Insulation level 1

[Anil Thapa]

Is the Category A, B and C mentioned in IEC 60502 same as Insulation Level 100%, 133% and 173% mentioned in UL or ICEA/NEMA Specification.
If yes, why there is not different insulation thickness for different categories in IEC 60502.

 

[7anoter4]

Actually, since IEC 60502-2 Table 1 – Recommended rated voltages U0 recommends the same [maximum] Uo for both category A and B only C is different.
Uo for A and B it is the Um/sqrt(3) but for C category it is the immediate upper Um/sqrt(3).That means if your cable falls on C category you have to choose the immediate upper rated voltage cable.
If we compare Table 6 – Nominal thickness of cross-linked polyethylene (XLPE) insulation with UL 1072 Table 13.1 it seems 133% corresponds to C but for 173% insulation thickness there is no standard indication.
I have not ANSI/NEMA WC 74/ICEA S-93-639-2017 with me, but if we read the ANIXTER [ attached link] Table 1 then for 133% the recommended thickness is more than recommended by UL and there is a recommended thickness for 173%.

https://www.anixter.com/en_ca/resources/literature/wire-wisdom/insulation-levels.html