# minimun installation temp nm



## te12co2w (Jun 3, 2007)

I haven't seen it anywhere, but it seems reasonable to expect that there is a minimum temperature below which nm-b should not be pulled? Manufacturer specs? Certainly no nec requirements that I could find. I've found that at -20F to -30F the sheath can crack. Don't really like working that cold anyway.


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## raider1 (Jan 22, 2007)

I am not aware of any mandated ambient temperature limitation as to when you can or can't install NM cable. I would say use common sense, if the insulation is going to crack then it is probably not a good idea to install the NM cable.

Here in northern Utah the winters get pretty cold so I feel your pain. (When it gets to -20f you usually don't feel much pain. )

Chris


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## te12co2w (Jun 3, 2007)

Here in northern Utah the winters get pretty cold so I feel your pain. (When it gets to -20f you usually don't feel much pain. )

Chris[/quote]


Right. Sometimes you don't even feel your fingers.


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## 480sparky (Sep 20, 2007)

I work in one jurisdiction that has a written code that NM cannot be installed in temps below 0°F.


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## frenchelectrican (Mar 15, 2007)

IMO for NM romex wires anything colder than 10°F i try to preheat it keep in warm place for while until that get warm then string it out soon as possible before the cold get it again.

just want to head up with the new Simpull THHN-THWN's and NM both stated that do not pull if colder than 10°F [ if i recall the instrucations stated that ]

i allready pull few NM's little colder than that and feel it get more brittle with it so kinda like judgement call on what you can do with super cold weather even in super cold room like industrail frezzer [ walk in or drive in type ] same thing too 

Merci, Marc


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## JohnJ0906 (Jan 22, 2007)

I sit here very thankful that temps that low are rare around here! :whistling2:


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## HighWirey (Sep 17, 2007)

"I haven't seen it anywhere, but it seems reasonable to expect that there is a minimum temperature below which nm-b should not be pulled?"

Yea, it's 75 degrees F . . .

"I've found that at -20F to -30F" - are you daft, man?":laughing: 

Best Wishes


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## kbsparky (Sep 20, 2007)

BELOW 20F we have had the outer sheath of romex crack open when pulling it in. 

Its time to go home at those temps, or get some heat source going ... :001_unsure:


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## HighWirey (Sep 17, 2007)

Been gone from Silver Spring, Maryland for forty years. Has it gotten that cold since I left. Brrrr . . .
75 degrees is my answer, and I'm stikkin' to it:jester: 

Best Wishes


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## shazam (Apr 16, 2007)

Perhaps this is where "in a craftsman like manner" takes place.

If you pull it and inspect it and it is ripped, broken, or cracked.....you will be replacing it , that simple.


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## goose134 (Nov 12, 2007)

> I've found that at -20F to -30F the sheath can crack. Don't really like working that cold anyway.


On the bright side, at that temp. I think it almost qualifies as a superconductor.:laughing:


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## te12co2w (Jun 3, 2007)

HighWirey said:


> "I haven't seen it anywhere, but it seems reasonable to expect that there is a minimum temperature below which nm-b should not be pulled?"
> 
> Yea, it's 75 degrees F . . .
> 
> ...


Apparently so.


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## Idaho Abe (Nov 28, 2007)

*Min Temp for NMB*

In N Idaho if it is below freezing and no heat in building I look for cracking and separation of the outer insulation. If present I require replacement.


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## brian john (Mar 11, 2007)

> Silver Spring, Maryland


You'd hardly recognize downtown and up town you'd avoid.


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## Celtic (Nov 19, 2007)

shazam said:


> Perhaps this is where "in a craftsman like manner" takes place.
> 
> If you pull it and inspect it and it is ripped, broken, or cracked.....you will be replacing it , that simple.


A little tape will fix ripped, broken, or cracked sheath on NM...no problem...just keep the tape warm in your pocket :thumbsup: 





> 39.
> I have a Romex cable in a wall that got nicked. Only the outer sheathing was slightly damaged. Can I repair that damage with electrical tape and not replace that Romex cable?
> 
> Answer:
> ...


http://iaei-western.org/Files/2005/2005_Section_Code_Panel.pdf



There is a letter/document from Southwire that details the "process" to repair a damaged jacket on their NM product.
The link I had for it is 404.


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