THHN on Ladder Tray

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luckylerado

Senior Member
I am looking over a set of drawings. The design engineer indicates installing single strand #12 AWG conductors for 120V controls of several new constant current regulators in a regulator station. The path indicated is a 3"x9" ladder tray with transitions at each end to EMT.

I do not doubt that I can install the wire on tray but what are my options for an appropriate transition to EMT on each end?

Any suggestions would be appreciated.

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Smart $

Esteemed Member
Location
Ohio
...I do not doubt that I can install the wire on tray...
But perhaps you should. To be a single-conductor, it has to be a type rated for tray installation. You cannot install THHN, if that is all the wire is rated, in cable tray [392.10(A)].
 

Jraef

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Occupation
Electrical Engineer
But perhaps you should. To be a single-conductor, it has to be a type rated for tray installation. You cannot install THHN, if that is all the wire is rated, in cable tray [392.10(A)].
He's right. You can however get Tray Cable with multiple #12s in it. That's the official way to do that. At that point, the clamps and such are what you use for the transitions.
 

luckylerado

Senior Member
But perhaps you should. To be a single-conductor, it has to be a type rated for tray installation. You cannot install THHN, if that is all the wire is rated, in cable tray [392.10(A)].

In this case, the product data seems to indicate suitable for cable tray. It just seems janky. Thanks for the link.

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Smart $

Esteemed Member
Location
Ohio
In this case, the product data seems to indicate suitable for cable tray. It just seems janky. Thanks for the link.
I can't check because it appears Southwire's website is down at present... but tray rated single-conductor THHN/THWN-2 is usually only available in the larger sizes... say 1/0 and up, but don't quote me on that.
 

Smart $

Esteemed Member
Location
Ohio
Which is the "TC" marking on the insulation.
Actually, for THHN, the UL Wire and Cable Marking Guide says...
When evaluated for use in cable trays, the product is marked "for cable tray use", "for CT use" or "for use in cable trays."

If it were marked "TC", then it would be cross typed as Tray Cable.
 
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