220v circuit for welder


I need to add in a 220v circuit for a welder in my shop.
I have a seperate panel, and in that panel plenty of room for a 2-pole breaker.
There is already 3 x 220v 20 amp breakers in there, all on 12ga. wire.
The question is.. if I need to drop in a 30a or 40a breaker, what size wire do I need?
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Use #10 for 30 amp , and #8 for 40 amp, #6 for 60 amp
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You may want to go ahead and use #6 depending on the cable length. I have an extra long cable on mine so I can work out in the driveway if needed. I could tell the difference in the performance of the welder when I went from #8 to #6.. There is a welding group and you may want to ask your question there too.
Jimmie
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JIMMIE wrote:

bs
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On Wed, 18 Nov 2009 19:54:53 -0600, Steve Barker

means you DO notice a difference. If you weld at 80 amps on the short cord, you may need 90 or more on a long light cord.
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On 11/18/2009 5:54 PM Steve Barker spake thus:

So I guess you think Ohm's Law is what? just a good suggestion?
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theres no harm in a heavier wire, except it costs more
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David Nebenzahl wrote:

the basic home welder (200 - 225A) won't pull enough during normal use to even make bigger than a 10ga wire necessary. In fact, we've had our hobart wide open (200) on a project or two, doing spray arc, and still no problems with the 10ga feeder to the garage or the 10ga extension on the welder itself.
200A @ (about) 24v OCV, is about 4800 watts. So even if the input voltage was as low as 220, then you're still only pulling 21.8 A on the input side. And the welder is RARELY anywhere near wide open.
steve
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Could have been something else going on? Since then I replaced the old Lincoln AC unit with a Hobart AC/DC I dont know if I would still have the problem or not. The manual reccomended going up one wire size for longer runs. I did and my annoyance if not a problem went away. Dont think I going back to the old wiring just to find out.
Jimmie
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JIMMIE wrote: ...

If you're curious enough, look up the voltage drops for the wire size(s) and the run length(s) in the NEC tables. Might explain much...
That would likely be the reason for the above manufacturer recommendation as well.
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The input current under full load is closer to 50 amps. OCV is more like 80 but I dont know what importance that is.. 24 volts means you must be talking about a MIG machine. Mine is STICK which is constant current , not constant voltage.
Jimmie
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JIMMIE wrote: ...

Stick welder indeed controls to constant current but it is current at a particular voltage. 24VDC is quite typical.
The OVC isn't of any import to supply current requirements as it only exists while _not_ welding. It's simply a maximum at the electrode when not in contact w/ a workpiece.
--


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kansascats wrote:

It's a good thing there has only been one 220v welder with only one current requirement ever made in the history of the world!
Jon
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kansascats wrote:

Not enough information. What is the current requirement of the welder and what is its duty cycle? (length of run generally doesn't matter because most welders don't care about voltage drop.) There are special rules for welders that may allow you to use smaller wire than for any other type of dedicated circuit.
OTOH, if you think you might plug an electric stove in that outlet someday to roast an extra turkey, you might want to use full-size conductors anyway.
Bob
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I keep and run a 250 amp AC/DC Lincoln tombstone on #6 and have not had any problems. I rarely ever get the welder up past 125 or so.
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kansascats wrote:

30A with 10ga wire is PLENTY big for a 200A welder.
Hell, we fed an entire detached garage 250 feet from the house with 10ga wire buried for 35+ years. Ran welder, compressor, grinders, Unit heater, lights fans etc. Never a problem.
s
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On Wed, 18 Nov 2009 13:03:19 -0800 (PST), kansascats

What are the requirements stated by the welder manufacturer? The wire gauge choice is simple #8 but you need to know what the welder expects for neutral/grounding thus your choice of 8/3 or 8/4. Same goes for the breaker rating, do what the welder manu recommends.
I am a retired oilfield mechanic and welder. Used a portable all my working life. Now use a Miller 180 MIG at home on 220 but on 10/3 because it was already available. The welder has a 30% duty cycle so I've not had problems. I build tube steel race car chassis and use the 180 every day for 4 or 5 hours on and off.
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