electrical cable next to heating ducts

I am trying to run a new electrical line but have a tight space where there is a heating duct. That brings the cable close and potentially touching the house heating duct. I saw a reference to cables in such a situation requiring insulation or 1" air space.
What kind of insulaiton would you use. Household fibreglass? or is there some special requirements.
Thanks Chris
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This is Turtle.
I would try Wire hangers and a 1" air space. Anything less than 1" of air space is less that what should be done. So you may try running the wire in flex condiut till it passes the duct pipe and then pull the conduit away from the duct with hangers as much as you can or get the 1" air space.
TURTLE
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Don't think I have 1" of space, so would flex conduit work even if it was close to the heating ducts Thanks Chris

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Thanks for the insight. Is the conduit fairly flexible as I also have a tight bend to deal with Chris

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Where does this silly idea come from? The 2005 code has specifically addressed this saying it is OK to put cables in raceways. In fact stripping the jacket off voids the listing. As for the "fishing" question, look into"MC" cable. This is an assembled cable in a spiral flex aluminum jacket.
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On Mon, 07 Mar 2005 01:17:15 -0500, snipped-for-privacy@aol.com wrote:

Don't know! Our state hasn't adopted 2005 NEC yet, the 2002 is still the governing version. This will change in a few months.
But.... I've heard this so many times, to not put NM in conduit. When right in ART 334 says you need to do it, when tranversing floors and tells you to do it where physical protection is needed. Even a note in Chapter 9 explains how to calculate size when using an multiconnductor cable for conduit sizing.
To reiterate, I hear from any seasoned electricians, no cables in conduit. The stick to their stories even after looking at the book, but then, I guess they have to do what the boss says.
later,
tom @ www.MedicalJobList.com

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Code cite, please? Unless that's a change in the 2002 Code, I believe you're mistaken.
-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
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On Mon, 07 Mar 2005 11:28:43 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Couldn't find it in 2002 NEC.
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The only time you should be stripping the jacket off romex is when you've decided to use it for sculpture.
Can't you just use THHN cable? I'd be mildly surprised if the heating duct operated in excess of 160F.
--Goedjn
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wrote:

See other post for my clarification, it maybe allowed by code. Someone posted it about protecting the cable. I always error on the safe or over do it side of the fence.
Joseph

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I think I mis-spoke here as to stripping the romex, not a good idea. I meant that to go from romex to conduit you would have to go with individual conductors. I have to be more careful in posting here, and to be clear in the info given. I am an HVAC tech not electrician.
Joseph

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On 7 Mar 2005 18:44:42 GMT, snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

If the wiring method is conduit, single conductor is the cheaper way to go, so common sense kicks in here, right?

Help me here, where is it that it's not permissiable to use sheath nm in conduit where physical protection(you call "spot mechanical protection")? Book is big, and I'm learning everyday.

Nipples need to worry about conduit fill, just that you goto 60% column, instead of the others. I think the tiny-tiny piece for floor transistions is ignored, but once again, I have to check the notes in chaper 9.

You are mentioning Canada a lot, so maybe we are in different books.
:\
later,
tom @ www.BookmarkAdmin.com
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It boils down to something like this:
- you have to consider "conduit fill" (possible overheat issues) and potentially conductor derating. - when the wiring system _needs_ to be in conduit (ie: Chicago codes, or hazardous location rules), you must use unsheathed cable. You can't get away with stripping the sheath off and running individual conductors. It's no longer a "permitted" use of the wire... - when you're using it for "spot mechanical protection" of a system that's otherwise permissible as NM, inspectors will give you a certain amount of leeway. This is partially codified (IIRC a 1-2' limit on "sleeves" without having to worry about conduit fill), and partially "inspector permitted". - whatever you do, they'll be concerned that it's done without damaging the cable (eg: cable pulling grease if necessary)
For example, I've had inspectors approve 3-6' "drops" of NM sheathed cable in PVC electrical conduit [*]. Mostly 14/2 (wg for the Americans ;-) in 1/2" PVC, but also several of 14/3 and even one of 10/3 also in 1/2" PVC.
[Note that in no case is there more than 3 current carrying conductors in the PVC - the sheath wouldn't let you...]
In Canada, we also have a provision by which we can bury NMW (aka UF, looks just like ordinary NM, only heavier) in PVC black irrigation tubing (as long as it's the CSA-approved grade), to reduce burial depth requirements by 6".
In both cases, while the length of conduit is longer than the 1-2', the inspector knows that a free-air conduit on a wall is going to be okay heat-wise, and buried system will generally not have trouble with heating either.
[*] wired garage NM on ceiling, since walls already finished, the shop outlets and switches are on PVC conduit "drops" on the inside wall face to provide mechanical protection agains the wall.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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That is the reason we certify and license inspectors in Florida now. Too many guys were making up rules as they went along
BTW what is the derating factor for 3 THHN conductors in a pipe? What is it if these 3 conductors are in NM-b cable in the same pipe?
Hint: they are the same
ZERO derating ... in both cases
In fact, if you had FOUR 2 wire+g NM-b cables in a pipe (normal room temperature) it could still be used at it's full rating.
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