Hello Raza

with Voltage always think of partial discharge of the cable between solid and the insulation and when a spark jump the insulation gap.

Exact the rated voltage tells the cable should be used till maximum 500V and it is safe.

Mostly this indication is together with the rated temperature and sometimes with the thickness of the cable.

The thickness is quite important for the rated current.

Hope it helps a bit.

Kin

Raza, to elaborate on Kin's answer, the voltage rating usually refers to the high voltage breakdown of the insulation. This is the voltage where the current can jump through the insulation from one conductor to another or to metal in contact to the outer wall of the cable.

Normal frequency insulation test of insulating material of cable, with it thickness used in H.V. Testing laboratory would decided the voltage rating, it is give in table with it size and capacity by manufacturers......

Thank you so much all of you for your helpful answers.

Tom Bauer And if I have a wire with voltage rating of 500V, and this is the only wire in my setup. and it is completely in air, with no contact to any conductor or any metal. You can say, in one big room, this wire is going from one part to another(in the air).

In this case, Can I pass 1000V from this wire, because It doesn't have anything nearby to affect, even if the current jumps over the insulator?

Thank you

Raza, Yes you can. Don't touch! :)

Raza, I agree with Tom - Here's why: The copper itself has no voltage limit. Breakdown is caused by the steepness of the voltage gradient between the copper and ground. If the wire is in air, as you described, you are adding insulation.

A pulsed cable will break down more readily. Also, a high-voltage cable resting on a grounded plate may fail at a significantly lower voltage than rated.