What size wire for 250ft run?


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Old 07-16-07, 08:20 AM
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What size wire for 250ft run?

I need to run electric to my shed which is almost 250ft from the main panel. I need a minimum of 20amps (120) there so I can run a table saw, but ideally, I'd like to get install a 50amp sub panel. So what size wire do I need?

A friend of mine says if I want 20 amps, all I need is 8awg copper, but the online calculators keep telling me either 3 awg for aluminum or 4 awg for copper.

What is correct?

Thanks!!
 
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Old 07-16-07, 08:27 AM
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You are correct, if you really want 20 amps available on a 120 volt circuit and wish to keep voltage drop to less than 3 percent.

However, you can do much better than that.

Look for aluminum mobile home feeder cable, and use that to run a sub panel.
 
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Old 07-16-07, 08:47 AM
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Agreed. Use a #2-2-2-4 aluminum mobile home feeder direct-burial cable with a 50A subpanel. It's sold as a 100A cable, but should only be used for 50A at your distance. The #2 aluminum cable probably isn't too much more expensive than the #8 copper.
 
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Old 07-16-07, 07:50 PM
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Thanks folks... I guess I'll need to find a low cost source for some 2224. It's going to cost me way more then I want to spend, but it's way cheaper then copper.
 
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Old 07-23-07, 09:31 AM
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Costs.....

Just a word from another DIY'er....... I just ran 220 80'.With 3 #4's and 1#8 as ground...... All copper ..... It cost (just for the wire) $640.00 ......... Ouch
 
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Old 07-23-07, 07:48 PM
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Suggestion: Check and see if your table saw motor can be wired to run at 220V. My understanding is that the voltage drop for 220V is 1/4 that of 110V.
 
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Old 07-23-07, 11:10 PM
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The voltage drop for 240 volts is the same as 120 volts.

Roger
 
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Old 07-24-07, 09:36 AM
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The voltage drop is the same, but is less of an impact. For example, a table saw at 120v may pull 16A, but at 240v will only pull 8A. 16A over a long distance will have more of a voltage drop than 8A.

So my understanding is that all else being equal, wire larger equipment at 220 vs 120 (presuming it's designed as such).
 
 

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