cable rating free air or not

[dm9289]

In going thru some sizing exercises in our plant I was confused on if a cable was free air or not for its ampacity rating.

We have a piece cable 300feet long 3-500KCM in a jacket it leaves 480V low voltage switchgear travels no conduit attached to beams with old 2 piece clamp spaced off of steel I-beams , goes to our factory ceiling again attached with 2 piece clamps spaced off of steel I- beams, then enters another motor control center conduit length about 5 feet.

Would this be considered free air cable for ampacity rating

Thank you so much, I could find no good definition for free air, especially for an unusual cable like this

Dave

 

[infinity]

Is this a flexible cord? If so look at 400.5(A).

 

[petersonra]

Is this a flexible cord? If so look at 400.5(A).

would a cord even be allowed for this kind of application?

 

[dm9289]

Yes the cord is flexible, this installation was done in 1956 so my guess is its not currently OK for new build

 

[don_resqcapt19]

The "free air" ampacity table only applies to single conductors. It does not apply to jacketed cables with more than on conductor.