Grounding grid @MWAA

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thomas zakotnik

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Frderick, MD
Is there a certain distance away from the building that a grounding grid shoulds remain? Note ; the buildings excavation exceeds the building perimeter by 24-36". The excavation is filled with stone (57). We are reluctanct to install a ground rods & test wells inside that area!
Please respond.
 
The building ground ring is usually intended to reduce the touch potential to a safe level between a person standing outside, and then leaning in to touch the building.

Crushed rock is used as a good insulator between a ground grid and walking surface anyway, i.e. look around at substations, what do you see on the ground! You might want to investigate whether or not you have a ground potential difference issue, since there is so much rock. If the ground you are referencing is intended to create a low impedance ground path for sensitive electronic equipment then moving it outside the 36" shouldn't make a difference. Calcs will have to be done to prove the design will work.
 
kingpb,
The building ground ring is usually intended to reduce the touch potential to a safe level between a person standing outside, and then leaning in to touch the building.
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That doesn't really work with standard ground rings. A ground ring is a far cry from the ground grid used in a substation.
Don
 
Don,

I agree with your assessment 100%. Unfortunately, I have seen many individuals put ground rings around buildings for no reason other then with the misconception that they are actually providing some type of protection to personnel. Sort of a misplaced feel good thing.

If the ground ring is intended as part of the lightning protection system, then it needs to be installed beyond the building drip line anyway, which could certainly be outside the 36" mark in question.
 
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