[AT] grounds
K7jdj at aol.com
K7jdj at aol.com
Tue Dec 18 20:35:04 PST 2007
In a message dated 12/18/2007 5:03:15 P.M. Pacific Standard Time,
drupert at premier1.net writes:
the final analysis it's really their interpretation of the NEC that counts
Dudley,
I agree, but on occasion have dug my feet in and gone up the chain if it
will require a lot of work to correct.
The statement "it all depends" is an understatement when it comes to the NEC
and it's interpretation. I too have called and talked with the LOCAL
inspector who will be inspecting to get HIS requirements. There is a bit of a turf
war in this area between the power provider (Puget Sound Energy) and the
State inspectors. I have been caught in this battle and the State inspector won
because, if he will not sign the permit, Puget Power can not provide
service.
I don't exactly agree that the code hasn't changed on the subject of
secondary panels. There have been additional articles and exceptions made over the
years but basic premise that a spearate ground system is required has not
changed. Art 250.32 part (B)
(1) "states that grounded circuit conductor of a feeder to a separate
building may not be bonded and grounded to a grounding electrode if an equipment
grounding conductor of any type recognized by 250.118 is run with the circuit
conductors" (from McGraw-Hill's NEC electrical code handbook 24 th edition,
2002). It is generally much more economical to install ground rods than run
the required ground conductor - especially with the present price of copper.
Part of this section specifically address buildings that house livestock. I'm
sure most dairy farmers can attest to what works and what doesn't. There are
several issues for them that may require some creative grounding and what may
work for one location may not work somewhere else. I can tell you that at
many FAA mountain top locations (big rock piles) it is very difficult to
obtain an adequate ground. The McGraw-Hill book is very good and gives narrative
on the changes and additions of exceptions. I am not up to date with the
2008 code, as I really don't have a need now that I've retired. I did check to
see if anything had changed on the 25 ohm requirement and it appears that it
will not change. Over the years I have found it takes me a lot of reading
and re-reading the NEC to understand the intent of the requirements and then
I call the inspector. :)
Like farmer says check the grounds, I like to say "It all depends"
especially when it involves the NEC.
I have enjoyed all the posts on this and other subjects but usually stay in
lurk mode as I put in long hours with my excavating business.
Gary
Renton, WA.
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