The other day I was at a commercial job site where I seen residential type JB's (internal clamps designed for NM cable) being used with BX. The armoured sheath was brought into the JB and clamped. Anti-shorts were used and the end of the armour was wrapped with electrical tape. Never seen BX cable terminated in this manner. Acceptable or poor trade practice?

Not a 'normal trade practice' here as you described. There are (US) j-boxes designed and listed for AC/BX. The internal cable clamp has a 'ring' on the end for the conductors to pass thru, and retain the armour. Some say it is to retain the anti-short.

I have seen that type clamp modified for NM, the NM listed clamps used for AC/BX. And a few terminations with tape.

I would leave a red tag for what you described.

Curious...what exactly would the red tag be directed at in your jurisdiction? Would it be the use of a NM clamp on a AC type Cable?

I looked at the CEC 12-610 "Terminating armoured cable" and can't find anything that specifies that the cable can't be terminated with a clamp designed for NM cable. The only rule that mentions the use of a connector or clamp states "shall be of design as to leave the insulating bushing or it's equivalent visible for inspection".

While it looks "wrong" to me I can't seem to articulate as to why.

The tape would interfere with the ground. The armor and the small ground wire just inside it form the ground, and the box clamp is supposed to contact it and make the ground circuit connection. If the tape was under the clamp, that won't happen and the inspector would red tag it.

Normally the complaint would be that the gadget is not 'listed' for this particular duty.

In particular, AC & MC connectors specifically have geometries that stop the red hats/ anti-short bushings from falling out (e-tape wrapping is not deemed a substitute) and they also provide a visual gap such as to permit the inspector to see that the red hat has been installed.

Ok, finally found a rule that might apply and support the thought that it looks wrong (poor trade practice):

CEC 12-3022 Entrance of conductors into boxes, cabinets and fittings

(5) Where metal-sheathed conductors enter boxes, cabinets, or fittings, the box connector shall be installed in a manner that will meet the requirements of Section 10 without injury to the conductors and shall be the of a type for use with the cable.

My main concern would be the 'tape' you mentioned which may be insulating the bond of the AC armour and the box.

NEC 110.3 (b) "Failure to follow mfg instructions" (not verbatim NEC words) as the NM clamps are for NM, unless they are ID'd for AC, which some are.

Text from the 2011 NEC...
320.40 Boxes and Fittings. At all points where the armor
of AC cable terminates, a fitting shall be provided to protect wires from abrasion, unless the design of the outlet boxes or fittings is such as to afford equivalent protection, and, in addition, an insulating bushing or its equivalent protection shall be provided between the conductors and the armor. The connector or clamp by which the Type AC cable is fastened to boxes or cabinets shall be of such design that the insulating bushing or its equivalent will be visible for inspection. Where change is made from Type AC cable to other cable or raceway wiring methods, a box, fitting, or conduit body shall be installed at junction points as required in 300.15.

I based my previous comments on your description.

Concerning bonding/grounding, that thought came to mind but it appeared there was caution taken to keep the taped portion past the point where the clamp met the armour. I don't know why someone would go through the effort for such an installation. BTW, you could still see "some" of the anti-short showing through and therefore could possibly satisfy the rule regarding "visual inspection" of it's presence. Maybe.

OK, now that there are other comments that posted while I was typing and cutting and pasting and answering the phone.

Thanks to wa2ise, and Tesla for jumping in.

And Potseal for the CEC article.

To expand further on this topic here's a style of junction box that has a built-in connector:



While many of you might be familiar with this type of junction box that can be used with NM or AC type cables I myself have never used such an item.

In the article it mentions not to allow the armour "penetrating into the box". Originally I thought that would be the wording of a rule I would find in the code book. Possibly that's why I thought the installation I had described in the OP looked wrong to begin with.

Those j-boxes look very economical to buy and install...

But I'd never want to trim out such boxes.

Just too tight for my taste.

But then, I work in a concrete and steel world, wood... not so much.

I've never heard of a box being described as residential or commercial. Even cable isn't classified that way. Depending on the structure, non-metallic might be acceptable in a commercial structure or bx might be required in a residential structure.

Tape on bx is wrong. It seems to be acceptable to let the anti-short fall out but if you let the tape interfere with the bond, it's bad.

Yes, that is bad terminology on my part.

TWH...

My AHJ prohibits power wiring smaller than #12 in commercial build-outs, prohibits Romex except for habitation, prohibits the use of #16 as lumiere taps -- in the NEC style.

(ie field wiring to said lumieres.)

Etc. etc.

Also prohibited is the used of plastic j-boxes in commercial work -- unless specifically sanctioned.

In sum, my AHJ is much more restrictive than the NEC across all manner of materials and techniques that would save on expenses.

Like Chicago, California is paranoid. For them it's cows and lanterns. For us it's earthquakes.

Just to Add something to this thread I now see that BX Connectors are also rated for NM cable.

Ugh! This thread is really about what vexes me at my industrial location daily: work performed by electricians and contractors who are not familiar with industrial work.

Purchasing does not seem to understand that simply having a license is not enough! Or, for that matter, a journeyman card.

During their apprenticeship, electricians are SUPPOSED to be exposed to all the various methods. In reality, most spend most of their time with the same contractor, doing the same handful of tasks. Now, with the collapse of the housing bubble, all manner of residential and service firms are trolling for the commercial and industrial jobs. Add to that customers who have poor project management, and you have a formula for trouble.

Match the parts to the method. It's that simple. Sometimes that means you can't get away with using the absolute cheapest parts.

Our electrical inspectors are officers who enforce the adopted standards. Saying your inspector has different rules is tantamount to saying your police officers issue speeding tickets below the posted speed limit. I would have the same opinion of both of them.

Just to keep it on track, the parts in question did match the wiring method and are approved for that use.

I caught that a couple months ago. Is that new? I used to point and laugh at nmd in an L16; but, I also used to laugh at 6 x #12 in a conduit on a 20 amp breaker and now it's legit.

I think it was 3months ago i spotted the new usage. I used to point also :)now for the DIY service calls connectors over tight and shorting the cable

twh...

You're missing it: these modifications are OFFICIAL modifications.

They are not specific to any particular inspector.

The NEC is only a starting point for the California Electrical Code.

Potseal,I've seen what you describe get inspected.The tape insulates the cable from the box and also makes it hard to see the anti short.The use of the NM strap often pulls the anti short out of the cable during installation and can force the armor into the insulation when you tighten it down,something a ac strap has been designed not to do.What it came down to was that the NM strap isn't listed to be used with AC and while he didn't make me fix it he made it clear that he could.He could also probably fail it on workmanship alone.
This was a hospital and they had wired an entire floor like this consequently it been ten years and so far so good.
Furthermore most hardware stores have no clue what that bag of funny little red things are that come with a spool of armored cable and throw them out.I ran out one day and tried to pick up some anti shorts at a few well known hardware stores and and they had no clue what i was talking about so I doubt any DIY wiring jobs have them.

frank...

I can't say it's an industry trend...

But about eight-years ago I noticed that MC (250 foot coils) were delivered with dinky red hat bags. The vendor started pushing red hats as an 'a la carte' material.

I was expected to order them as a separate line item from that point onwards.

Our 1,000 foot reverse-wound MC spools were routinely shipped without red hats attached. (They wouldn't have survived if the attempt was made. These spools were rolled everywhere, too heavy to pick up.)

(For those unaware: the industry sells these spools all of the time. You have to ask for them, they may not be stocked. They are 'reverse-wound' because the BIAS of the tape is reversed from that of the common coils. As you know, coils have to be entirely laid out if you intend to pull MC into tin studs without hanging up the tape. (tape = sheilding metal cladding -- it's the NEMA industry term -- the name comes naturally if you saw how it was delivered -- and wrapped around the conductors.)

Reverse-wound MC is much easier to pull into a building. It's much easier to unspool off of a spindle/ floor rollers. It's not prone to kinking or snarling during the process. It does have angular momentum issues -- like all other wire spools it wants to 'run on.' Re-spooling over-run wire is a snap. The longer spools reduce 'end-tags' by 75%. (One spool versus four coils)

I don't work the Romex end of the market, but I assume that it's also availble in longer spools.

As for job site theft: the average Joe can swing a coil under his arm. A spool is another matter, entirely. They're not sold through the big box stores. I would love to think that one thousand foot spools would give the grab-and-go thieves out there second thoughts.

Tesla:
I'm sure you realize this is a Canadian topic.

I get my spools in 150m or 492 ft so id want two bags.If the anti shorts aren't there they had better be somewhere else in the pile of stock or the wholesaler will be finding a way to get them to me,it's a no brainier.If they don't survive shipping that's their problem not mine.I also stock anti shorts separately but i expect a bag on every spool as well.Why should we pay for them when this has been the standard for years.
Also if I'm spending tens of thousands or more a year at a wholesaler they best be getting it right 90% of the time or I simply switch them up when i get pissed off.
Every wholesaler I deal with knows i have no problem dropping them for another.I don't pick up stock they send a rep and he takes a stock list to be shipped.I also take a picture of his stock list to cover my butt and then cut the PO.He shows up every two weeks to check the basic stock bins unless I call an and tell him not to bother(which means they screwed up one to many times).
I have a boss who has no patients when the parts aren't there to start work.Time is money and if the wholesaler wants to waste it,out they go.I generally bounce between 3 wholesalers,when one starts screwing up too much I just move to the next guy and the rest have to wait until their turn comes up again.
The wholesaler I have now has been trying to ship cheap thin metal two hole 1/2" conduit straps instead of the thicker single hole type.Something that small is annoying enough when drilling even standard 5800 psi concrete that they are told replace it with the right straps,plus I don't like the looks of them when they are used.
Maybe this sounds a little mean but know one takes garbage from me.Mistakes will happen but bags of cheap tie wraps that don't hold or L16's that are missing the clamps and have enough slag left on the locking nut to slice up the electricians hands just don't cut it(excuse the pun).If they want to save money by selling me cheap time consuming parts that damage employees hands i don't need them and I guarantee I don't see any savings just comp claims.Neither will i accept substituted parts,half orders or lackadaisical pickers(shippers) at the wholesalers.Its usually not the reps fault.
I do the best work I can and try to be professional,as such I expect the same from the people I work with.
As for the hardware stores that don't know what an anti short is,they shouldn't be selling AC to DIY's.it's simply a disservice to a customer who knows no better.That's just my opinion.When i pull Ac into a drop ceiling I just jamb a 2ft toilet plunger handle across the T bar so the cable slides over it nicely and have spring clips for metal studs,just have to remember to remove them when in done for the next job.Reverse wound AC cable should be standard but.....