings or structures in any part which aircraft containing Class 1 (flammable) liquids or Class II (combustible) liquids or Class II (combustible) liquids WHOSE TEMPERATURES ARE ABOVE THEIR FLASH POINTS are housed or stored and in which aircraft might undergo service, repairs, or alterations. It shall not apply to locations exclusively for aircraft that have never contained fuel or unfueled aircraft". As I read this, both conditions must be met, 1) the aircraft with fuel in the tanks must be in a building with temperatures above the flashpoint of the fuel (which will never happen) AND 2) the aircraft will be stored in a hangar which might undergo service, repairs, etc. Yes we do some servicing of struts, tires, add oil, etc., but we are not a repair shop and do not have the capability for major aircraft maintenance.

Something doesn’t seem right here. If it’s a paint hangar we understand this because they have volatile compounds in use continuously with vapors in the air. The flash point of jet fuel is is over 100 degrees F. (Both Jet A and Jet A-1 have a flash point higher than 38 °C (100 °F), with an autoignition temperature of 210 °C (410 °F).) We'll never see those kind of temps in the hangar, therefore, we should not fall within the scope as defined in 513.1. At our airport we must all in be in violation because for years we have stored our planes in our corporate hangars with fuel on them and we do not have spark proof equipment. You will find NO explosion proof extension cord electrical reels in any hangar facility at our Airport, and I would venture to guess, ANY civilian airport in the state, unless it is a paint facility or maintenance facility where they have open fuel tanks (even then there are separate requirements for working in enclosed spaces). They have, however, wired the new hangar in accordance with NEC 513. All of the electrical outlets that the electrical reels would plug into have GFI protection.

Any help with this to help define the applicability of the scope would be appreciated before we go spending big bucks on explosion proof equipment.

Thanks - Hawk55
 

anthonysolino

Senior Member
i it seems like it would a class 1 div 1 area? you are saying there is combustibles and flammables in the same space? theres a ticker at the end,
" shall not apply exclusively for aircraft that have never contained fuel" if your hangar has fuel, and combustibles the flash point language I do see the issue there I will try and read further today. getting ready to head out the door.
 

Hawk55

Member
There are no Flammable liquids, i.e., flashpoints <100 degrees F in that space and the jet fuel in the enclosed tanks in the plane is a combustible liquid , i.e., flashpoint >100 degrees F.
 

rbalex

Moderator
Staff member
Reading the Scope of an Article is always a good idea. I would also review Section 513.3 and apply Section 504(A) to it before deciding the reel is in a classified location.
 

Hawk55

Member
Thank you for your reply, Bob. Good advice! I also contacted a very large aircraft maintenance facility in Appleton, WI to see how they handled this situation. Obviously, they do have areas that are significantly code restricted, but for their basic maintenance hangar they used a shunt short circuit breaker controlled with a thermostat set to interrupt power at 95 degrees F, below the 100 degree flashpoint of jet fuel. Quite an ingenious solution, I think, that was approved by their regulatory inspectors for their specific application. Drawing attached. The bottom drawing controls the whole power panel. The other two options would not need to shut the whole panel off, just the circuits you wanted to control.
 

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rbalex

Moderator
Staff member
Ingenious or not, it's not a recognized Protection Technique. [Section 500.7] It might fly under Section 500.8(A)(3).

Since I don't know/have the Section 500.4(A) documentation for the installation, I can't say for certain, but I suspect the reel isn't in a classified location. The cords may be subject to Section 501.140, but it wouldn't require a Class I reel. It may affect the connectors at the utilization end.
 
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