[RE-wrenches] Stainless steel, self-tapping grounding screws

[Mick Abraham]

 Nick didn't specify screw diameter, but assuming #10-32:

Try #96024A310 from McMaster-Carr (www.mcmaster.com) These cut threads into
aluminum pretty well.

I also use stainless "external star" washers for the ground lug task:
#98438A230, same source. One washer between lug and solar module frame bites
into both surfaces.

The above mentioned screws require a 5/32" pilot hole. If your modules don't
already have that you'll need to protect the Tedlar back sheet with a scrap
of wood then drill through the aluminum flange. This operation is possibly
non-code, possibly non-acceptable to your authority having jurisdiction, and
possibly a reason for the module manufacturer to disallow warranty on the
drilled modules. Drama, drama, drama.

A 5/16" hex bit is required to drive the thread cutter screws and I find
this cannot be done by hand. A cordless drill works but be careful to not
strip out the aluminum threads you're cutting. Get them tight...but not too
tight.

Side Note: The same screws do not tap well into the thin NEMA 1/NEMA 3R
steel pulling boxes. The cutting teeth seem to grind away before they get a
good bite in the steel.

Jolliness,

Mick Abraham, Proprietor
www.abrahamsolar.com

Voice: 970-731-4675


On Fri, Oct 23, 2009 at 6:17 PM, Nick Soleil <nicksoleilsolar at yahoo.com>wrote:

> Hi wrenches:
>     I am looking for a new source for stainless steel, self-tapping, 32
> thread per inch screws to bond Ilsco lugs to module frames.  I used to buy
> these from Fastenal, but they don't supply them anymore.  I have been using
> WEEB lugs, but one city jurisdiction doesn't allow them without the letter
> of authorization from BP Solar.  I have contacted BP a couple times,
> requesting that they provide a letter to WEEB, and I heard, "it's
> complicated."  I guess so.
>     Maybe I will bolt the Ilsco lug through a threaded hole.
>  Nick Soleil
> Project Manager
> Advanced Alternative Energy Solutions, LLC
> PO Box 657
> Petaluma, CA 94953
> Cell: 707-321-2937
> Office: 707-789-9537
> Fax: 707-769-9037
>
>
>
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