using conductors from NM in conduit

Status
Not open for further replies.
infinity said:
Why don't they just use "regular" conductors in the cable with the markings on them? :slaphead:

I see MC cable that has individually marked conductors.
Click to expand...

1. Because it costs more, and the NM market is quite price competitive?
2. MC costs a lot more per foot than NM, and it can better accommodate the higher component wire cost?
 
GoldDigger said:
1. Because it costs more, and the NM market is quite price competitive?
2. MC costs a lot more per foot than NM, and it can better accommodate the higher component wire cost?
Click to expand...

I'm wondering how much more could it cost to use a marked conductor in a NM cable? The fact is that the conductors in NM are stripped out every day and used in raceways.

I would guess that many the conductors feeding AC units all over the place are left over scraps from the cable used to feed the disco from the interior. I run 100' of NM cable to the disconnect but then need to buy 3-500' spools of marked conductors to go the last 3' into the unit? ;)
 
Yeah, I am kinda favoring a load of the simpull wire for my next trip to jamaica- think that is 2500 feet for 12 guage... lol... radio shack used to sell 25 foot batches of 12 gauge back when I got ham gear from them- i used it for antenna wire a lot, stranded...
 
infinity said:
... The fact is that the conductors in NM are stripped out every day and used in raceways. ...

...
Click to expand...

But if in quantity, it's not for any good reason.

The only good reason I can think of for wanting to do this in the first place is to pull a short distance from where you transition from a standard NM wiring method, without having to splice in a j-box. We face this in solar with some frequency, e.g. NM run to the attic for micro-inverters and then we want to pull it through the roof and a few feet on top of the roof to get to a j-box on the solar array. But you don't want to have to splice twice, or splice in a tight attic, so you strip the last 5 feet to pull through your conduit on the roof. Many other inside/outside type transitions might be similar.

But it's just not worth avoiding the splicing if your raceway is 50ft long. So if that's what we're talking about, it's being done for a bad reason, which probably boils down to not having bought or brought the right material to begin with.
 
ActionDave said:
Well of course. Infinity is not talking about stripping out a dozens of feet of romex, he's talking about what almost all of have done, stripping out one to ten of fifteen feet or so and stuffing it into some conduit.
Click to expand...

jumper said:
But some of us do not admit to it...yeah,yeah I’ve done it...:D
Click to expand...

Yup that's it. We've all done it and most of us won't lose any sleep over it either. :)
 
As to it being "THHN", that might be true ONLY if it is NM-B. THHN = Thermoplastic (i.e. PVC) High Heat Nylon jacketed. I have NEVER once seen a nylon jacket on the individual conductors used inside of standard NM. NM-B does have it, so it's probable that the wire mfrs are just using THHN when they make up NM-B, but because they DON'T need the "high heat" since the cable is only rated for 60C anyway, they don't bother printing that on the insulation because it might lead to confusion.

So that's really the problem. The wires inside of NM-B do have the same insulation you find on THHN, but with no markings here is no NEC designation for that type of wire, so it cannot be (legally) used. The wire inside of plain NM is even worse in that it does not even have the same insulation as THHN...
 
Craigv said:
I mentioned earlier that a 15ft roll off 14/2 at the big box is about 9 bucks, or 60 cents a foot....
Click to expand...
It seems bizarre to me that a product whose price should be so driven by a commodity (copper) has such a non-linear per-unit price. I guess what it is is the DIY'er subsidizing the pro.

I've also noticed that 100ft of 14/2 NM-B is about $30, where as 100ft of THHN is about $20 (so $60 for ground/neutral/hot). Even MC/BX/AC is cheaper than the THHN.
 
Last edited:
Why do we continually have this discussion? Why doesn’t the NEC just compel the wire manufacturers to imprint the wire ratings on the wires before the jacket goes on?

$$$ I guess. :roll:
 
goldstar said:
Why do we continually have this discussion? Why doesn’t the NEC just compel the wire manufacturers to imprint the wire ratings on the wires before the jacket goes on?

$$$ I guess. :roll:
Click to expand...

I would love it if we could just have more standardization with wire types. We have these other issues with conductor properties like sun-res, CT use, USE thats not also RHH-2 that some have and some dont. I dont even know if we really need both XHHW and THHN anymore........everything has everything! Ill gladly pay an extra penny a foot, the manufacturers can make a penny less per foot, which they will make up by less production runs and inventory.
 
I guess I'm an Odd Ball. I never really had an issue with changing over to a different conductor on the load side of an AC disconnect or the like.

Actually, I'm all for it.

I've never been a fan of bare EGC's and solid wire in flex anyway.

JAP>
 
Status
Not open for further replies.
Top