[RE-wrenches] DC GEC Sizing Issue - Water Main GE

[Garrison Riegel]

Thanks Dave, that is definitely helpful.  

I was thinking that all inverters should be considered as one system, but I
realize now that is not the case from a code perspective when sizing the
GEC.  It makes sense that the individual inverter should be the extent of
the "system," as there are many different configuration possibilities and
the Code cannot be rewritten for each one.

Thanks again,

Garrison

Garrison Riegel
Project Manager 

Solar Service Inc
[p] 847-677-0950
[f] 847-647-9360
www.solarserviceinc.com

NABCEP Certified Solar PV and Thermal InstallerT


-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Dave Click
Sent: Wednesday, July 25, 2012 9:32 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] DC GEC Sizing Issue - Water Main GE

Garrison,

In this case, the "largest conductor supplied by the system" is quoted 
from 250.166(B) and note that "the system" refers to the "dc system":

**
250.166 Size of the Direct-Current Grounding Electrode Conductor. 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).

(B) Not Smaller Than the Largest Conductor. Where the *dc system* is 
other than as in 250.166(A), the grounding electrode conductor shall not 
be smaller than the largest conductor supplied by the system, and not 
smaller than 8 AWG copper or 6 AWG aluminum.
**

As for the suitability of a water pipe as a "pipe electrode" it's not 
something I've done personally. After further research it seems like the 
water pipe probably fits not as 250.52(A)(5) but as (A)(1). So if you're 
going to building steel or a water pipe, 250.166(B) is applicable and so 
8 AWG Cu should be acceptable for this connection.

Hope that clarifies!
DKC