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houstonbrama 04-15-2008 04:13 AM

Barn Connection
I want to run lights in my barn. Lights only. The barn is aprox 100' to 130' from the house. I have 2 spare 30 amp breakers in my house box. Can I run 10/2 wire from the house breaker box and install a small breaker box in the barn for this?

Termite 04-15-2008 10:33 AM

#10 is ok for 30 amps, but you're talking about major distance there, which could very possibly be a conductor sizing issue.

If it were mine, it wouldn't be #10, or 30 amps for that matter. If you're buying the wire and the sub-panel, you could spend a little more on wire to do it right and actually run a 60 amp or so...Something that can do more than just power a light or two.

Do you know the ins and outs of wiring a sub-panel? Not the same as the main at all. Are you burying the wire or putting it in a conduit underground? You sure you're getting the right type of wire (hint...not romex)? Are you doing it overhead (hint...not romex)?

This might be a little much to tackle unless you're well-versed in electrical. I'd suggest you hire an electrician, or talk to your local or county inspector so they can help you size conductors, float neutrals in the panel, and otherwise understand what you're doing.

jrclen 04-15-2008 10:41 AM


Originally Posted by houstonbrama (Post 116456)
I want to run lights in my barn. Lights only. The barn is aprox 100' to 130' from the house. I have 2 spare 30 amp breakers in my house box. Can I run 10/2 wire from the house breaker box and install a small breaker box in the barn for this?

With 10-2 with ground, you can run a single 30 amp, 120 volt circuit to the barn. At 130 feet you could have a maximum 13 amp load, to stay within an acceptable voltage drop, on that wire. That would give you 1560 watts of lights. You could install a single circuit breaker in the barn to protect a smaller wire running to the switch and lights. I would use a single 15 amp circuit breaker in the barn.

I will assume you will be burying this 10-2, and it is rated for burial or use inside buried conduit, such as type UF. #10 cannot be strung overhead.

houstonbrama 04-15-2008 11:30 AM

I have not bought the wire yet. I plan to bury the wire in conduit. I have nevr wired a sub panel but it can't be all that difficult. I've done quite a bit of electrical work in doors but never outside such as this.
So if I upgrade to a 60 amp breaker and sub panel at the barn, wouldn't I need like #4cu for this?

Stubbie 04-15-2008 11:39 AM

It would appear that you are trying to stay within your budget with the information you have posted. Wanting lights only. #10 awg copper uf-b or thwn in conduit will certainly do lights at that distance as John has mentioned. Only thing I would add is if you get yourself a gfci 20 amp single pole breaker (a little more expense) and your doing direct burial underground... the trench would only need to be 12 inches instead of 24 inches as mandated by your local codes. That is a good investment if your digging the trench yourself.

If you do not already have the 10/2G (be sure it has the ground wire) purchased then you could also consider these.....

If you wanted you could have the option of running those lights on a 3 way set-up allowing you to turn them off and on at the house or barn.

Another option would be to run a 240 volt multiwire 10 awg copper using your two 30 amp breakers and sharing a neutral. Then split that multiwire at the barn into 2 120 volt branch circuits. You would be able to run some gfci protected receptacles and lights this way.

Edit: My cannot use the 30 amp breakers in this set-up you must use a 15 or 20 amp double pole breaker.

houstonbrama 04-15-2008 12:18 PM

Yea, I am on a budget. I'm in the Army and just returned from Afghanistan. So the "barn fund" is not small, but it is by no means large. When you're building the barn from scratch, ya gotta save where you can. Thanks for the info Stubie. I like the idea of using the 220V idea. I hadn't thought about that.

Stubbie 04-15-2008 01:01 PM

I should mention that I have an error on the breakers. You would need to purchase a 20 amp double pole breaker, 30 amps is not allowed for lights and general purpose receptacles. These breakers are not much cost. I will correct my oversite in the previous post so as not to confuse anyone.
You will need a simple double pole snap switch as a disconnect at the barn to disconnect both the conductors of the multiwire then you can connect two 12/2 G's off the load side of the switch for your receptacles and lights. Probably will want to hit another switch so you can control your lights after the disconnect of course. The disconect will be just that... it controls the power at the barn and will be 'on' most of the time. Use a big switch box like a 4x4 with single gang cover for your disconnect and label it 'DISCONNECT". Connect both neutrals of these 12/2's to the neutral of the 10/3G. Remember the 10/3G is for voltage drop.

Remember 20 amp double pole breaker not a 30.

Thank You for your service to our country....:thumbsup:

Stubbie 04-15-2008 02:23 PM

1 Attachment(s)

Drew up a little diagram of how this multiwire will the image to enlarge

220/221 04-15-2008 04:25 PM

I would run a 50 amp circuit to a sub panel. If you are going thru all the trouble of doing it, you might as well do it right and be prepared for future needs.

Start with a 2 pole 50 amp breaker. $10

Run 1" PVC 18" deep to your barn $100........

into a 10-12 space main breaker sub panel. $60

Pull 3, #8 THWN (2 blacks and one white) and a #10 green. $200 (copper is getting crazy expensive)

Termite 04-15-2008 04:34 PM

Nothing overly difficult about wiring a sub panel, but there are some things to know. Mainly, the neutrals/neutral bar must be completely isolated from the grounds/ground bar. In most panels, this is as simple as removing the green screw that bonds the bar to the jacket, as well as any bonding bridle that connects the bars. Neutrals on one bar, grounds on the other!

Thanks for your service to our country. :thumbsup:

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