NEC Code Question - Flexible Metal Conduit

I know, not the "right" group - but please help if you can! :)

I really thought I had seen it all... I've discovered we have a installation crew that is using BX "Greenfield" ( flexible metal conduit) as a protective sleeve around everything from 120/2

08 VAC devices on a branch circuit, to coax, and even fiber optic.

BUT - not "box-to-box" with fittings like a normal person would do.

Instead, they cut the BX Flex and then there's a sharp edge. So, they take multiple wraps of electrical tape to "build-up" the power cord diameter so the cord doesn't get cut or damaged.

In other words, picture an appliance that is "cord and plug" connected. (i .e., It is not hardwired into a box - it has a cord and plug.) Now, "prote ct" this cord with BX Flex (FMC) but don't put fittings on either end. Ins tead, use a boatload of electrical tape and other crap to try to protect th e cord from the sharp edge of the BX. (Normally, the BX would go into a sp ecial fitting, and then attach to a box. The fitting prevents the BX from coming into contact with the conductor / jacket.)

QUESTION: Exactly how does this violate NEC? I'm sure this approach is total bullshit (and not even remotely safe!), but I can't find the silver bullet clause where I can go to the person respons ible for this horseshit and get it to stop.

If I can't find the NEC clause that prohibits this, I'm just going to try t o kill it under 400.8(1) that flexible cord is no substitute for permanent wiring and just ignore the armor part altogether - which is really the only reason they are using the Flex in the first place.

Still -- this practice is so idiotic, it has to be explicitly prohibited. Right?

Thanks in advance, as always.

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If you can run Romex you can have flexible metal shielding all you want, OV ER THE ROMEX. It still has to be clamped at each end, is it ? A dweeb that would do that probably didn't and it probably isn't Romex. You can't just h ang single insulated wire anywhere. Even if it was legal it is shit work. I would not have let the guy leave. i certainly wouldn't have paid him, neve r pay labor up front. If you do you might need a gun to get satisfaction. E xplain that to the next contractor you meet who wants a bunch of money upfr ont. If he says he has to pay his guys tell him it is his job to make payro ll, not yours. That is why he is the boss and makes more money.

And you can't bundle class one and class two wiring, i.e. if there are any electrical supply wires in there that means no phone, intercom, cable TV or anything else. However fiber optic are not conductive so that is actually OK, though I wonder why someone would do it. And if the fiber optic cable h as a conductive sheath it is a nono.

So, where did you find this top notch work ? If you bought the place you sh ould have gotten money off for this masterpiece.

Pictures would be cool if you have hosting.

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(flexible metal conduit) as a protective sleeve around everything from 120 /208 VAC devices on a branch circuit, to coax, and even fiber optic. "

Sorry, in my amusement I forgot about that part. It is time to fire them. ( or make them do it right but don't hold your breath) I would. Don't put you r name on this, if you are just an employee then make the suits aware of it and if they don't correct it keep your resume' or CV up to date. They coul d get bit in the ass.

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would be a better place to answer this.. but you will need to ignore the flood of OT politics over there. mark

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NEC Article 348 covers flexible metal conduit used for power distribution, and 348.28 TRIMMING - All cut ends shall be trimmed or otherwise finished to remove rough edges, except where fittings that thread into the convolutions are used.

Article 348.56 Splices and Taps refers to Article 300.15 Boxes, Conduit Bodies or Fittings - Where Required. This sections required fittings specifically designed for the conduit system being used to be installed at each conductor splice point, outlet point, switch point, termination point or pull point, with some specific exceptions including:

(C) Protection - A box or conduit body shall not be required where cables enter or exit from conduit or tubing that is used to provide cable support or protection against physical damage. A fitting shall be provided on the end(s) of the conduit or tubing to protect the cable from abrasion.

Often overlooked are the basic requirements in Article 110 including

110.2 conductors and equipment acceptable only if approved (by authority having jurisdiction, not by NEC!) and 110.3 (B) Installation and Use - listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling. Your BX is listed and you can get the installation instructions from the manufacturer.

When dealing with shoddy work like this it is sometimes necessary to have the job inspected by a licensed electrical underwriter for leverage with the contractor and/or inspector, or possibly the appropriate court.

Reply to
glen walpert

Is trhe BX grounded? Sounds like "no". I think that makes it illegal right there.


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Jon Elson

If for no other reason that the parts aren't being used as intended (listed) to be used, the installation doesn't meet code.

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?"Is trhe BX grounded? Sounds like "no". I think that makes it illegal right there. "

Not necessarily. It is called greenfield because a green wire is required for grounding because the shield itself can't provide adequate grounding due to its construction.

Pretty sure it still has to go into work boxes with clamps etc. :-0 Also the inside needs to be trimmed no matter what so it doesn't cut the insulation on the wires, tape does not cut it.

And if there is a phone, cableTV, intercom or low voltage wire in there with electrical power from the mains it is totally not code.

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On Tuesday, March 27, 2018 at 11:54:31 AM UTC-4, glen walpert wrote: ... and 110.3 (B) Installation and Use -

Thanks Glen. !!

110.3(B) might do it.

This is one our own in-house installation teams, not an external contractor we've hired. Our own guys are screwing up (they should know better), but the folks involved are not under my direct control -- else this horseshit w ould never happen in the first place! I want my ducks in a row before I he ad over there....

Even it if (somehow) meets NEC, I'm going to put a stop to the practice any way.

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for grounding because the shield itself can't provide adequate grounding d ue to its construction.

the inside needs to be trimmed no matter what so it doesn't cut the insulat ion on the wires, tape does not cut it.

ith electrical power from the mains it is totally not code.

I thought it was called Greenfield because that's the guy who invented it? But I like the green ground wire angle too. :) BTW, I learned it as BX or Flex. Not Greenfield. Might be a locale thing?

To my knowledge, there have been no instances where CAT-II circuits have be en mixed in with low-voltage stuff -- but then, I never would have believed people would use BX without connectors for protecting conductors, when the BX itself causes the very same problem for which protection is sought!

But -- people are stupid.

When used strictly for armor purposes, 250.86 may exempt the FMC from havin g to be grounded. (?) Not that it matters for my purposes here. Just an i nteresting observation. ?

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The MOST highly skilled electricians in the area, like the ones who wire nuclear power plants etc. and are in local 38 refer to it as that. That is the reason they gave me. If the inventor's name is the same (at least they consider) it is coincidence.

Conceivably could be wrong which would make an in-trade thing. Like calling those loaded AC voltmeters they use "Wiggies", which is actually one brand name.

So that's where I got it.

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Genericized brand names are all over the place. At the first place I worked, it wasn't "flexible solvent-resistant conduit", it was "sealtite".

Genericization is technically illegal, but people keep doing it. :-/


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Reply to
Tim Williams

Perhaps but if they only do it among themselves...

Like at one shop we called heatsink compound "bird shit". Of cou5se we did not call the supplier and order bird shit.

We got it in a tube that went into a caulking gun. I liked it because it ma de it easy to apply correctly. You don't want to spread it out, you put a d ab or a bead at the pressure point(s) and when you tighten down the part it squeezes the excess out. That way you avoid air pockets.

But if you try to order bird shit they will think you are trying to get "do uble naught spy stuff". A drink for who knows that reference...

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