Cable Voltage Grade Selection

Hallo everyone,

this is my first post since I have just subscribed.

I have the following problem:

IEC 61892-4 says that

"The typical rated voltage (U) for control and instrumentation cables considered in this

standard is 250 V.

In some instances for conductor sizes 1 mm2 and larger, or when circuits are to be supplied

from a low impedance source, 0,6/1 kV rated cables shall be used as control or

instrumentation cables"

I would like to understand which are the aforementioned instances.

Moreover, I usually use 250V rated cables for AI/AO/DI and 0.6/1kV ones for DOs (solenoids). Is this a good engineering practice or is there a better way to proceed?

Please consider there are 24VDC supplied circuits or 4-20mA loops.

Thanks in advance for your help.

Byez