Would like to wire barn.


Old 08-28-09, 08:46 PM
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Would like to wire barn.

I have a barn about 100 feet away from my house and would like to run some wire to it for lights, compressor, 110 welder etc. Nothing real big. I believe my compressor is 40 amp. My house has a 200 breaker box and my sone got me a 70 amp breaker box for father's day. (for in the barn) Question is,,,what wire should I use to run to the barn? I went to Home Depot and the guy there showed me some large black insulated wire with aluminum he said I should use. But costly, wow. I'd like to go some what cheaper if possible. Any ideas? Also I'm not that good with house current but not afraid to try.
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Old 08-28-09, 08:58 PM
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Hehe, he showed you the aluminum? just look at the copper and you will say wow that aluminum is cheap. He should have showed you the 2-2-4 URD cable. It is a direct burial and costs 1.08 per foot at the Home Depot in my market. The quad cable comes in at 1.10, but you will need to ground it with rods out at the barn. I would however recommend going with a 100 amp panel in the garage just to cover your bases. Voltage loss won't be a big issue especially with a 220 line at 100 feet, but 70 just cuts it close. There is always potential for upgrades in the future where in that case you would have wished you used the 100. Maybe regift it to your neighbor who maybe building a 2 car garage with lights and a couple outlets.

As far as other routes. I can't remember the prices for UF cable, but in order to get it around 1.08 a foot, your looking at maybe 12 gauge copper wire. That would be absurd for what you are looking to accomplish. The 2-2-4 aluminum will get you 100 amps to the garage and by far become the cheapest option. Remember those prices they show you for copper, are for one length, so triple that, and you have the price of just the wire per foot. Say 4 copper is .79 your in it for at least three bux with the price of conduit figured in as well. The URD aluminum is a direct burial cable like I mentioned, no conduit except for where it runs up and above ground.

Edit, I should have asked what code your working with. Around here anybody and everybody gobbles up 2 aluminum and inspectors never say a thing.

Last edited by mjjstang; 08-28-09 at 10:31 PM.
Old 08-28-09, 10:15 PM
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You are required to run a grounding conductor to your outbuilding if you are on the 2008 code. You will also need to install 2 ground rods unless you have water in the barn. Then you need to install one and bond the water pipe.

The panel you got needs to either have a main (or a back fed breaker) or only be able to have 6 breakers installed. 70 amps is the max amperage rating that can be on the sub panel. I suggest going either 60 or 100 amps due to the availability of breakers in retail markets. Most cases I suggest installing PVC conduit due to the cost of cable, but direct burial can be fine option as well. Cable must be buried 24" and PVC down 18". IF you run THHN in PVC you can run #6 copper (#10 for ground) for 60 amps and #3 copper (#8 ground) for 100 amps.

BTW - #2 aluminum is too small for 100 amps. Smallest you could go is #1 XHHW.

Last edited by Tolyn Ironhand; 08-29-09 at 08:19 AM.
Old 08-29-09, 11:51 AM
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let me expand to Toyln's comment with 2008 NEC code if you going to use the #2 alum cable you will have to use 90 amp breaker on that cable so it will be wiser to get #1 alum cable and that will slove the issue there.

The costwise between the two is not huge diffrence between the two.

Yeah if you see the price of copper you will be suprised what they cost right now I just really can't tell you the excat price of the copper conductors right now due diffrent area have diffrent price so check out in your area to see what it reflect the price there.

But one serious head up if you going driect burial cables make sure you have sand or something very soft to cover the cable and do not nick the conductors the word it mean like a small cut on the conductors just trust us you will see why in a second.
Due if you have a small nick over the time the water or any type of moisture work it way in and it can eat up alum cable like big time so just becarefull when you bury it.

Myself I rather run in the conduit so that way if you have issue with conductors it easy to pull it out and snake in the new one in.

The other thing it will be good idea to run second conduit for phone or data cable something you may want to do that down the road.


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