Typical values for different materials are listed below.

Values are taken from IEC 60287-2-1 Ed.2.0 with following additions or deviations:

Symbol
$\rho_{\mathrm{ab}}$
Unit
K.m/W
Used in
$T_{\mathrm{2_{\mathrm{1}}}}$
Choices
MaterialValue
PE3.5
PVC5.0 (Un <= 3kV)
6.0 (Un > 3kV)
EPR3.5 (Un <= 3kV)
5.0 (Un > 3kV)
POC5.0
IIR5.0
NR7.0
PP5.0
SiR5.0
CR5.5
CSM9.1
CJ6.0
RSP6.0
BIT6.0
FPOC6.6
FPP10.0
tape6.0