Sub panel ground wire size ?

Posted by RicodJour on May 5, 2009, 1:09 pm

On May 5, 12:15=A0pm, jamesgan...@gmail.com wrote:

> > On May 4, 3:36=A0pm, jamesgan...@gmail.com wrote:

> > > On Apr 7, 7:32=A0am, jamesgan...@gmail.com wrote:
> > > > I'm going to put a subpanel in a garage. =A0I'm going to run #4 cop=

per

> > > > off a 70 amp breaker for the hots and neutral. =A0It's about 70 fee=

t and

> > > > #6 would probably do but I picked up a partial roll of #4 cheap. =

=A0But

> > > > what I don't know is what the rules are for thegroundwiresize?
> > > I never found anyone with an answer for this. =A0How do you figure ou=

> > > the ground wire size for a subpanel?

> > Did you look? =A0I DAG'dhttp://www.google.com/#hl=3Den&q=3Dwhat+size+gr=

ound+wire+subpanel

> > and the first hit answers your question and tells you the relevant
> > code. =A0The Terry Love forum hit near the top is also pertinent, as is
> > this:http://www.codebookcity.com/codearticles/nec/necarticle310.htm

> Neither one really answers my question for a 70 amp circuit. =A0I saw it
> said #8 for 100amp. =A0I've stumbled across other posts that refer to
> tables. =A0I'm guessing it's decided by the supply size breaker, not the
> breakers in the sub panel. =A0Given #8 for 100amp I'm guessing maybe I
> could use #10 for 70 amp? =A0I've got to go about 70 ft so I don't want
> to buy any bigger wire than I have to.

If it's a cost question, sell the #4 you got for cheap and buy #6 with
#8 ground. I'd figure the #4 is about twice the price of the #6 so
you probably wouldn't have to go back into your pocket.

The NEC is copyrighted, as are most codes out there. You won't find
them online - just snippets here and there. Even if you had the book
in front of you, it still won't address every situation. That's where
the inspectors come in as they're the guys in the trenches
interpreting the code...for good or bad.

R

Posted by on May 5, 2009, 2:32 pm

> On May 5, 12:15=A0pm, jamesgan...@gmail.com wrote:

> > > On May 4, 3:36=A0pm, jamesgan...@gmail.com wrote:
> > > > On Apr 7, 7:32=A0am, jamesgan...@gmail.com wrote:
> > > > > I'm going to put a subpanel in a garage. =A0I'm going to run #4 c=

opper

> > > > > off a 70 amp breaker for the hots and neutral. =A0It's about 70 f=

eet and

> > > > > #6 would probably do but I picked up a partial roll of #4 cheap. =

=A0But

> > > > > what I don't know is what the rules are for thegroundwiresize?
> > > > I never found anyone with an answer for this. =A0How do you figure =

out

> > > > the ground wire size for a subpanel?
> > > Did you look? =A0I DAG'dhttp://www.google.com/#hl=3Den&q=3Dwhat+size+=

ground+wire+subpanel

> > > and the first hit answers your question and tells you the relevant
> > > code. =A0The Terry Love forum hit near the top is also pertinent, as =

> > > this:http://www.codebookcity.com/codearticles/nec/necarticle310.htm

> > Neither one really answers my question for a 70 amp circuit. =A0I saw i=

> > said #8 for 100amp. =A0I've stumbled across other posts that refer to
> > tables. =A0I'm guessing it's decided by the supply size breaker, not th=

> > breakers in the sub panel. =A0Given #8 for 100amp I'm guessing maybe I
> > could use #10 for 70 amp? =A0I've got to go about 70 ft so I don't want
> > to buy any bigger wire than I have to.

> If it's a cost question, sell the #4 you got for cheap and buy #6 with
> #8 ground. =A0I'd figure the #4 is about twice the price of the #6 so
> you probably wouldn't have to go back into your pocket.
> The NEC is copyrighted, as are most codes out there. =A0You won't find
> them online - just snippets here and there. =A0Even if you had the book
> in front of you, it still won't address every situation. =A0That's where
> the inspectors come in as they're the guys in the trenches
> interpreting the code...for good or bad.
> R- Hide quoted text -
> - Show quoted text -

Yes, I've noticed that about the code. Seems stupid, it should just
be on the internet. Sounds like I need to use #8 for my ground to
meet the code I'd rather just go ahead and do that than try to "trade
in" the #4 I have now for different wire. I'm not getting this
inspected but the various building codes are generally good sense so I
try to follow them.

Posted by RicodJour on May 5, 2009, 2:54 pm

On May 5, 2:32=A0pm, jamesgan...@gmail.com wrote:

> > If it's a cost question, sell the #4 you got for cheap and buy #6 with
> > #8 ground. =A0I'd figure the #4 is about twice the price of the #6 so
> > you probably wouldn't have to go back into your pocket.
> > The NEC is copyrighted, as are most codes out there. =A0You won't find
> > them online - just snippets here and there. =A0Even if you had the book
> > in front of you, it still won't address every situation. =A0That's wher=

> > the inspectors come in as they're the guys in the trenches
> > interpreting the code...for good or bad.

> Yes, I've noticed that about the code. =A0Seems stupid, it should just
> be on the internet. =A0

Agreed. It's as stupid as if you had to BUY your 1040 forms. I would
also think that someone could mount a Freedom Of Information act class-
action suit and spank the fookers into open-sourcing code.

> Sounds like I need to use #8 for my ground to
> meet the code =A0I'd rather just go ahead and do that than try to "trade
> in" the #4 I have now for different wire. =A0I'm not getting this
> inspected but the various building codes are generally good sense so I
> try to follow them.

The NEC, while arcane at times, is much more rationale and arbitrary
than a lot of the building code. Some of the local villages around
here adopt modifications to the state code that are so stupid that you
want to cry. 'Luckily' they have part-time building inspectors who
aren't up on the code themselves, so everyone starts in the same place
- in a hole!

I actually had one inspector show up after framing was completed on a
small remodeling job, and ask where the window header was! The
structure was all exposed and there was only one window opening in the
project... I stood there with my mouth literally hanging open and
pointed wordlessly to the area over the window.

R

Posted by Wayne Whitney on May 5, 2009, 4:24 pm

> The NEC is copyrighted, as are most codes out there. You won't find
> them online - just snippets here and there.

Actually, the NEC is available in two places on line:

At <http://www.nfpa.org>, if you register for a free account. The NEC

is known as NFPA 70. If you search their site and go to the web page
for NFPA 70, at the bottom are links for "View this document" for the
2002, 2005, and 2008 versions.

At <http://resource.org/bsc.ca.gov/index.html>, you can find the

California State building codes. The California Electrical Code is
the 2005 NEC with some amendments.

Cheers, Wayne

Posted by RicodJour on May 5, 2009, 5:10 pm

> > The NEC is copyrighted, as are most codes out there. =A0You won't find
> > them online - just snippets here and there. =A0

> Actually, the NEC is available in two places on line:
> At <http://www.nfpa.org>, if you register for a free account. =A0The NEC
> is known as NFPA 70. =A0If you search their site and go to the web page
> for NFPA 70, at the bottom are links for "View this document" for the
> 2002, 2005, and 2008 versions.
> At <http://resource.org/bsc.ca.gov/index.html>, you can find the
> California State building codes. =A0The California Electrical Code is
> the 2005 NEC with some amendments.
> Cheers, Wayne

Thanks for that info. I registered for the free account and viewed
it. Not a very user-friendly way of accessing it - I hate the Java
applet, but, hey, it's free and right from the horse's mouth.

R

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Sub panel ground wire size ? - Page 2