compressor 110v or 230v

[chris yount]

my trusty compressor I had for the last 10 years died over the weekend.I have my eye on one that is availible in 110 or 230 volts.I've never used a 230 volt compressor.Are there any major advantages to the 230 motor.would these advantages be worth wiring a new circuit in my garage?
I use it for nail guns,spraying finishes and genral auto repair.
thanks for your help

[Bob Cooper]

mine is 230 the only disadvantage is if you need to plug it in anywhere else -- lack of plugs. Also i you need to run it remotely...via an extension cord would be a pain.

[Jon Dieterlen]

A dual voltage motor will draw 1/2 the amps at 220v vs 110v. This tranlates into: less heat, longer lasting switches, motors, start capacitors, etc. I have a 2 HP compressor that was originally wired 110V. The presure switch burned up after a couple years. I replaced the switch and changed the motor to 220v. After 20 years of daily use, still running strong. Any motor over 1 hp will benefit from 220v line voltage.

[chris yount]

Thanks for your replies.
I think I will get the 220 version. the old 110 I had really seemed to draw alot of juice at start up.So it shouldbe better on my wallet as well as the machine.sounds worthwhile to intall a 220 outlet.

[Mike Henderson]

A dual voltage motor will draw 1/2 the amps at 220v vs 110v. This tranlates into: less heat, longer lasting switches, motors, start capacitors, etc. I have a 2 HP compressor that was originally wired 110V. The presure switch burned up after a couple years. I replaced the switch and changed the motor to 220v. After 20 years of daily use, still running strong. Any motor over 1 hp will benefit from 220v line voltage.
I'm afraid the above is a misconception. The way a dual voltage (110/220) motor is made is that there are two sets of 110 volt coils. For 110 volt operation, those coils are put in parallel. For 220 volt operation, those coils are put in series. In either case, the coils have exactly the same voltage dropped across them and the same current through them. The electrical power is the same and the heat is the same.

The only thing that does change is the current in the wire feeding the motor - for 220 volt operation it's half what it is for 110 volt operation. For properly wired circuits and proper sized feed wire, it doesn't matter whether you run the motor at 110 volts or 220 volts.

Mike

[Gene Michael]

I have a Sears Craftsman 3 1/2 hp with a 25 gallon tank that I've been using for fifteen or so years for everything from spraying finishes to running air tools to work on cars. It's been very dependable. 2 years and 9 months after I bought a portable Porter Cable compressor to use with nail guns, it died. The Craftsman has an oil lubricated compresor; the Porter Cable is oilless. Based on these experiences, I favor oil lubricated compressors as well as those that have a good rep for quality. As for 120 versus 240 volts, everything I've ever read is that the power of a motor remains the same if you double the voltage and half the amps. It seems reasonable to expect the heat factor to be related to the power developed and the load applied, but I don't know that this is always true. I'd be interested in hearing from others about this.

[Art Mann]

Mike is correct. There is no benefit, from a durability or power standpoint, of converting from 120V to 240V. However, if you can afford it, I would buy a 240V compressor simply because they are of higher capacity. You are somewhat limited in your choices of air tools and spray guns with a motor that runs on 120V, 15A.

[Rob Will]

OK Art and Mike, here's what I think about 115v vs 230v for light machine tools.

With neither conductor grounded the electrical potential between the two conductors is greater (double) in a 230v citcuit.
With twice the voltage, the current (ampreage) in any single conductor is half.
With half the ampreage requirement, the voltage drop in any given circuit is half.
With half the ampreage requirement, the load on any individual breaker contact is half.Does the motor really care? Not if the correct voltage is delivered.
Does this translate to energy savings? No
Does voltage drop translate into more heat? Yes - both in the motor and in the wires that serve it.
(this includes those cheezy 15A 115v receptacles that people plug 1HP air compressors and table saws into)

Should things like air compressors be on a 230v circuit? I think so because they start and stop all the time and tend to be equipped with fairly large motors that approach the capacity of most 115v circuits.

Also, 230v circuits tend to be more "dedicated" in nature and thus not be sharing a breaker with various other things about the house. Electric motors have a large current requirement, especially upon startup. So regardless of voltage, an air compressor is a good place to have a dedicated circuit.

With the same size wire, I think 230v does a better job of delivering electrical energy to larger tools and appliances. That's why we usually have 230v air conditioners and water heaters. Perhaps we are all saying the same thing but I don't want to steer people away from using 230v circuits.

JMHO,

Rob

[Mike Henderson]

OK Art and Mike, here's what I think about 115v vs 230v for light machine tools.

With neither conductor grounded the electrical potential between the two conductors is greater (double) in a 230v citcuit.
With twice the voltage, the current (ampreage) in any single conductor is half.
With half the ampreage requirement, the voltage drop in any given circuit is half.
With half the ampreage requirement, the load on any individual breaker contact is half.Does the motor really care? Not if the correct voltage is delivered.
Does this translate to energy savings? No
Does voltage drop translate into more heat? Yes - both in the motor and in the wires that serve it.
(this includes those cheezy 15A 115v receptacles that people plug 1HP air compressors and table saws into)

Should things like air compressors be on a 230v circuit? I think so because they start and stop all the time and tend to be equipped with fairly large motors that approach the capacity of most 115v circuits.

Also, 230v circuits tend to be more "dedicated" in nature and thus not be sharing a breaker with various other things about the house. Electric motors have a large current requirement, especially upon startup. So regardless of voltage, an air compressor is a good place to have a dedicated circuit.

With the same size wire, I think 230v does a better job of delivering electrical energy to larger tools and appliances. That's why we usually have 230v air conditioners and water heaters. Perhaps we are all saying the same thing but I don't want to steer people away from using 230v circuits.

JMHO,

Rob
Rob - I certainly am not attempting to steer people away from using 220 volt circuits. Everything you say above is true, except for the lower heat in the motor, and are good reasons for someone to put a tool on a 220 volt circuit.

The point I was trying to make is that *to the motor* it doesn't matter whether it is running on 110 volts or 220 volts. It will have the same power, generate the same heat - everything will be the same no matter what voltage you run the motor on.

Regarding the heat in the motor itself (not in the wires serving it), because of the way dual voltage motors are made, the current and voltage drop across the coils is exactly the same no matter which voltage you run the motor on. But in a more general sense, doesn't it make sense that the same heat would be generated if the motor is producing the same power, no matter what voltage is used? There's just no free lunch.

Mike

[Rob Will]

Hey Mike,
I agree, I was talking about additional heat generated in the motor IF voltage drop occurred in the wiring leading to the motor. (Low voltage situation = hot motor). Again, I think we are saying the same thing.
Rob

[Howard Acheson]

Folks, I may be wrong but I believe that Chris was asking about a single voltage motor. The compressor was available with a 120 volt motor or a 240 volt motor--not a dual voltage 120/240 volt motor. The difference is that horsepower of a dual voltage motor remains the same no matter what the input voltage. But, a separate 120 volt only motor is different from a single voltage 240 volt motor. Essentially, it's best to check the amperage of both motors for an indication of its power. The single voltage 240 volt motor may be a larger horsepower motor.

Of course, I could be wrong about the two motors that Chris is speaking of.

[Art Mann]

Rob,

I suggest you read Mike's original explanation again about the way 120/240V motors are wired up. You might also google up a circuit diagram if you know how to interpret them. There is Z E R O difference in the current going through the individual windings in the motor wired for 120 or 240. It is a parallel vs. series configuration. You really must understand what that phrase means to understand the situation. While it is true that the lower feed current from the breaker will reduce losses in the line, that loss is negligible in comparison to the losses in the motor windings.

People will sometimes see an improvement in motor performance going to 240V, but that is because their original AC wiring is deficient.

[Rick Christopherson]

This is a different question from what is typically asked, in that the OP is not rewiring an existing compressor, but buying a new compressor pre-configured. Therefore, the answers are a little different.

First off, there is not enough information about the proposed compressor to properly answer the question--namely the proposed size. If the compressor draws less than 15 amps, then I recommend sticking with the 120 volt model. If the compressor is almost 20 amps (at 120 volts), then I recommend going with the 240 volt model. Between 15 and 20 amps is more of a gray area. In this situation, regardless which voltage is chosen, it may be likely that a new dedicated circuit would have to be run. With a properly sized new circuit, the voltage of the compressor will have no impact on the performance.

Because this model is apparently available in either configuration, then it is also likely that it is a portable-size compressor. If you plan on keeping this as a stationary compressor, then it makes no difference which voltage you choose, but the 240 volt may be the better choice. If you anticipate the need to ever use this compressor as a portable, then going with the 120 volt will be more versatile for you.

As for the previous comments regarding voltage drop at the respective voltages, this is an overstatement and is typically made without actually determining the applicable voltage drops. Any properly sized circuit that is in compliance with the NEC will have a voltage drop of just a couple of volts, regardless which voltage the tool is operated at. The voltage from the power company can fluctuate by this amount throughout the day.

[Tom Veatch]

Assuming identical power in both 120 and 240 motors and identical circuit wiring from transformer to motor in both cases. Advantage to the 240 due to lower (1/2) amperage draw equating to lower voltage drop/line losses in the length of wiring from the transformer to the motor. Lower voltage drop in the line equates to higher voltage available at the motor and more efficient operation.

Someone mentioned extension cords which certainly should be considered for a portable compressor. Same condition holds, lower line loss due to lower amperage with the 240 motor. Assuming the same gauge cord for both, the 240 cord can be twice as long for the same numeric voltage drop, or 4 times as long for the same percentage voltage drop. Don't have a 240 extension cord? Replace the ends on a 120 cord with 240 plug and receptacle devices available at your local borg/hardware/electrical supply store.

Bottom line: Go with the 240 if possible.

[Jim Becker]

The 240v units have more horsepower are usually set up for higher capacities. Good move if you can do it!