220/240 volt advantages?

[Jim Morgan]

Years ago, I ran a 220V circuit to power my tablesaw. I recently acquired a lathe that also requires 220V. While I'm at it, is it worthwhile to add 220V drops to other machines that can run on that voltage (jointer, bandsaw, etc.)? For home shop motors that can run on either 110 or 220, what are the advantages of higher voltage? Cooler running? Greater longevity?

[andrew whicker]

Runs cooler because it uses less amperage which also costs you less money.

I think 220v is worth it. I was given an old version of a Grizzly dust collector that ran 220v ONLY. It has been replaced by a new design that runs either 110v or 220v. The sacrifice is that the new unit is capped at 12 amps @ 110v / 1.5 HP while my old one is capped at 2 HP because it can take a higher amperage @ 220v and Grizzly didn't have to worry about making the motor compatible w/ 15 amp 110v.

You probably have a few 20 amp 110v circuits in your house, but that's as high as I've personally seen. Where as 220v are commonly wired for pretty high amperages (high HP).

3 phase is even better. I just picked up a 3 (three) amp 3 HP 480 v dust collector. Pretty awesome.

[Michael Burnside]

In the context of motors, it mainly comes down to the ability to do work at a given current. With 240V there is a higher voltage potential and to do the same work it requires half the current. In a residential context you can get a very powerful 240V motor pulling say 12A and generating 3 horse power. In contrast to do that same thing at 120V you're needing double that current. Wiring, breakers, etc. all need to be setup to protect the cabling delivering the power to the machine. So, manufacturers will generally half the horse power instead so it fits better in the application because >20A breakers and wiring at 120V is exceedingly rare. I preplanned by shop setup and I only went 8 120V 20A services as there really aren't a lot of 120V tools that pull more than 15A.

By having 240V available now YOU have the option to decide what kind of power you need at a given machine. Maybe 120V is sufficient, maybe you need more and now you have the option.

In terms of reliability, cooler, etc. it's largely splitting hairs assuming it's a quality tool built to purpose. 240V will give you a bit more efficiency, but often you're also getting more power so heat/power really varies by machine and application.

[Jim Becker]

In the context of woodworking, 240v machines typically have higher horsepower motors and higher capacities for work as a result. So having multiple 240v outlets can allow you to have the opportunity leverage the more capable machines should you want or need them. While you can have all the machines you can only use one at a time on the same circuit, if you also put in a 240v dust collector, that should have a separate circuit from the other machines. The only other reason to have additional 240v circuits in most one-person shops is for special needs, such as a CNC machine that requires a four wire circuit, a Mini SPlit HVAC system, a welder that requires a higher amperage circuits, etc. For the shared machine circuit, set that up so it able to handle the amperage of the highest rated tool (typically 30 amp in a woodworking shop for a big saw, J/P, etc) and standardize your receptacle/plugs to that higher amperage for flexibility.

[Lee Schierer]

For a given motor Power is power no matter the voltage. There is no significant advantage of running a motor of a given horsepower at 240 volts versus 120. 240 Volts does allow you to use smaller gauge wire which will save some cost on wire but the 240 volt breakers, plugs and receptacles will cost more.

Here is a link to more discussion (https://sawmillcreek.org/showthread.php?19211-Rewiring-a-Motor-for-240V) of this.

[Anthony Whitesell]

Runs cooler because it uses less amperage.

Electric cost won't change. (120V @ 15A = 1.8kW, 240V @ 7.5A = 1.8kW)

Gauge wire required is smaller, thus less expensive for the same motor. Or for the same expense (installation of 12g wire) you can run high HP motor. On a 120V 20A breaker with 12g wire the highest HP motor is 2, whereas a 3HP motor can be run on the same wire using 240V.

Spin up time will be less, but not by an amount that a human would care about.

[Ken Fitzgerald]

For a given motor Power is power no matter the voltage. There is no significant advantage of running a motor of a given horsepower at 240 volts versus 120. 240 Volts does allow you to use smaller gauge wire which will save some cost on wire but the 240 volt breakers, plugs and receptacles will cost more.

Here is a link to more discussion (https://sawmillcreek.org/showthread.php?19211-Rewiring-a-Motor-for-240V) of this.


Runs cooler because it uses less amperage.

Electric cost won't change. (120V @ 15A = 1.8kW, 240V @ 7.5A = 1.8kW)

Gauge wire required is smaller, thus less expensive for the same motor. Or for the same expense (installation of 12g wire) you can run high HP motor. On a 120V 20A breaker with 12g wire the highest HP motor is 2, whereas a 3HP motor can be run on the same wire using 240V.

Spin up time will be less, but not by an amount that a human would care about.

I agree!

When I built my shop, I put 240v.a.c. boxes evenly dispersed around the perimeter walls so in the future I could place higher horsepower equipment where I wanted. Then I, also, wired them with 12 gauge wire so I could put heavier duty motors near those outlets as I deemed necessary. I put one in the wall between the walkin-door IIRC wired with 10 gauge and the insulated garage door so if I decided I needed use a welder it was handy to put the welder outside when welding.

[andrew whicker]

Your motor will run more efficiently, but, yes the practical side of things... you'll save pennies.

My point still stands: 220v gives you more freedom for bigger machines. If you want bigger and better machines that consume more HP, you will have to use 220v. I don't see a woodworking tool company building a 110v motor that consumes more than 15 amps. But, maybe they exist. IDK. I haven't looked. Seems oddball to me.

Edit to add:

To remove confusion. When we are buying electricity from the utility company they don't care about your motor OUTPUT power. They care about the INPUT power. The INPUT power = OUTPUT power + X power (real life inefficiency of your motor). X power is less for higher voltages, hence you buy less power from the utility company for a given OUTPUT power.

Maybe that difference is small and/or the motor is turned on so infrequently that practically speaking it makes no difference, but I feel like there is some confusion above regarding this point.

[roger wiegand]

Many more options for VFDs to give you three phase power and variable speed where that matters. You can often go down a step in wire gauge (or up a step in amperage without rewiring).

I'm not sure what advantages, if any, there are for 120V power. Much of the rest of the world gets along fine without it.

I wired all the outlets in my shop except for the dedicated single machine 240V circuits as MWBCs (multiwire branch circuits) giving me both 120 and 240 V options at every drop as well as ability to plug two 120V larger loads in at a single drop. Yes, a bit of extra wire cost in theory, but it only take one reorganization of the shop to recoup what was, at the time, a very small difference in price between 12-2 and 12-3 cable.

[John TenEyck]

What Lee said. There is no difference inside the motor.

John

[Mike Stelts]

If you want bigger and better machines that consume more HP, you will have to use 220v. I don't see a woodworking tool company building a 110v motor that consumes more than 15 amps.

Since the largest 120V outlet is 20A, the biggest motor that can run on it is 16A. That's why you'll never see a larger 120V motor.

[Anthony Whitesell]

Since the largest 120V outlet is 20A, the biggest motor that can run on it is 16A. That's why you'll never see a larger 120V motor.
I only did a quick look.

Grizzly G0513X2 Bandsaw "Motor: 2 HP, 110V/220V (prewired 220V), single-phase, 19A/9.5A"

BALDOR 1425RPM 184T TEFC 1PH MOTOR L3609T-50 110V 25A/220V 12.5A

Not that I would want to run either of those motors on 120V. But there are motors that can be wired on 120V that require more than 20A service.

[Mike Stelts]

I only did a quick look.

Grizzly G0513X2 Bandsaw "Motor: 2 HP, 110V/220V (prewired 220V), single-phase, 19A/9.5A"

BALDOR 1425RPM 184T TEFC 1PH MOTOR L3609T-50 110V 25A/220V 12.5A

Not that I would want to run either of those motors on 120V. But there are motors that can be wired on 120V that require more than 20A service.

Sorry, I didn't finish my point earlier... Nobody would sell these motors wired for 120V, because they wouldn't pass UL. If they exceed 16A (80% of 20A), they can't be sold for 120V. If one decides to rewire for 120V, it's at their risk, not the manufacturer's. The practical limit is about 1.75 Hp; e.g. SawStop and Powermatic offer 1.75Hp motors.

[Anthony Whitesell]

Sorry, I didn't finish my point earlier... Nobody would sell these motors wired for 120V, because they wouldn't pass UL. If they exceed 16A (80% of 20A), they can't be sold for 120V. If one decides to rewire for 120V, it's at their risk, not the manufacturer's. The practical limit is about 1.75 Hp; e.g. SawStop and Powermatic offer 1.75Hp motors.

If the motor has the option to be wired for 120V, independent of who does the wiring, and is UL listed then it is UL listed in both 120V and 240V configurations. The owner needs to know they need an L5-30 30A 120V outlet wired with 10g wire if they intend to run the motor on 120V.

[Malcolm Schweizer]

Another way of saying what others have said: to get the same HP as a 220V/20A circuit from 110V, you would need 110V/40A, which just isn’t a thing. Your limit for 110V (or 115V) is usually 15A but could be higher on a 20A dedicated circuit. Although vacuums advertise 6 “peak” horsepower, for example, that’s just a burst at startup. The real horsepower maximum you will get from 110V is around 3.5HP.

[Anthony Whitesell]

Another way of saying what others have said: to get the same HP as a 220V/20A circuit from 110V, you would need 110V/40A, which just isn’t a thing. Your limit for 110V (or 115V) is usually 15A but could be higher on a 20A dedicated circuit. Although vacuums advertise 6 “peak” horsepower, for example, that’s just a burst at startup. The real horsepower maximum you will get from 110V is around 3.5HP.

Not sure why you think 120V 40A is not a thing. OK. 40A is almost not a thing. But 120V 50A is. (I'm not sure I would want to deal with it. But it is a thing.)

Breaker:
https://www.lowes.com/pd/Square-D-QO-50-Amp-Single-Pole-Circuit-Breaker/5001496497

Outlet:
https://www.lowes.com/pd/Utilitech-Black-50-Amp-Round-Rv-Industrial-Rv/3775479

List of all outlets:
https://www.generatorjoe.net/html/web/outlet/quailplug.html

[Mark Gibney]

For those of you who claim a motor will run cooler / more efficiently at 240 because it uses less amperage can you explain a little deeper, please.

Because my understanding is that power used is measured in watts.
Watts is voltage x amperage.
So 120 V x 10 amps = 1,200 Watts
and 240 V x 5 amps = 1,200 Watts

I don't see any difference.

[Anthony Whitesell]

For those of you who claim a motor will run cooler / more efficiently at 240 because it uses less amperage can you explain a little deeper, please.

Because my understanding is that power used is measured in watts.
Watts is voltage x amperage.
So 120 V x 10 amps = 1,200 Watts
and 240 V x 5 amps = 1,200 Watts

I don't see any difference.
Efficiency is not power nor wattage.

Driving force makes a difference. It is similar to driving a nail using a 16oz hammer versus a 8oz hammer. With the lighter hammer the nail has to be hit twice as hard to provide the same force, in doing so efficiency is lost.

The efficiency difference, the temperature difference, and the startup time are nearly (if not actually) impreceptible to the human senses. The differences are really splitting hairs. Does 70.8% vs 70.2% (made up numbers) really make a difference? The few degrees cooler the motor will run may help the longevity of the motor in the long run, but doubtful it would effect the intermittent use that woodworkers use and run their motors.

If you want the actual numbers and formulas, I can go dig out my power books from college and get back to you later.

[Rich Engelhardt]

Back when I worked at Builder's Square (1986-ish), one of the vice presidents invested a ton of his money in Puma compressors. We (the stores) were forced to close out Campbell Hausfeld and replace them all with made in China Puma compressors.
I'll never forget the fiasco.

There was a "wheel barrow" model targeted at contractors and roofers, that was electric and retailed for about 1/3 less than anything else on the market.
We got a shipment of them in - all wired for 120V - 25amp or 30amp, I can't remember - all I know is that it was so high it would trip the breaker as soon as the switch was thrown.

Every single one of them we sold came back. None of them we able to run.

The stores had to eat that loss and to make matters worse, once they were written off to no value, we got more shipped in to take their place.

[Anthony Whitesell]

Back when I worked at Builder's Square (1986-ish), one of the vice presidents invested a ton of his money in Puma compressors. We (the stores) were forced to close out Campbell Hausfeld and replace them all with made in China Puma compressors.
I'll never forget the fiasco.

There was a "wheel barrow" model targeted at contractors and roofers, that was electric and retailed for about 1/3 less than anything else on the market.
We got a shipment of them in - all wired for 120V - 25amp or 30amp, I can't remember - all I know is that it was so high it would trip the breaker as soon as the switch was thrown.

Every single one of them we sold came back. None of them we able to run.

The stores had to eat that loss and to make matters worse, once they were written off to no value, we got more shipped in to take their place.

What plug did they come with? 5-15 or a 5-30? It would not surprise me if (a) they came with no plug and a 5-15 was added [ie., the wrong plug] or (b) came with a 5-30 and someone made an 5-30 to 5-15 adapter. Either way a portable compressor (especially targetted at field work by contractors) that required a 30A service, was a pretty silly design/machine. IMO.

[Keegan Shields]

The greatest benefit is that you can now buy used 220v machines and step up from the consumer level equipment. I’ve experienced far less competition for 220v machines than 110v on CL.

[Paul F Franklin]

For those of you who claim a motor will run cooler / more efficiently at 240 because it uses less amperage can you explain a little deeper, please.

Because my understanding is that power used is measured in watts.
Watts is voltage x amperage.
So 120 V x 10 amps = 1,200 Watts
and 240 V x 5 amps = 1,200 Watts

I don't see any difference.

I don't want to step on any toes, but there is no difference. Inside a standard motor capable of being wired for 120 or 240 are two sets of two coils. For 120 the two coils of each set get wired in parallel in the motor terminal block. For 240 they get wired in series. Each coil sees 120 volts no matter which way it is wired. The same current flows through each coil no matter which way it is wired. There is no difference in losses or efficiency *inside* the motor.

All of the points made in the thread about being able to run larger motors, using smaller wire, etc, are true, but the motor itself doesn't care or see any difference.

[Cameron Wood]

For those of you who claim a motor will run cooler / more efficiently at 240 because it uses less amperage can you explain a little deeper, please.

Because my understanding is that power used is measured in watts.
Watts is voltage x amperage.
So 120 V x 10 amps = 1,200 Watts
and 240 V x 5 amps = 1,200 Watts

I don't see any difference.



Current capacity in wires varies with temperature. Running more current heats the wire- that heat is wasted efficiency. 5 amps in a wire runs cooler than 10 amps in a wire.

[Rod Sheridan]

Runs cooler because it uses less amperage.

Electric cost won't change. (120V @ 15A = 1.8kW, 240V @ 7.5A = 1.8kW)

Gauge wire required is smaller, thus less expensive for the same motor. Or for the same expense (installation of 12g wire) you can run high HP motor. On a 120V 20A breaker with 12g wire the highest HP motor is 2, whereas a 3HP motor can be run on the same wire using 240V.

Spin up time will be less, but not by an amount that a human would care about.

Motor temperature will not change whether it’s running on 120 or 240 volt

In 120 volt mode you have 2 windings with 7.5 Amperes current, in 240 volt mode you have 2 windings with 7.5 amperes current, exactly the same in both cases.

Regards, Rod

[glenn bradley]

Runs cooler because it uses less amperage.

Electric cost won't change. (120V @ 15A = 1.8kW, 240V @ 7.5A = 1.8kW)

Gauge wire required is smaller, thus less expensive for the same motor. Or for the same expense (installation of 12g wire) you can run high HP motor. On a 120V 20A breaker with 12g wire the highest HP motor is 2, whereas a 3HP motor can be run on the same wire using 240V.

Spin up time will be less, but not by an amount that a human would care about.

Glad Anthony chimed in with this. There is a lot of misunderstanding about this. Watts are watts and that's what you pay for.

[Dan Friedrichs]

You have sufficiently large gauge wire for the length of the circuit and the load? 120V is fine.
You want to save some money by using smaller-gauge? Use 240V.
The motor doesn't care either way.

Cost of the wire is the only concern. All this about efficiency/losses/"running hot"/cost/etc is either plainly wrong or so trivial as to be meaningless.

[Michael Burnside]

You have sufficiently large gauge wire for the length of the circuit and the load? No benefit to 120V.
You want to save some money by using smaller-gauge? Use 240V.
The motor doesn't care either way.

Cost of the wire is the only concern. All this about efficiency/losses/"running hot"/cost/etc is either plainly wrong or so trivial as to be meaningless.

This is pretty much correct. The efficiency is in the cost factor of the wiring to carry that power. I wouldn’t call that meaningless, but you’re pretty much on point otherwise.

[Dan Friedrichs]

This is pretty much correct. The efficiency is in the cost factor of the wiring to carry that power. I wouldn’t call that meaningless, but you’re pretty much on point otherwise.

Oh, for sure - a 240V 15A circuit could be run on 14AWG wire that is less than half the cost of a power-equivalent 120V 30A circuit on 10AWG wire.

I meant that the concerns about losses are trivial. E.g. if you had a 16A 120V circuit 100' long, you'd lose about 3% more power versus 8A 240V on the same-sized wire, and even that is only when the tool is running at full-load.

[Jason Roehl]

Something to consider when wiring: You can run 12/3 w/ground to receptacle boxes, then alternate 120V receptacles on the black and red hot legs. Then, if you need 240V, you have the wiring in place to make a 240V/20A receptacle. Or, you could even run 10/3 and have the possibility of future 240V/30A, but a little more difficulty in the wiring, 10 gauge wiring being a little stiffer to work. I always pigtail receptacles—I attach a 6” lead of solid 12-gauge wire to the receptacle screws, then wire nut those leads to the circuit wiring in the box. Those leads need to match the amp rating of the breaker, though.

[Mike Cutler]

The greatest benefit is that you can now buy used 220v machines and step up from the consumer level equipment. I’ve experienced far less competition for 220v machines than 110v on CL.

Yep, this is the one and only advantage.
A person will evolve to a point where they need/want bigger, more powerful, machines. Especially the dust collectors.
If you're going to run 240 circuits, do the wiring once and install 10awg. Yes, I know 12awg will work for most machines in a garage shop, but 10awg has you prepared when you do want to finally step up.

[Jason White]

Some people will say more powerful. Ignore those people. Advantages are blades come up to speed more quickly and less amp draw.

[Jim Morgan]

Thanks to all for the responses!

The concensus is that it doesn't matter to the motor whether it is wired for 110 or 220. But there is this from the 2005 thread that Lee Schierer referenced:


In my case the motor on my Delta Contractor's saw specifically states that it is 1 1/2 hp at 110, and 2 hp at 220. This was hottly debated on another board when a Delta rep was responding to messages and he was able to explain how it worked, but he was adamant that on my motor it would run at 2hp wired for 220.

Any ideas what was going on there?

Regarding the suggestion by Roger Wiegand and others to run 12/3 & then either use 1 hot+neutral+ground for 110 outlets or 2 hots+neutral+ground for 220 outlets, a couple of Code questions.
First, can multiple 110 circuits share a common neutral? Breakers protect the hot legs from overloads, but in the event that both hot legs were running just under full load, could the neutral get dangerously hot?
Second, how is the 12/3 connected at the service entrance? Using paired single-pole breakers could create a dangerous situation: shutting just one off while working on the circuit would leave the other leg still energized, with potentially fatal consequences. This must be prohibited by the code. But if a double-pole breaker is used, will an overload on just one leg trip it?

Finally, as Jim Becker points out, in a one-man shop, it doesn't matter how many machines are connected to a single circuit, so long as only one is in use at any time. As he says, some things should be on separate circuits. A dust collector for one (ftr, mine is on a dedicated 110 circuit). Also, shop lighting! If a machine trips a breaker, you would not want to be plunged into darkness - certainly not while sharp blades may still be moving.

[Mike Henderson]

Thanks to all for the responses!

The concensus is that it doesn't matter to the motor whether it is wired for 110 or 220. But there is this from the 2005 thread that Lee Schierer referenced:



Any ideas what was going on there?

Regarding the suggestion by Roger Wiegand and others to run 12/3 & then either use 1 hot+neutral+ground for 110 outlets or 2 hots+neutral+ground for 220 outlets, a couple of Code questions.
First, can multiple 110 circuits share a common neutral? Breakers protect the hot legs from overloads, but in the event that both hot legs were running just under full load, could the neutral get dangerously hot?
Second, how is the 12/3 connected at the service entrance? Using paired single-pole breakers could create a dangerous situation: shutting just one off while working on the circuit would leave the other leg still energized, with potentially fatal consequences. This must be prohibited by the code. But if a double-pole breaker is used, will an overload on just one leg trip it?

Finally, as Jim Becker points out, in a one-man shop, it doesn't matter how many machines are connected to a single circuit, so long as only one is in use at any time. As he says, some things should be on separate circuits. A dust collector for one (ftr, mine is on a dedicated 110 circuit). Also, shop lighting! If a machine trips a breaker, you would not want to be plunged into darkness - certainly not while sharp blades may still be moving.

This is possible if the motor contained a circuit that limited the current when operating at 120 volts. The motor could then be limited to 1 1/2 HP. When operating at 240 volts, the circuit could allow sufficient amps to genearate 2 HP.

There was a lathe company that did that with the motor they had on the lathe. If I recall, it was maybe 1 1/2 HP or 1 3/4 HP when operating at 120 volts and 2 HP or a bit more when operating at 240 volts. The reason for that limitation was that you can't get 2 HP worth of power from a 15 amp 120 volt circuit.

Mike

[Dan Friedrichs]

The concensus is that it doesn't matter to the motor whether it is wired for 110 or 220. But there is this from the 2005 thread that Lee Schierer referenced:
Any ideas what was going on there?

In that particular case, the motor is a 2HP motor, but Delta derated it (marked a lower maximum amperage and lower HP) for the 120V connection option. They did this so it could be sold with a 15A 120V plug. Had they left it marked 2HP and the higher amperage, it would have required a NEMA 5-20 plug, which most people don't have circuits and receptacles to support. With the correct 20A 120V connection, it would supply 2HP.

This gets a bit into the weeds, but a motor's rating is somewhat of a squishy concept, to begin with. It's just some tradeoff of cost, size, weight, performance, reliability, duty cycle, load characteristics, acceptable temperature rise, allowable operating ranges, etc. So nothing untoward about them deciding to mark it differently at a different voltage.



Regarding the suggestion by Roger Wiegand and others to run 12/3 & then either use 1 hot+neutral+ground for 110 outlets or 2 hots+neutral+ground for 220 outlets, a couple of Code questions.
First, can multiple 110 circuits share a common neutral? Breakers protect the hot legs from overloads, but in the event that both hot legs were running just under full load, could the neutral get dangerously hot?

This is called a "multi-wire branch circuit". Because the two hot legs are out of phase, the neutral carries only the imbalance between, which limits the max neutral current to the maximum difference between the two legs, which is the same as the breaker rating.



Second, how is the 12/3 connected at the service entrance? Using paired single-pole breakers could create a dangerous situation: shutting just one off while working on the circuit would leave the other leg still energized, with potentially fatal consequences. This must be prohibited by the code. But if a double-pole breaker is used, will an overload on just one leg trip it?

Correct, in a MWBC the breaker handles must be tied. Breakers with tied handles will trip both if either trips.

[Michael Burnside]

James, don’t over think it. There are a few exceptions, in this case sometimes a motor that supports both voltages will have a winding imbalance that isn’t double. The general discussion here is sound.

[Paul F Franklin]

It is possible to wind a motor with taps on the coils so that the number of turns used can be different when changing the configuration from 120 to 240. This could create a motor that delivers more power at 240 than at 120. One reason to do this would be to allow operation on a 15 amp 120 volt circuit (at reduced HP). So it can be done, but it's not common, and most dual voltage motors don't do it this way. The Nova voyager drill press has similar capability, but achieves it electronically, not with tapped coils.

Regarding the shared neutral circuit; it is allowed by code as long as a the two hots come from different legs of the 240 source and a 2 pole breaker is used. Because the two legs are out of phase with respect to each other, the sum of currents in the neutral is never more than the rating of one side of the two pole breakers. For example, if one leg is drawing 15 amps and the other leg is also drawing 15 amps, the current in the neutral will be zero. If one leg is drawing 15 amps and the other 0 amps, the current in the neutral will be 15 amps.

Shared neutral circuits were fairly common in my area for many years. They save a little money because you have 4 wires (2 hots, a neutral, and a ground) to serve 2 circuits instead of 6 wires if the two circuits were run separately. They are still allowed by the code, but have fallen out of favor for a number of reasons, one of which is the necessity for using 2 pole GFCI or AFCI breakers which tend to be a lot more expensive than 2 single pole GFCI or AFCI breakers. Also, I can't tell you how many times I have found shared neutral circuits that had be "rearranged" by someone not familiar with them such that both circuits were moved to the same leg of the supply. That *will* overload the neutral.

[Rich Engelhardt]

What plug did they come with? 5-15 or a 5-30? It would not surprise me if (a) they came with no plug and a 5-15 was added [ie., the wrong plug] or (b) came with a 5-30 and someone made an 5-30 to 5-15 adapter. Either way a portable compressor (especially targeted at field work by contractors) that required a 30A service, was a pretty silly design/machine. IMO.They came in with a 5-15 plug.
The machines were obviously made in a foreign country and not thought out very well.
It was a silly design as well as a silly idea.
Like I said above though, a Builder's Square VP was heavily invested in the Puma line and he made sure that's all the stores were allowed to carry.

[Greg Funk]

I don't want to step on any toes, but there is no difference. Inside a standard motor capable of being wired for 120 or 240 are two sets of two coils. For 120 the two coils of each set get wired in parallel in the motor terminal block. For 240 they get wired in series. Each coil sees 120 volts no matter which way it is wired. The same current flows through each coil no matter which way it is wired. There is no difference in losses or efficiency *inside* the motor.

All of the points made in the thread about being able to run larger motors, using smaller wire, etc, are true, but the motor itself doesn't care or see any difference.In theory, if all the wires feeding the motor and the internal motor windings had zero resistance you'd be correct. In reality, when a motor starts it can easily draw 6 time the FLA amps which, for a larger motor powered by 120V, can be 100+A. There will be significant voltage drops in the wires and the motor won't see 120V until it's started. Many years ago I had a 120V table saw that was slow to start. After re-wiring to 240V it would 'snap' up to speed much faster. Even when running under full load the 120V version of the motor will generate less power as the wiring losses will be higher for 120V.

[Anthony Whitesell]

In reality, when a motor starts it can easily draw 6 time the FLA amps which, for a larger motor powered by 120V, can be 100+A.


There will be significant voltage drops in the wires and the motor won't see 120V until it's started.
If there is more than a 6% drop in line voltage at the motor, then the branch impedence of the building wiring is too high thus indicating there is something wrong (corroded connection?) and an electrician should be called in to check things out before that high resistance connection causes enough heat to melt something.


Even when running under full load the 120V version of the motor will generate less power as the wiring losses will be higher for 120V. There are two sets of windings in a 120V/240V motor. In 120V they are in parallel, in 240V they are in series. Being they are the same windings with the same resistance, dissapating the power, there is no difference in the wiring losses within the motor.

Therein lies one of the factors related to the difference in the startup speed. The voltage loss in the building wiring is less with 240V. Wire has resistance, and voltage loss is current * resistance. Less current = less voltage loss.

[Tim Greif]

Regarding those Delta motors rated at different horsepower, depending on whether it was configured for 115 or 230 volt operation, I have one of those saws and still use it today. You'll note that the current draw at 230 volt is more than half the draw at 115, so something is definitely going on here. it may well be that Delta derated the saw's claimed power at 115 so they could supply it with a 15 amp plug. I've always used the saw at 115 and have had no problems cutting anything. I firmly believe that unless the motor has completely different windings for 115 and 230 volt configuration, the motor will produce the same horsepower regardless of the voltage.
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