Running electric to a barn


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Old 06-15-18, 06:21 AM
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Running electric to a barn

Hello, Iím looking to run power underground to a barn. I need to know the best wire to use and what route to take. Itís a 200amp main service coming to the house, from the house Iíd like to add a 60 amp two-pole breaker to power a sub panel in the barn that will be used for lighting and some power tools. The distance from the barn to the main panel is right around 200í. The main panel is on the exterior of the house, but the wire will need to run into the basement/crawlspace (more of a cellar really, not livable or used space) to get to the panel as that is the most direct route. What wire would be acceptable for this use, and is there a problem with running the wire into the house?
 
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Old 06-15-18, 06:26 PM
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Hi,so if this run will be entirely above ground ?
Geo
 
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Old 06-16-18, 05:10 AM
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No, it will be run below ground from main panel to barn.
 
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Old 06-16-18, 06:03 AM
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Inside the house I would suggest running a cable unless it is easy (fairly straight) to run a conduit. Then where it exits the house install a box and convert it to PVC conduit and run thhn/thwn conductors underground to the barn. Your other option would be to run UF the entire way (direct burial) but the cable would still be required to be protected when not in a wall (studs or joists) or 24" underground.

I just remember that you may only have no more then 360 degrees worth of bends in the conduit run, The conduit must be installed completely before pulling in the wire, and must be buried minimum of 18" down.

At 200' you may also have voltage drop issues depending your expected load. Many people mistakenly calculate voltage drop by the full rating of the breaker or the sub panel. This is not correct as very rarely is a feeder used to full capacity. If you are really only going to use some lights and light power tools you would likely be just fine with #6 copper wires. However if you think this could turn I to something more then you should consider upsizing the wire to compensate for voltage drop.

I have a horse barn at my house about 220' away and I ran #8 thhn in conduit connected to a 50amp breaker. The barn has lights, a shallow well, and some heaters to keep the water from freezing. I have never had an issue with voltage drop. Just some food for thought.
 
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Old 06-16-18, 08:19 AM
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Would an aluminum 2-2-2-4 mhf feeder be sufficient? I know it will have to be in conduit inside the house.

I plan on running pvc conduit the entire run underground.
 
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Old 06-16-18, 08:46 AM
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I would run individual conductors, if you are using PVC, that 2 2 2 4 is way over sized # 4 THWN/THHN would be plenty IMO.
Geo
 
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Old 06-16-18, 09:02 AM
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#4 is almost $1 per foot and I need 4 conductors thatís $4 a foot. He mhf is only $1.43 per foot. Copper is too expensive for the length Iím running
 
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Old 06-16-18, 09:17 AM
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You could use aluminum XHHW #3 0r #2 for three of the wires and #6 aluminum for ground. (Upsized based on 200 foot run.)
 
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Old 06-16-18, 09:49 AM
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What is the point of installing a subpanel feed with 60 amp breaker expecting that the full 60 amps will be only rarely needed and that significant voltage drop will be suffered near or at the full 60 amps?

When the full 60 amps is drawn, chances are that it will be for just a short period of time but the draw will be in connection with something that is very sensitive to voltage drop such as a motor starting up.

IMHO no, you would not base the feed capacity (in terms of wire gauge) on the sum of the ratings of the breakers in the subpanel but yes you should select the wire gauge to provide the full number of amperes which the circuit is described as providing and probably protected for not subject to brownout conditions voltage drop..

No. 4 copper or #3 aluminum would be right for 60 amps here.
 

Last edited by AllanJ; 06-16-18 at 10:49 AM.
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Old 06-16-18, 11:05 AM
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[What is the point of installing a subpanel feed with 60 amp breaker expecting that the full 60 amps will be only rarely needed
For the same reason you install a 200amp service in a house never expecting to get even close to the 200 amps. If you expect to get close to the maximum capacity of the panel you should be installing a larger panel/feeder.

I have only seen a few items that are affected by voltage drop, and that drop was greater then 20%. Most of them have been UPS backups or very sensitive electronics.

All that said, I would agree with running large wire is a good idea. 2-2-2-4 is fine as it might be more readily available at the home store. You could then upsize that breaker if you choose. You are really limited by the materials you can get locally.
 
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Old 06-16-18, 02:46 PM
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I appreciate all the help. Would a 2-2-4-6 work for this application? Itís easier to get and cheaper (but I can still get 2-2-2-4 no problem). And Iím thinking 2Ē conduit?
 
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Old 06-16-18, 03:59 PM
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Would a 2-2-4-6 work for this application?
It should but it depends on the 120v loads.
 
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Old 06-16-18, 07:06 PM
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You may want to check prices at an electrical supply house if there one near you, prices are MUCH higher in the big box stores, at least around here.
Geo
 
 

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