Running Electrical From House To New Pole Barn

[kohner]

All right folks, I have spent countless hours researching and think I understand this, but I'd really like someone to proof my electrical plan. A "Relative" was supposed to help me with this, but I think he has told me wrong already as he advised I only run 3 conductor wire instead of 4 to the sub-panel.

I have a new 40x64 pole barn that is about 60 feet from the house. I already have 2" conduit run between for the cable. From the main house panel I will have a 100 amp breaker and use 2-2-2-4 AL Mobile Home Feeder (see pic) to the sub-panel in the barn. The sub-panel at the barn has a removable bridge between the neutral and ground bars that I will remove leaving the neutral separated from the ground. The ground side is bonded to the panel. I will also run a #6 solid copper ground to 2 ground rods outside the barn.

Does this make sense? What am I missing? Where the conduit comes into the house there will be about 12 ft of cable running inside the house before the main panel. Since the cable says indoor/outdoor can I do that or does it need to be in conduit in the house? Can this cable be in conduit between buildings? I appreciate any advice. I will also be consulting an electrician before everything gets turned on, but want to get started on this.

 

[Norcal]

#2AL is only good for 90A max unless it meets the criteria allowing a 100A breaker to be used, and a feeder to a outbuilding does not.

 

[kohner]

#2AL is only good for 90A max unless it meets the criteria allowing a 100A breaker to be used, and a feeder to a outbuilding does not.

Ok, I will look for a 90A breaker to replace the 100A I was planning on using.

 

[pattenp]

MHF must be in conduit where above grade and that includes inside the building. Even though it's direct bury putting it in conduit is added insurance against damage plus makes it easier to replace if needed. Best to use 2" conduit.

 

[liliysdad]

I just laid 120ft of MHF in 2" pipe this weekend. No problem in that size PVC.

 

[wyliesdiesels]

Yeah your buddy is wrong.

Just show him the diagrams on the electrical FAQs sticky.

As to the panel, do you have a pic?

Usually the bars on each side are for neutrals and you add ground bars. It will be less messy if you have a neutral bar and a ground bar on each side.

 

[kohner]

Yeah your buddy is wrong.

Just show him the diagrams on the electrical FAQs sticky.

As to the panel, do you have a pic?

Usually the bars on each side are for neutrals and you add ground bars. It will be less messy if you have a neutral bar and a ground bar on each side.

I don't have one handy, but can get one tonight. I'm open to ordering the grounding bar for it.

 

[pattenp]

I don't know why it didn't sink in what you were saying about the bridge between the bars. As Wylie stated, use a ground bar kit. Usually the manufacturer does not suggest the removal of that bridge strap and does say to remove the bonding screw and use a ground bar kit.

 

[PWC Repair]

I ran 90a service to my shop pretty much exactly what you describe. I could only find a 70a breaker for my panel locally and I've never come close to needing all of that yet.

 

[kohner]

Thank you all for your help. I will go ahead and get the ground bar kit. I have to order it, but I did find a 90A breaker for the main house panel even if I won't ever come close to needing that.

 

[BB Sig]

What wire calculator are you using for this? If I run this through Paige Wiring's calculator I get 1/0 AL and 1 gauge for copper.

 

[pattenp]

What wire calculator are you using for this? If I run this through Paige Wiring's calculator I get 1/0 AL and 1 gauge for copper.

Something is wrong with that calculator. #2Al with a 240V 90A load at 60ft is under 1.5%VD. I find this one to be very accurate... http://www.nooutage.com/vdrop.htm

This one is okay... http://wiresizecalculator.net/

This is more detailed for input data... http://www.electriciancalculators.com/calculators/wireocpd_ver_1.html


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[alfredeneuman]

What wire calculator are you using for this? If I run this through Paige Wiring's calculator I get 1/0 AL and 1 gauge for copper.

You entered the full 100A load @60' with a max VD of 3%.
As the OP said in the post above yours
"I have to order it, but I did find a 90A breaker for the main house panel even if I won't ever come close to needing that
The calculation should be performed according to the load, not the breaker size

 

[BB Sig]

Thanks for the links!

 

[wyliesdiesels]

What wire calculator are you using for this? If I run this through Paige Wiring's calculator I get 1/0 AL and 1 gauge for copper.

Thats way overkill.

#2 al will do just fine @ 60’....