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07-28-2009, 12:34 PM
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#1
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electrorick
Join Date: Mar 2008
Location: Savannah, Missouri
Posts: 47
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neutral size rule
Where in the code do I justify the size of the neutral being smaller than the hots in a service
I know why I just can't find the rule
Rick
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07-28-2009, 12:59 PM
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#2
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Ax grinder
Join Date: Jan 2007
Location: North Logan, Utah
Posts: 446
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Take a look at 230.42(C) and 220.61.
Chris
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07-28-2009, 05:28 PM
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#3
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Senior Member
Join Date: May 2009
Location: Chapel Hill, NC
Posts: 602
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How about 250.24(C)(1)
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07-28-2009, 07:59 PM
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#4
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Ax grinder
Join Date: Jan 2007
Location: North Logan, Utah
Posts: 446
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Quote:
Originally Posted by Dennis Alwon
How about 250.24(C)(1)
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That section is referenced by 230.42. 
Chris
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07-28-2009, 08:42 PM
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#5
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Rat Bastard
Join Date: Oct 2008
Location: Hack City, USA aka New Orleans
Posts: 1,521
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Does anyone even use this rule?...I always just wire the neutral the same size as the ungrounded conductors. I guess on a huge commercial job with thousands of feet of wire maybe?
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07-28-2009, 08:46 PM
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#6
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Moderator
Join Date: Jan 2007
Location: Beautiful Cumberland Valley, in PA
Posts: 5,846
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Quote:
Originally Posted by NolaTigaBait
Does anyone even use this rule?...I always just wire the neutral the same size as the ungrounded conductors. I guess on a huge commercial job with thousands of feet of wire maybe?
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I have the option of buying SEU with the smaller neutral. I often do.
__________________
-Marc, ABC, XYZ, PhD, 1-2-3
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07-28-2009, 08:50 PM
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#7
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Rat Bastard
Join Date: Oct 2008
Location: Hack City, USA aka New Orleans
Posts: 1,521
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Quote:
Originally Posted by MDShunk
I have the option of buying SEU with the smaller neutral. I often do.
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I wasn't aware they made it that way. What's the cost difference?
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07-28-2009, 08:53 PM
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#8
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Moderator
Join Date: Jan 2007
Location: Beautiful Cumberland Valley, in PA
Posts: 5,846
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Quote:
Originally Posted by NolaTigaBait
I wasn't aware they made it that way. What's the cost difference?
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about a nickel a foot.
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-Marc, ABC, XYZ, PhD, 1-2-3
-Someday, I'll wear pajamas in the day time.
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07-28-2009, 08:55 PM
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#9
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Rat Bastard
Join Date: Oct 2008
Location: Hack City, USA aka New Orleans
Posts: 1,521
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Serious?...That isn't much of a savings.
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07-28-2009, 08:56 PM
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#10
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Moderator
Join Date: Jan 2007
Location: Beautiful Cumberland Valley, in PA
Posts: 5,846
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Quote:
Originally Posted by NolaTigaBait
Serious?...That isn't much of a savings.
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If you have to carry the roll of it from the store to the truck, you might appreciate the savings in an entirely new way.
__________________
-Marc, ABC, XYZ, PhD, 1-2-3
-Someday, I'll wear pajamas in the day time.
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07-28-2009, 08:58 PM
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#11
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Rat Bastard
Join Date: Oct 2008
Location: Hack City, USA aka New Orleans
Posts: 1,521
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Quote:
Originally Posted by MDShunk
If you have to carry the roll of it from the store to the truck, you might appreciate the savings in an entirely new way.
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Good point. I had to run a 70 feet of 4/0 ser feeder in a fishing camp 16 feet off the ground the other day. A few less pounds would have been nice.
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07-28-2009, 09:34 PM
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#12
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Senior Member
Join Date: May 2009
Location: Chapel Hill, NC
Posts: 602
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I often install 400 amp services with 2- 200amp panels outdoors that have feed thru lugs. I then pipe to the inside panels sometimes 50- 75 feet away with 3/0 copper and a 1/0 grounded conductor.
If the calculated load was small enough I could actually go down to a #2 in each panel but I never have done that.
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07-28-2009, 09:41 PM
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#13
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Senior Member
Join Date: Feb 2008
Location: Atlanta, Ga/Hamilton, Al
Posts: 1,840
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Often times the neutral size is a spec'd size. Seems like most of the jobs I do spec full size neutrals.
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07-28-2009, 09:47 PM
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#14
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Senior Member
Join Date: May 2009
Location: Chapel Hill, NC
Posts: 602
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Quote:
Originally Posted by InPhase277
Often times the neutral size is a spec'd size. Seems like most of the jobs I do spec full size neutrals.
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I don't doubt it but I bet you do commercial work and not resi work where the neutral is spec'd.
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07-29-2009, 03:38 PM
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#15
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electrorick
Join Date: Mar 2008
Location: Savannah, Missouri
Posts: 47
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wire price diff
Quote:
Originally Posted by NolaTigaBait
Does anyone even use this rule?...I always just wire the neutral the same size as the ungrounded conductors. I guess on a huge commercial job with thousands of feet of wire maybe?
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I went to get feeders for 200amp panel
3/0 3/0 1/0 copper was $9.00 a foot x 20' = $180.00
4/0 4/0 2/0 al was 2.50 a foot x 20'= $ 50.00
the 4/0 4/0 2/0 was on the roll already together
and of course I'm comparing copper to al price not 3/0 vs 1/0 price
Rick
__________________
I know you understand
what you thought I said
but what you heard
is not what I meant
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07-29-2009, 03:42 PM
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#16
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electrorick
Join Date: Mar 2008
Location: Savannah, Missouri
Posts: 47
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so what size ground do you use on those?
I am doing one like that now
this in ref to Dennis and his 400 amp service feeding two panels
__________________
I know you understand
what you thought I said
but what you heard
is not what I meant
Last edited by RICK BOYD; 07-29-2009 at 03:45 PM.
Reason: get the question to proper person
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07-29-2009, 05:56 PM
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#17
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Senior Member
Join Date: May 2009
Location: Chapel Hill, NC
Posts: 602
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Quote:
Originally Posted by RICK BOYD
so what size ground do you use on those?
I am doing one like that now
this in ref to Dennis and his 400 amp service feeding two panels
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Your EGC is determined by 250.122 and what size OCPD you have. In my case a #6 is all that is needed to each panel, but I often pull #4 simply because I stock that size.
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07-30-2009, 11:56 PM
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#18
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Senior Member
Join Date: Nov 2007
Location: Chicago
Posts: 397
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Doing a job for a hospital now and each MRI room calls for one ground and an isolated ground, each to be the same size as hots. For what it's worth, in Chicago neutral must be same size as ungrounded conductors in services up to 400 amps.
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07-31-2009, 10:16 AM
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#19
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Senior Member
Join Date: Jun 2009
Location: U.S.
Posts: 133
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I've been on jobs where they oversize the neutral and call it a super neutral.
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08-01-2009, 12:50 PM
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#20
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Senior Member
Join Date: Apr 2009
Location: Canada
Posts: 633
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I've seen a lot of jobs lately that they spec a larger (or even doubled up) neutral for feeders.
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