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Posted By: CTwireman New Romex cable - 05/15/02 03:47 PM
Check out www.southwire.com

Does anyone else think this cable should have been invented a long time ago?
Posted By: sparky Re: New Romex cable - 05/15/02 11:34 PM
Quote
"Historically, contractors have used three conductor cables and a shared neutral for two bedroom circuits to reduce the labor costs over installing two cables," explained Dave Mercier, technical director for Southwire’s Electrical Division. "However, with the newly required AFCI breakers for bedrooms, many builders must now use separate neutrals when two circuits are needed. Southwire’s new 2/2/conductor cable with two neutrals solves this problem for the contractor while continuing to offer labor savings and convenience," he added.

would'nt 2P AFCI's be simpler, as well as easy on the box vol, 3 vs. 4 wires...
Posted By: sparky66wv Re: New Romex cable - 05/16/02 12:10 AM
Is white with a red stripe legal for a neutral?

I do like the new colored jackets; nice design decision.

On a side note: Is copper really cheap for everyone right now? I've been getting Rx 12-2-G for $0.08 per foot, which is a really good price for around here.
Posted By: rkukl Re: New Romex cable - 05/16/02 12:16 AM
Great idea leave it to the manufactures to find a way to capitalize on a change we’ve all been moaning over.
Hope my supply house gets some real soon!!!
Posted By: Rabbit Re: New Romex cable - 05/16/02 12:54 AM
I'm not a residential man but why not just pull two 12/2 w/g's. Just seems like something else to have to buy.
Posted By: Electric Eagle Re: New Romex cable - 05/16/02 02:46 AM
I've never liked using 3 wire to vrun 2 circuits because you have to use a common trip breaker and later someone thinks its a 220(240) circuit. So if the wire isn't more than 2 times as expensive, I could see using this alot to run home runs in lots of areas. Just think you can run one wire for 2 kitchen small appliance circuits or as Southwire says, 2 bedrooms.

I also like Southwires new color coding, we now can keep our 14 and 12 separate. If they would only make more colors like cat5 has to keep circuits color coded.
Posted By: resqcapt19 Re: New Romex cable - 05/16/02 03:28 AM
Sparky,
Quote
Is white with a red stripe legal for a neutral?
That is a good question. It appears to me that the stripe is only permitted for a "second system" grounded conductor. Is a grounded conductor for a second circuit a "second system"?
Quote
D) Grounded Conductors of Different Systems. Where conductors of different systems are installed in the same raceway, cable, box, auxiliary gutter, or other type of enclosure, one system grounded conductor, if required, shall have an outer covering conforming to 200.6(A) or 200.6(B). Each other system grounded conductor shall have an outer covering of white with a readily distinguishable, different colored stripe other than green running along the insulation, or shall have other and different means of identification as allowed by 200.6(A) or (B) that will distinguish each system grounded conductor.
Don(resqcapt19)
Posted By: caselec Re: New Romex cable - 05/16/02 05:08 AM
Electric Eagle, you are not required to use a common trip breaker when using three conductor cable for multi-wire circuits.
Posted By: Redsy Re: New Romex cable - 05/16/02 11:05 AM
I like the colored NM cables.
Don,
I know you know this. Different systems refer to different characteristics or sources.
caselec,
If the multi-wire circuit terminates on a single strap in a residential application, a double pole breaker is required.
Posted By: resqcapt19 Re: New Romex cable - 05/16/02 12:22 PM
Redsy,
So then the use of this cable is a violation of 200.6.
Don(resqcapt19)
Posted By: Redsy Re: New Romex cable - 05/16/02 01:12 PM
I believe that literally speaking, it violates 200.6(A). The "colored tracer threads in the braid" statement doesn't apply here.
200.6(D) seems explicit in it's intent.

That being said, I think this stuff will probably be approved in many residential applications.
Posted By: CTwireman Re: New Romex cable - 05/16/02 01:36 PM
'66-

Wire is quite cheap right now, and it has been for the past few years. $.08 a foot sounds similar to prices around here (new england). Enjoy these prices while they last!


Code issues aside, this new cable is also great for electricians who don't like using multiwire circuits.
Posted By: resqcapt19 Re: New Romex cable - 05/16/02 02:32 PM
Redsy,
I agree that it has a good use and will most likely be accepted by the AHJ, but it is a code violation. Maybe we'll see proposals from Southwire for a 2005 change.
Don(resqcapt19)
Posted By: sparky66wv Re: New Romex cable - 05/19/02 02:49 PM
What about ampacity derating for cables with more than 3 current carrying conductors?

Assuming 20 Amp required for each kitchen circuit, seems it would have to be #10 to be Kosher...
Posted By: motor-T Re: New Romex cable - 05/19/02 03:50 PM
'66
Thats a good question, if the neutrals are considered current carrying conductors then we would have to derate 80 %, Right ?
But for derating purposes can we not use the table 310.16 which gives No.12 at 25 amps and the 80 % would be 20 amps???


-Mark-
Posted By: caselec Re: New Romex cable - 05/19/02 05:37 PM
Actually 334.80 says you can use the 90C column for derating purposes. #12 = 30 amps X 80% = 24 amps, well over the 20 amps permitted.
Posted By: sparky66wv Re: New Romex cable - 05/19/02 07:11 PM
Ampacity derating is something I don't quite fully comprehend...

It is so ignored here, that and conduit and box fill...

The more I learn, the more I realize what I don't know...

And there's unlicenced people out here "doing folks a favor" and they think they know enough.

Go figure...

[Linked Image]
Posted By: Fred Re: New Romex cable - 05/19/02 07:47 PM
The 4 conductor NM will also be handy for wiring those bath heat-vent-light units.
Posted By: sparky Re: New Romex cable - 05/19/02 09:29 PM
Fred,
you may be onto something there....
Posted By: Bjarney Re: New Romex cable - 05/19/02 10:18 PM
On the 4-wire romex, don't forget the soon-to-be onslaught of Euro-crazed demands for residential 3-phase receptacles and appliances! NEMA anticipated this long ago with L21-20 and L21-30 wiring devices. Be sure and stock up on ‘em on your next trip to the supply house.
Posted By: Electricmanscott Re: New Romex cable - 05/19/02 11:18 PM
Seems like an excellent idea. Neutrals are considered current carying? I have been using 12/4 for years for bath heat/vent/lights/nightlights. It has a red, black, blue, white, and ground. I guess you could mark one of the colors white and have the same product. I will use it when it becomes available.
Posted By: Redsy Re: New Romex cable - 05/20/02 11:35 AM
See 310.15 (B) (4) regarding the neutral as a current carrying conductor. Except when carrying only the imbalance from the other conductors, the neutral is a current carrying conductor and must be accounted for.

As far as derating ampacity goes..
110.14(C)(1)stipulates which column to use for ampacities based on conductor size & equipment temp. ratings.
But for derating purposes, look under the appropriate column (310.16) to find the initial ampacity for your conductor type. Then derate.
Example: If you had a 3, 50 amp, 3 phase loads and used #6 THHN in a single raceway. (total 9 #6 THHN in raceway.)
1) Table 310.16(90c column) allows 75 amps for #6.
2) 310.15(B)(2) requires derating to 70%.(9 conductors).
3) .7 x 75 = 52.5 amps.
Note that if you used the 75c column for your derating, your ampacity at 70% would be only 45.5 amps,(7 x 65) and you would need a larger conductor.


Anyone else?


[This message has been edited by Redsy (edited 05-20-2002).]
Posted By: Electricmanscott Re: New Romex cable - 05/20/02 11:45 AM
Got it. Thanks
Posted By: sparky66wv Re: New Romex cable - 05/20/02 01:09 PM
Redsy,

Where I get confused is whether to derate at the ampacity of the the expected load, or the protected load... For example, do I protect #12 wire at 20A (the amount that it is protected) or the 180W (the amount assumed for a receptacle load)...

That would be a big difference!
Posted By: Redsy Re: New Romex cable - 05/20/02 04:00 PM
66wv,
Well, for #14 through #10, see the asterisk at the bottom of table 310.16.

But, to answer your question, derate the CONDUCTOR.
In other words, if you have a 60 amp load with 2 THHN conductors no derating is required. Use the 75c column(per 110-14(C)(1)) which shows a #6 as good for 65 amps.
If, however you had 4 current carrying conductors and needed to derate to 80% as required by table 310.15(B)(2)(a), you may use the 90c column which shows 75 amps for THHN. 75 x .8 =60 amps. You are still good with #6. If, however you used the 75c column to derate, you would have needed to go to a larger conductor because .8 x 65 =52 amps.
I hope this helps (and I hope I'm correct) [Linked Image]
Posted By: hurk27 Re: New Romex cable - 05/26/02 01:07 AM
What happend to the new "2002" requirement that any conductor smaller than a #6 has to be permetly marked from one end to the other.
I thought this would sopt us from using the neutrals for switch leg or hot feeds down to a dead end switch?
____________________________________________
Fred The 4 conductor NM will also be handy for wiring those bath heat-vent-light units.
_____________________________________________
Posted By: Fred Re: New Romex cable - 05/26/02 03:28 AM
200.7(C)(1) "If part of a cable assembly and where the insulation is permanently reidentified to indicate its use as an un-grounded conductor, by painting or other effective means at its termination, and at each location where the conductor is visible and accessible".
Posted By: Gwz Re: New Romex cable - 05/26/02 12:00 PM
Redsy,

For the Derating, don't forget the 105ºF attic.

Of course it was not NM cable, but recently seen an installation of 2" RMC on a roof top which had 32 #10 THHN/THWN current carrying conductors on 20A CB's.
The ampacity of the #10 was less than 12 Amperes.
Some loads were greater than 16 amperes and were 24/7/365 loads.
Posted By: Redsy Re: New Romex cable - 05/28/02 11:01 AM
Good point.

Yeah, the attic, the boiler room, etc.
Any time you even pass through an area where the ambient temp. is higher than other portions of the run, you should use the higher temp. for derating purposes. Correct?
Posted By: pauluk Re: New Romex cable - 05/28/02 02:54 PM
Don't know about under the NEC, but that's the way we do it here: Derate according to the highest temperature the cable passes through.
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