(see 4.Insert 165
correlation with the material groups not practical. Therefore, this part uses the CTI
values categorize insulation materials.
For the purposes this part, materials are separated into [three] groups
according their CTI values, follows:
Material Group (600 CTI)
Material Group (400 CTI 600)
Material Group III (175 CTI 400)
The CTI values above refer values obtained, accordance with IEC 112. However, has been
found experience and tests that insulating materials having higher
performance also have approximately the same relative ranking according
to the comparative tracking index (CTI).2)
.8
