# Different Sized Conductors



## mikeb (May 1, 2009)

Here's the scenario:

We need to run 5MW 4160V TEMPORARY power distribution and have three 500MCM and three 4/0 15kV Copper shielded conductors available. This would translate to about 700 Amps passing through the conductors. If we ran one of each sized conductor on each phase (ie A phase would have one 500MCM cable and one 4/0 cable), would this be okay? I have heard differing theories, however, I am looking for a definitive answer. I have always thought the copper is copper and you want enough from point A to point B to carry the load. I have also heard that since the current likes to float on the outside of the copper, different sized conductors tend to pull more current on one cable and could overheat one of the cables.

PS -- This will be a balenced system.

Thanks,


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## Bob Badger (Apr 19, 2009)

mikeb said:


> If we ran one of each sized conductor on each phase (ie A phase would have one 500MCM cable and one 4/0 cable), would this be okay?


It would be fine if you are looking to melt the 4/0.

NEC 310.4 prohibits the mixing of sizes on each phase.


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## mikeb (May 1, 2009)

Thanks! This is what I needed.


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