Running power underground to my pole barn

[mmcmac]

I live in Springfield, Missouri and I want to run power underground to my pole barn which is about 125 feet from my shop. I have 50amp service in the shop. I have a box on the outside of my shop that has 2-40amp breakers in it. All I want in my barn are 3 outlets and 2 lights. I don't foresee ever needing more than this. I have read a thousand different opinions of what I need in the way of wire. I know that I need UF and I plan to bury it in a conduit. Question is, what is enough? Will 12/3 UF-B/WG do the trick? I plan to hire an electician to actually hook everything up, but want to have the wire already buried to avoid that expense. Hope somebody can help me clear all the opinions with facts. Thanks in advance for your help!

 

[theoldwizard1]

If you want 15A in the barn you are going to need #8 cooper. You can push that to 20A, but will be slightly over the 3% voltage drop recommendation (it is a recommendation; I would do it). You could also use #6 THWN aluminum. Which ever you choose, you will need to splice some 12-2 on to it so you can attach switches, outlets, lights, etc. Splicing aluminum to copper is acceptable if done correctly !

UF-B can be direct buried (24" down). I recommend schedule 80 plastic conduit from the bottom of the trench (use a "sweep" type elbow there) up to the elbow going into the building. If you choose to use #6 THWN aluminum, it would require conduit from end to end, not just in the trench.

If you don't have an electrical panel in the shop you are likely going to need one installed.


EDIT : If you have any kind of livestock in the barn, I highly recommend running EMT (metal conduit) to EVERYTHING ! Much less chance of them "nibbling" on it !

 

[pattenp]

Little vague on your needs. What do you foresee the 3 outlets being used for? What are you going to use for the 2 lights. What do you think the combined amp load will be in the pole barn at any one time? The existing panel on the shop has two 40A breakers. Are you going to put in an additional breaker for the pole barn or are you saying you are going to add the pole barn circuit off one of the existing 40A breakers? Do you just want 120V or also 240V available?

 

[mmcmac]

Thanks for the reply. The outlets will only be used for a couple of box fans. The lights will only be one bulb fixture and a flood light on the outside. All of these could be on at once but nothing else. I only want 120v.

 

[theoldwizard1]

Thanks for the reply. The outlets will only be used for a couple of box fans.

Hmmm ... Horses ? I have a friend who has horses and their "run ins" have box fans. They buy all that they can find at yards sales and, if necessary, but cheap ones from Walmart. They last about one summer and are cheap. The horses love them !

 

[pattenp]

If all you want is 120V and because of the distance you should run 10/2 UF-B. Put it on a 20A breaker from the shop and split it up from a junction box in the pole barn to your outlets and lights using 12/2 NM-B. If you use a 20A GFCI breaker at the shop then the UF cable can be buried 12 inches. If you use a regular breaker then the UF needs to be buried 24 inches.

Edit: If you put it in PVC conduit with using a regular breaker it needs to be buried 18". The 24" is direct bury.

 

[tankd0g]

I just ran 100ft of 4/3 ACWU90 direct burial and it was cheaper than 6/3 copper and conduit, like less than half the price cheaper. If cost is a concern you might want to look into aluminum direct burial.

 

[pattenp]

ACWU90 is a Canadian product. I don't think it's available for use in the US market. The OP could use some #8 aluminum THHN/THWN or XHHW in conduit.

Edit: I just checked on this and there is a US product of the same type and it is Armorlite-MC PVC jacketed. This may be a good option. The copper is..http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet162
The aluminum is .. AlumaFlex http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet265

I just ran 100ft of 4/3 ACWU90 direct burial and it was cheaper than 6/3 copper and conduit, like less than half the price cheaper. If cost is a concern you might want to look into aluminum direct burial.

 

[theoldwizard1]

If all you want is 120V and because of the distance you should run 10/2 UF-B. ...

I rounded the length of the run up to 150' which is why my calculator came up with #8 (8/2 UF-B).

 

[Aceman]

Don't forget a disconnect....a snap switch would be fine.

 

[pattenp]

Good point. That's the benefit of having several well experienced people looking at these post. Helps preventing things from slipping through the cracks.

Don't forget a disconnect....a snap switch would be fine.

 

[mmcmac]

Thanks to everyone for the responses! This helps me a lot! It seems like you are all on the same page and that makes me feel good about going forward with this. One additional question though, I'm not familiar with a snap switch. I'm sure the electrician that I hire will know, but I'm just curious. Thanks again folks!

 

[Charles (in GA)]

A snap switch is nothing more than a heavy duty, appropriately rated "light switch".

A 30 amp, double pole "light switch" is permitted by code for this type of installation. The switch becomes the main disconnect for the building, everything else splits off after that.

http://www.homedepot.com/p/Leviton-...ch-White-R62-03032-2WS/100356941#.UlWxRNK-2uI