Size wire going to pole barn panel?

   / Size wire going to pole barn panel? #1  

Cox89XJ

New member
Joined
Mar 6, 2012
Messages
12
Location
Belvidere TN
Tractor
DX24E Farmall
Pole barn is 145 feet from the main panel. I was hoping that # 2 aluminum would be okay with a 90 amp breaker feeding the sub panal at the building?
 
   / Size wire going to pole barn panel? #2  
Really depends on the loads you plan to be putting on it. Are you going to have a bunch of machines running at once or just a few lights, etc. I have #6 Going to my old shop and no issues. Lights, air comp., welder etc. Of course, my shop is only 30feet from main.If you aren't using all at once, works. Whether or not it is code in your area, who knows?
 
   / Size wire going to pole barn panel?
  • Thread Starter
#3  
It's going to have to be inspected. Loads will just be my 20 amp 220v air compressor, 50amp welder and lights and plugs. 90 amps will do it. I just don't know if # 2 aluminum will pass inspection that far from the main panel?
 
   / Size wire going to pole barn panel? #4  
If I recall, for aluminum you go next size larger to obtain equivalence of copper wire.
ex; #10 alu = #12 cu.
All being said, I suspect that you only need about #6, remember your welder wont be drawing all that many amps. (just look at the lead they install, #10?) also do you intend to use 3/16 rod and weld 100% time? If like most hobbyist welders I bet most of your welding will be with 1/8" rods and never at 100%
Sure your welder can run @ 230 amps but most 1/8 rods use in the 100 amp range.
No matter what you do just make sure you use the correct breaker sized for the wire.
 
   / Size wire going to pole barn panel? #5  
I would recommend going to 1/0 wire, and you should be able to go to a 100a breaker. That way, if you and a buddy are working, you can run a chop saw, an air compressor, welder, and lights all at the same time. 1/0 copper wire is rated at 150 amps. Going one smaller for aluminum is 125 amps. Going 145' you might consider a 100 amp breaker. I think #2 al wire with a 90a breaker should be fine as well, I just like a little wiggle room.
 
   / Size wire going to pole barn panel? #6  
Pole barn is 145 feet from the main panel. I was hoping that # 2 aluminum would be okay with a 90 amp breaker feeding the sub panal at the building?

Cox,

Are you running overhead, direct burial, or in conduit. That equates to 3 different wire sizes by code. The inspector does not care how you load a circuit only that the system will support the allowable wire/breaker capacity. In my area 100A is the minimum feeder size for any type garage/shop remote from the main panel and the load center has to have a main breaker. Check the local code requirement on grounding/bonding as this varies by jurisdiction from the national code. If the shop is a steel frame bldg or has a metal skin the frame and skin have to be bonded to the electrical ground system, same with water and gas piping

Get one of those DYI electrical manuals at the big box store, it will have the wire ampacity charts and other good info to keep you out of trouble and SAFE.

#2 aluminum triplex cable will get you 100A any of the 3 ways. In conduit or direct burial make sure it is approved for that use and wet locations. Because you are going 130 feet, probably closer to 140-150 feet once you add the ups and downs you need to go to #1 for full capacity w/o any measurable voltage drop. Don't forget the anti-oxidant splicing/terminal compound for that aluminum. Myself I would pay the difference for copper, your choice. Alum is pretty standard for arial installations due to weight, the poles can be further apart (another wrinkle to work out).

If you do not go with a 100A 240V now you nwill kick yourself hard somewhere down stream. Things always grow over time as we find out when we have to redo to larger later.

Ron
 
   / Size wire going to pole barn panel?
  • Thread Starter
#7  
Thanks for the replies. I know 90 amps will supply all the power I need. What is questionable is 145 feet and the # 2 aluminum THWN wire buried 2 feet deep in 2 inch Sch 40 PVC conduit.
 
   / Size wire going to pole barn panel? #8  
   / Size wire going to pole barn panel?
  • Thread Starter
#9  
   / Size wire going to pole barn panel?
  • Thread Starter
#10  
Rough in passed inspection. Inspector agreed with # 2 aluminum wire and 90 amp breaker feeding from power pedestal, since it's a 145 feet run. He said I also needed a 90 amp breaker in the building breaker panel also. I said okay, because he is the one I got to please. I had a 100 amp breaker installed in my 100 amp panel but, I was thinking I could have even used a 200amp breaker panel in the building because the 90 amp breaker in the power pedestal is protecting the # 2 aluminum wire? Another thing he said for me to do, was pour concrete over the conduit where it entered the building because it was less than 18 inches deep. The ditch was 24 inches deep, but where it went into the building I had not put my 90 degree elbow quite deep enough. Well 4 bags of sak crete and some water took care of that.
 

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