Cable Jacket = Raceway?

gblentzMarch 30, 2012

Could someone please offer some clarification of 725.55(A)? As it seems to read, LV and line conductors are prohibited from sharing the same raceway. But does the outer jacket of a multi-conductor cable constitute the cable's own raceway, insofar as of The Code is concerned? More to the point (and noise issues notwithstanding), can speaker wire, CAT-5, RG-6, etc., be installed in a common conduit with NM?

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Ron Natalie

Do you mean 725.51(A)? There is no 725.52.
If we're talking about running multiple conductors/cables in a conduit/raceway, the derating (or as the 2011 code calls it, ampacity adjustment) rules apply.

There are issues installing NM in conduit PERIOD. You need to explain what it is you are trying to do.

    Bookmark   March 30, 2012 at 10:48AM
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gblentz

Not 725.52--725.55. Well there WAS a 725.55, at least up through the 2005 NEC anyway... seems to have been either rescinded or moved. It basically stated that Class 2 & 3 circuits can't occupy the same raceway as Class 1. I was looking for clarification of "raceway," and whether the sheath on an NM cable would serve to fulfill the separation clause in this case. If the statute is no longer on the books it's a moot point, but I can't imagine they'd just do away with something like that. Any idea where it went?

I have a 1-1/2" conduit from our basement to the attic space through which RG-6 is presently run. I may have a need for line voltage in the attic at some point, and the conduit would greatly simplify installing a run of NM.

I'm guessing derating is one of the issues of NM in conduit to which you refer. Are there others?

Thanks.

    Bookmark   March 30, 2012 at 12:53PM
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petey_racer

That is not a conduit or raceway. It is a sleeve for protection/accessibility.
I see no problems running NM in that sleeve, in fact it's done all the time.

    Bookmark   March 30, 2012 at 1:39PM
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Ron Natalie

I mistyped. 725.55 from 2005 is now 725.136 in the 2008 and later codes.

You can't run the class 2 and 3 in the cable with the NM jacketed wire. Sorry. The insulation on it isn't up to it.

Passing through three stories is not a "sleeve" Petey.
The cable will need to be derated.
But that still doesn't change the fact that you can't mix it with other unrelated cables that have insulation that is not up to the job.

NM isn't class 1.
RG-6 cabling isn to any of the Article 725 stuff most likely anyhow, it comes under article 820.

    Bookmark   March 30, 2012 at 4:54PM
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gblentz

ronnatalie, I'm trying to understand... I'd always thought that you could mix and match coax, CAT-5/5e/6, HDMI, VGA, remote signaling cable, whatever, as long as it's less than 48v, and shove it all down a conduit together. Is this not correct?

If it is correct, then the point of my question is whether or not the sheath on an NM cable constitutes a "raceway" in the eyes of The Code. If it indeed does, why should the insulation on any other cable external to that raceway matter one way or another?

If The Code does not consider the NM sheath to be a proper raceway then, naturally, the point is moot. :-)

    Bookmark   April 2, 2012 at 8:11PM
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Ron Natalie

I didn't say you couldn't, I was pointing out that neither NM nor TV coax is covered by Art. 725.

NM is not a raceway.

NM in the conduit will need to be derated EVEN if there is no data wiring within.

    Bookmark   April 3, 2012 at 8:12AM
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brickeyee

"mix and match coax, CAT-5/5e/6, HDMI, VGA, remote signaling cable, whatever, as long as it's less than 48v, and shove it all down a conduit together."

OK except for "remote signalling cable" depending on if it falls into a recognized NEC control group (power limited, etc.)

What you cannot do is put NM or power wiring in the same conduit (or any other raceway) without some physical separation unless you can show that all the wiring has insulation up to the highest voltage in the raceway.

    Bookmark   April 3, 2012 at 10:25AM
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petey_racer

Personally I would not have any problem running NM with coax or cat5 in this "chase".
No way I'd call it a "conduit".

That's just me though.

    Bookmark   April 3, 2012 at 5:30PM
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bus_driver

To me it is clear that running individual conductors, such as THHN, in a conduit or raceway with CAT6 (and similar) would require that all have insulation rated for the highest voltage in the conduit or raceway. But nothing prohibits running the NM cable, which has an outer covering, and the CAT6 through the same bored hole in a framing member. In my mind, a sleeve consisting of PVC conduit running from basement to attic in a house for the purpose of installing cables after the house is completed is suitable for both the NM cable and the CAT6 together.

    Bookmark   April 4, 2012 at 10:09AM
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brickeyee

A stub bay (AKA a 'chase' is not a 'raceway' under the NEC.

Nor is the hole in a wood member.

A section of conduit IS a raceway, even if it is not part of a conduit system.

Derating is not required in short lengths of conduits used for physical protection by an exemption.

It is sort of left to the AHJ to decide when the 'short lengths' become excessive.

There is no exemption allowing other wiring besides power wiring in the conduit.

If you want a conduit run from basement to attic for non-power wiring put one in.
But keep the branch circuit wiring in a separate conduit.

Your individual AHJ may have an opinion on this.

Try asking them ahead of time, preferably in writing (even though they CAN change their mind at ANY time).

    Bookmark   April 4, 2012 at 10:25AM
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pharkus

My understanding was always that all of the wires/cables had to have an insulation rating at least equal to the highest voltage present.

Some cheap "alibaba" RG-6 cable I found on google has a rating of "300/500V" - running 120 next to it? Go ahead.

"West Penn Wire" claims 300V for theirs. Again, go ahead.

I wasn't able to find anything in the first page of google results LESS than 300V. Indeed, the CATV wiring out back in our server room also says 300V.

Check the cable to be sure of course...

    Bookmark   April 17, 2012 at 9:26AM
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