Running Power to Shop Area

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Old 12-03-14, 09:48 PM
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Running Power to Shop Area

Hi, I need to run power to my shop area. My level of electrical expertise is I can change out a breaker and that's about it and I ran some underground conduit and some wire one time and I still have the wire snake we used. There is a breaker box is on our main power pole that is about 130 feet away. What wire should I use for that distance?
Load
1) Welder - 80 amps
2) Compressor - 24 amps
3) Shop tools, lights, receptacles - 60 amps
Would I run the wire from the breaker box on our pole? Should I just do the trenching and wire pulling and let an electrician connect it or use a book to do it?
Thx
 
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Old 12-04-14, 03:46 AM
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Welcome to the forums! I can't speak for your location, but when I built my shop, I had separate underground service installed. Mine is a little further away from the house than yours, but I would have done it anyway if it were closer.

The amperage draws you mention seem quite high. Most welders run off a 50 amp circuit. Is yours an extremely heavier duty one? Most compressors can be configured to run off 240 volts, thereby reducing their amperage load in half. May be a consideration. 60 amps for shop tools is a bit high, too, but we don't know what tools you will be using at one time.

Is your shop area attached to the house? Or is it a separate building? What does the breaker box on the pole service and how large is it?
 
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Old 12-04-14, 07:54 AM
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The big question is how much are you willing to learn & study up on versus just getting it done quick? I'll throw another option out there of you hooking up with an electrician who is willing to have you do all the grunt work (trenching, conduit, wire pulling) to save labor cost; and they do the permits, material spec, and hookups.

My ballpark guess for what to do where would be to set a 100A panel in the shop, run #2/0-2/0-2/0-1 aluminum USE cable trenched 24" deep from the panel to the pole and feed with a 100A breaker. A factors that would change this would be if you plan to have multiple workers in the shop at the same time.
 
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Old 12-04-14, 08:12 AM
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I agree on the welder. . never have used one myself that had that much of a draw. Are we talking about an arc welder? How many amp welder?? If it is MIG or such, it is much less. I'm guessing you have a small 80A ARC welder. It doesn't mean it draws that much. I bet it may even be a 120V plug in?
 
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Old 12-04-14, 05:03 PM
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Thx for those replies. The breaker box is about 30 ft away from the house on the power pole and services the house with a 100a breaker, 2 60a breakers and a 30a RV outlet. I'm not sure of the box amp rating, where would I look to find that? The shop area is about 250 ft from the house.

My welder is in a shed close to where the shop will be. It is a 250 amp, 240 volt Miller Dialarc, the manual said if I want to weld at maximum amperage I should have a 125 amp breaker but I have been talking to people on our welding forum that say if most of my welding is with 1/8" rods (which it is) that 60 amps works fine, I kicked it up to 80 just in case I use some 5/32" rods for some heavier welding.
The shop is not built yet so I was just estimating amperage. I figured it was better to have 60 amps available and not need it than to not have enough. I can figure the size of the breaker after I have it built and see what it's going to draw.
Can 120v motors run off 240v? (compressor) I didn't know that.
The more I think about it, the more inclined I am to get an electrician to handle the permits and wire connections.
 
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Old 12-04-14, 05:21 PM
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Check the nameplates on all your large tools. Most can be converted to 240 volts by changing wiring in the "pecker head" or control box. Of course the plug will need changing as well. They nameplate will have dual voltage (120/240) and dual amperage (15/7.5). Amperage and voltage are directly inverse from each other. If you increase voltage, you decrease amperage. Watts will stay the same, so there is no saving on electricity bills, as such, but you will find less dragging, faster spool ups, etc with the higher voltage.
 
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Old 12-05-14, 07:44 AM
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Do you know the duty cycle on the welder? That will ultimately determine the wire size you need. The exact breaker size is a little less important for a heavy duty welder.

Do you want to use more than one tool at a time or is it a one man shop?
 
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Old 12-05-14, 08:42 AM
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Most of my welding is around the 100 amp setting which for this welder is a 100% duty cycle. It is a stick welder so the maximum continuous weld is only for the time it takes to burn one 1/8" stick. I will be getting a Millermatic 251 mig welder in the next year or so but it consumes less power than this welder.
I will be using the shop by myself most of the time but there will be times when I'm working together with someone on projects.
 
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Old 12-05-14, 09:16 AM
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Most of my welding is around the 100 amp setting
That does not tell us how many amps the welder draws. Lets say your actual voltage at the welding rod is 15 volts. At 240 volts that is less than 7 amps. Numbers for illustration only. Actual amount of amps will vary.
 
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Old 12-05-14, 12:48 PM
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At the highest setting (250 amps) it uses 30 volts. The breaker recommended in the manual for using at the highest setting is a 125 amp breaker.
Here is a link to the manual
http://www.millerwelds.com/om/o314u_mil.pdf
 
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Old 12-09-14, 11:15 AM
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Well, wondering why ray hasnt replied to my post. What I'm wondering is why you would think this welder would draw such a low amount of amps when Miller recommends a 125 amp breaker for it?
 
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Old 12-09-14, 11:22 AM
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Not a welder expert so I am not embarrassing myself again.
 
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Old 12-09-14, 01:16 PM
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Welders are a unique beast in the electrical code -- they even have their own section with entirely different wire and breaker sizes. I'll stick with my original recommendation of a 100A service with #2/0 aluminum feeder. You could put in a 125A main breaker and a 125A welder breaker if you want to crank the thing to max, but realistically a 100A main in the panel and a 100A branch breaker for the welder will work for nearly any weld job you want to tackle. As you can see from the manufacturer's instructions you can install the welder with #8 copper wire from the panel even though it has a 100A or 125A breaker.
 
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Old 12-10-14, 11:30 AM
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Thx for responding Ray! Pooks, that sounds like a good recommendation. I think for now I'm just going to run a #8 extension cord to the welder since I can move the welder to within 78' from the breaker box which will not exceed the maximum run allowed for the #8 wire and still be only 15 ft from my welding table. That way I can use the welder now and find an electrician who will work with me on this.
Thx!
 
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Old 12-10-14, 11:51 AM
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Should be ok, just make sure to stay within the duty cycle limits of the welder with that much cord laid out. You don't want to cook anything expensive.
 
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