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04-15-2009, 11:29 AM   #1
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## Circuit Size Question

We're having our new home wired soon. My husband wants an outlet to run his Mig welder in an entrance room that leads into the basement. The welder (Lincoln Mig 140C) runs on 120 v., 1 phase, 60 Hz. The spec sheet says to run it on a 20 amp circuit. My question is, can we have a 30 amp circuit installed to insure that there is adequate wattage for running the welder with its peak demand? I know we'd have to have 10 ga wire with the 30 amp circuit.

The electrician eluded to a 20 amp circuit being the highest you could put on a 120v system. However, I've seen references to 30 amp circuits, so I'm trying to figure out what all this means.

Last edited by techinstructor; 04-15-2009 at 11:37 AM.

04-15-2009, 11:50 AM   #2
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Quote:
 Originally Posted by techinstructor We're having our new home wired soon. My husband wants an outlet to run his Mig welder in an entrance room that leads into the basement. The welder (Lincoln Mig 140C) runs on 120 v., 1 phase, 60 Hz. The spec sheet says to run it on a 20 amp circuit. My question is, can we have a 30 amp circuit installed to insure that there is adequate wattage for running the welder with its peak demand? I know we'd have to have 10 ga wire with the 30 amp circuit. The electrician eluded to a 20 amp circuit being the highest you could put on a 120v system. However, I've seen references to 30 amp circuits, so I'm trying to figure out what all this means.
A 120 V circuit can be any amperage, but what the electrician meant was that 20 A is as large a circuit that you can put a regular receptacle on that will accept 15 or 20 A plugs. So, no, you cannot install a 30 A circuit for this welder. The manufacturers designated it 20 A, therefore it should operate happily on a 20 A circuit.

 04-15-2009, 11:54 AM #3 Member   Join Date: May 2008 Location: Apple Valley, MN, USA Posts: 1,003 Rewards Points: 508 If the welder uses a standard 15 amp or 20 amp edison style plug, then no you cannot protect its circuit with a 30 amp breaker. What the electrician was probably trying to indicate is that you cannot put a standard outlet on a breaker higher than 20 amps. They do make 30 amp 125 volt recepticals, but they are typically twist-lock style (or the RV TT-30). If the welder has the 20 amp "T-style" plug, just put in a 20 amp outlet on a 20 amp breaker. If you are running a long distance to the main panel you could use 10 guage wire on the 20 amp circuit to limit voltage drop, but this would likely have to be several hundred feet before you would even see an issue.

 04-15-2009, 12:11 PM #4 Member   Join Date: Jan 2009 Location: South of Boston, MA Posts: 17,248 Rewards Points: 2,000 As stated Depending upon the distance from the panel to the outlet: It may help to upgrade the wire to #10 but use a 20a breaker The spec sheet/plate indicates its peak usage - 20a
04-15-2009, 05:40 PM   #5
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## Welding machine circuit

Install the breaker and wire according to the spec sheet.

If the spec states 20 amp that's it no more no less.

 04-15-2009, 06:24 PM #6 Member   Join Date: Jul 2008 Location: NW of D.C. Posts: 5,990 Rewards Points: 2,000 From other posts, it seems that welders draw current that is over the CB rated steady-state value, but for such short periods that the CB holds. Some 20A CBs can hold 40A for up to 60 seconds. Last edited by Yoyizit; 04-15-2009 at 06:36 PM.
 04-15-2009, 07:44 PM #7 Member   Join Date: Jul 2008 Location: Iowa Posts: 1,543 Rewards Points: 1,000 If you want the 30 amp ability, than have him run 10/2 (I would run 10/3 in case of a 240v device) he would then just put in a standard receptacle and 20 amp breaker, but you could then have an electrician up the circuit to 30 if you ever needed 30.
04-15-2009, 08:32 PM   #8

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Quote:
 Originally Posted by rgsgww If you want the 30 amp ability, than have him run 10/2 (I would run 10/3 in case of a 240v device) he would then just put in a standard receptacle and 20 amp breaker, but you could then have an electrician up the circuit to 30 if you ever needed 30.
While this is not a bad idea, why would you run 10/3 for a 240v circuit?
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04-15-2009, 08:59 PM   #9
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Quote:
 Originally Posted by Speedy Petey While this is not a bad idea, why would you run 10/3 for a 240v circuit?
what else would a hack do?...of course you run a 10/3 duh

 04-15-2009, 09:00 PM #10 Member   Join Date: Jul 2008 Location: Iowa Posts: 1,543 Rewards Points: 1,000 Hey! My bad. 120/240
04-15-2009, 09:03 PM   #11
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Quote:
 Originally Posted by NolaTigaBait what else would a hack do?...of course you run a 10/3 duh

Yup, 10/3 everybody knows that!

04-15-2009, 09:08 PM   #12

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Quote:
 Originally Posted by rgsgww Hey! My bad. 120/240
I thought so. That's why I put the winky guy in there.
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06-28-2009, 08:24 AM   #13
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## Mig welder outlet

I also need a recept. for a mig welder.
Thought maybe I could sneak in a question or two.
Primary input data is: 230 vac, 22.5 amps, 60Hz.
Can I use #6 awg. with a 50 amp. recept. on a 50 amp. 2-pole breaker?
Or does the breaker and/or wire need to be smaller?

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