# why doesn't 4/2 NM cable exist?



## MDShunk (Jan 7, 2007)

Type SE


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## MTW (Aug 28, 2013)

mikewillnot said:


> Manufacturers seem to make 4/3 NM (3 conductors #4 AWG plus ground). None seem to make 4/2 NM (2 conductors #4 AWG plus ground).
> Why is that?


The laws of supply and demand. I've only seen 4/3 NM cable once and it's very expensive to buy. I'm guessing it's at least 8-9 times more expensive than comparable aluminum SE cable which 99.9% of electricians in my area use anyway.


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## frenchelectrican (Mar 15, 2007)

mikewillnot said:


> Manufacturers seem to make 4/3 NM (3 conductors #4 AWG plus ground). None seem to make 4/2 NM (2 conductors #4 AWG plus ground).
> Why is that?


I have see 4/3 NM from time to time but never 4/2 NM due the market demand so therefore it genrally more expensive with 4/3NM vs #4-3 SE or #4-2 SE cable ( more than 5 X cost per liner foot ) 

IIRC at least one manufacter did make 4/2 NM cable long time ago but not anymore unless someone mention a current item.


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## Southeast Power (Jan 18, 2009)

mikewillnot said:


> Manufacturers seem to make 4/3 NM (3 conductors #4 AWG plus ground). None seem to make 4/2 NM (2 conductors #4 AWG plus ground).
> Why is that?


What would the application be?
What are you using it for if you don't mind a question??


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## MDShunk (Jan 7, 2007)

Seems like large NM is mostly used for large resi condensing units and resi air handlers with a little bit of electric heat.


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## MTW (Aug 28, 2013)

MDShunk said:


> Seems like large NM is mostly used for large resi condensing units and resi air handlers with a little bit of electric heat.


I see it used for subpanels and ovens and ranges mostly. We have almost no electric air handlers and most a/c's are high efficiency due to the high cost of electricity here.


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## nrp3 (Jan 24, 2009)

I have some 2-3 NM in the garage left over from a job in Duxbury. Not often I need copper, when Aluminum SE is less expensive. Same thing, subpanels, HVAC equipment, etc. Sometimes MC is more readily available and I'll price it accordingly.


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## 99cents (Aug 20, 2012)

Why wouldn't you run a neutral to a sub?


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## Bird dog (Oct 27, 2015)

99cents said:


> Why wouldn't you run a neutral to a sub?


You would. The OP is basically asking about 4-2 with ground which you might use on equipment (like an AC unit for example) not a panel.


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## MechanicalDVR (Dec 29, 2007)

I'm more an MC guy but never saw a need for 4-2NM.


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## Bird dog (Oct 27, 2015)

MechanicalDVR said:


> I'm more an MC guy but never saw a need for 4-2NM.


If you ever needed it, get the 4-3 & cap off one conductor. KISS rule.


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## MechanicalDVR (Dec 29, 2007)

Bird dog said:


> If you ever needed it, get the 4-3 & cap off one conductor. KISS rule.


Exactly my thoughts on the matter but I was trying to think of when I ever would have wanted 4-2nm and drew a blank.


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## matt1124 (Aug 23, 2011)

We're not allowed to use aluminum here, except for the line side of the meter. 

4/3 NM is very common here, many places stock it.
6/2 seems to be the largest available, possibly special order.


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## paulengr (Oct 8, 2017)

You can just use MC anywhere you’d use NM.

Or better yet if you can find it, TC-ER. This was originally tray cable but passes the MC mechanical spec so is allowed almost anywhere MC is allowed. It is much more flexible and you terminate with CGBs instead of TNCs and just use a knife to remove the jacket instead of a saw or pipe cutter to cut the armor.

Our Northern friends are real gluttons for punishment and use Teck-90 which is like MC except it has a solid corrugated armor jacket instead of spiral wound. Really nasty stuff. I’ve only seen it once or twice in the states because it’s rated for Div 1/class 1 areas where MC and TC-ER are only good to class 2 so when you really need SOOW for a somewhat flexible joint like for a valve on a coal bin, this works and eliminates glands and conduit.


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## BlackHowling (Feb 27, 2013)

Teck90 is rarely corrugated armor. Have only come across it twice over thousands of cables.


paulengr said:


> You can just use MC anywhere you’d use NM.
> 
> Or better yet if you can find it, TC-ER. This was originally tray cable but passes the MC mechanical spec so is allowed almost anywhere MC is allowed. It is much more flexible and you terminate with CGBs instead of TNCs and just use a knife to remove the jacket instead of a saw or pipe cutter to cut the armor.
> 
> ...


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## MDShunk (Jan 7, 2007)

paulengr said:


> You can just use MC anywhere you’d use NM.
> 
> Or better yet if you can find it, TC-ER....


Says the guy who sounds more and more detached from everyday electrical work with each new post. :sad:

Both of those may be true statements, but profoundly uneconomical (and attendantly strange) in locations where NM cable would otherwise be permitted.


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## Bird dog (Oct 27, 2015)

MDShunk said:


> Says the guy who sounds more and more detached from everyday electrical work with each new post. :sad:
> 
> Both of those may be true statements, but profoundly uneconomical (and attendantly strange) in locations where NM cable would otherwise be permitted.


One is a troll (OP) and the other one is an engineer. :vs_laugh:


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## JoeSparky (Mar 25, 2010)

Assuming it's resi, Just use #2 SEU aluminum. Hard to find a SH or big box that doesn't have it.


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## MTW (Aug 28, 2013)

Bird dog said:


> If you ever needed it, get the 4-3 & cap off one conductor. KISS rule.


I'm not sure why I would feel compelled to spend $7-9 a foot for 4/3 NM when equivalent 2/3 SEU is around $1 per foot.


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## Bird dog (Oct 27, 2015)

MTW said:


> I'm not sure why I would feel compelled to spend $7-9 a foot for 4/3 NM when equivalent 2/3 SEU is around $1 per foot.


I'm sure you're right, but, the OP said 4-3.


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## MTW (Aug 28, 2013)

Bird dog said:


> I'm sure you're right, but, the OP said 4-3.



And I think we all steered him away from that. :vs_laugh:


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## MTW (Aug 28, 2013)

matt1124 said:


> We're not allowed to use aluminum here, except for the line side of the meter.


What communist enclave would that be?


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## mikewillnot (Apr 2, 2013)

The application is an EV charger that needs only two hots and a ground, copper, run through a basement where piping would be very difficult. In the garage, pvc sleeve is no problem.


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## Bird dog (Oct 27, 2015)

Sothwire, page 2, SER 2 conductor with bare concentric ground (formerly known as "three conductor")...

https://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet274


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## MDShunk (Jan 7, 2007)

I've ripped out copper SE cable before, but I've never actually seen it stocked anywhere to buy. Might be a regional thing. Maybe coastal areas? You can find lots of things in catalogs that would be special order, if you were so inclined. I favor using things I can get my hands on easily. In the case of this EV charger, I'm not sure what I'd do. I understand most of them are marked "copper conductors only". I suspect I'd run AL SE almost all the way and changeover to copper THHN in a 4-11 nearby and nipple up/over to the charger. I really have no idea. That's just my gut feeling about what I'd do.


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## 3DDesign (Oct 25, 2014)

Local supplier has 125 ft rolls of 4/3 NM-B for $439.
No 4/2 available


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## JoeSparky (Mar 25, 2010)

MTW said:


> I'm not sure why I would feel compelled to spend $7-9 a foot for 4/3 NM when equivalent 2/3 SEU is around $1 per foot.


Hell, I've even wired a few A/C units in 6 SEU instead of 8/2 romex. Local supplier stopped carrying it :sad:


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## mikewillnot (Apr 2, 2013)

I'm thinking about pulling in liquidtight non metallic through the basement with thhn inside.

The charger mfr specifies copper, and in my opinion given the nature of the load for good reason.


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## matt1124 (Aug 23, 2011)

MTW said:


> What communist enclave would that be?


Tulsa and Pryor, Oklahoma. I'm sure there are several others here.

You'd think I was going to burn the whole City of Pryor down when we ran SER to a sub and the service conductors were aluminum without "sunlight rated" printed directly on the jacket not just in the spec sheet.


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## splatz (May 23, 2015)

mikewillnot said:


> I'm thinking about pulling in liquidtight non metallic through the basement


I'd just run 1" EMT, running flex any distance looks sloppy. Pipe goes quick and easy in residential basements, especially if you don't get too snobby about an extra coupling here and there and a very little more scrap than some Pipelangelo would make.


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## JoeSparky (Mar 25, 2010)

Hell, if you really insist on copper, my supplier has 4 SEU copper for 4 bucks a foot. At that size car charger, you need a disconnect anyways. Run aluminum to the disconnect and copper off the load side. The car charger instructions only specify copper because the lugs are not rated for AL.


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## Gnome (Dec 25, 2013)

paulengr said:


> Our Northern friends are real gluttons for punishment and use Teck-90 which is like MC except it has a solid corrugated armor jacket instead of spiral wound.


I must have installed thousands of kilometres of TECK cable; never seen it with a corrugated armour. Teck differs from MC in that it has a waterproof jacket between the armour and conductors and a weatherproof jacket on top of the armour.

It is hazardous location legal though you have to use the right (expensive,epoxy filled) connectors in those locations.


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## Norcal (Mar 22, 2007)

JoeSparky said:


> Hell, I've even wired a few A/C units in 6 SEU instead of 8/2 romex. Local supplier stopped carrying it :sad:



Used to be very common here to run it to ranges, & dryers, thankfully codes changed, that is a application I never liked, but A/C's are a good use of it.


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## eddy current (Feb 28, 2009)

paulengr said:


> Our Northern friends are real gluttons for punishment and use Teck-90 which is like MC except it has a solid corrugated armor jacket instead of spiral wound. *Really nasty stuff.* I’ve only seen it once or twice in the states because it’s rated for Div 1/class 1 areas where MC and TC-ER are only good to class 2 so when you really need SOOW for a somewhat flexible joint like for a valve on a coal bin, this works and eliminates glands and conduit.
> 
> 
> Sent from my iPhone using Tapatalk



??? I don’t think the stuff you saw was teck90.
Teck90 is super easy to install actually.


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## pudge565 (Dec 8, 2007)

MDShunk said:


> Seems like large NM is mostly used for large resi condensing units and resi air handlers with a little bit of electric heat.


Largest units I have seen were MCA of 50-55A which worst case would require a 6 AWG. I have never ever run into any piece of equipment in a resi install that would require 4 AWG copper.



Bird dog said:


> You would. The OP is basically asking about 4-2 with ground which you might use on equipment (like an AC unit for example) not a panel.


You could run 2 wire with ground to a sub panel as long as you are feeding only line to line or line to neutral loads. There is no requirement that you must run a neutral/grounded conductor to any panel except the service equipment.



matt1124 said:


> We're not allowed to use aluminum here, except for the line side of the meter.
> 
> 4/3 NM is very common here, many places stock it.
> 6/2 seems to be the largest available, possibly special order.


Please post up that local amendment. Just because an inspector says you can't doesn't fly. The inspector is only allowed to enforce the adopted standards and the NEC does not limit the use of aluminum wires or cables to the line side of meters so unless the governing body has made and adopted an amendment the inspector is wrong.



paulengr said:


> You can just use MC anywhere you’d use NM.
> 
> Or better yet if you can find it, TC-ER. This was originally tray cable but passes the MC mechanical spec so is allowed almost anywhere MC is allowed. It is much more flexible and you terminate with CGBs instead of TNCs and just use a knife to remove the jacket instead of a saw or pipe cutter to cut the armor.
> 
> ...


That is not true. It is marked as TC cable which means you must follow the rules in article 336. Until the 2017 code cycle the -JP rating is not recognized and there are no provisions that allow a TC-ER-JP cable to be installed like NM cable. 336.12(2) prohibits tray cable from being installed outside of a raceway or cable tray except as permitted in 336.10(7) which applies to industrial establishments only.

In the 2017 they added to 336.12(2) except as provided in 336.10(4),(7)(9), or (10). 336.10(9) is new and allows the use of TC-ER in 1 and 2 family dwellings provided it is installed in accordance with part II of article 334. To be pulled through framing members though it has to have the -JP rating.

In fact I just failed a generator install last week because they used Generac Composite TC-ER-JP cable outside of a raceway after they got into the structure. Unfortunately, PA is still on the 2008 NEC so it is prohibited from being outside of a raceway or cable tray. They had other issues with that install as well.


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## pudge565 (Dec 8, 2007)

I do agree that MC is the better choice in this case, readily available and useable pretty much anywhere NM can be. The support and securement is also farther apart so you can save some money on that, of course if you're fishing it that is a moot point.


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## lighterup (Jun 14, 2013)

pudge565 said:


> Largest units I have seen were MCA of 50-55A which worst case would require a 6 AWG. I have never ever run into any piece of equipment in a resi install that would require 4 AWG copper.
> 
> 
> 
> ...


This is exactly why I say there are differences GEOGRAPHICALLY and
being from Ohio , I can speak confidently that you could travel across
a county or muni line here and find "rules / local amendments" and such
that it will make your head spin.

Not all jurisdictions follow the NEC. Some are wealthier communities
who have the money to spend on "legal departments" who make up
thier own by laws , encat them through their local legislative department
and Bada Boom...it's a local law.

Here's a recent one (story) that was related to me by another EC.

His company got a contract to wire a larger home (14,000 sq ft).
They go in , they use aluminum for the service , aluminum SER 
for sub feeding various sub panels , and before I forget , 14 awg 
CU NM cable where permitted by NEC.

Service & Rough-in inspection was failed , miserably .

This community (Hunting Valley) does not allow aluminum 
_for anything[/I ]annnnnd , not allowed to wire any
branch circuits or feeders in 14 awg.

Made them tear it all out._


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## Dennis Alwon (May 9, 2009)

Years ago I used to buy 2/3 nm in copper but I doubt my suppliers keep that around anymore. #2 is the largest the NEC allows in either copper or aluminum for nm cable


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## pudge565 (Dec 8, 2007)

lighterup said:


> This is exactly why I say there are differences GEOGRAPHICALLY and
> being from Ohio , I can speak confidently that you could travel across
> a county or muni line here and find "rules / local amendments" and such
> that it will make your head spin.
> ...


_

The inspector has to provide the written amendment that the install violates is my point. He or she can't just decide one day that aluminum isn't allowed. I was in no way saying they can't make amendments I am just saying that those amendments must be documented and adopted as law._


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