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hairba11 · Nov 24, 2008, 09:45 AM

Built a pole barn in the back yard, was going to upgrade the house service and run from there, but thanks to the county I am running separate service.

I have the 3" conduit, I know I need to leave 35' coiled at the bottom of the utility pole, and want to run about 5' inside the barn to get to the main panel.

With a 320' run, and a 400 amp service, what gauge wire should I run?

I'm thinking 0000 aluminum could do it with about a %10 or %11 voltage drop, but I don't know if it will be pushing it on the distance.

stanfortyman · Nov 24, 2008, 09:50 AM

I would STRONGLY suggest you get a professional to do this job.

For the looks of your post you would be best served doing this.

4/0AL is not even close to big enough.
And 10%-11% VD is NOT acceptable for a service!

hairba11 · Nov 24, 2008, 10:03 AM

Why, its just electricity.

And only 240 volts.
480 is where I start to get concerned. 720 is where I call for help.

The power company is going to install the meter, and hook it to the transformer.

I just have to get appropriately sized wire in 3" conduit, 2' underground.

I have the conduit, I have the trench dug, now I'm just trying to figure out how big I have to go with the wire.

hairba11 · Nov 24, 2008, 10:19 AM

OK, Butler Supply agrees that 4/0 Al will be too light, but they don't know whether 250 or 350 would carry it.

350 may not fit in 3" pipe. Yippie.

stanfortyman · Nov 24, 2008, 10:25 AM

Originally Posted by hairba11

Why, its just electricity.

:rolleyes:

At least it's not rocket science. Then you'd be in trouble.
Good luck with your project.

hairba11 · Nov 24, 2008, 10:32 AM

Thanks stanfortyman,

It is just aggravating that nobody will tell you anything because of liability.

I'd rather know how big I need to make the wire than to undersize the wire because nobody would tell me I was wrong.

stanfortyman · Nov 24, 2008, 10:51 AM

What you don't get is that there is WAY more than the wire size that you need to know.

A basic 200A service upgrade is one thing. A 400 amp underground is another thing entirely.
If you have to ask an internet message board something as basic as what size wire to use what else are you not knowing?.

hairba11 · Nov 24, 2008, 11:18 AM

What I don't know could fill a warehouse.

I called one of my friends who does general contracting, and he is calling the electrician they use, and I'll go from there.

:edit:

Ouch. Got the wire size. I can get it done for $2000 in aluminum, and $3200 in copper.