Cable Tray Open Air Ampacity

[Designer371141]

At what point when leaving cable tray and entering conduit do you loose the open air capacity on Tray Cable when ran through cable tray entire length except through 12" nipples at the panel, does the code specify a specific length of conduit as to when you loose that extra ampacity?

 

[Smart $]

In general, you apply 310.15(A)(2) Exception.

(2) Selection of Ampacity. Where more than one ampacity
applies for a given circuit length, the lowest value shall be
used.

Exception: Where two different ampacities apply to adjacent
portions of a circuit, the higher ampacity shall be
permitted to be used beyond the point of transition, a distance
equal to 3.0 m (10 ft) or 10 percent of the circuit
length figured at the higher ampacity, whichever is less.

Informational Note: See 110.14(C) for conductor temperature​

limitations due to termination provisions.​

 

[mayanees]

Ambient temp correction

Ambient temp correction

I think you get 24" with Table 310.15(B)(2)(a) note (2) adjustments shall not apply ....up to 24".