The values of the thermal resistivity of insulation are taken from standard IEC 60287-2-1 Ed.2.0 where available with the following additions:

• For the purposes of current rating calculations, the semiconducting screening materials are assumed to have the same thermal properties as the adjacent dielectric materials.
• Value for Polypropylene (PP) is taken from professionalplastics.com
• Value for Silicone rubber (SiR) is taken from shinetsusilicone-global.com

Symbol
$\rho_{\mathrm{i}}$
Unit
K.m/W
Related
$M_{\mathrm{i}}$
$U_{\mathrm{n}}$
Used in
$d_{\mathrm{ct}}$
$T_{\mathrm{1}}$
$T_{\mathrm{1t}}$
$X_{\mathrm{K}}$
Choices
MaterialValue
PE3.5
HDPE3.5
XLPE3.5
XLPEf3.5
PVC5.0 (Un <= 3kV)
6.0 (Un > 3kV)
EPR3.5 (Un <= 3kV)
5.0 (Un > 3kV)
IIR5.0
PPLP5.5
Mass6.0
Oil5.0
PP4.5
SiR5.0
EVA4.35