Electrical Service

[Northstar9126]

I am looking to build a pole barn / workshop and am looking for some help determining what I should use for the electrical service. The high demand items I am currently using include a 220 volt table saw, 220 volt compressor and a Millermatic 210 welder. The distance from the meter where the service breakers are to the pole building is 220 feet. How many amps should I run to the new building and what gauge wire, both aluminum and copper for price comparison, would you recommend. Thanks

 

[v8dave]

Run a 100 amp service. You will never regret it. But, it'll take #1 copper to get it. Fall back would be to run 50 amp service with #4 copper. Do a google search and you can get lots of answers. Here is one wire size table.

With a run of 200'+ you'll have a fair drop in voltage when any big motor (air compressor) starts up. Over kill on the basic service (i.e., 100 amp service) will help reduce this problem.

 

[rambler]

If it's a one-man shop, 60 amps will serve you, but do not skimp on the wire size, you do not want excess voltage drop. There are many voltage drop calculators on the web, enter your info & voltage drop really has to be less than 5, and less than 3 will help your motors run longer.

If more than one of those items is running at one time (2 people using the big toys) and you have the power available, 100 amp or more might be better.

--->Paul

 

[LarryD]

I'm gonna go with v8dave on the 100 amp service, I wouldn't go any lower.

I just helped a friend run a new circuit for his welder (Miller Matic 350P) and it took a 90A breaker, although the wire was sized for 70A. Derated by manufacturer so OK.

Unless you plan on getting high HP (3-5) tools, 100A should be a good value for you shop.

 

[deere755]

I am not an electrician but I just got done with wiring my shop. I had to run about 70 feet from the meter to the shop and I used #1 copper and a 100 amp service. I used all 12 gauge wire for all the outlets and lights. I am glad I did.

 

[flusher]

I have the same setup as you, garage/shop about 250 feet from my outdoor load distribution center (= weatherproof circuit breaker box mounted on a plywood board supported by galvanized fence posts).

Installed 100 amp breakers in the load center and ran #1 copper cable underground in PVC conduit. Use 50amp breakers in the garage for my 230V stick welder. All the other stuff there runs on 117V/20amp circuits.

 

[rambler]

</font><font color="blue" class="small">( I have the same setup as you, garage/shop about 250 feet from my outdoor load distribution center (= weatherproof circuit breaker box mounted on a plywood board supported by galvanized fence posts).

Installed 100 amp breakers in the load center and ran #1 copper cable underground in PVC conduit. Use 50amp breakers in the garage for my 230V stick welder. All the other stuff there runs on 117V/20amp circuits. )</font>

For that distance, the voltage drop calculators show you shoulda used 1/0 copper wire. Tho #1 wire is good for 90 amps at that distance, so likely not ever a problem, you are marginal.

Distance makes such a difference on wire size. At 70 feet, as someone else had, #6 wire would be good enough for 100 amps!

http://www.elec-toolbox.com/calculators/voltdrop.htm

--->Paul