Electric to Barn


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Old 03-18-19, 11:10 AM
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Question Electric to Barn

I want to run electricity to my barn. About a 70ft run underground in metal conduit. Already have barn wired for multiple lights and multiple 120 outlets. Which wire will be best to use? And do I have to put a GFCI in the barn?
 
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Old 03-18-19, 11:59 AM
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What kind of tools and appliances will you be using in the barn? Any heating or cooling equipment?

All receptacles in a barn require GFCI protection. Lighting does not.

It's pretty uncommon to use metal conduit for an outbuilding as you need to use threaded galvanized steel (IMC or RMC). These are expensive and difficult to work with compared to PVC. The only situation where it makes sense is if you really can't dig to 18" to plant the PVC pipe due to bedrock. Threaded steel can be buried at 6" depth.
 
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Old 03-18-19, 02:11 PM
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If doing conduit from panel to panel I suggest aluminum XHHW-2. If $$ is no object then use copper THHN/THWN-2. Copper will cost almost three times the cost of aluminum.
 
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Old 03-20-19, 06:38 AM
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Thanks. When I said metal conduit, I was referring to IMC. Yes, there will be a couple of air conditioners and an air compressor in the barn. Would that change what wire to use?
 
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Old 03-20-19, 07:07 AM
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It would increase the size of wire I use with compressor motors as they have a big start-up load. I would recommend a 60A service to a subpanel in the barn using #2-2-2-4 or #2-2-4-6 aluminum MHF cable. This cabled conductor is about $1.25/foot and can be installed in 1-1/4" conduit. It's a little bit oversized, but about the same price as a smaller copper circuit, but allows future flexibility.
 

Last edited by ibpooks; 03-21-19 at 05:10 AM. Reason: cable gauge
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Old 03-20-19, 01:21 PM
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Just to clarify the Mobile Home Feeder (MHF) in 2-2-2 has a #4 ground, not #6. Being a direct bury preassembled twisted cable makes it stiffer and tougher to pull through conduit than using individual conductors of XHHW-2. Even though 2-2-2-4 MHF meets the fill requirement for 1.25" conduit, I highly suggest not to use smaller than 1.5".
 
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Old 03-20-19, 02:40 PM
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For the cost, I would recommend using PVC instead of IMC. 1 1/2" IMC is going to cost you $40+ per 10' stick with no real benefit other than less digging.
 
 

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