Hi Rick,
I've been the same similar situation. I lost.
Your eletronegativities with the material you've
mentioned are ok. I lost to internal toothed
washers. The inspector wanted EXTERNAL toothed
washers. That insured seeing a toothed washer
during inspection. I managed to get by without
any special coatings. We had some paint over
the whatever plating was being used. I also lost
to just a wire from here to there. Had to heatshrink
it to avoid ANY possible abrasion of the insulation.
Someone mentioned torquing the nuts. Good point.
Talk about a simplicity being converted to complexity.
Make sure that this is the ONLY issue with this
guy. Sounds like the guy I had. He went one issue
at a time. Sorry to be so negative.
Regards ... Doug
bcoll...@gmicolor.com wrote:
>
> Rick Busche wrote:
>
> I have a projector assembly which is essentially a large metal
> structure (frame) with a metal projector platform which swivels for
> purposes of maintenance. The structure is painted steel, with pressed
> in bronze bushings at all motion points each of which have been
> measured at significantly less than 0.10 ohms. Arguably, there is no
> guarantee that these structures will remain bonded at these levels
> over time and bonding wires (braid, with crimped ring lugs) have been
> added across the pivot points. These wires are secured to the
> structure using a toothed washer and screw. The intent of the toothed
> washer is to bight through the paint to ensure conductivity.
> My customer's safety officer (in Europe) is now insisting that the
> paint must be ground off to bare metal and coated with Zinc paint
> prior to affixing the lug to the structure. I am concerned that this
> is an excessive requirement. It has been my understanding that the
> toothed washer (and the screw for that matter) creates a gas tight
> connection which is acceptable for all bonding requirements.
> I would be interested in hearing from the group regarding this bonding
> issue. I can find no standard or specification which disallows this
> biting washer or requires Zinc paint.
> Any comments would be appreciated.
> Rick Busche
> rbus...@es.com
>
> Reply:
>
> You may have already thought of this but...
>
> My approach to this kind of requirement is to respectfully ask the
> customer to cite the language in the standard that requires this
> construction. If they are unable to provide this reference, I would ask
> if they have a specific requirement for this construction method other
> than a standard. If they still cannot supply you with a good reason, I
> would have to say that you can decline their request.
>
> Bear in mind that these folks are your customer and this may be an
> unspoken expectation on their part. If it is something they are willing
> to pay for and you can charge them for it, it may be desirable to do.
>
> I learned long ago that if I cannot cite the standard that is the basis
> for my requirement (or finding in the case of auditing), I don't insist
> on having it my way.
>
> Regards
> Bob Collier
> Graphics Microsystems
> bcoll...@gmicolor.com
> Nobody pays me for these opinions, perhaps there is a reason...
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The comments and opinions stated herein are mine alone,
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