ECN Forum Forums General Topics of the Trade General Discussion Area Sleeve over MC cable

So if we're going to pick this to death, threaded half or even full couplings are not designed, manufactured or tested for joining connectors. Their purpose is solely for joining threaded conduits with tapered threads.

Yes we all do it and it will be done till the end of time, but that does not make it correct. That is why a fitting is made and more importantly tested to connect emt and rigid to flex and cable. In a similar way, threaded condulets are tapered to match threaded conduits, not emt or flex connectors which have no taper. But we still use them incorrectly all the time and will forever.

My point is that sometimes we do things in our trade which are not correct to the letter of the code or the UL listing, but so what? It is a big improvement over most of the worlds electrical wiring. How about European motor starters and circuit breakers that are over-rated and do not compare to Nema rated equipment. I could go on and on, but we are already bored! The sleeve provides more protection than no sleeve. The more complicated the code gets, the less likely that any of us know it all or comply.

What is the physical damage this MC may be exposed to?
I'ld be more worried about the water heater getting damaged in this environment.

Seems to be a whole lot about nothing here.

I’m not sure anyone is knit picking things here, especially NPT and NPSM or rigid fittings and their listed applications etc...

I will say though, that IMO, the installation the OP described is in compliance with the ’08 NEC as it is written in black and white.
The EC has met the requirements of the NEC regardless as to whether the inspector likes it on not... it is what I call, for lack of a better expression, a “shut up and sign” situation.

KJay, I agree, it was not long ago that a local inspector started requesting UL listed RX staples , as far as I know non were found.I think it just kinda went away.

Ob

OB:
Good point on dissimilar metals with al jacket MC and steel EMT.

Your method is an acceptable installation.

Dissimilar metals are always a concern. Key thing to remember is electrolysis needs a third component since there is no current present (at least there better not be) and that is an electrolyte. Without it you just have two types of metals doing its thing.

Different metals touching?

Let's get real. That same aluminum jacketed MC is routinely supported with galvanized steel clips, then connected to steel boxes with zinc connectors. Now we're worried about it touching a galvanised steel tube?

Other than the fact of MC/AC or RX Greg is right. We have had this discussion before. My thoughts then and now were, if the piece of conduit is less than 10' it could be used for protection from damage, once you start to go over the 10' mark, you might just as well run the conduit and be done with it.
If you were worried and dissimilar metals and if the metal conduit will become energized, then why don't you use PVC. It would protect the cable and not worry about the rest.

The longest "sleeves" I see are the ones that used to be mandated for RX running down outside block walls behind the sheetrock. Back in the olden days in Florida, they said the 1.25" was measured front to back from the drywall. Now they let it be horizontally from the furring strip and allow that to be a stacker. It was a bad decision in my opinion.
That only protects the cable from the sheetrock guy who knows where the wood is supposed to be. The homeowner, "probing" for the stud with a nail, is as likely to hit the wire as he is the stud.

The sleeves they put in were usually terminated with a EMT connector in the box and stapled where the RX came out so they were bonded. Occasionally, in newer work they had the EMT to RX connectors on top but usually the end was polished or they had a bushing on it.
I have seen them just dead end at the RX connector at the box and thus they weren't bonded. I thought that was sloppy work.

Just to join the chorus, I can think of two areas where one might routinely place a cable inside EMY for protection.

The first is the typical basement with exposed wiring. You're supposed to 'protect' the wires to a height of 6-1/2 ft, so cables run down to devices will often enter a pipe as they exit the ceiling level.

The second situation is where a cable passes through a 'classified' location. Often, the cable will be passed through a pipe, making the cable "outside" the classified location.