Welder and compressor wiring

[garrynok]

Currently I have a 5hp Ingersoll-Rand air compressor, rated at 15 amps, that sits close to the 200A main panel in the garage. The compressor is old but has the red button on it, overload protection. The total wire run is 20' of 12-2 from a double pole 20 amp, 240V breaker to a nema 6-30r.

I have a new Hobart Handler 187 welder that I'd like to use on this same outlet. I would use the compressor or the welder one at a time by manually switching the plug. These are seldom used items so this isn't a problem. My breaker box is pretty full so I don't want to run another circuit until I add a sub panel later on.

The welder draws 20.5 amps at 230V. It says it needs a minumum of a 25 or 30 amp breaker. It's confusing to me but it says 14ga. can be used for a distance up to 67'.

So here is my question to you guys. What is the easiest way to do this? It seems as though I would want 10ga. wire with a 30 amp breaker. Could I use a 30 amp breaker with the existing 12ga. and change the wall outlet and air compressor plug to a nema 6-50? I don't mind replacing breakers, wire and outlet if it's what needs to be done. I'd appreciate your thoughts.

Thanks for your thoughts. Garry

 

[Charles (in GA)]

There are special rules for welders that allow the wire to be undersized since welders have duty cycles and its tough to heat up a small wire feeding a welder. Air compressors are different, you need a properly sized circuit for it. All of this is to say that you don't have to undersize the welder supply, just that you can.

Personally, I'd go ahead and run a second circuit for the welder, with the plug you need for the welder and placard the receptacle that its for welder use only, and be done with it.

Charles

 

[dimarcelli]

Could I use a 30 amp breaker with the existing 12ga. and change the wall outlet and air compressor plug to a nema 6-50?

Yeah, except for the 12g part. You would need to pull some 10g for a 30 amp breaker.

 

[garrynok]

Thanks for the responses. Charles, I think I get you about the welder, it looks to me like the duty cycle on welders technically lets me get away with 12ga. What I don't understand is I thought the breaker was there to protect the wiring, not the end device. So if that is correct, why wouldn't a 15 amp compressor run on a 30 amp circuit, especially since the compressor motor has overload protection. Not arguing at all, just trying to learn. You are right, I should fix it correctly with two circuits.

 

[dimarcelli]

As far as i know that's the way it's supposed to be. The breaker is sized for the wire. A 15 amp compressor would work fine on a 30 amp circuit. To me it's strange the welder came with a 6-50 plug but i guess they probably stock one size for all the models and it's easier. As charles was saying, article 630 states :

"Conductors that supply one or more welders shall be protected by an overcurrent device rated or set at not more than 200 percent of
the conductor rating."

So technically you would be okay.

If it was me, I would just buy a short section of 10/2 and rewire the outlet, with a 6-50 plug and 30a breaker. Change compressor plug and good to go. Reason being, mainly convenience. If you buy something else down the road that's 240, using more power you'll be covered. Also, if someone comes in there after you say, sell the home, and plugs in something like a heater, using 23-25 amps it would not work with the 12/2.

 

[garrynok]

Dimarcelli, I'm going to follow your thinking and redo the outlet correctly for the welder. The reasons are:

1. The physical location for the outlet is more in line with where I want the welder in the future.
2. I have three slots left in my breaker box. Two will be used for a future sub panel. One will be used for a dedicated microwave feed (I'm completing a kitchen redo).
3. When I add the subpanel I'll run a 20amp feed and relocate the air compressor. This will be this year, I just need to use the welder right now.

Thanks for the help.

 

[theoldwizard1]

The quick and simply solution is install the 30A breaker and upgrade to 10 gauge wire.

My breaker box is pretty full so I don't want to run another circuit until I add a sub panel later on.

Another simple solution. Install some tandem breaker on existing 15A and 20A circuit and can free up some slots quickly !

 

[garrynok]

Another simple solution. Install some tandem breaker on existing 15A and 20A circuit and can free up some slots quickly !

My breaker box is a Cutler Hammer no. 2200. I don't have a clue if tandems are allowed, or if they are, where they are allowed.

 

[pattenp]

My breaker box is a Cutler Hammer no. 2200. I don't have a clue if tandems are allowed, or if they are, where they are allowed.

The box should have an id such as CH#### or BR####

Example CH42B200V no tandems or BR4050B200VA1 takes tandems.

 

[garrynok]

The breaker box was installed in 1974. It says it's a type CC. I'm assuming it doesn't take tandem breakers, does anyone know? Thanks.

 

[Zeke]

There is always the right way to do it and just gettin' it done. Personally, I wouldn't change much. The Hobart 187 draws 20.5 amps wide open.

I see wiring things up in a hard wire situation having consequences. I don't see the consequence in using the existing outlet for the welder.

The question I have, is that the correct outlet for that circuit? I don't think it is. So why does the compressor have this plug? What plug came on the Hobart (if any)?

If you use the correct outlet and the correct plugs on your equipment, what can go wrong?

So I said what I would do. You asked for advice. I would tell you to convert it all to 6-20.

 

[garrynok]

The question I have, is that the correct outlet for that circuit? I don't think it is. So why does the compressor have this plug? What plug came on the Hobart (if any)?

If you use the correct outlet and the correct plugs on your equipment, what can go wrong?

So I said what I would do. You asked for advice. I would tell you to convert it all to 6-20.

Zeke thanks for your comments. The air compressor has a 6-30p on it (even though it is rated 15 amps), not a 6-20p. The Hobart 187 has a 6-50p on it.

After giving it a lot of thought today, I've decided to replace the existing 20 amp breaker with a 30, replace the 12/2 with 10/2 and leave the 6-30r in place. I'll make up a 50' extention cord which I need anyway for the welder with a 6-50r on one end and a 6-30p on the other. This way I have a true 30amp circuit and down the road, no one can plug a big welder into it.

 

[Zeke]

Works for me and you'll have plenty of voltage at the business end of your extension cord. Welders like that. I don't know about all welders, but I know MIG machines don't like to be starved.