Insulated wire like THHN XHHW on cable tray

[eunji]

Hi,

When I reviewed the NEC 392 (Cable tray), there is restriction of single conductor to 1/0 and larger.
Also, equipment grounding wire has to be bigger than 4AWG.
In table 392.10 (A) Wiring Methods, I can't find the insualted single wire like type THHN, THWN and XHHW.

My questions are
1. Do I have to understand that insulated single wire has to be bigger than 1/0?
2. Is there any way to use smaller size like 6AWG ground wire for circuit?

Thank you!

 

[augie47]

Close....
Single conductors need to be 1/0 OR larger (not larger than 1/0)
EGC must be #4 or larger {see 392.10(B)(2)}
Conductors such as THWN-2 and XHHW can be obtained with CT rating.

 

[qcroanoke]

Close....
Single conductors need to be 1/0 OR larger (not larger than 1/0)
EGC must be #4 or larger {see 392.10(B)(2)}
Conductors such as THWN-2 and XHHW can be obtained with CT rating.

That's why you run it as a cable with a CT rating.

 

[tom baker]

And CT cable is much easier to install than a bunch of single conductors