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.
[email protected]
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
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