Plasma Cutter with Compressor - Too Much Current?

[RichT]

My detached garage has a 40amp 220v circuit with a Quincy 5HP 60gal compressor rated at 27amps full load. Looking at picking up a Thermadyne Cut38 Plasma rig rated at 19amps full load. Since the Plasma requires some compressed air, its likely both will be running simultaneously from time to time. Would this be a breaker problem on my 220v garage circuit?

 

[mars1952]

My detached garage has a 40amp 220v circuit with a Quincy 5HP 60gal compressor rated at 27amps full load. Looking at picking up a Thermadyne Cut38 Plasma rig rated at 19amps full load. Since the Plasma requires some compressed air, its likely both will be running simultaneously from time to time. Would this be a breaker problem on my 220v garage circuit?

I think that you need a higher amp set up. The problem is going to be when the compressor starts up. There will current draw beyond the 27amps when the compressor motor starts against a load.
Good Luck, Marshall

 

[RonMar]

Or get yourself a smaller portable compressor that meets the specs of the Plas and shutoff the big comp when you are cutting... The smaller compressor might be handy if you ever need to go cut somewhere other than your garage

 

[gary1611]

Heres the cheap easy solution. A 60 gal compressor holds a lot of air let it pump up fully the shut it off and use the plasma the air should last through a lot of cutting. when it gets low let turn the compressor on and let it pump up. This is a great solution if its occasional use. The next cheap solution would be to check the supply wire for amperage rating and see if it can support a 50 amp breaker by code. if it can replace. Third run new wire but with the cost of copper you'd probably want the first method unless mino. Also if you can run additional circuits in the garage run one just for the plasma.

 

[ultrarunner]

You might want to check your existing wire gauge and the distance between the main and sub-panel.

My friend was in the same situation and until his electrician said the feeder wire to his shop was rated for 70 amp and the 100 amp rated panel had 50 amp breakers... so all he had to do was upgrade to 70 amp breakers.

 

[mars1952]

Heres the cheap easy solution. A 60 gal compressor holds a lot of air let it pump up fully the shut it off and use the plasma the air should last through a lot of cutting. when it gets low let turn the compressor on and let it pump up. This is a great solution if its occasional use.

I like this idea. The smaller less expensive plasma cutters have a low cycle time, usually less than 30%. In other words, if the cycle time is 30% you can only run the plasma cutter three minutes out of every ten. You have to let the plasma cutter cool for seven minutes. During those seven minutes you can run the compressor. You might even be able to rig up an automatic switch that turns off the compressor when you run the plasma cutter.
Good Luck, Marshall

 

[yomax4]

You really should not have a big problem with this. After all, All you will do is "maybe" pop the breaker.. There is another option, Thermal Dynamics has the Dragun + 230v with built in Compressor. Cuts 1/2 inch like crazy. Priced very similatr to the Cutmaster 38. ( I am A Thermal Dynamics Rep.)
Good Luck.

 

[jeff_jeff]

I have a similar setup in my shop - I'm wired for 40 amps 220v max - I run a 40 amp plasma cutter with my 2hp air compressor with no problem - the compressor often cycles while I'm cutting.

I think it would be a real hassle to have to turn the comressor on and off between cutting jobs, or when you need more air - I'd see what happens with your big compressor, and if your breaker blows, by a smaller one (as previously suggested)

 

[RichT]

Thx all for your inputs. The subpanel on my detached garage is supplied by 6awg copper wire in conduit from a 50amp breaker at the main, about 120ft away. I'm using a 40amp breaker at the sub for the 220v circuit.

Looking thru the code book again, I might be able to upgrade to a 60amp breaker at the main and 50amp at the sub with the 6awg.

I do have a Sears 5HP (actually 2HP) 30gal portable compressor if needed, but would rather figure out how to make this work with my Quincy.

 

[ovrszd]

I have a similar setup in my shop - I'm wired for 40 amps 220v max - I run a 40 amp plasma cutter with my 2hp air compressor with no problem - the compressor often cycles while I'm cutting.

I think it would be a real hassle to have to turn the comressor on and off between cutting jobs, or when you need more air - I'd see what happens with your big compressor, and if your breaker blows, by a smaller one (as previously suggested)

I'm running a 5 HP compressor and my Plasma cutter on a 40 amp circuit.

I agree that it would be a total hassle to turn the compressor on and off. My compressor cycles frequently when using my cutter on long and multiple cuts. I've had my compressor kick on while I'm cutting and haven't tripped the breaker.

 

[SPIKER]

6 ga THHN is good for 63 amps, BUT not sure of the run/length you have so you may have had it de-rated for the voltage drop.

hope that helps.


I would suggest like someone already did, turn off compressor cut, stop for plasma cooling & on with compressor... much easier than running new wire if need be.

markM

 

[philbuilt]

Here is my though, You have a double pole 40 amp feed to the garage that = 80amps -20% for a total of 60amps use.
you should be ok. Please correct me if I'm wrong.
Phil

 

[Stimw]

Plasma cutters use a lot more air than you think because they use it during post cooling. If you hit the trigger it will run cooling air for 30 seconds or more after you stop cutting.

 

[RichT]

6 ga THHN is good for 63 amps, BUT not sure of the run/length you have so you may have had it de-rated for the voltage drop.markM

That is my concern. My 2002 NEC 2% voltage drop one way distance table shows 6awg with 50amps at 115ft which is in my ballpark. A 3% drop with 60amps puts me well within the run length. Any electricians on-board which can render an opinion?

 

[Highbeam]

I have run a plasma cutter and 5HP air compressor to cut metal in the field with, get this, my 5500 watt generator. Now granted the 220 plasma cutter wan't a high amp unit it still worked.

Both loads are 220 so the poster's setup should work fine. Nothing to lose by trying.

If you can use a 60 amp breaker on that 6 gauge circuit that is good news, I thin kyou can. Now is there a reason you need to use anything less than that same 60 amp main breaker at the sub panel? If the breaker protects the wire then it would seem that your 60 amp feed from the main panel could support a 60 amp main breaker at the sub.

 

[mudcat]

Here is my though, You have a double pole 40 amp feed to the garage that = 80amps -20% for a total of 60amps use.
you should be ok. Please correct me if I'm wrong.
Phil

 

[bucmeister]

Here is my though, You have a double pole 40 amp feed to the garage that = 80amps -20% for a total of 60amps use.
you should be ok. Please correct me if I'm wrong.
Phil

That would be 40 amps @ 120 in each of two legs for 80 amps total @ 120 volts, however only 40 amps when looking at it from the 240 volt configuration.

 

[philbuilt]

bucmeister,
You are right I checked with our company electrician. I do plan on putting my amp meter on my panel this weekend to check the running amperage. Now it's more of a curiousity than anything for me.

 

[390GT]

No problem replacing 40 amp breaker with a 50 amp in the subpanel.