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#97406 02/18/06 08:37 PM
Joined: Mar 2005
Posts: 240
Member
i have a sub 50 amp sub panel that i want to put in a detached maint/gar building.
to save money on wire i am going to run two #6's for the lines and one #8 for the neutral(derating the neut)along with a #10 ground. my question is does this sound code compliant, we derate neutrals for the service feeders and this is going to be a feeder so it seems very complicit to me.

am i on the right page? any codes that i am missing which would forbid this derating?
thanks guys,
h20

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Joined: Mar 2005
Posts: 240
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oh yea it is a metal building which i will bond the beam structure and will drive two ground rods down at the building too.

Joined: Jan 2004
Posts: 1,507
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By not knowing what your load is, I can't tell you that you can or can't derate the neutral. Also, I would be interested in how you terminate the neutral and ground wires in the sub panel. Where do you connect the Grounding Electrode Conductor in the sub panel?


George Little
Joined: Jun 2005
Posts: 821
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There's no need to install ground rods if you run a separate equipment grounding (bonding) conductor (E.G.C.) to the detached garage.

See more about this topic here: https://www.electrical-contractor.net/ubb/Forum1/HTML/006874.html

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Joined: Dec 2003
Posts: 751
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Hold on. You must ALWAYS install a grounding electrode system for a detached building with more than a single multiwire branch circuit. It doesn't matter if your have three or four wires; with or without an equipment grounding conductor.
see 250.32


Earl
Joined: Dec 2003
Posts: 751
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The neutral may only be derated if there is sufficient straight 240 volt loads to warrant it.
see 220.22


Earl
Joined: Apr 2004
Posts: 60
M
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If your neutral busses are specifically listed at 75C and you use 75C rated wire, then #8 copper is fine for a 50A feeder because that wire is still rated at 50 amps.


Mark
Kent, WA
Joined: Jun 2005
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My bad.

Yes, a grounding electrode MUST be installed on any detached building.

Joined: Aug 2003
Posts: 173
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Quote
Yes, a grounding electrode MUST be installed on any detached building.
...that is fed with a feeder.
If you only run a circuit no rod is needed.
See: 250.32


Speedy Petey

"Anyone who has never made a mistake has never tried anything new." -Albert Einstein
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