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
[email protected]
