Where is Ground Clamps [RE-wrenches]

[Jay Peltz, Peltz Power]

Hi John and Bill,

OK, so here is my question.

I'm holding in my hand a "grounding screw" from Sharp/Schott.  This screw is
SS, is machine thread, and is really really small.  It is so small that it
will rattle around in the listed grounding hole.  Yes it has a star washer.

How is using this any different than installing a star washer on the frame
either under the mounting frame or a surface attachment for the top down
style?

And if the manufacture gives me a grounding screw, can I use anything else
without voiding the UL warranty?  If so, can I install the ground anywhere,
or do I have to use the approved grounding hole?

Thanks

jay.








----- Original Message -----
From: "John Berdner" <jberdner at sma-america.com>
To: <RE-wrenches at topica.com>
Sent: Monday, April 21, 2003 10:55 AM
Subject: RE: Where is Ground Clamps [RE-wrenches]


> Jay:
>
> The problem with grounding through the frame is that many of the frames
> are anodized aluminum (read as excellent insulator).  Unless the
> structure has been evaluated as a grounding member you can't rely on it
> to provide the equipment ground.  I think this could be solved with
> insulation piercing hardware, e.g. star washers, but so far none of the
> structure manufacturers has developed this concept to the point that it
> can be listed as a means of grounding.  In absence of Listed "systems"
> that provide equivalent grounding means, the Code says you have to run a
> ground wire to every module to make sure it stays grounded.  The UL
> requirement for a ground is 0.1 Ohms at 60 Hz.  Given that we are
> talking about dc I think UL would also want to see a dc impedance
> measurement as well.
>
> Based on my own experience I have measured grounding impedances far
> above this level when using only the frames for grounding.  Others such
> as J. Wiles and B. Brooks have also confirmed high ground impedance on
> frames when only the structures are used. Until we have a grounding
> structure system I think you have to run a ground wire (even one long
> one daisy chanied) to every module.  Also, J. Wiles has convinced me
> that all splices in the equipment ground wires should made with "non
> removable" pressure connections, i.e. butt splices or ferrules. Just my
> $0.02.
>
> If you have any questions or if I may be of any further assistance,
> please do not hesitate to contact me.
>
> Best Regards,
>
> John Berdner
>
> SMA America, Inc.
> 12438-C Loma Rica Road
> Grass Valley, CA  95945
> 530.273.4595 - Tel
> 530.274.7271 - Fax
>
> -----Original Message-----
> From: Jay Peltz, Peltz Power [mailto:jay at asis.com]
> Sent: Monday, April 21, 2003 09:50 AM
> To: RE-wrenches at topica.com
> Subject: Re: Where is Ground Clamps [RE-wrenches]
>
> Hi Dean,
>
> Can you give me the code # that states all panels must be grounded in
> addition to the metal frame they are on?
>
> One installer I know puts in the permit all grounding to be done in
> accordance with 250.136(a).  This allows for only a single ground wire
> from
> each seperate array.  Makes it much easier.
>
> thanks,
>
> jay
>
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