My son would like to power up his garage. It's about 130' from the house. He has a 220v/50a welder, 220v/30a compressor, and the other assorted power tools. He asked which would be best to use. Told him I'd check with the experts, although I'm leaning towards the #6. If there's a question...go bigger.
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#6 or #8?
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#6 is good for 65 amps, #8 - 40. Go with the next size #4 copper is good for 95 amps. The compressor and welder would be intermittent loads. For 130 feet you got to consider voltage drop too - 3% per hundred feet. When you figure voltage drop it's the total length of the run times 2 because you're figuring one wire out and one wire returning giving a total distance of 260 feet, be it 120 volts or 220 volts. If you want I can get you the factors that play into the voltage drop formula.
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That #4 sounds like a good plan, considering how he manages to play with so many motor driven toys at once. Most problably he'll be using that compressor for doing his grinding, and while it's trying to keep up, he'll then jump back to welding....
Now, just generally, what do you mean by 'factors'? Besides the diameter and sharp bends, what else could there be?
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VOLTAGE DROP HAS TO DO WITH THE TOTAL LENGTH OF THE CIRCUIT - ONE WIRE OUT, ONE WIRE RETURNING - CO-EFFICIENT OF EXPANSION, RESISTIVITY OF THE WIRE, SIZE OF THE WIRE IN CIRCULAR MILS, COPPER LOSSES ETC. SHARP BENDS HAVE NO PLAY IN THE CIRCUIT. BURIED OR IN FREE AIR ETC. The theory part I wouldn't worry about just remember that at 100 feet there's a reduction of total voltage of 7.2 volts. By increasing your wire size - you start out at 100 amps you want 100 amps at the load.
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Bob, was thinking about feeders and I remember doing a job in Lake placid. What we used for feeders for long runs was type MC cable with a poly covering on the MC cable. This went direct burial about 16 inches down, didn't have to be in concrete or sand - regular earth was ok - inspector approved it. There's the feeders and a reduced neutral in it along with a continuous copper ground in it.
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