Cable ratings - constant load?

[Ian1981]

Hi,
When choosing a cable, you should focus on the installation conditions. Derating factors can significantly change the base value of current carrying capacity. Are there any loaded neighboring cables or communications?

In any case, initially the cable was selected at the limit, without current margin. Next is your case without correction factors:
View attachment 59020
and the report ….
View attachment 59021
Can you clarify the installation conditions and the effect of the loaded neighboring cables?

You should be limiting your maximum cable temperature to 70 degrees thus the ccc will decrease, unless it is ascertained that the Switchgear that the cable it is terminating to is suitable for 90 degrees, which in most cases is no.

 

[Alex-SL]

If we limit the maximum cable temperature to 70C degrees, then the current carrying capacity of the cable Cu 35 mm2 is 119 A only (with the C-installation method).


To supply a load of 150A per phase, then you need to use a cable Cu 70mm2 (this will be with a small margin).