# How can we calculate the current (I) if we have cable with 25 mm size for 480V?

1. Oct 5, 2009

### megatronic

dear engineer,

how can we calculate the current (I) if we have cable with 25 mm size for 480V?
and are there any other parameters we should know to calculate the current.

(for plant project purpose)

2. Oct 5, 2009

### MATLABdude

Are you asking what the maximum safe current is for this size of cable, or asking how much current you have when you short out 480V with a segment of this cable?

If you're asking how much current is carried to a load when using a 480V supply, this is determined chiefly by the load, and not the cable (though clearly, you need to ensure that the cable can carry that current, otherwise you'll just have burnt / melted cable)

3. Oct 5, 2009

### megatronic

thanx MATLABdude, you are right the cable should be chosen by considering the load and the current carried to the load.
however what I meant is the maximum current appropriate for this size of cable.

4. Oct 5, 2009

### stewartcs

Is 25 mm the diameter or do you mean 25 mm^2 for the cross-sectional area?

CS

5. Oct 10, 2009

### megatronic

the cross section 25mm^2

6. Oct 10, 2009

### MATLABdude

That sounds like it's somewhere between 3 and 4 AWG cable:
http://en.wikipedia.org/wiki/American_wire_gauge

The ampacities are listed for various insulator temperature ratings. You also need to ensure that the jacket is rated for the voltage that it's carrying (otherwise, you might have arcing through the insulation between cables lying side by side).

7. Oct 11, 2009

### megatronic

thanx MATLABdude the link will be useful

8. Oct 29, 2009

### mexmet

visit this site.
Simply and quickly..

http://www.incable.somee.com [Broken]

calculating drop-voltage, current control

Last edited by a moderator: May 4, 2017