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
There is already 3 x 220v 20 amp breakers in there, all on 12ga.
The question is.. if I need to drop in a 30a or 40a breaker, what
size wire do I need?
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.
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.
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.
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.
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.
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.
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
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.
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
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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