ECN Forum Forums Code Related Discussion NEC & other Code issues "Forbidden" Fittings?

Reno:
Text in the link also states...see 300.11

300.11 (A) states near the end of the text "Cables and raceways shall not be supported by ceiling grids."

IMHO, that Caddy item is useless as far as code compliance.

The PATA conduit reference points to such usage in South America.

Everything about them points to retrofit work.

ERICO used to have an entire suite of cheesy clips oriented towards running EMT immediately above a T grid -- junction boxes included.

They never made economic sense during a TI.

But I can certainly see them being used by service electricians for this or that....

As for myself, if I had to pull circuits during a service call -- above a soft lid -- I'd go with MC virtually every time.

I can't say as I've ever run across one -- installed or otherwise!

The Bridgeport brochure seems to indicate that the MC change-over fitting is UL listed, so if wire marking is the actual problem, then wouldn't that mean that technically you couldn't strip and terminate things like MC, NM or SE cables in a device box, ceiling box, panel board, service equipment, appliance or light fixture, etc., since the individual unbroken conductors are not marked with their UL/ETL listing, voltage rating or insulation type. I'm just wondering if there is some type of maximum NEC length limitation for listed cable assemblies that have the outer jacket removed for splicing and termination.

This is pretty much an unenforceable rule. Certainly you could say the 6-8" of wire exposed in the box is statistically likely to contain the once every 2' writing but it is not a certainty. I also have not seen anything embossed on the jacket on most of the MC I see. Maybe it is just my old tired eyes, I have a hard time reading glass fuses too.

I think we all ignore those device to device jumpers that are made up from scraps of wire from cables.

Certainly it is a rule and if I see something that looks like "automotive" wire I would get a bit more curious but if it looks like THHN and it is the right size, I would give them the benefit of the doubt and assume it is THHN. I guess you could chew on the insulation a little and see if it tastes like THHN.

IIRC Jay, such standards are NEMA standards....

And since the industry is using the same - or nearly the same --wire drawing machines it's not an issue of economics to have the product information rolled onto the outer cover.

This is also how the NEMA crowd brands their wire.

As you might imagine, not one of the NEMA players wants knock-off THHN entering the American market.

At some point, legal jargon has to stop and common sense an common practice have to 'step up.'

The point has been made at this forum several time that you may only use listed / Chapter3 wires in a raceway. Does anyone recall the code reference that was cited?

A box is a box, and not a 'raceway,' thus the issue does not arise for pigtails in boxes.

There's also a 'listing and labelling' issue. UL requires conductors (wires) to be marked every so often with certain information, including the NEC abbreviation for the type of insulation.

MC is listed as a 'cable,' and is evaluated as a whole. While UL allows a variety of standard insulation types to be used within the MC, the only marking required is that on the outer jacket of the MC. There's no requirement to mark the individual conductors.

While, as far as I know, all MC is made using ordinary building wire (such as THHN), it's not required that the insulation be identical in form and thickness to building wire. One can speculate that unlike 'ordinary' wire, thinner, or alternative, insulation being present. After all, the individual wires will never be exposed to sunlight or pulled through pipes.

Without the marking we don't KNOW the wire meets Chapter 3 requirements ... so we're technically not allowed to run it through a raceway.

The same issue applies to NM.

That's why I question how the fittings can be used in a code-compliant manner.

Make sense or not, I've encountered entire office buildings that were wired using t-grid clips, mounting pipe and boxes directly to the grid. It's actually a pretty decent way to power the lights. That's why I was surprised to see the NEC outlaw them.

Californian earthquakes convinced most that the grid fails pretty catastrophically.

It's at that point that the grid-supported schemes revealed themselves to be sources of ignition.

To top it all off, the manufacturers of the grid, itself, wanted no part of the liability that would come from sanctioning such a scheme. (Johns Manville, IIRC.)

So when the question was put to them they rejected the whole idea.

Imagine what the politics must have been. JM (and others) all denying that their product was ever engineered to tolerate such a burden. ("...And thanks for finally asking us about it.")

310.11

If you left the marker tape in the MC with the bundle of wires
it could be said they were identified but it still would not satisfy 310.11(B)(1)

One problem I see with applying 310.120 "Marking" as a standalone article is that it states "All Conductors and Cables". Cable assemblies are made up of conductors, so the way it reads you would also have to include equipment conductors, since there is no exception or reference back to other articles that allow for equipment grounding conductors to be bare, covered or insulated. AFAIK, only insulated conductors are marked, so technically bare and covered equipment grounding conductors wouldn't be allowed to be used anywhere, not even in raceways or cable assemblies, but I've never heard of any inspector applying the article that way.