Where is Ground Clamps [RE-wrenches]

[Jay Peltz, Peltz Power]

HI Jeff,

Thanks for the input.

I wonder what in 10 yrs the inpedence will be like with any type of screwed
in fitting?  These grounds need to last for 25+ years.

I'm going to spend the summer, checking every old metal rack I can find and
see what the resistance is between the panels and frames.  I've got lots of
systems that are 15+ yrs old on metal frames.

I'll keep you up to date.

jay
----- Original Message -----
From: "Jeff Clearwater" <clrwater at earthlink.net>
To: <RE-wrenches at topica.com>
Sent: Monday, April 21, 2003 11:46 AM
Subject: Re: Where is Ground Clamps [RE-wrenches]


> Hey Jay,
>
> That grounding screw and approved grounding hole from Sharp is a
> joke.   Good example of the disconnect between some designer in some
> office in Sharp, the Code,  and good common sense professional
> installation practices.  If I'm going to ground something to handle
> the 15 amps required and not have it corrode for the life of the
> system, then any electrician knows the difference between a 15 amp
> solid connection and a manufacturer's ground screw that's only use is
> for the miscellaneous bolts recycling container!
>
> I use 1/4" SS button hex head screws - coarse thread -  on the block
> style Aluminum ground lugs with SS external star washers that dig
> into the sides of the oval mounting hole (not the "approved ground
> hole") on the Sharp panels really well.  Tourqed to 10 foot lbs they
> are a far superior ground to any silly 1/16" machined slotted head
> screw that you can barely get a driver on.  I run a continuous 8
> gauge solid CU to every panel down the one continuous line created by
> any unused mounting hole set.
>
> If that voids my UL warranty well then it's the industry that has to
> change - not my practices.  I'm glad to stretch for Code compliance
> but not when it's ridiculous!
>
> Jeff C.
> Village Power Design
>
> >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.
> >
> >
> >>  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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> --
> ~~~~~~~~~~~~~
> Jeff Clearwater
> Village Power Design Associates
> Sustainable Energy & Water Solutions for Home & Village
>
> 877-SOLARVillage
> PO Box 764
> Boonville, CA 95415
>
> 61 Baker Rd
> Shutesbury, MA 01072
> 413-256-6777, 413-825-0372 (Fax)
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`~
>
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