Thermal Resistivity of Flame Retardant Foam Materials in Power Cable's entry point to the Substation 1

[Oblsss]

Hello!!

While I was working on some ampacity calculations, concerning several parallel circuits of distribution cables laid in a concrete ductbank,
I wondered whether there is a chance that the high temperature point of the cable routing lies in the entry point to the Substation.
It is common practice to use flame retardant foam-like materials and I wanted to know the values that thermal resistivity of these materials can take
and whether they should be examined more carefully in the abovementioned calculations.
Any suggestions or related informations are welcomed ...

Regards,
George

 

[waross]

Due to the short distance involved and the high thermal conductivity of either copper or aluminum conductors the effect is often ignored.

Bill
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"Why not the best?"
Jimmy Carter

 

[dpc]

Check with the manufacturers. But agree with Bill, I think you're in the weeds since the distance is very small. If you're getting that close on the heating calculation, probably need to change something. The calculation is not all that accurate due to the numerous variables.

 

[7anoter4]

See: Ampacity Derating and Cable Functionality for Raceway Fire Barriers by Steven P. Nowlen
U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, DC 20555-0001
In subpart G is presented a program in Fortran.
In Appendix A The Thermal Conductivity of a Composite Cable Bundle it is a list of thermal conductivity.