Solid Bottom Open-top Cable Tray Ampacity

[Julius Right]

Cable Ampacity in solid-bottom [metallic] open-top ?usually in a power station-one could calculate it following J.Stolpe-"Ampacities for Cables in randomly filled trays"/1971way.
But in N.E.C. world it is only a tiny mention in-N.E.C. 2011-392.17(2)(c )
"Exception to (2)(3): For solid bottom cable trays the ampacity
of single conductor cables shall be determined by
310.15(C)."
310.15(C) Engineering Supervision. Under engineering supervision,
conductor ampacities shall be permitted to be calculated
by means of the following general equation:
I=sqrt((Tc-Ta)/(Rdc*(1+Yc)*Rca))*10^3 A
How to calculate Rca?:rant:
Nor Neher&McGrath neither IEC 60287 has a reference.
On the other hand, even Stolpe does not give how to calculate Rca since his method it is a global calculation.

 

[Dennis Alwon]

That's the job of the engineer.

RCA is the effective thermal resistance between the conductor and the ambient conditions, which can require significant empirical or theoretical effort to estimate

This was taken from here