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Is chase nipple (+ bonding bush) proper way to mate RMC w/ sub-pa

Posted by fixizin (My Page) on
Sun, Feb 6, 11 at 23:32

It seems that die-cast wet-location j-boxes have deep threaded channels--at least on the top and bottom--with nicely rounded entries, such that no bushing is required, just thread, say a 6" RIGID nipple, right into it, apply silicone sealant, done on that end...

But when bringing the other end of that RMC nipple into the knockout of a sheet-metal box, I'm guessing a simple pair of locknuts (inside/outside) is not adequate, as wires would be exposed to edges of nipple/conduit. I'm thinking put a chase nipple inside box, then (female) coupler to mate with the 6" nipple, yes/no/that's the only way/are you crazy? ;')

Also, are one or more BONDING bushings involved, to maintain GND? Wanna get it right-eous.

Thanks in advance, best practices always.

Follow-Up Postings:

OK, fog is clearing...

Today I looked into a similar setup w/ IMC coming in, and it did have 2 lock nuts--inside & outside--but then there was a red plastic bushing over the very end, to protect the insulation on the conductors.

Not sure if that's code-compliant, but it seems reasonable and adequate as far as providing a flared/beveled/soft transition zone for wires to enter conduit.

Only remaining question is, do the two locknuts constitute adequate GND bonding? Seems to do the job on EMT connectors.

RE: Is chase nipple (+ bonding bush) proper way to mate RMC w/ su

Don't everyone pipe up at once... you'll cause a "Denial-Of-Service" clog on my converted telegraph wire internet service, lol...

RE: Is chase nipple (+ bonding bush) proper way to mate RMC w/ su

I don't know your local code on this, but here it is a question of wire size for bushing requirements, having said that, you can never go wrong putting on a plastic (or metal)bushing to protect the wire. A pair of nuts(inside/outside) PROPERLY tightened is adequate ground.


Thanks, I've got the plastic bushing, and locknuts, and spanner thingy, and will go with that. (Not sure how I would tighten the chase nipple anyway, w/ box against wall, etc... UNnecessary complication.)

I'm just running two AWG12 THWN through a 1/2" nominal dia. RIGID nipple, to a single-gang wet-loc box w/ 20A GFCI--VERY short run... NOT in a seismic zone, lol.

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