On Thu, Mar 8, 2012 at 9:52 PM, Wayne <wmc_st at xxiii.com> wrote:
>>> The electrician did mention ground rods at the sub-panel. B I forgot to
>>> add
>>> that, my bad.
>
>
> That sounds TOTALLY wrong. B I flunked out of EE and am not a licensed
> electrician. B But AFAIK, the neutral and ground should be "bonded" at ONE
> point and ONE POINT ONLY. B A subpanel should have a separate neutral and
> ground wire run to it, and the bonding bar between the the two in the box
> should be removed, to create an "isolated ground" whereas a main entrance
> panel has the two connected.
Nope. Subpanel in a detached structure requires a ground electrode.
(That can be a ground rod, or other approved real earth ground.) See
NEC 250.32. That's different from tying the safety ground and the
neutral together ('bonding'). The ground and neutral are almost never
allowed to be bonded at the sub-panel (and where you could do it, it's
not a good idea). Subpanel inside the same structure (like, say, an
attached garage, or an office building with panels per floor or
tenant) does not require a separate ground connector (There's probably
some situation where it does. i"d have to look it up to see if it's
allowed.). Neither does just running a circuit to an out building.
--
David Scheidt
dmscheidt at gmail.com
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