Welder, Plasma Cutter, Compressor Wiring Question

[Johnkn]

Greetings,

I purchased my first plasma cutter recently, and with its addition, am considering a new welder and some wiring changes in my garage.

I have a 220V compressor which plugs into a dedicated 20A receptical, I think the compressor draws ~15A as I recall.

Thinking of upgrading my welder to a new Miller 190 MIG which comes with a 50A 220V plug yet draws 21.7A.

Considering upgrading my compressor circuit to run both the compressor and new welder. Would this work: 1) replace current 20A 220V compressor breaker with new 50A 220v breaker in the panel to 2) #6-#8 AWG inside existing metal EMT to 3) existing 20A compressor recepital (pigtailed) then 4) up to new 50A receptical labled "welder only"? The total run length from the panel to the recepticals is about 40'.

Trying to upgrade to a single 220 circuit running both the compressor and new welder. PS, welder would be very seldom used, only a few times a year.

thanks

 

[ThomasH]

Yes, that would work, however, if the one circuit is already in place why not just leave it there and run a new circuit? If you ever need to use the plasma cutter (and it is large enough to use a 220 circuit) then two circuits would be required anyway.

The #8 wire would legal for a welding circuit only, however for the small bump in price I would put in #6 and then the circuit could be used for any larger 220 volt use.

 

[Johnkn]

"If the one circuit is already in place why not just leave it there and run a new circuit? If you ever need to use the plasma cutter (and it is large enough to use a 220 circuit) then two circuits would be required anyway."

I already have a dedicated circuit to run the plasma cutter off of, I can use one of the recepticals for my car lifts. Also, electrical panel space is all but gone, and the walls where the EMT conduit is run is basically covered with cabinets and large tool boxes. It would be much easier to pull the existing wiring out and pull new wiring behind it.

thanks

 

[ThomasH]

"If the one circuit is already in place why not just leave it there and run a new circuit? If you ever need to use the plasma cutter (and it is large enough to use a 220 circuit) then two circuits would be required anyway."

I already have a dedicated circuit to run the plasma cutter off of, I can use one of the recepticals for my car lifts. Also, electrical panel space is all but gone, and the walls where the EMT conduit is run is basically covered with cabinets and large tool boxes. It would be much easier to pull the existing wiring out and pull new wiring behind it.

thanks

The next question is whether the EMT is large enough to accommodate both circuits? If so, I would put both in the conduit, otherwise your plan sounds sensible to me.

 

[CDN Farm Boy]

So if I'm understanding you right, both plugs (the 20A compressor and 50A welder) would be on the same breaker?

If I'm right, that would NOT be legal here. Good friend of mine is an ESA inspector and I'd inquired about the same thing to save on wires/breaker cost. According to him, the only things that can be on branch circuits (multiple items on same circuit) is lights and regular receptacles. Everything else requires their own dedicated circuit. Could it be done, yes but if something went south, it would likely void your insurance.

 

[crackerjack222]

If the emt is large enough, run new #6 wires to a subpanel. Then you could have 2 or more breakers in it to run the welder, compressor and plasma and maybe something else.

 

[dstig1]

If I understand you , you want to 1. upgrade the breaker to 50A. 2. Upgrade the wire to take that 50A, and then 3. Put a 20A AND a 50A receptacle on the end of it. The strict NEC code answer is NO since the 20A outlet is not rated for the circuit at 50A. You could put 2 50A outlets, perhaps (assuming the inspector doesn't go after the dedicated circuit like CDN farm boy noted, which I am not sure about, but it may be a Canadian rule), but a 20A and a 50A would not fly. You could put 2x 50A outlets and then change the plug on the compressor to a 50A one, though. The purpose of a breaker is to protect the house wiring, not the equipment. As long as the house wire, outlets, and the breaker match, then you are most of the way there.

 

[ThomasH]

If I understand you , you want to 1. upgrade the breaker to 50A. 2. Upgrade the wire to take that 50A, and then 3. Put a 20A AND a 50A receptacle on the end of it. The strict NEC code answer is NO since the 20A outlet is not rated for the circuit at 50A. You could put 2 50A outlets, perhaps (assuming the inspector doesn't go after the dedicated circuit like CDN farm boy noted, which I am not sure about, but it may be a Canadian rule), but a 20A and a 50A would not fly. You could put 2x 50A outlets and then change the plug on the compressor to a 50A one, though. The purpose of a breaker is to protect the house wiring, not the equipment. As long as the house wire, outlets, and the breaker match, then you are most of the way there.

Conduit can carry any number of wires, roughly up to 50% of the cross-section of the conduit. There are simple tables for different EMT and the number of various gauges of wires that can be fed through them.

I asked you what size conduit do you have? It's a fundamental question and will drive the decision whether it can be used for additional wires. I was suggesting that it *might* be possible to put a second circuit in the conduit, and a second box on the end so you have two breakers, two sets of wire, and two outlets. Doing some of the combo things you were mentioning would be dangerous and not code compliant.

 

[dstig1]

Yes, Thomas, what you are suggesting is possible, if the EMT is big enough (I'd have my doubts as it is probably 1/2"...it would probably work in 3/4"), but I do not believe it is what the OP was proposing, per quote from his first post:

Trying to upgrade to a single 220 circuit running both the compressor and new welder.

 

[pat32rf]

Your Miller has a fifty amp plug on it because that is a common size for welders. My Lincoln also has a 50 amp plug, but gets fed thru a 30 amp disconnect with 30 amp fuses and number ten wire. Number eight would be better IF I were starting fresh but the ten was there when we moved in 15 years ago. I have probably blown 4-5 fuses in that time....
I would go to #8 if possible (forty amp), and install two welder outlets on the same circuit, in different places just so you can move around the garage....Otherwise just stick with #10 and fuse it at thirty amps, again with one outlet by your work bench, the other over by your compressor. There is no reason why you cannot put a 50 amp welder plug on your compressor.....