Dual voltage compressor wiring

[rd65]

I have a Craftsman 92116474 27 gallon vertical air compressor that can be wired 115v or 230v. All of my 120v outlets are 20 amp. Should I convert compressor to 230v? What is the benefit? The drawback being I can currently plug this in anywhere vs my one 240v outlet.
Speaking of 240v outlet, what should I be running for a breaker? It is currently wired 40amp using 8 awg thhn. Will this be sufficient for welding?

 

[sberry]

40A will be sufficient for most machines that come with a 50A plug. 8 can be used on 50A for welders. But,,, has your comp been tripping a breaker on 120V? This is the main reason to change it,,,, if it works don't mess with it.

 

[rd65]

40A will be sufficient for most machines that come with a 50A plug. 8 can be used on 50A for welders. But,,, has your comp been tripping a breaker on 120V? This is the main reason to change it,,,, if it works don't mess with it.

No, compressor has not tripped breaker. The reason for the 40 amp breaker is because I was going to use that for my heater but the one I bought only required 30amp breaker. So the 40 amp breaker will be for the 240 outlet.

 

[mark-NJ]

IMO, if you have 240 readily available, then *ANY* machine that draws between 15A-20A @ 120 should be re-wired for 240, if possible. If the current is below 15A, then leave it at 120.

Voltage drop over a length of wire (like the distance from your service to your tool) is based on wire size & current. By re-wiring high-current tools to 240 (doubling the voltage), you're reducing the current to half, and the Vdrop will be reduced.

My Jet tablesaw came wired for 120....and would bog down readily. Re-wiring to 240, and it will tear through 3" white oak without breaking a sweat.

So: What does your compressor draw?

 

[sberry]

There is a good chance that it will be limited to a 30 breaker at 240. It likely has a bit less than 15 run on 120, if it comes factory cord then it came 15 end.

 

[strutaeng]

"If you convert it to 220V, it makes it more efficient!"

Is that the wheeled black model? I would keep it 120V since it is portable, in case you have to take somewhere...

 

[wyliesdiesels]

What is the HP rating on the motor nameplate?

 

[rd65]

Yes, that is the model. 27 gallon, 1.9 running HP, 15 amps @ 120v. I will have to get home to check out info on motor plate.

 

[Stuart in MN]

Yes, that is the model. 27 gallon, 1.9 running HP, 15 amps @ 120v. I will have to get home to check out info on motor plate.

I don't see any reason to change it from 120 to 240. It won't be any more efficient, you won't save any money on power, and if you leave it at 120 you can plug it in anywhere.

 

[wyliesdiesels]

Yeah people have this false perception that changing the voltage on a motor will save them electricity costs because the amps are reduced.

Doesnt work that way.

Electricity is billed in watts not amps.

 

[sberry]

Only thing would be a fuzz of heat loss in the wire but its miniscule. As long as the wire is not so long it causes real performance drop its not much a problem, we looking at 100 ft +. Wire welder ay 22A, about 8v or so. A load about 30% higher, 50% more depending on how you look at it. Be slightly different if this was 24/7 for decades. And,,,, that math is for 100 ft. Less than that obviously less loss.

 

[rd65]

Looks like I am going to leave as 120v. I like that idea better than changing to 240v since it keeps the portability of unit intact. Thanks for all the feedback.