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Searching for a wire type

MatBirch

Well-known member
Joined
Oct 10, 2013
Messages
419
Location
Filer, Idaho
Hoping to find a stranded 12/2 w/ ground NMB type wire.

My application is construction of truck bodies and trailers. We often rough in both our 120/208 as well as 12v buried in the walls. Wire is routed through the furring, then walls are insulated with often up to 4” of expanding urethane foam, prior to lining with either plywood or aluminum.

We currently use MC armored cable, and while it works, it’s expensive, time consuming to install, fills up space quickly in places we often don’t have room for. Also of course requiring dedicated termination ends.

Over the years, solid wire was tried, but suffered failures due to vibrations of the vehicles. Therefore stranded wire is a must.

While our industry is not subject to a typical municipal permit/inspection system, or even required to be “code compliant”, we work very hard to maintain all work to NEC standards for materials and workmanship. We often do have units that are overseen by L&I or other 3rd party inspectors.

Any ideas?
Thanks!
 
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Norcal

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Joined
Mar 16, 2008
Messages
13,767
I have only seen NM cable with stranded conductors once and it was in a 1950’s mobile home that was burned because of a idiot smoker AKA a legal drug user but that was the only time. May even still have the piece somewhere that I saved.
 
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yatg

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Joined
Aug 16, 2019
Messages
2,830
Location
Southern Oregon
Vibration would be my call.

Obviously.

I was looking for more detail, like did it fail in the middle of a run or at a device or something else.

I stripped down an old 1977 travel trailer this year and didn't see any problems with the NM cable in it.
 
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MatBirch

Well-known member
Joined
Oct 10, 2013
Messages
419
Location
Filer, Idaho
Thanks gang!
This gives me some good stuff to chew on. I forwarded the info to the boss.

As for the failures with solid wire- most units would be fine, but we build of oilfield service vehicles. They live a HARD life. Most of the failures were the solid wire fracturing at clamp points in devices, likely from vibration while in transit. Washboard roads, etc...failures went to nearly nil with the switch to stranded wire.
 
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