[RE-wrenches] 4/0 GEC

[Drake Chamberlin]

Hi Russ,

That is how I see it too.  There are times that I shudder when we 
connect to an underground piping system, because as far as I can 
tell, the inspector could require a 4/0 GEC which would not only cost 
a fortune in copper, but pose technical difficulties.

Drake


At 08:14 PM 3/3/2009, you wrote:
>Hi Drake,
>
>The NEC says that "The size of the grounding electrode conductor for 
>a dc system shall be as specified in 250.166(A) and (B), except as 
>permitted by 250.166(C) through (E)."
>
>The "except as permitted by" is what allows us to not run a 4/0 GEC.
>
>250.166(C) says that the GEC doesn't have to be larger than #6 
>copper for connection to a rod, pipe, or plate electrode.  (I don't 
>think pipe-as-part-of-the-plumbing-system is what is meant by "pipe" 
>there, since 250.52(A)(5) and (A)(7) are referenced, and 
>250.52(A)(1) deals separately with metal water pipes that come up 
>from underground.)
>
>250.166(D) says that the GEC doesn't have to be larger than #4 
>copper for connection to a concrete encased electrode.
>
>No mention is made of the maximum size of GEC connected to the 
>plumbing system in section 250.166, so the size of the GEC in that 
>case might have to comply with (A) and be way larger than necessary.
>
>That's how I see it, at least.
>
>Russ
>
>Russell Mueller
>SolarRay Inc.
>russ at solarray.com
>
>
>
>Drake Chamberlin wrote:
>>Hello Wrenches,
>>
>>Revisiting the grounding requirements for DC systems,  the 
>>grounding electrode conductor is still required to be as large as 
>>the "largest conductor supplied by the system" (250.166(B).  When 
>>we run a GEC to a piping system, or the re bar cage embedded in the 
>>concrete foundation of a building, it still reads like we need to 
>>meet this requirement.
>>
>>If the system is a 24 volt, battery connected, VFX 3524, it still 
>>seems that we would need to run a 4/0 GEC.  Inspectors backed off 
>>making us do this a dozen years ago. Why are we not being required 
>>to do this now?
>>
>>Thanks,
>>
>>
>>Drake Chamberlin
>>Athens Electric
>>OH License 44810
>>CO License 3773
>>740-448-7328
>>740-856-9648
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Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
740-448-7328
740-856-9648