General welder input wire advice

[bcarwell]

I have a shed about 150 feet from a utility pole. The pole has a breaker panel servicing the house. I want to buy a Miller stick welder for use in the shed with a max DC weld of about 200 amps (for rare instances, mostly though I'd be at 150-180 amp settings).

A few general questions to get me in the ballpark before I start talking to electrical contractors and shopping for wire, breakers, panels, etc.

First, what size wire does it sound like I'd need for the 150 foot run from the pole to the shed ? I would not be running anything else in the shop other than a few 100 watt bulbs while welding (mostly ranch stuff- tractor mods, etc.) and think the duty cycle would be fairly normal or low.

Second, what kind of buriable electrical conduit should I be looking for for the run to carry the wire ? What's it called and is there a specific number correlating to the wire size you're running through it ?

And finally, would there simply be a subpanel and single additional breaker at the utility pole, and then another subpanel with additional breaker at the shop ?

Is there any website that gives tables of wire gauge, amperage and distance ?

Thanks for any general information on this kind of setup.

Bob

 

[gizmo]

Bob,

I think I may have a similar welder in my shop. It is a Miller Thunderbolt AC/DC 225Amp. It requires a 240VAC, 60Amp service. You will probably need to install a 100A subpanel in your shed with a dedicated 60A breaker for the welder and a couple breakers for lighting and misc. loads.

You will need to verify that the breaker on the pole is 100A with appropriately sized feed wire. You can get direct bury cable for the run from the pole to the shed and save yourself the conduit expense. The required wire size would be 2AWG for copper or 1AWG for aluminum, but you can verify this yourself by consulting the NEC tables. NEC table are available on numerous internet sites; just do a search.

You also need to verify that the full load voltage drop will be less than about 3% for the chosen wire size at 150ft. I think 150ft may be short enough that the voltage drop will not require a larger wire size, but its worth a check. Again, voltage drop calculators are available on the net.

 

[bcarwell]

Many thanks Gizmo for the quick and clear answer. I checked and the drop over 150 ft. is about 2 % so I should be good to go. Great tip about getting buriable wire to save on conduit. And it was also helpful to give me a clue what a 200 amp stickwelder might be drawing. Sounds like at 60 amps a 100 amp circuit would be perfect and give me some additional capacity, as I'm always warned to be careful about buying less tractor/wire/etc. than you need. Now to find that wire, which I am sure is not gonna be cheap...

Farmer Bob

 

[72chevy4x4]

I've done the exact same thing...although it's been a few years ago. I did use conduit-the stuff you buy at Lowes in the electric isle and 'think' it was 2" (could have been 2.25"). When I priced the direct burial and the conduit + 3 conductors + ground, it seemed to be much less expensive. I ended up buying a large roll of the electric wire and cut three lengths, then pulled them at the same time through the conduit. It's not easy stuff to work with, but I was able to do it all myself. Try your best not to bend the cable too much b/c the jacket of the cable protects the cable from the elements (oils, gas, etc...)

You'll also need a 100A breaker in the box inside your home. My county requires the cables to be in a conduit all the way to the box-the problem with direct burial cable was I couldn't find it at Lowes w/ enough amperage capacity.

 

[gemini5362]

The advice you have been given is very correct. I might add a stronger statement in that I think a 100 amp panel with 20 amp for the lights and some receptacles would be mandatory. I also think you might want to go ahead and make a small investment in a grounding rod and grounding wire at the shed. You will probably need 115 volt receptacles for running a grinder or drill that kind of thing. If you daisy chain the receptacles ( wire from breaker to one receptacle then wire from that one to the next etc) You can make the first receptacle a GFI and then all the rest will be protected. If you are going to run 100 amp service the other posters are right with #2 copper or #1 aluminum. I have not purchased any underground wire lately but the regular #2 was not real cheap. You might want to invest in conduit just because the price of the conduit might be cheaper than the difference between underground feeder wire and normal wire.

 

[wushaw]

Bcarwell, If your in the rock area of Austin then putting it in conduit would be the safest method in the long run.

 

[Lynkage]

Bcarwell, If your in the rock area of Austin then putting it in conduit would be the safest method in the long run.

I also would run conduit in the 2" range with no more than 2 90's. Every 90 you add makes it harder and there is a code as to how many you can use in one run.

It also allows addition if needed. Just a thought

 

[caver]

Check your local codes if any. If you run aluminum underground (direct burial)be gentle as it only takes a tiny hole to cause failure in the future.

Electrician on a good day.