Constant Y for cables in ducts

According to IEC 60287-2-1 Ed.3.0 (2023)

Symbol
$Y_d$
Unit
K.m/W
Choices
MaterialValue
PE0.0037
PP0.0037
PVC0.0037
WPE0.001
Metal0.011
Fibre0.006 (air)
0.01 (buried)
Earth0.0036
Cem0.006 (air)
0.011 (buried)