Running electric to my barn

Old 04-22-04, 09:06 AM
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Running electric to my barn

I am building a barn about 400' behind my house. My intention was just to run 12 gauge underground wire out to it fron the house. Someone told me that is too far of a run.
Is that too far? Could I run 10 gauge? What is the maximum distance I could run 12 gauge wire?
Old 04-22-04, 09:15 AM
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I am not intimately familiar with voltage drop calculations. However, I do know that 12 gauge wire won't cut it for that distance, at least not at any significant load.

I used an on-line calculator I found, and it told me that you needed #6, which seems large to me, but may not be. Let's see what one of the pros says.
Old 04-22-04, 10:14 AM
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It really depends upon _what_ you want to be able to run in your barn. If you just want to run a single 100W light, then running 12ga 600 feet is just fine. If you want to run a 5A circular saw, then 12ga will be _terrible_; the saw will have lots of trouble starting, and will stall very easily. If you want to run something larger, then 12ga could possibly even damage the equipment you are running, because the voltage drop would be so bad.

Digging the trench for the 600 foot run to properly bury the wire is a big expense; so you should figure out what you want to be able to run out at the barn, and then report back here so that we can suggest what size wire to use and how you should run it.

Bob, on the voltage drop calculation, if you want to run a 15A 120V load, and limit yourself to a 5% voltage drop, then you actually need something between 6ga and 4ga wire; your results are right in the correct ballpark.

Old 04-22-04, 06:36 PM
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Mark, post back with some kind of indication of what you will be using out in that barn and we can offer further help. But 400 feet is indeed a very long ways and the solution won't be cheap if the load is other than small. You might want to consider some other choice such as a generator or a separate power supply from your power company (which won't be cheap either).
Old 04-22-04, 07:48 PM
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Years ago I ran a feed to my barn. I went with aluminum and went overhead. The installation worked fine. Like the other guys said, though, the size wire you must use depends on how much you figure your load will be. The longer the run the more you need to consider your load. Copper is more expensive and much heavier than aluminum, that's why you choose aluminum for overhead feeds. They make special connectors for the stuff and it's important to use them an both ends of the aluminum wire. Farm supply stores, at least in my area, usually have a selection of wire for feeding barns. They also should have all the special connections where you join the aluminum to copper. Wire gauges for the aluminum should also be larger. If you decide that trenching is the way to go then getting some direct bury copper wire wouldn't be out of line. If you wish to pull a significant load then you have a tall order extending a 110vac feed 400', but it can be done, you just will have to pay for large copper or larger aluminum wire.

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