Nm - B??

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  #1  
Old 06-03-04, 01:20 PM
bdek
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Nm - B??

Hi Guys,

I have a partial coil of "older" NM - B (12/2/wg) that I would like to use up if it is still acceptable for residential use. The overall circumference of the jacket is a little larger than what is currently being sold in the home stores today. The insulation is slightly heavier on each conductor and does not have the clear/shiny covering. Is this wire still acceptable to use?

Is the insulation on both the older and newer type NM - B thermoplastic and is it rated for 90 degrees C.?

Looking for comments/reasons on why the change or upgrade to the newer
type NM - -B if other than one of manufacturing economics.

Thanks,
Bob
 
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  #2  
Old 06-03-04, 01:33 PM
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NM-B is fine, and may be used with fixtures requesting 90-degree wire. Use it.
 
  #3  
Old 06-03-04, 03:11 PM
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Quick question: Does the printing on the cable actually _say_ NM-B, or are you just calling the stuff NM-B? If the printing says NM-B, then John's answer holds. If the printing just says NM, then this wire is only rated for 60C.

-Jon
 
  #4  
Old 06-03-04, 08:03 PM
bdek
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Nm - B??

Jon,

The "printing on the cable" actually says NM - B.
Therefore it is now my understanding as per John Nelson that this cable is rated for 90 degrees C..

To answer part of my original question -- I would assume that the development of newer plastic insulations allows for the thinner coating on the individual conductors -- which ultimately has to be UL approved.

Also would the individual conductors if not jacketed be considered THHN?

Thanks again,
Bob
 
  #5  
Old 06-04-04, 06:55 AM
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The individual conductors are not formally rated THHN, but they are of the same construction as THHN (first bit of doublespeak). And although NM-B is rated 90 degrees for most purposes, it may not be protected by breakers sized to the 90-degree rating (second bit of doublespeak).
 
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