Where is Ground Clamps [RE-wrenches]

[John Berdner]

Jay:

I think that technically, according to the UL Listing of the module, you
have to use their hardware in the hole identified for the purpose.  That
being said, I don't think anyone will call you on it if you use other
holes or hardware.  I strongly suggest stainless hardware to avoid
galvanic corrosion issues even though SS is a terrible conductor.
Bronze grounding hardware is another choice - Ilsco (ilsco.com)makes
some nice stuff but it is spendy.  Be sure to use the stuff rated for
outdoor use if you go that route. 

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 11:09 AM
To: RE-wrenches at topica.com
Subject: Re: Where is Ground Clamps [RE-wrenches]

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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