running wire for welder and compressor
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New User
Joined: Nov 2005
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running wire for welder and compressor
Hey everyone ...need alittle help here please. Im running more electrical in my garage before I sheetrock. I plan on buying a Miller 175 welder and I currently have a 60 gallon (230v) craftsman compressor. My question is which is the proper wire to run for each piece of equipment. I have been told 10/3 or 10/4 will be fine. Is this correct? Thanks for any and all response
Elder User
Joined: May 2004
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From: Danville, Pa
Well, the miller requires 19.5A@ 230V and your compressor requires (if it's 3.2 Hp) 15A@ 230V. For the miller you are required to run 12-2 on a 2 pole 20 amp breaker. For the craftsman your are only required 14-2 on a 2 pole 15 amp breaker. Howerever For the craftsman I would also run 12-2 on 20A , plus I don't recomend running anything less than 12-2. Now if the run from the Sub panel is farther than 100 feet, go up one gauge to counteract the 5% voltage drop to make sure you have enough power. I.e. 12-2 -> 10-2 ect.
Btw, when buying NM-B 12-2 refers to 2 wires + ground = 3 wire romex. If your running MC (Metal Clad I think) then get 12-3.
Btw, when buying NM-B 12-2 refers to 2 wires + ground = 3 wire romex. If your running MC (Metal Clad I think) then get 12-3.
Elder User
Joined: Sep 2004
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There is a special section of the electrical code just for welders. (Article 630). The nameplate rating of the welder can be adjusted by the nameplate duty cycle when determining the ampacity of the branch circuit conductors. The Miller 175 probably has a duty cycle no more than 30 percent. The adjustment factor is 0.55 for this case, making the "effective" amps only 11.
You could run 14AWG to the welder and be code compliant. The 80 % rule does not apply to electric welders. Voltage drop is not much of a problem with a MIG welder, since the machine is constantly adjusting its output to hold a constant output voltage, regardless of the amount of current flowing (or input voltage)
That said, I would not bother with smaller than 10 AWG wire for a new welder circuit. The breaker, connectors, and effort to run the wire costs much more than more robust wiring. You never know what machine you will buy next.
You could run 14AWG to the welder and be code compliant. The 80 % rule does not apply to electric welders. Voltage drop is not much of a problem with a MIG welder, since the machine is constantly adjusting its output to hold a constant output voltage, regardless of the amount of current flowing (or input voltage)
That said, I would not bother with smaller than 10 AWG wire for a new welder circuit. The breaker, connectors, and effort to run the wire costs much more than more robust wiring. You never know what machine you will buy next.
Posting Legend
Joined: Sep 2001
Posts: 30,255
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Originally Posted by fefarms
...That said, I would not bother with smaller than 10 AWG wire for a new welder circuit. The breaker, connectors, and effort to run the wire costs much more than more robust wiring. You never know what machine you will buy next.
Hotshot
Joined: Nov 2000
Posts: 11,591
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From: Pflugerville, tx
so, I am wiring for a Miller SD 180.
the manual (http://www.millerwelds.com/om/o360j_mil.pdf) says
All values calculated at 40% duty cycle.
Input Amperes At Rated Output - 54
Max Recommended Standard Fuse or circuit breaker Rating In Amperes
Time-Delay - 60
Normal Operating - 80
Min Input Conductor Size In AWG - 8
Min Grounding Conductor Size In AWG - 8
that sounds a lot bigger than for the 200 above..
The manual also says that the cord comes without plug, but as I recall (its at my sons house), this has a 4 prong plug on the end, but the cable is only supposed to have three wires.. 2 hot and 1 ground.
so do I really need 8ga from the panel to the wall plug?
Sam
the manual (http://www.millerwelds.com/om/o360j_mil.pdf) says
All values calculated at 40% duty cycle.
Input Amperes At Rated Output - 54
Max Recommended Standard Fuse or circuit breaker Rating In Amperes
Time-Delay - 60
Normal Operating - 80
Min Input Conductor Size In AWG - 8
Min Grounding Conductor Size In AWG - 8
that sounds a lot bigger than for the 200 above..
The manual also says that the cord comes without plug, but as I recall (its at my sons house), this has a 4 prong plug on the end, but the cable is only supposed to have three wires.. 2 hot and 1 ground.
so do I really need 8ga from the panel to the wall plug?
Sam
Fleet Mechanic
Joined: Jul 2000
Posts: 1,493
Likes: 346
From: SE Iowa
Originally Posted by sdetweil
so, I am wiring for a Miller SD 180.
the manual (http://www.millerwelds.com/om/o360j_mil.pdf) says
All values calculated at 40% duty cycle.
Input Amperes At Rated Output - 54
Max Recommended Standard Fuse or circuit breaker Rating In Amperes
Time-Delay - 60
Normal Operating - 80
Min Input Conductor Size In AWG - 8
Min Grounding Conductor Size In AWG - 8
that sounds a lot bigger than for the 200 above..
The manual also says that the cord comes without plug, but as I recall (its at my sons house), this has a 4 prong plug on the end, but the cable is only supposed to have three wires.. 2 hot and 1 ground.
so do I really need 8ga from the panel to the wall plug?
Sam
the manual (http://www.millerwelds.com/om/o360j_mil.pdf) says
All values calculated at 40% duty cycle.
Input Amperes At Rated Output - 54
Max Recommended Standard Fuse or circuit breaker Rating In Amperes
Time-Delay - 60
Normal Operating - 80
Min Input Conductor Size In AWG - 8
Min Grounding Conductor Size In AWG - 8
that sounds a lot bigger than for the 200 above..
The manual also says that the cord comes without plug, but as I recall (its at my sons house), this has a 4 prong plug on the end, but the cable is only supposed to have three wires.. 2 hot and 1 ground.
so do I really need 8ga from the panel to the wall plug?
Sam
For your welder, it should be a 3 prong plug. My Millermatic 251 has a 3 prong. As far as wire size. The Miller site is correct. You only need to run 8/2 wire (if its a 3 prong) and 8/3 if its a 4 prong. I do however agree with Torque1st. If a manual calls for a 50amp breaker, I wire it for a 50amp breaker. In this case, 50amp calls for 6ga. wire. Saves a lot a hassle down the road if you upgrade to a bigger welder or maybe even a plasma cutter or TIG welder. Depending on your garage setup, I'd look at running metal conduit and using THHN wire. The price of copper is getting insane, and this may save you a few dollars. Figure cost of either conduit vs. Romex and see which one wins.
Stryder
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