long cable runs and voltage drop

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Hfalz1

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Houston, Tx.
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Electrician
I'm needing to feed a 100A single phase 120v/240v panel and the closest power is 500+ feet away. The customer is wanting to just run the wire like an SO cord on the grass temporary. Do they make an SO cord that big? I'm thinking it would have to be a 350 MCM?
 
Hfalz1 said:
I'm needing to feed a 100A single phase 120v/240v panel and the closest power is 500+ feet away. The customer is wanting to just run the wire like an SO cord on the grass temporary. Do they make an SO cord that big? I'm thinking it would have to be a 350 MCM?
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This is temporary? Is the load really 100a or more like 50a on a 100a panel? For about a 120a (give or take) 3phase load, I've run over 500' using single conductor 4/0 copper from a 200a feed with an acceptable voltage drop. Consider a using generator, too.

If this is a permanent install, check out the cost of transformers vs the cost of wire and send 480v or 600v instead of 240v for the distance.
 
I agree with zbang in that 350 may be overkill. Try to determine your actual load, not panel size, and check a VED calculator. 4/0 should be suitable for a 100 amp load at 500 ft.
That said, a Type G or W portable cable is available, even in 350kcmil if that's what is needed however the price might lead you to other options.
 
Welcome to the forum!

Agree with the others on calculating the load, then going from there. A temp install to run saws and the like that will be on only minutes at a time could have more VD than a permanent install. Also, look at paralleling smaller cables than using a single 350.

My calcs show a 2/0 AL conductor for 120V, 50A, or 240V, 100A to 500' with 6.8% VD. You shouldnt have 100A of load on one leg and nothing on the other.

http://www.southwire.com/support/voltage-drop-calculator.htm

You can find used 25kVA xfmrs for a lot less than new if you're going to have a permanent install at that distance, tho they will cost more than even 500 MCM AL.

Another option is a buck boost and send ~10% over nominal to account for the voltage drop.
 
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