Single conductor smaller 1/0 on cable tray

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kikeblackberry

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Hi, somebody could explain me the technical reason why single conductors smaller 1/0 AWG are not allowed for use on cable trays by NEC 392.10(B)(1)(a)?. Let?s suppose Type TC single conductors smaller than 1/0 are available in commerce.
 
kikeblackberry said:
...Let?s suppose Type TC single conductors smaller than 1/0 are available in commerce.
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That would certainly be interesting. Art 336.2 defines TC as a factory assembly of two of more insulated conductors ....

Do you have a reference for these 1/c - type TC?

ice
 
kikeblackberry said:
Hi, somebody could explain me the technical reason why single conductors smaller 1/0 AWG are not allowed for use on cable trays by NEC 392.10(B)(1)(a)?. ....
Click to expand...

I'm not much help. I supect it is an insulation mechanical strength issue. NEC allows grounding conductors down to #4, but not power conductors. No clue how 1/0 was chosen. Possibly another of the Code Panels throwing a blindfolded dart at an ouija board. Believe me, ii's not an easy task - you try getting a dart to hold still while you tie a blindfold on it.

kikeblackberry said:
...Let?s suppose Type TC single conductors smaller than 1/0 are available in commerce.
Click to expand...
I suspect you meant CT listings. TC is under NEC 336 - entirely different. If so, there are different specs outside of the US. For example Mexico allows use of CT listed single conductors, in cable trays, down to #4. Nope, I don't know how they decided on that either.

ice
 
Single conductor are often referred to as CT rated (Cable tray). An example http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet165

I agree that NEC 392.10(B)(1)(a) limits installations in an industrial environment to 1/0AWG and larger, BUT in a non-industrial environment, like a data center or office space, if you could find CT rated conductors smaller than 1/0AWG, I don't think anyone can stop you.

392.10 only has the limitation for industrial, nothing for other space types.
 
Ron,
The rule in 392.10(A) limits you to the wiring methods shown in Table 392.10(A) if you are not in an industrial occupancy. 392.10(B) expands that to permit single conductors 1/0 and larger along with the wiring methods in T392.10(A) if you are in an industrial occupancy.
 
don_resqcapt19 said:
Ron,
The rule in 392.10(A) limits you to the wiring methods shown in Table 392.10(A) if you are not in an industrial occupancy. 392.10(B) expands that to permit single conductors 1/0 and larger along with the wiring methods in T392.10(A) if you are in an industrial occupancy.
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Thanks, I hadn't looked at it that way before.

FWIW Is there a definition of "power cable" in the code that could be interpreted to mean a single covered conductor rather than a factory assembled group of conductors? The table allows "Other factory-assembled, multiconductor control, signal, or power cables that are specifically approved for installation in cable trays" which a CT conductor would be
 
ron said:
Thanks, I hadn't looked at it that way before.

FWIW Is there a definition of "power cable" in the code that could be interpreted to mean a single covered conductor rather than a factory assembled group of conductors? The table allows "Other factory-assembled, multiconductor control, signal, or power cables that are specifically approved for installation in cable trays" which a CT conductor would be
Click to expand...

type W is listed as portable power cable and is available in single conductor. I don't know if it is approved to use in cable tray though.
 
One of the issues the code has is the use of the terms "conductors" and "cables". In many cases, but not all, where the code uses "conductor" it means a single conductor and where it uses "cables" it means two or more conductors in an assembly with or without an outer covering.
This should really be addressed in the code as it is a source of confusion.
 
Thanks you guys,
Sorry if I misspelled the letters, I mean CT type single conductor and i did the question because while viewing General Cable?s online catalog (http://www.generalcable.com/generalcable/iCatSearch.html?ic=f0cdd4eb&sc=XHHW-2 CT) I bumped into ref. XHHW-2 CT (page 83) where sizes less than 1/0 are shown while Southwire's table start from 1/0 AWG.

So I just try to figure out why NEC doesn?t allow smaller sizes than 1/0 on cable trays.

But regarding Ron?s comments, if CT type conductor fits Table 392.10(A) as "Other factory-assembled, multiconductor control, signal, or power cables that are specifically approved for installation in cable trays", sizes smaller than 1/0 could be used in a non-industrial environment on cable trays in accordance with NEC?
 
kikeblackberry said:
But regarding Ron?s comments, if CT type conductor fits Table 392.10(A) as "Other factory-assembled, multiconductor control, signal, or power cables that are specifically approved for installation in cable trays", sizes smaller than 1/0 could be used in a non-industrial environment on cable trays in accordance with NEC?
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:thumbsup:
 
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