Type NM in EMT

[LarryFine]

So why isn't that a violation of 310.120(A)? Otherwise, I agree that the NM to conduit transition fitting, along with stripping the NM sheath, would be a change in wiring method, and so the 312.5(C) becomes moot, as a cable is no longer entering the cabinet.

So, leave the sheath on if you prefer. I'm certainly not saying that you may not have the sheaths 1/4" in.

If you don't strip the NM sheath, there's no 310.120(A) issue. But I think if the switchover clamp connector is far enough away from the cabinet, it's hard to argue that the cable is secured to the cabinet.

In my opinion, as individual conductors in a conduit and no longer in a cable, it need not be so secured.

As with almost all NM installations, the sheath is secured where it enters the cable clamp, wherever it is.

 

[roger]

Yes, and I'm suggesting that those rules do not apply to an enclosure-to-enclosure conduit, regardless of the wiring method within.

Of course the rules do not apply to a complete conduit or tubing run, that was why I said "for the discussion at hand"

Roger

 

[LarryFine]

Of course the rules do not apply to a complete conduit or tubing run, that was why I said "for the discussion at hand"

My apologies. I was addressing the claim that the 18"-to-10' sleeve rules apply to all NM installations.

 

[roger]

My apologies. I was addressing the claim that the 18"-to-10' sleeve rules apply to all NM installations.

 

[wwhitney]

On the topic of sheath length, there's also 300.12: "Mechanical Continuity — Raceways and Cables. Raceways, cable armors, and cable sheaths shall be continuous between cabinets, boxes, fittings, or other enclosures or outlets."

So even if the NM sheath doesn't have to enter the cabinet by 1/4", it does have to extend to the cabinet. The requirement includes "fittings" which covers the case of changeover fittings and stripping off the sheath, when that is allowed.

Cheers, Wayne

 

[LarryFine]

On the topic of sheath length, there's also 300.12: "Mechanical Continuity — Raceways and Cables. Raceways, cable armors, and cable sheaths shall be continuous between cabinets, boxes, fittings, or other enclosures or outlets."

So even if the NM sheath doesn't have to enter the cabinet by 1/4", it does have to extend to the cabinet. The requirement includes "fittings" which covers the case of changeover fittings and stripping off the sheath, when that is allowed.

I would argue that the "continuous" applies to the "raceway", not what's inside it, and the "cable sheath" refers to when the cable is the wiring method. If a cable is in a continuous conduit, as opposed to a sleeve, the wiring method is the conduit, not the cable.

Just my ever-so-humble opinion.

 

[wwhitney]

So, leave the sheath on if you prefer. [. . .]
In my opinion, as individual conductors in a conduit and no longer in a cable, it need not be so secured.

It sounds like you're saying that even when the sheath is intact all the way into the cabinet, we don't have to consider it a cable anymore, because it's installed in conduit? I'm having trouble with that sleight of hand, seems to me it's still a cable.

The simplest solution to me is to add an exception to 312.5(C) reading something like "where cables are installed in a complete raceway from another enclosure." That distinguishes it from the existing exception and takes care of things.

For NM, I'm somewhat open to the idea that you could strip the sheath off starting at the changeover fitting, save a sufficient length of the sheath, and slip it over the conductors inside the cabinet only, to satisfy 310.120(A), since NM conductors aren't marked.

For cable methods containing marked conductors, 310.120(A) is a non-issue, so it's easy to comply with 312.5(C) by stripping the sheath off at the changeover fitting.

Cheers, Wayne

 

[wwhitney]

If a cable is in a continuous conduit, as opposed to a sleeve, the wiring method is the conduit, not the cable.

That is plausible, can you point to any NEC language that reflects that point of view? E.g. I would buy that if instead of "cable sheaths" 300.12 said "sheaths of cable-type wiring methods."

Cheers, Wayne

 

[tom baker]

A clamp type fitting is not required at the end of the EMT, and the sheath must extend into box. Arlington makes a push in plastic bushing for the end of the EMT. Its very clear in 334.15 C

 

[wwhitney]

A clamp type fitting is not required at the end of the EMT, and the sheath must extend into box. Arlington makes a push in plastic bushing for the end of the EMT. Its very clear in 334.15 C

Yes, 334.15(C) is very clear on the case of a "device or outlet box" mounted on the "wall of an unfinished basement."

However, my question is about a panelboard cabinet, to which 334.15(C) wouldn't apply, even if the cabinet is mounted on the wall of an unfinished basement.

Cheers, Wayne

 

[tom baker]

Yes, 334.15(C) is very clear on the case of a "device or outlet box" mounted on the "wall of an unfinished basement."

However, my question is about a panelboard cabinet, to which 334.15(C) wouldn't apply, even if the cabinet is mounted on the wall of an unfinished basement.

Cheers, Wayne

My post was related to the original question. This post has diverged since then

 

[wwhitney]

My post was related to the original question. This post has diverged since then

The original question was pretty broad, it doesn't specify what's at each end of the EMT. So far I've found:

334.15(C) Yes, if on an unfinished basement wall with one end open and the other end in a device or outlet box.
314.17 Yes, if both ends are device or outlet boxes; securing to the boxes is probably not required.
300.15(C) Yes if both ends are open and the EMT is a sleeve
312.5(C) Yes, when one or both ends is a cabinet, provided the cable is secured to the cabinet somehow.

Anything I missed?

The details on how 314.17 (is it correct that the NM doesn't need securing to the outlet box?) and 312.5(C) (is it correct that the NM does need securing to the cabinet?) apply are still open to discussion.

Cheers, Wayne