Grounding & Bonding Aircraft Hangars

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north star

Senior Member
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inside Area 51
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Greetings to all !

I am seeking information on the Grounding & Bonding of
military aircraft hangars [ i.e. fixed wing & helicopters, various
types of airframes ].........Our Hangar facilities have a
requirement to have the Hangar Grounds & Bonding Points
checked & certified as to their "connectivity & Ohm levels."

In an initial review of IEEE 81, it appears a though there is a
10,000 Ohm threshold on the static grounds, and a 25 Ohm
threshold on if the grounds are attached to the "power ground".

My questions are in regard to the 10,000 Ohm threshold on
the static grounds.

That 10,000 Ohm threshold seems high to me.......Is this the
normal threshold amount on these types of grounds ?

Any information \ standards \ codes that you can provide
will be greatly appreciated.



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luckylerado

Senior Member
10K ohms is correct. Army and Airforce have different rules for static grounds and moorings and there are different rules for inside vs outside a hanger. I have not installed within a hanger.

Look at UFC 3-260-01 for more info.

These are a huge pain in the butt to install in my experience but we have nothing but rock in our area.
 

north star

Senior Member
Location
inside Area 51
~ ~ @ ~ ~


Thanks **lucklerado** for your reply !

I have a copy of the UFC Standard that you referenced.

I am just pondering the 10k Ohm level.........That just seems
like a rather high amount of resistance, versus the "Inside the
Hangar" normal power system grounding level of 25 Ohms.

I am not versed in the "static resistance requirements"
[ RE: NFPA - 77 ]. :dunce:


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luckylerado

Senior Member

I am just pondering the 10k Ohm level.........

I do not have a reference but I believe that the static voltages can be so high that discharge through a very low impedance to ground would create hazardous current to flow or potentially an arc flash condition. I am thinking a discharge like a high voltage capacitor. Don't put your body between the aircraft and the static grounding point.

Just my thoughts....
 

luckylerado

Senior Member
I do not have a reference but I believe that the static voltages can be so high that discharge through a very low impedance to ground would create hazardous current to flow or potentially an arc flash condition. I am thinking a discharge like a high voltage capacitor. Don't put your body between the aircraft and the static grounding point.

Just my thoughts....

So, I was way off. See below from UFC 3-575-01

2-1.4 Resistance to Ground
.
"Current caused by static electricity is typically on the order of milliamperes. A
resistance to ground of 10,000 ohms is more than adequate to bleed off normal static
charges. All grounds used for static protection in DoD facilities, including those for
aircraft and fuel tanks, must have a maximum resistance of 10,000 ohms. Any danger
of electrical shock hazard caused by the 10,000 ohm value can be eliminated by proper
bonding to other grounding media."
 
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