Grounding metal elbows in services with nonmetallic conduit

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rwr

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What is the requirement for grounding metal elbows on service conductors installed in nonmetallic conduit and encased in concrete? Section 250.86 Exception #3 states that they do not have to be grounded if encased in a minimum of 2" of concrete but this section applies to "Other Conductor Enclosures and Raceways." Section 250.80 applies to Service Raceways but the exception in this section only mentions 18" of cover and does not include the wording with regard to concrete encased. Is it the intent to require grounding metal elbows in service raceways that are encased in 4" of concrete?

Rick Roof, P.E.
RWR Engineering
 
rwr said:
What is the requirement for grounding metal elbows on service conductors installed in nonmetallic conduit and encased in concrete? Section 250.86 Exception #3 states that they do not have to be grounded if encased in a minimum of 2" of concrete but this section applies to "Other Conductor Enclosures and Raceways." Section 250.80 applies to Service Raceways but the exception in this section only mentions 18" of cover and does not include the wording with regard to concrete encased. Is it the intent to require grounding metal elbows in service raceways that are encased in 4" of concrete?

Rick Roof, P.E.
RWR Engineering
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As I have read this exception, encasing in concrete for your application does not give relief from the bonding requirement. It is either 18 inches of cover or bonding.
 
The exception found in 250.80 talks about it being " isolated by possible contact by a minimum cover of 18" .... It never cotemplates what the "cover" is to be comprised of. Most would assume some sort of dirt type product, I think this elbow is isolated from possible contact when covered by 4" of concrete , but as far as the wording goes,... you need another 14 " of "cover" to meet the requirement of the exception.
 
I think the panel is well aware of the difference between the exception in

250.80 Service Raceways and Enclosures

and that of exception #3 of article ;

250.86 Other Conductor Enclosures and Raceways.

dcspector I'm not sure what Article 300.5 has to do with the the grounding requirement found in 250.80??
 
I don't think that either exception provides any real degree of safety if a hot conductor would fault to the metallic 90.
Don
 
don_resqcapt19 said:
I don't think that either exception provides any real degree of safety if a hot conductor would fault to the metallic 90.
Don
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I agree if one of the ungrounded conductors faults to the sweep , there will be current flowing in the earth back to the source , It would seem that if one's self were to provide a path with less resistance ,..one's arse just might get fried.
 
dcspector I'm not sure what Article 300.5 has to do with the the grounding requirement found in 250.80??[/QUOTE]

MD It has nothing to do with bonding......I was looking for some type of def. or requirements for....COVER!
 
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