NM in conduit

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resistance

resistance

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An example of why you shouldn't run NM-B in conduit outdoors. The wire was installed in a black tube 30 feet long:
 
Once upon a time there was some kind of conduit/cable assembly that the POCO's used for underground secondary that looked for all the world like black poly water pipe with URD preinstalled. It has a proper name, but it escapes me at the moment. It was intended to be plowed in. I see it from time to time, generally in 1970's work.

Curtis, any idea how long this was installed before it failed like that?
 
I have seen this done a lot when a yard post light has been converted from gas to electric. They just pulled romex through the abandoned gas line from the basement/crawl to the post light.
 
mdshunk said:
. . . It has a proper name, but it escapes me at the moment. . .
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354.2 Definition. Nonmetallic Underground Conduit with Conductors (NUCC). A factory assembly of conductors or cables inside a nonmetallic, smooth wall conduit with a circular cross section.



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From the NEC Handbook:
Nonmetallic underground conduit with conductors (preassembled conductors in conduit) has been used by electric utilities for outdoor lighting for several years. It is supplied in continuous lengths on coils or reels or in cartons. It consists of nonmetallic conduit with the conductors pre-installed by the manufacturer. The product is designed to allow conductors to be removed and reinserted; therefore, maintenance is <not, added by me> an issue.

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We still use it in sizes #2 Al. and 2/0 Al. and just call it cable in conduit. We use it only for street lighting. :smile:
 
iwire said:
OK, wheres the exception that allows removal of the labeling at a panel? :grin:
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There isn't an exception. The markings are on the cable are required. You just striped the sheath to terminate in the panel. Same thing applies to j-boxes. I don't think anyone has been called of the 24-inch rule of 310.11(B) for stripping 25" of sheath off NM in order to reach a breaker at the bottom.

If you lose sleep over this, try putting in a proposal for the '11.... there's still time.:smile:
 
resistance said:
An example of why you shouldn't run NM-B in conduit outdoors. The wire was installed in a black tube 30 feet long:
Click to expand...

Any chance this "black tube" conduit was in the open and not buried? Could the conduit have been heated by direct sunlight? Not suggesting that sunlight melted the NM-B, but may have raised the temperatures of the raceway and conductor environment.
 
mdshunk said:
Once upon a time there was some kind of conduit/cable assembly that the POCO's used for underground secondary that looked for all the world like black poly water pipe with URD preinstalled. It has a proper name, but it escapes me at the moment. It was intended to be plowed in. I see it from time to time, generally in 1970's work.

Curtis, any idea how long this was installed before it failed like that?
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Its most likely what the NEC calls NUCC Art 354 or so, or the same as HDPE Art 353, which is NUCC less the conductors
 
tom baker said:
Its most likely what the NEC calls NUCC Art 354 or so, or the same as HDPE Art 353, which is NUCC less the conductors
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Those are pretty new articles in the NEC, but I've observed those products in use by the utilities for decades. I wonder why it took so long to gain NFPA favor?
 
resistance said:
An example of why you shouldn't run NM-B in conduit outdoors. The wire was installed in a black tube 30 feet long:
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That looks like aluminum.
 
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