# Nm-b romex run outdoors



## alexb5647 (Nov 27, 2012)

My uncle has a log cabin that he gave to me and it was built back in the 40's. Since he's was an industrial electrician he redid the electrical in 1990 because of few plugs and knob and tube wiring.  In order to avoid so many wires running along the wall he decided to drill through the floor and run the wire under the cabin to the next plug, switch, or if its a home run line. I looked under the cabin just recently and he just ran the romex loosely and it's laying on the ground. It doesn't look deteriorated or chewed. Some circuits close to the panel he just stapled the cable real nice and neat along the wall or ceiling. All junctions have covers and romex clamps on all boxes. All cables are stapled within 6" of fixture and stapled every 12".  Also he put in some outdoor lighting on the porch and he just drilled through the logs from the inside and just ran romex out to the light. Is this acceptable by code? My uncle is not around anymore so I can't ask him. Any info would be appreciated.


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## Wuzzat? (Nov 27, 2012)

If the life of Romex is 50 years, one question is: "How long will NMB last under these conditions?"
And, "Is it long enough?"


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## alexb5647 (Nov 27, 2012)

I was just wondering if this is up to code. I'm sure i will have to replace it in the future. I'll just run 12-2 UF with conduit when I replace it. The underside of my cabin is dirt which is always dry. I just wasn't sure if romex being outside and laying on the ground is ok.


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## JoeD (Nov 28, 2012)

I sure hope the life of Romex is more than 50 years. My house is 55 years old and has never been rewired.


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## Wuzzat? (Nov 28, 2012)

JoeD said:


> I sure hope the life of Romex is more than 50 years. My house is 55 years old and has never been rewired.


The cable guy who told me that did/could not define "End of Life" for Romex.


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## nealtw (Nov 28, 2012)

I wouldn't leave them laying on the ground.


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## Wuzzat? (Nov 28, 2012)

nealtw said:


> I wouldn't leave them laying on the ground.


It's probably classified in the NEC as a damp or wet location and so you are supposed to use UF cable.
I guess if you megger it once in a while and see a significant degradation in the insulation resistance it should be replaced.  
Another test would be to put a GFCI upstream of this cable.


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## alexb5647 (Nov 28, 2012)

nealtw said:
			
		

> I wouldn't leave them laying on the ground.



I stapled them to the joists so there not on the ground anymore.


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## Wuzzat? (Nov 29, 2012)

alexb5647 said:


> I stapled them to the joists so there not on the ground anymore.


Then the question is: "Can NMB be used in an unconditioned space?" If the cable sees more than 30C you might need to derate.


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## nealtw (Nov 29, 2012)

Then the question is: "Can NMB be used in an unconditioned space?" If the cable sees more than 30C you might need to derate. 
Wouldn't that be the same as an attic with a moisture problem.


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## Wuzzat? (Nov 29, 2012)

nealtw said:


> Then the question is: "Can NMB be used in an unconditioned space?" If the cable sees more than 30C you might need to derate.
> Wouldn't that be the same as an attic with a moisture problem.



Yes, unless the cable has some kind of cognition that we do not and can not know about (see Emergence).  
Always a pleasure, nealtw. . .


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## Wuzzat? (Nov 30, 2012)

nealtw said:


> Then the question is: "Can NMB be used in an unconditioned space?" If the cable sees more than 30C you might need to derate.
> Wouldn't that be the same as an attic with a moisture problem.


Seems damp to me.
http://www.paramount-lighting.com/wet_locations.pdf


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## nealtw (Nov 30, 2012)

I think the smaller cables should be run thru holes in the joists too.


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## ROMEXCABLEFAN (Mar 6, 2013)

alexb5647 said:


> My uncle has a log cabin that he gave to me and it was built back in the 40's. Since he's was an industrial electrician he redid the electrical in 1990 because of few plugs and knob and tube wiring.  In order to avoid so many wires running along the wall he decided to drill through the floor and run the wire under the cabin to the next plug, switch, or if its a home run line. I looked under the cabin just recently and he just ran the romex loosely and it's laying on the ground. It doesn't look deteriorated or chewed. Some circuits close to the panel he just stapled the cable real nice and neat along the wall or ceiling. All junctions have covers and romex clamps on all boxes. All cables are stapled within 6" of fixture and stapled every 12".  Also he put in some outdoor lighting on the porch and he just drilled through the logs from the inside and just ran romex out to the light. Is this acceptable by code? My uncle is not around anymore so I can't ask him. Any info would be appreciated.


If you ever replace this cable you would need to use the UF-B product Romex ®NM-B cable.  It is permitted to be used for both exposed and concealed work in normally dry locations per NEC® 334.10(A)(1) and not permitted in damp or wet locations per NEC 334.12(B)(4).  Any cable lying on the ground needs to be supported. - The cable needs to be supported and secured every 4 and within 12 of each box, cabinet, conduit, or other termination. NEC 334.30(A)
This answer is intended to apply to Romex® Brand NM Cable.  For other NM cables, please check with those respective brand suppliers or cable manufacturers.  Romex® is a Registered Trademark of Southwire Company.
 This communication is for general informational purposes only and is not intended to constitute advice.  As all the facts and circumstances in any given situation may not be apparent, this communication is not intended to be, and should not be, relied upon by the reader in making decisions with respect to the issues discussed herein, and the reader assumes the risk if he or she chooses to do so. The reader is encouraged to consult an expert before making any decisions or taking any action concerning the matters in this communication. All warranties, express or implied, including warranties regarding accuracy, adequacy, completeness, legality, reliability, safety or usefulness of any information, ARE DISCLAIMED.  Southwire Company is not liable for any damages however caused and on any theory of liability arising in any way out of the information provided or the reader's use of it.


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## nealtw (Mar 6, 2013)

Hey Romex: Welcome, great info until you dropped your lawyer on us. All that legal stuff is understud here


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## CallMeVilla (Mar 6, 2013)

How nice to have you very own cabin!  

If you are running conduit, you need stranded wiring, not UF or ROMEX sheathed.  Heat builds up and so code requires strands.  UF can be undergrounded but the aboveground stubs should be in conduit until you hit the required depth in the dirt (prevents critter gnawing on live wiring).  

In California, we are required to bury UF or conduit a minimum of 14" below ground (which is exactly what I did today, BTW).  

Here is a resource for you to consider:  http://www.familyhandyman.com/DIY-P...Wiring/how-to-bury-underground-cable/View-All


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## wireless (Mar 8, 2013)

CallMeVilla said:
			
		

> How nice to have you very own cabin!
> 
> If you are running conduit, you need stranded wiring, not UF or ROMEX sheathed.  Heat builds up and so code requires strands.  UF can be undergrounded but the aboveground stubs should be in conduit until you hit the required depth in the dirt (prevents critter gnawing on live wiring).
> 
> ...



What code is that exactly?!


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## CallMeVilla (Mar 9, 2013)

Well, wireless, you can start here and follow the NEC  ....
http://electrical.about.com/od/codesregulations/a/NEC_outdoor_wiring_tips.htm


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## wireless (Mar 10, 2013)

CallMeVilla said:
			
		

> Well, wireless, you can start here and follow the NEC  ....
> http://electrical.about.com/od/codesregulations/a/NEC_outdoor_wiring_tips.htm



Really the NEC requires stranded wire in conduit?


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## CallMeVilla (Mar 10, 2013)

In case you did NOT read the very helpful article from The Family Handyman I provided, here is the pic for buried plastic pipe wiring  ...  Note also the more shallow undergrounded wiring is encased in metal conduit   ....  BUT BOTH are done without the ROMEX sheathing.


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## JoeD (Mar 10, 2013)

CallMeVilla said:


> In case you did NOT read the very helpful article from The Family Handyman I provided, here is the pic for buried plastic pipe wiring  ...  Note also the more shallow undergrounded wiring is encased in metal conduit   ....  BUT BOTH are done without the ROMEX sheathing.


Actually both are done separate wires fed into the conduit. You can not strip NM cable and use it in conduit. The wires from inside a NM cable are NOT suitable for this use. You must use proper rated THHN/THWN wires.


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## CallMeVilla (Mar 10, 2013)

Good point, Joe  ...  For those who do not know, stand-alone THWN cables are coated in PVC, as opposed to vinyl, to assist in water resistance.  THHN wire is typically two-conductor with ground, and found in the familiar ROMEX cabling that wires homes, e.g. 12-2.  The coating also explains the slight price difference between the two  ... and the noticeable price difference between ROMEX cabling (cheaper) and THWN stranded cabling.  In harsh climates these are important differences to know!


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## JoeD (Mar 10, 2013)

THHN is NOT two conductor with ground. It is single wire, either stranded or solid. The wire inside NM cable is NOT suitable to be used in place of THHN. It is not labelled as THHN and can not be legally used in conduit.


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## nealtw (Mar 10, 2013)

PVC, as opposed to vinyl, as in poly vinyl chloride?


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## CallMeVilla (Mar 11, 2013)

Rather than get caught up in the chemistry of coatings, how about this:
1.The "T" stands for thermoplastic insulated cable.
2.A single "H" means the wire is heat resistant.
3."HH" means that the wire is heat resistant and can withstand a higher temperature. This wire can withstand heat up to 194 degrees Fahrenheit.
4.A "W" means that the wire is approved for damp and wet locations. This wire is also suitable for dry locations.
5.The "X" means the cable is made of a synthetic polymer that is flame-retardant.
6.The "N" is for the nylon coating that covers the wire insulation.

Go here for more:  http://electrical.about.com/od/wiringcircuitry/a/wirelettering.htm


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