Jeremy,
Most modern portable "contractor's special" generators have
GFCIs, because seldom are they used with a ground connection.
The GFCI is incorporated as a safety feature and the neutral is
integrally bonded to the chassis of the generator. By hooking it
to an inverter with its own neutral-ground bond, you
automatically create a ground loop and the GFCI trips. These
generators are designed to be a sole source of AC, and not to be
wired into an existing system with its own neutral-ground bond.
Typically only higher-quality generators allow the neutral to be
unbonded from the chassis (i.e. floated), and those that do
don't have the GFCI. There's no fully Code-compliant solution of
which I'm aware. Ideally, you would move the generator far
enough from anything grounded to the main system, treat the
gennie as a "separate structure", ground it to its own rod, use
its internal bond, and hardwire the output without a grounding
conductor between the two systems.
In many installations this approach isn't possible. Years ago I
asked John Wiles about this. His advice then was to connect all
conductors between the gennie and the system - one or two hots,
neutral and grounding - and allow the ground loop. The grounding
conductor would carry a portion of the neutral conductor's
current between the two. The logic is that this is safest option
when it can't be wired correctly. To do this you'd bypass (or
replace with a standard receptacle) the GFCI.
Make sure that the neutral and ground are bonded at the mains
panel; otherwise you're dependent on the gennie to make the
bond.
Allan
Allan Sindelar
al...@positiveenergysolar.com
NABCEP Certified PV
Installation Professional
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder, Positive Energy, Inc.
A
Certified B CorporationTM
3209
Richards Lane
Santa Fe, New Mexico 87507
505 424-1112 office 780-2738 cell
www.positiveenergysolar.com
On 10/13/2013 7:57 AM, All Solar, Inc. wrote:
Wrenches
I recently visited a site where their backup gen has GFCI outlets used for input to the FX inverter.
They finally tried to charge the batteries, and it trips the GFCI.
As a test I replaced it with a standard outlet and it works fine.
I have never used a gen with GFCIs, In fact most are hard wired.
Is the outlet the problem or is there really a ground fault?
Is there a safety issue?
I'm pretty sure the neutral and ground are bonded at the mains panel.
Thanks
Jeremy Rodriguez
All Solar
Sent by Jeremy's iPhone. Sorry for typos and shorthand!
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