I'm looking at compressors and a few I'm interested in can run on either 110 or 220. It is already wired for 110, what would be the benefit of rewiring it to 220??

 

The motor will start easier and run more economically using 220V instead of 110V.

 

Why would it run more economically?

 

You pay for electricity in watts, and watts = volts x amps. 120V @ 30 amps comes out the same mathematically (and cost-wise) as 240V @ 15 amps. More or less.

240V motors tend to be slightly more efficient than 120V motors. A few pennies per hour max. Really not a big deal. Higher voltage AC motors also tend to spike above their ratings much less during start up as compared to lover voltage AC motors.

For example, my old clausing lathe has a baldor 120V/240V AC motor in it. When wired to 120V, the garage lights go almost all the way off for a fraction of a second when I turn the machine on. Wired for 240, they don't even flicker, and the machine doesn't make that machinery struggle noise either. This might be very key for an air compressor as those motors are asked to really right some serious resistance - 120-160psi in a tank with a piston trying to push more in as the motor starts.

Higher current circuits (120V @ 30A) require a heavier gauge wire/outlets than a lower current circuit (240V @ 15A), so you'll notice some installation cost there. A few feet of wire is not a big deal but if the wire run is 30+ feet you would notice the difference, especially if your required to run armored wire (BX) or install the wire in conduit depending on the destination, wire route, and your local codes that were added on top of the NEC (NY is notorious for this, for example).

 

15A at 110V vs. 7.5A at 220v.. same amount of watts (power), but the 220 will be able to move through resistance easier.

Bottom line, the line to your garage is probably 15A @ 110v, but a 220 will also be 15A @ 220v.
Your compresser will run at 15A at 110V but will run at half the amps at 220, same amount of power, half of what is available vs. ALL that is available. On a 110 when it's really cold, has old oil or *something*, it will pull more than 15A at 110V trying to start and will probably trip your breaker, after it has run for a while with some compressors the wire/motor will get warm, increase resistance it will have to pull more power (say 20A when building pressure) and will trip your breaker.
This wont ever happen with 220, you'll always have more than enough power left over to cold start, overheat or whatever the hell else you wanna do with it.

Most compressors are at the limit of what a household line can produce.. you can't really run them alongside other stuff on the same line, it's not particularly safe if your lines arent in top shape, etc.

in the end 220 is less of a headache with stuff that requires lots of power.

edit: this is assuming you have a normal 15/20A line as most people do. Mine trips my breaker when it's cold, plus I've seen a lot of complaints on review sites about 110v compressors tripping breakers.
It's just gonna happen for most people unless conditions are right, lines, compressor, oil, weather, etc.

 

My import "toy" contractor 120V compressor doesn't even start when it's below 36 degrees. When I apply the power I get exactly one "putt" then the motor stops and buzzes until circuit breaker built into the unit pops 4 seconds later.

Which sucks for me since my garage isn't heated.

Years ago I ran a hard line down one garage wall to feed various points in the garage so I don't have to have a 50' rubber hose tangled in my legs as I work in different parts of the garage. This hard line also elbows through the garage wall at the bottom into a crawl space and terminates at the other end of the crawl space almost at the basement ceiling. I used this to provide air for tools when installing my server farm in the basement - air drill, air chisel, etc. Just last week I remembered that port was there, so my "toy" air compressor now sits in the basement at the bottom of the stairs, feeding the hard line in the garage.

Now it can be -50 and I'll still have air - even though that compressor is rather minimalistic considering what I ask it to do most of the time.

But it's funny... for years I'd bring it inside into the foyer for a few hours to warm it up, then hump it back outside so I could use it for a couple of hours before it froze to death yet again.

 

Takes me a bit but I'm able to get mine started regardless of how cold it is.. press the start button, press the breaker button.. do this about a dozen times for 35F, quite a few more if it gets much colder but eventually it does start.

I guess they expect most people to quit working when its that cold out.. they don't know me though, nothing can keep me away from my truck.

 

I guess that answered my question thanks

 

Not an authority, would seem with the 120v would limit one to a max. of between 6-8 cfm, whereas, the 220v would allow for more options. I am one for going bigger. Perhaps an electrican can advise if possible to branch off the 220v line and allow to add a 120v outlet.

dave

 

I have a 30 year old, dual voltage Craftsman. It starts easier and runs cooler on the higher voltage. Less current flowing in the same wires (motor windings) is bound to be cooler and therefore more efficient.

JIm

 

I had the same problem, I had a 110 volt compressor, & everytime it was cold I would blow breaker!! The 220 I have now will start when it is freezing out!!

 

I just bought a 220v compressor today.. nice one, 15A @ 220v, dual piston compressor, gonna be a monster.

I worry though, it said it had a 27A power draw at start, that's a lot of damn power.