ECN Forum Forums Code Related Discussion NEC & other Code issues How is this legally used

http://www.aifittings.com/catalog/flex-ac-mc/zinc-combination-couplings/8675



They say it transitions (2) MC cables to 3/4" EMT but how does it work?
Are you stripping the armor off the MC cable and pulling it through the pipe? I always heard that was illegal because the conductors are not properly marked. I understand there is no danger but aren't rules, rules?

By the book, rules are rules. Sometimes, "Stevie Wonder glasses" come to play.

110.3 B instructions, listed product, etc.

I did come upon MC (HCF) that had the conductors marked as THHN/THWN, which was a rare find.

I am not sure I ever saw a cable with marked conductors but that would make this legal. It wasn't the sort of thing I would be flagging but it is a rule. One of my early mentors Joe Tedesco, could really get cranked up about this sort of thing. I always tried to temper my opinions by being able to demonstrate a hazard. In most cases that is pretty easy.

Now, there is a blast from the past. Mr. Tedesco!
Yes, Joe could get really up there with things like this.

My philosophy is 'kinder and gentler' with the stupid stuff; as long as it is safe, and not a hazard.

Heck, I just heard of a guy that red tagged a sub-panel in an unfinished basement for not being energy compliant??

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In the job I had, I had all the responsibility and no power. Most of my installers were state employees and they could just say no. I managed to keep things safe by explaining the hazard more than the rule and a few times I just fixed it myself. I carried scraps of wire and tools with me.
The worst seemed to be volunteers in the park system who claimed to be retired pros from up north and thought building to the 68 code was good enough. They got some of that wrong. I really had trouble with sub panels in second buildings. I couldn't convince them they needed a 4 wire feeder. In one case I did get someone else involved to resolve it but they never called me back to inspect the replacement. As far as I know that permit has been open since 2002. I never signed off on it. I rationalized that since they had observed the pre 96 code it wasn't that dangerous.
The best work was in the prison system and the DOT. Some of those convicts were wizards with an EMT bender. One guy bent "2000" in a single stick of 1/2" and it had 3 conductors in it when I saw it. Nobody else had looked up. The guy running the job made them take it out and out in a straight piece but I wasn't going to tag it. I thought it was funny. I bet that is in his office. (Hendry correctional). The guy running projects at Desoto was a real pro. His jobs were always perfect. That was where I saw the prettiest pipe work.

Only today did I realize what bothered me about this fitting. Somewhere, in a long forgotten corner of my mind, an ancient memory stirred. I realized I had encountered it. Today that memory came out of hibernation. A look at the Arlington link confirmed what I suspected.

The fittings I had encountered were similar, designed to attach to a box using a 1/2” knockout. I saw them long ago, deep within the recesses of UL’s labs. I saw them used on manufactured equipment submitted for testing. That is, the components were used in the manufacture of listed equipment — not by electricians in the field.

Look closer at the product description. They’re for use with 3/8” MC. When have you ever bought “3/8” anything? No, these are used for cables containing small gauge control wires. The sort of wires used for thermocouples, thermostats, limit switches, and the like. As such, the complete jacketed cable is pulled intact into the conduit.

True, I can recall a few times I’ve used salvaged 3/8 jackets to run ordinary wires into equipment using similar fittings. Usuall this was when I needed a cable run considerably farther than the factory supplied leads. That placed the burden of wire identification on me. I used a similar trick to provide additional protection (vermin risk) to the thermostat cable I ran along with the line set for the air conditioning.

When they refer to "Trade Size 3/8" cable" they seem to be talking about 12/2 or 14/2 MC or AC cable based on other ads I see in EC&M magazine. That is significantly smaller than 1/2" Greenfield and probably 3/8" ID.
The ad for the fitting in question says it is used with a "surface mounted box or switch" that gets connected to a whip above a suspended ceiling. It doesn't sound like a 725 wiring method to me.