Wiring a Pole Barn

rocky · 01-25-2006, 03:04 PM

I am going to build a pole barn and would like some advice on what wire to run to it. I have a 200 amp service box just for the barn (a seperate 200 amp box going to the house) and want to trench in wire to the barn. At this time I only plan to use 110 tools (table saw, power tools, etc) but want to bury the right wire now in case down the road I want to use a 220 hook up for a welder or whatever. What wire should I run....is 10-3 w ground ok or should I go 8-3 or even 6-3?

jbfan · 01-25-2006, 07:29 PM

200 amps for a pole barn is a bit much. How far are you trenching? As a min. you will need 2 ought wire and 2 inch conduit. How big is this barn? Are you going to add heat and air? Kitchen? Bathrrom?

rocky · 01-27-2006, 11:29 AM

It is going to be a 30'x40' and I will be trenching about 125'. Don't really know what my plans are down the road, right now just a workshop and storage. Just want to put in enough the first time just in case. I don't see adding a bathroom or kitchen, at most just using some 220 for equipment like a welder or the like. I want to put in enough but at the same time I don't want to overkill either. The 200 amp service box is already there....was cheaper to put it in when the house was built last summer.

powrus · 01-27-2006, 05:33 PM

Just like Jbfan said for the size of the cable. Your issue probably will not be the size of the main breakers within the new building, but rather the distance (125 ft) from your existing power source. Bad news, but you're gonna have to consider a new "feed" to your new building.

Speedy Petey · 01-28-2006, 10:17 AM

125' is not that far at all for a feeder. The issue is where are you going to terminate that 2/0cu (or 4/0al) in the main panel?
Do you have a feed-through panel at the house? Either way, to get 200 amps to the shop would require larger than a 200 amp service to the house.
You can use less than 200 amps to the shop and still use the 200 amp panel but this is not normally recommended.
IMO you should use 2" conduit all the way and run #4cu (or #2al) as a 100 amp feeder to the shop.

rocky · 02-01-2006, 09:52 AM

When I built my house last summer I had the utility co set two seperate 200 amp service boxes (they both feed into one meter) on a post that is 100' from the house. One service box feeds into the house. I now want to trench in wire (approx 125') from the second service box to a shed I am going to build in March. Will a 6/3 w ground outdoor wire cover most applications down the road? Also, if I use outdoor wire....do I need to use conduit, why can't I just bury the wire 2 feet deep?

Speedy Petey · 02-01-2006, 07:03 PM

What is a "serivce box"? Is it a meter pan? Disconnect? What size wire is feeding it?

You can feed the barn with 100 amps or more. For 100 amps you need #2al or #4cu. For 200 amps you need 4/0al or 2/0cu.
I will add a STRONG recommendation for conduit the whole way.

rocky · 02-02-2006, 02:35 PM

Please excuse me, I really don't know much about electrical work and terms. Be assured that I will get a professional to hook everything up for me, I just want to get a grip on what wire to bury. What I am calling a service box is the box that the electric company installed on the post.....they also set a transformer next to it....I assume a connection is made from the transformer into the service box and then a connection is made to the house (underground approx 100'). They installed a second service box on the post whick I also assume is connected to the transformer...this is the box I want to connect to the shed approx 125' away. I have been told that a 10/3 with ground wire (this is the way is is identified at my local builders supply store) will handle a 220 hookup in the shed? Also....if I do not plan to run any additional wire to the shed in the future, why do I need to use conduit if the wire I buy is outdoor wire? I don't understand what #4cu or #2al relates to the 10/3 with ground wire (3 strands of 10 gage wire with a 4th ground wire) I find in the store?

Speedy Petey · 02-02-2006, 07:34 PM

You CANNOT use 10/3 for a service. The #4cu & #2al is just that. #4 gauge copper or #2 gauge aluminum conductors. As opposed to #10.

I'm still not sure what your service box entails. Is this just a meter pan, or is there a disconnect breaker out there? This is one of the main things we need to clear up.
Can you possible post a pic of the service post the POCO provided?

To be honest, if you are considering #10 to feed the whole pole bard, and do not know what the conductors I was referring to are, I really feel you would be better off just letting an electrician doing the whole thing. Either that or have him come out and explain exactly the things you can do prior to his coming to complete the job.
Without knowing exactly what you have and/or seeing it, it is hard to get a grip on what you could possibly do yourself.