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# Wiring length for outside 50 amp circuit

#1
07-14-11, 10:10 AM
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Join Date: Jul 2011
Location: USA
Posts: 2
Wiring length for outside 50 amp circuit

I'm planning to run a circuit about 700 feet to a barn. 50 amp.

How far should I go to have max voltage and what needs to interrupt the cirucuit? A junction box every so many feet? And which gauge? The wiring will be buried in pvc pipe. Thanks , mary

#2
07-14-11, 10:31 AM
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Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,296
When you run a circuit a long distance you need to increase the size of the wires to compensate. It is best not to have any interruptions in the circuit between the main building and the barn.

Based on my calculation for the two hots and neutral wire, you should use copper wiring no smaller than #1 AWG or aluminum wiring no smaller than #2/0 AWG. The ground wire can be #6 if copper or #4 if aluminum. (Prepare for sticker shock) In either case you would want PVC conduit at least 2" or a direct burial cable like URD or USE-2.

Are you sure that you need a full 50A at the barn?

#3
07-14-11, 04:06 PM
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Location: Twin Cities, MN
Posts: 11,984
Is the barn closer to the utility's power lines? Maybe you could get another service installed just for the barn.

#4
07-17-11, 11:59 PM
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Join Date: Mar 2006
Location: NE Wis / Paris France{ In France for now }
Posts: 4,808
700 feet is pretty long run IMO there is the other suggest is use the transfomer to boost the voltage to 480 volts so you can use smaller conductor the cost of the conductor for that long can be justifed over the transfomer cost { this part it will be wise have a electrician assist you if you go this route }

So if you do go this route you will need either 10 or 15 KW { depending on how you set up the barn plus will need welder or not ( if welder then increase to 15 KW )}transfomers the cost of the single phase transfomer on state side I am not sure due I am used with European prices so again have the electrician assist you on this one the cost to use the transfomer plus smaller conductor may be cheaper than use very large 1/0 Alum on that distance { If I did my figures correct on state side you should able use #6 CU or #4 alum }

If you do go that route just make sure you put a warning sign next to the conduit or on the conduit say " 480 volts " so that way someone be aware with it.

Merci,
Marc

#5
07-18-11, 08:43 AM
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Join Date: Dec 2010
Location: Cressona, Pa, USA
Posts: 2,546
If you do go that route just make sure you put a warning sign next to the conduit or on the conduit say " 480 volts " so that way someone be aware with it.
I've seen orange stickers that you can stick directly to the conduit/boxes.

#6
07-20-11, 04:06 AM
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Join Date: Jul 2011
Location: USA
Posts: 2
Thank you everybody,,, i'll check with my local electrician too.! mary

#7
07-20-11, 10:20 PM
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Join Date: Mar 2006
Location: NE Wis / Paris France{ In France for now }
Posts: 4,808
Great.,, Just keep us posted how it come out.

Merci,
Marc

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