# Electrical questions--Power to barn



## Blackbird (May 12, 2008)

I want to run power from the house to the barn. I was thinking about running a feeder from my 200A service panel to a subpanel (100A) in the barn going underground through conduit from the house to the barn. At present I was thinking that something like aluminum 2-2-2-4 cable should be sufficient.

My questions:

Can I use a SER cable if I put it in conduit? I know it's not permitted for direct burial, but can it be used in conduit that is permitted for underground use?

I've seen what is referred to as mobile home feeder, which is rated USE and so can be used underground. But my residential code book says that USE can't be used "inside buildings." Does that mean not at all, anywhere inside? Can I run it from where it comes into the house to the service panel? Is that considered "inside"?

I've also read somewhere that type USE-2 CAN be used inside--but if it is in conduit? Is this right?

If I can't use type USE cable inside, do I have to make a transition somewhere? E.g. at an external junction box? 

This stuff confuses me.

Jim


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## DaleK (Sep 23, 2004)

If you're that confused already, get an electrician to do it right the first time.


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## cfabe (Feb 27, 2005)

You cannot use SER cable underground at all, conduit or not. Here's the code reference from the 08 NEC:
338.12 Uses Not Permitted.
(A) Service-Entrance Cable. Service-entrance cable (SE) shall not be used under the following conditions or in the following locations:
(1) Where subject to physical damage unless protected in accordance with 230.50(A)
(2) Underground with or without a raceway
(3) For exterior branch circuits and feeder wiring unless the installation complies with the provisions of Part I of Article 225 and is supported in accordance with 334.30 or is used as messenger-supported wiring as permitted in Part II of Article 396


You're right that the USE cable is supposed to terminate in a box outside the house. Like if you were installing a service and would run the USE to the meter mounted on the house. So to be by the code you'd need a j-box on the outside of the house to transition to another wire type. That said, lots of guys get away with just running it to the panel if the panel is on an exterior wall. 

338.12 (B)
(B) Underground Service-Entrance Cable. Underground
Service-Entrance Cable (USE) shall not be used under the
following conditions or in the following locations:
(1) For interior wiring
(2) For above ground installations except where USE cable
emerges from the ground and is terminated in an enclosure
at an outdoor location and the cable is protected in
accordance with 300.5(D)

2-2-2-4 will only be okay for short distances at 100A. You have to do the voltage drop calculations and keep your drop under 3%. There's lots of calculators online that do the calcs but beware that they don't all agree. If any doubt, going to the next larger size won't hurt (well, only in the wallet).


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## Old Vet (Oct 15, 2006)

Blackbird said:


> I want to run power from the house to the barn. I was thinking about running a feeder from my 200A service panel to a subpanel (100A) in the barn going underground through conduit from the house to the barn. At present I was thinking that something like aluminum 2-2-2-4 cable should be sufficient.
> 
> My questions:
> 
> ...



Your local codes and your power company will have the answer to those questions. It varies from location to location but here I would use 0 copper wire for 100 amps either over head or buried in a conduit. The trouble with Aluminum is that it expands a lot and the connections become loose and will ark. That is why it is no longer used in buildings at all. Is your service out side your building if so then you can use it to the barn as long as it is outside and doesn't come into the building. But copper clad wire is not that expensive and you can use smaller wire than aluminum.


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## cfabe (Feb 27, 2005)

Old Vet, I'm not sure if you have priced wire lately but for running power to a barn copper is going to be at least 3 times as expensive as aluminum. Aluminum is used all the time with no problems, you just need to use the proper oxidation paste on the connections and torque them to spec.


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## tyusclan (Jan 1, 2005)

cfabe said:


> Old Vet, I'm not sure if you have priced wire lately but for running power to a barn copper is going to be at least 3 times as expensive as aluminum. Aluminum is used all the time with no problems, you just need to use the proper oxidation paste on the connections and torque them to spec.


I hear this all the time, and I still won't use it. 

The cost is a small price to pay for me to have peace of mind.


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## Old Vet (Oct 15, 2006)

cfabe said:


> Old Vet, I'm not sure if you have priced wire lately but for running power to a barn copper is going to be at least 3 times as expensive as aluminum. Aluminum is used all the time with no problems, you just need to use the proper oxidation paste on the connections and torque them to spec.


I am sure that you can use it but I wouldn't. I would use copper clad wire in all of my own wiring that I do by my self or hired done. You use proper antioxidant paste and tighten the post on every connection that I do. I am sure the code is to use aluminum only above ground but you can do what ever you want to. It is not my house that may burn down or loose power to it. Even the power company uses aluminum for service above ground and then change it to copper before it goes into the weather head.


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## rambler (Jan 20, 2004)

You might want to have a pro do this for you, sounds like you are out of your element, & getting the backbone wrong, you can set up quite a trap for someone or some critter down the road....

You failed to tell us the distance you wish to run the power? That makes a big difference on wire size.

Direct burial aluminum is the common thing around 'here', I know in other places folks turn up their nose at either aluminum, or at direct burial, but you'd be an odd duck to do it any other way 'here'.

--->Paul


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## Ozarka (Apr 15, 2007)

I wish I had a dollar for every foot of "direct burial" alum. wire I have dug up and replaced with wire in conduit for some feller who wanted to get by cheaply. Of course if you look at the fine print it says to bed it in sand and no one around these parts ever did. I have heard that there are regions of this country where there ain't no rocks but that is prob'ly gub'ment propaganda. Meanwhile, here in the ozarks we'uns have learned to use conduit. The rocks are so thick here that they breed during the winters and make lil' rocks. That's why the state capitol is named that...


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## tyusclan (Jan 1, 2005)

Ozarka said:


> I wish I had a dollar for every foot of "direct burial" alum. wire I have dug up and replaced with wire in conduit for some feller who wanted to get by cheaply.


Yep.

When it comes to electrical "cuttin' corners" to "save money" rarely does either. You wind up spending way more of both time and money later on.


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