Gridtie, breaking grounded conductor [RE-wrenches]

Nick Nicholas, APS APS at SBCGLOBAL.NET
Tue Feb 24 11:36:47 PST 2004


Hi Bob:
    The Sunny Boy's negative/ground bond is not bonded when the GFCI Fuse is
removed.  Therefore, some shock hazard is present.


            Nick Nicholas
            Chief of Engineering
            Alternative Power Systems, Inc.
            135 Colfax Ave. Grass Valley CA 959545
            530-274-0588 530-274-0589 530-913-5605
            aps at sbcglobal.net alternativepowersystems.com



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Alternative Power Systems
www.alternativepowersystems.com
aps at sbcglobal.net
135 Colfax Ave.
Grass Valley, CA 95945
(530) 274-0588 phone
(530) 274-0589 fax
----- Original Message ----- 
From: "Bob Maynard, Energy Outfitters" <bob at energyoutfitters.com>
To: <RE-wrenches at topica.com>
Sent: Tuesday, February 24, 2004 11:00 AM
Subject: Gridtie, breaking grounded conductor [RE-wrenches]


> Wrenches,
>
> Now that Oregon has a gridtie rebate program (severely under funded), we
are starting to feel many of the inspector related issues that have been
discussed before.  Oregon's program in addition to inspection by the AHJ,
must pass inspection by the rebate program's own inspectors.  The
contractors in certain Oregon jurisdictions are being told by the AHJ's
inspector that a  dc disconnect is required at the array on roof mounted
arrays, any advice is appreciated on the best way to address this.
>
> More importantly is a recent issue brought up by a program inspector.
What could be happening?
>
> The inspector said that he received an electrical shock from the negative
conductor within the dc disconnect of a standard residential, battery less,
PV system. At first, this seemed very odd to me since the unbroken conductor
should be bonded to ground and thus possesses the same potential as ground.
Upon further discussion with him,  he is convinced the system is ungrounded
since the grounding bond occurs on the ac side and the GFI prevents the
proper dc grounding. He contends that the bond needs to occur at the source;
the PV array. I am still puzzled about this. Since the grounded bond occurs
within the inverter, does this not properly perform the bond required
between the negative dc conductor and ground. Could there possibly be a
capacitive charge build up. If so, how is it possible with a bonded
connection to ground?  His recommendation now is that the dc disconnect must
break the array positive AND negative.
>
> We've got some real pro's on this list and I look forward to their input.
>
> Regards,
> Bob Maynard
> Energy Outfitters
>
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