Rick, It took a while to find, but page 19 of CSA Technote TN-017 dated Jan. 13, 1993, covers the construction which you describe. I suspect that CSA C22.2 No. 0.4 also covers the construction, but I don't have a copy of that standard (I shouldn't admit to that should I !!! ).
The Technote states: "If the metal surface is painted, it shall be scraped to remove paint at point of connection (masking is recommended while paint is applied.). In lieu of scraping, a star-toothed washer (not a split type lockwasher) may be used between the lug (or eyelet) and the metal to pierce the paint of equipment used on circuits fused at 15 A max. .... etc....." So your construction should be acceptable if it is connected to a 15 A or less branch circuit. If rated higher than that, you could resort to the test described on the referenced page 19 for circuits rated 20 A and greater. I think that you could even run the test on the complete assembly rather than test each bond individually. I've FAXed you a copy of that page, but I recommend that you get a copy of the entire Technote and also C22.2 No. 0.4 from CSA. Gabriel Roy (21) Personal opinions expressed only, not corporate (thank heaven). ---- 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
