Fw: Module grounding revisited [RE-wrenches]

[Tom Lane, Energy Conservation Services]

mill finish bright aluminum anodized aluminum rails no colors  will provide
perfect contact with stainless steel 8-18 marine grade fasteners ---
aluminum will migrate to the copper IF  there is any electrolysis making an
even better contact ---copper will NOT  migrate to aluminum . I to seems
like some people do not GET IT -- THE FRAME is the best placeb to mate the
aluminum to the grounding lug -- the framewalls of solar modules are
aluminum --- common  walking around  logic makes the frame the best place to
ground
----- Original Message -----
From: "Allan Sindelar" <allan at positiveenergysolar.com>
To: "New wrenches posting" <RE-wrenches at topica.com>
Sent: Wednesday, October 30, 2002 11:38 AM
Subject: Fw: Fw: Module grounding revisited [RE-wrenches]


> Here's John Wiles' response to William's question on rack versus module
> grounding:
> > Allan:
> >
> > No.  This comes up every year.  I address it at least once a year in
> > Code Corner.  I wish more people would read it.
> >
> > Early in the days of PV (early to mid 1970's), Jet Propulsion Labs,
> > Underwriters Laboratories (UL) and the PV module manufacturers
> > determined through extensive and widespread testing and field
> > experience that it was not possible to obtain adequate module
> > grounding through the mounting bolts used to fasten the module frame
> > to a grounded mounting structure.
> >
> > Aluminum oxidizes very easily and quickly.  The oxidation is an
> > insulator.  Anodized modules (brown or other color) are also
> > insulated by the anodizing.  These insulators are hard to break down
> > and hard to stay broken down with normal mechanical fastenings of
> > module frames to module racks.
> >
> > For this reason, UL Standard 1703 requires that a specific grounding
> > point be identified and hardware be supplied for each module to
> > ensure that the proper grounding is made and maintained.  This is
> > usually a self tapping screw made of stainless steel that must cut
> > 2.5 threads in the aluminum module frame.  Some modules have threaded
> > stainless steel inserts to meet this requirement.  UL tests this
> > grounding connection for continuity and voltage drop with current
> > injection to all other parts of the module frame and to any other
> > exposed metal on the module.
> >
> > The NEC requires that all equipment be installed in full compliance
> > with any instructions or labels furnished with the product.  The
> > module instructions and the marked green grounding point on the frame
> > override any general requirements found in either Article 690 or in
> > other sections of the code.
> >
> > >John, is William correct as you see it?
> > >Allan
> > >
> > >----- Original Message -----
> > >From: "William Miller" <wrmiller at slonet.org>
> > >
> > >Friends:
> > >
> > >I am researching some new module mounting for rooftops-- more on that
> later
> > >as it develops.  One question pertinent to the design is module frame
> > >grounding.  One concept I had been wanting to research is that of
> grounding
> > >only the rack frame.  The Code seems to allow this:
> > >
> > >690.43 Equipment Grounding.
> > >Exposed non-current-carrying metal parts of module frames, equipment,
> > >and conductor enclosures shall be grounded in
> > >accordance with 250.134 or 250.136(A) regardless of voltage.
> > >
> > >Researching further:
> > >
> > >250.136 Equipment Considered Effectively Grounded.
> > >Under the conditions specified in 250.136(A) and (B), the
> > >non-current-carrying
> > >metal parts of the equipment shall be considered effectively grounded.
> > >(A) Equipment Secured to Grounded Metal Supports. Electrical equipment
> > >secured to and in electrical contact with a metal rack or structure
> provided
> > >for its support and grounded by one of the means indicated in 250.134.
> > >The structural metal frame of a building shall not be used as the
> required
> > >equipment grounding conductor for ac equipment.
> > >
> > >Therefore, if one grounds a rack frame, the modules being "secured to
and
> > >in electrical contact with" the racks renders the module frames
> > >"effectively grounded".
> > >
> > >Comments?
> > >
> > >William Miller
> > >
>
> - - - -
> To send a message: RE-wrenches at topica.com
>
> Archive of previous messages: http://www.topica.com/lists/RE-wrenches/
>
> List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm
>
> Check out participant bios: www.mrsharkey.com/wrenches/index.html
>
> Hosted by Home Power magazine
>
> Moderator: michael.welch at homepower.com
>
>
>

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

==^================================================================
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

T O P I C A -- Register now to manage your mail!
http://www.topica.com/partner/tag02/register
==^================================================================