Grounding electrode required?

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dana1028

Senior Member
Just wanted to double check before I opened my mouth.

This structure [?] is a post with (2) 50A, 240V receptacles [feeders for 2 spider boxes] supplied from 200A panel across the street [trenched underground to feed this location.].

As I understand 250.32(A) [2011 NEC] - there should be a grounding electrode installed as this is considered a structure [?].

Thanx for any assistance.

Dana

PS - for those of you who like to dissect - there are (4) #8 THHN/THWN current carrying conductors with 50A OCPD
 

jaggedben

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Sounds like it is fed with a single branch circuit, and you are running an equipment grounding conductor with the circuit. In that case, no grounding electrode is required according to the Exception to 250.32(A).

Which is good, because we can avoid debating if it's a structure. :roll:
 

don_resqcapt19

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Sounds like it is fed with a single branch circuit, and you are running an equipment grounding conductor with the circuit. In that case, no grounding electrode is required according to the Exception to 250.32(A).
Four current carrying conductors sounds like two branch circuits to me.
Which is good, because we can avoid debating if it's a structure. :roll:
No need to debate, just look at Article 100.
 

infinity

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I'm probably in the minority but couldn't a post just be considered a support? A strucuture cannot have two branch circuits to it so this entire install is NG. Similar to this, which IMO is code compliant.

Two%2BRec%27s-One%2BStructure.jpg
 
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infinity

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It is a support, a support that was built or constructed. :D

Yes, one of the absolute worst definitions in the entire NEC. If you look at that photo I posted it defies any rational logic as to why this is a violation. :slaphead:
 

iwire

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Yes, one of the absolute worst definitions in the entire NEC.

As I understand it it comes directly from the building code. I don't think it is bad.

If you look at that photo I posted it defies any rational logic as to why this is a violation. :slaphead:

So in a trailer park we should be allowed to run 2 or 3 or four branch circuits to a post to supply trailers instead of a feeder with breakers?

Or a detached garage with a work shop can have two dozen branch circuits from the main house?


My point is why does the size of the structure change what is safe and what is not?
 

infinity

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I don't see how a piece of wood in the ground is in any way nearly equivalent to a detached garage. The reasons for limiting a detached garage to a single circuit or a feeder shouldn't apply to a few receptacles mounted to a block of wood. The definition as it applies to all installations, even those involving a wooden support for receptacles is too broad.
 

dana1028

Senior Member
I don't see how a piece of wood in the ground is in any way nearly equivalent to a detached garage. The reasons for limiting a detached garage to a single circuit or a feeder shouldn't apply to a few receptacles mounted to a block of wood. The definition as it applies to all installations, even those involving a wooden support for receptacles is too broad.

With respect to the piece of wood in the ground; would this not also apply to a pole mounted distribution panel [temp power pole] on a construction site fed from another location? i.e. no grounding electrode system required.
 

iwire

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would this not also apply to a pole mounted distribution panel [temp power pole] on a construction site fed from another location? i.e. no grounding electrode system required.

The NEC requires a grounding electrode system at temp power poles supplied by services or feeders.
 

kwired

Electron manager
Location
NE Nebraska
I'm probably in the minority but couldn't a post just be considered a support? A strucuture cannot have two branch circuits to it so this entire install is NG. Similar to this, which IMO is code compliant.

Two%2BRec%27s-One%2BStructure.jpg

Attach same equipment to something naturally occurring and you don't have a "structure".

Now if that naturally occurring "something" were not in it's naturally existing space maybe that changes things.
 

infinity

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Attach same equipment to something naturally occurring and you don't have a "structure".

Now if that naturally occurring "something" were not in it's naturally existing space maybe that changes things.

Good point, so if you want to install two receptacles at one location you first need to plant a tree and then attach them to the tree. This is why I find the broadness of the definition of a structure and how it applies to various NEC sections somewhat absurd. :slaphead:
 

dana1028

Senior Member
The NEC requires a grounding electrode system at temp power poles supplied by services or feeders.

So, from the original post - we have temporary power supply [(2) 50A feeders], fed underground, and the equipment is installed on a post [vs. a pole]. This scenario does then require a grounding electrode system.
 

iwire

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Location
Massachusetts
I don't see how a piece of wood in the ground is in any way nearly equivalent to a detached garage.

In size only, electrically nothing is different.

The reasons for limiting a detached garage to a single circuit or a feeder shouldn't apply to a few receptacles mounted to a block of wood.

I understand you feel that way but I have not seen any reason that should be true.

Lets look at it from the other direction. :)

If I was allowed to run multiple circuits to a 'piece of wood in the ground' there is no electrical safety reason I should not be allowed to run multiple circuits to a detached building.

The result is the same, I would have to find and isolate the source to work on the circuits.


The definition as it applies to all installations, even those involving a wooden support for receptacles is too broad.

Have you considered even for a moment that maybe that is exactly what the NEC intent is even if it makes life more difficult for us?



Good point, so if you want to install two receptacles at one location you first need to plant a tree and then attach them to the tree. This is why I find the broadness of the definition of a structure and how it applies to various NEC sections somewhat absurd. :slaphead:

I do not see the absurdity in the definition, I don't mean any disrespect in that.


Absurd is the suggestion of planting a tree to escape rules that exist for a reason. (we assume.:))
 

kwired

Electron manager
Location
NE Nebraska
So, from the original post - we have temporary power supply [(2) 50A feeders], fed underground, and the equipment is installed on a post [vs. a pole]. This scenario does then require a grounding electrode system.

Yes we need a GEC, but we also now have violations regarding 225.30 if we have two circuits supplying one structure.

Another way around this though it really doesn't make much sense is to put each receptacle on it's own post(structure).
 
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