Is 220 less expensive to operate?

[glenn bradley]

I've gotten conflicting info on this fairly straightforward question. If my TS draws 15amps at 110v and 7.5 amps at 220v does this equate to savings on my electric bill? MY TS and DC both will run either way. I'm just a hobbiest but, less money on juice = more money for wood!

TIA.

[Randy Gillard]

No. Same power either way.

[tod evans]

glenn, same bucks to the electric company.........tools will last longer and run a little better on 220 though....02 tod

[glenn bradley]

Thanks guys. And double-thanks for a simple answer. People kept trying to explain HOW a motor works when all I wanted to know was how much draw there was, one vs. the other. Maybe someday my shop will grow up and I'll have a tool that REQUIRES 220.

Thanks again.

[Larry James]

Thanks guys. And double-thanks for a simple answer. People kept trying to explain HOW a motor works when all I wanted to know was how much draw there was, one vs. the other. Maybe someday my shop will grow up and I'll have a tool that REQUIRES 220.

Thanks again.

Glenn, in general both use the same power. A 1 HP motor is a 1 HP motor - the motor requires the same power (read that $$$), regardless of voltage. An important consideration is the size of the wire supplying the motor. If the current (amp) draw is near the max capacity of the wire the voltage may decrease - the lights dim thing - when the motor is working under high load.

Larry

[glenn bradley]

Thanks Larry. Fortunatly the previous owner of the house was a metal worker and wired accordingly. No dimming lights, knock on wood.

[Hoa Dinh]

Glenn,

Internally, the motor windings are all 120V. If you wire the motor for 120V, the windings are connected in parallel. If you wire the motor for 240V, the windings are paired up in series, each pair then are connected in parallel. Each winding always sees 120V across its terminals in either case.

So the windings don't know if the motor is 120V or 240V. The notion of "saving money" or "better for the tools" is a myth.

The main purpose of 240V is really to allow the use of wire (and things like connectors, screws, switch, ...) of smaller size (compared to 120V). If the wiring for 120V is sufficient, there is no benefit to convert to 240V.

[chris del]

I have to agree with the others about 120/240V on a given motor having the same amount of hydro usage, however I should point out that a 1hp of today can be greatly different than one from 50 years ago....
Even today you can buy different motors that are more or less efficiant.
Up here in Canada in some industries a High efficientcy motor is a requirement when replacing or for new applications.....

Sorry for my poor spelling!!! Can figure out spell check on here.....

[Bruce Wrenn]

I have to agree with the others about 120/240V on a given motor having the same amount of hydro usage, however I should point out that a 1hp of today can be greatly different than one from 50 years ago....
Even today you can buy different motors that are more or less efficiant.
Up here in Canada in some industries a High efficientcy motor is a requirement when replacing or for new applications.....

Sorry for my poor spelling!!! Can figure out spell check on here..... Replacing an existing motor with an energy efficent one make sense on motors that run 24/7. The savings on electricity over the life of the motor will more than pay for the difference in cost. Kinda like GE's new locomotives-They save enough on fuel cost over the life of the locomotive, to pay for locomotive.

[Chris McDowell]

Glenn the only reason I run 220 on most of my machinery is the advantage of being a little easier on a motor that's running for long periods of time. I have had people claim it makes your bill cheaper, but have never seen anything that reflected that in my bills.

Chris

[Brian Clevenger]

Watts = Volts X Amps.

It doesn't matter how you do the math, electric companies charge for kW use.

If a motor draws 10 amp at 220 = 2200 watts
If a motor draws 20 amp at 110 = 2200 watts

[Don Baer]

Brain's got it Watts is Watts

[Frank Hagan]

I've gotten conflicting info on this fairly straightforward question. If my TS draws 15amps at 110v and 7.5 amps at 220v does this equate to savings on my electric bill? MY TS and DC both will run either way. I'm just a hobbiest but, less money on juice = more money for wood!

TIA.

AMPS x VOLTS = WATTS

In most areas, you pay for electricity by kilowatt hour or kWh. 1 kWh = 1000 watts, so if you divide your WATTS by 1000, you come up with the kWh that motor will use in one hour of operation (if it really did have that exact amp draw and voltage).

So the rating plate itself says that the electrical use is the same:
110 x 15 = 1,650 WATTS (or, 1.65 kWh)
220 x 7.5 = 1,650 WATTS (or, 1.65 kWh)

[Jason Roehl]

AMPS x VOLTS = WATTS

In most areas, you pay for electricity by kilowatt hour or kWh. 1 kWh = 1000 watts, so if you divide your WATTS by 1000, you come up with the kWh that motor will use in one hour of operation (if it really did have that exact amp draw and voltage).

So the rating plate itself says that the electrical use is the same:
110 x 15 = 1,650 WATTS (or, 1.65 kWh)
220 x 7.5 = 1,650 WATTS (or, 1.65 kWh)

Close, but no cigar. 1 kWh = 1000 Wh, not 1000 W. A 100 W light bulb that is on for 10 hours is 1 kWh of electrical usage. (watts x hours).

[Rob Russell]

Glenn the only reason I run 220 on most of my machinery is the advantage of being a little easier on a motor that's running for long periods of time. I have had people claim it makes your bill cheaper, but have never seen anything that reflected that in my bills.

Chris

Chris,

The motor doesn't know if you've got it wired for 120v or 240v. The only real difference is that being wired for 240v means the amperage flowing through each conductor is cut in half. 240v-wired motors may seem to "spring to life" a bit faster than 120v-wired motors, but only because the 240v-wired motor has 2 conductors to pull the startup current through. It's sort of like being able to suck from 2 garden hoses at once.

There are folks who will say that motors run dooler when wired for 240v and that's a bunch of hooey, provided the building wiring is capable of sustaining full voltage at 120v. It is true that the building wiring will heat up ever so slightly more when a 120v-wired motor is run vs. a 240v-wired motor, but we're talking about very small differences that you'd need serious test equipment to measure.

The one time when it will make a bit more of a difference is when the machinery is a long way from the panel - like 100'. Over that distance, you'll see more voltage drop on a 120v circuit than on a 240v circuit.

I've always wired my stuff for 240v 'cuz thats the way I wanted it.

Rob

[Rick Christopherson]

240v-wired motors may seem to "spring to life" a bit faster than 120v-wired motors, but only because the 240v-wired motor has 2 conductors to pull the startup current through. It's sort of like being able to suck from 2 garden hoses at once. Rob, Even though you reiterated my sentiments on this issue, the explanation of the difference between 120 volts and 240 volts is confusing.

Both 120 volt and 240 volt circuits still have 2 current carrying conductors. The current flows equal, but opposite through both conductors. In other words, during any single instant in time, current will be flowing “IN” through one conductor and flowing “OUT” through the other conductor. Because this is AC power, this flow gets reversed 60 times per second.

I think what confuses many people is that we call one of the wires in a 120 volt circuit a “Neutral”. This is just a name, and it does not impact how the power is transferred to the load. There is still 120 volts between the two conductors.

[Mark Rios]

Chris,

.............It's sort of like being able to suck from 2 garden hoses at once.

Rob


Rob, why do you suck through garden hoses?

:D :D :D

[Rob Russell]

Rob, Even though you reiterated my sentiments on this issue, the explanation of the difference between 120 volts and 240 volts is confusing.

Both 120 volt and 240 volt circuits still have 2 current carrying conductors. The current flows equal, but opposite through both conductors. In other words, during any single instant in time, current will be flowing “IN” through one conductor and flowing “OUT” through the other conductor. Because this is AC power, this flow gets reversed 60 times per second.

I think what confuses many people is that we call one of the wires in a 120 volt circuit a “Neutral”. This is just a name, and it does not impact how the power is transferred to the load. There is still 120 volts between the two conductors.

Rick,

What I was thinking when I wrote the post was that 240v circuits have 2 hot conductors vs. 1 hot and a grounded/neutral. I realize that the difference between 240v and 120v is more accurately explained as the 240v system has a higher voltage potential between the conductors and that's what really reduces the current flow, but for many folks the analogy of trying to suck from 1 garden hose vs. 2 is probably easier to understand. I know that's not technically accurate, because the power doesn't just "flow out" (whereas you more accurately described how current flows). Your point hints towards the fact that many folks dont understand that the grounded/neutral conductor carries just as much current as the hot conductor.

The point of the thread is whether there is a cost difference between 120v and 240v. Given that purpose, explaining 120v vs. 240v as being the same amount of water split between 2 hoses for 240v is probably good enough and is a bit more understandable to folks who don't understand electricity the way you do.

Mark,

I don't generally make a habit of sucking through garden hoses :cool:. I wil admit that I have - on occasion - had a drink from the garden hose when I was out working, grubby from head to toe, thirsty and didn't want to take the time to dust off and strip off the work boots just to go in and get a drink.

Rob

[Rick Christopherson]

Rob, I really disagree with this idea. I think it actually causes more confusion than it helps. An analogy is supposed to help people understand a complex situation by putting it in more common terms. Yours actually isn't an analogy at all because it is not representing the actual situation.

If you want to come up with a proper water-based analogy, you should be thinking along the lines of the voltage is equivalent to the water pressure, and the power output being how much work that water can do.

Here's a hint: You can have a huge volume of water flowing, but it won't do any work because it has no pressure and is therefore moving very slow. Conversely, you can have a super high pressure stream moving very fast (like a squirt gun) but it can't do any work because there is no volume behind the flow.

Water is commonly used as an analogy for electricity because it very closely follows all of the same rules of electricity. If I'm not mistaken, hydraulics follow virtually the same basic equation as Ohm's law.

Your two-hose example is actually 180 degrees backward from the actual situation.

[Curt Harms]

Brain's got it Watts is Watts

Ya think we could convince the utility companies to charge by amps instead of watts??:D

Curt

[Shaun Wilson]

...or gallons? ;)

[Shaun Wilson]

Glenn, to answer your original question - yes, but likely only by a penny or two. Everything else being equal, electricity flows more efficiently at higher voltage. That is why long range power transmission lines typically run at several hundred thousand volts! -it is simply more efficient.

Shaun

[Mac Cambra]

The advantage that comes from running at the higher voltage is obviously the lower current level to produce the same power output. What ni ine has yet to mention is the energy wasted as heat due to series resistance of the wiring and efficiency of the motor. The heat is a function of the current and the resistance I mentioned. Power (heat dissipation)=current^^2*resistance. The lower the wire gauge (thicker wire) lower the resistance, that is why higher currents require thicker wire to avoid fires.

I guess it is a little more complicated than assuming both configurations are equal, bottom line is I expect that there would be cost saving however they are likely negligible unless like someone else indicated that the machine is under contuous use.

[Frank Chaffee]

…But what does this mean for the personal woodworking shop?

I thought that somewhere between Nicola Tesla’s demise (too bad for Phelps-Dodge, etc), and the creation of the REA, electrical transmission and distribution became an easily and safely used power source for us masses.

Please correct me if I am wrong, but I am under the impression that…

Watts (the measure of work done (746 point some odd of which equate to one horsepower)), equals Volts times Amps.

Variables include voltage supplied by the power company (typically guaranteed to be w/in +/- 10%), amperage rise due to resistance along wiring run (twice the voltage in 240 equals one half the resistance in comparison to 120), the relative costs of wire gauges required for 120 vs. 240 volt, and the efficiency of given motor(s) at 240 and 120 volts.

Near as I can tell the only factors that woodworking shop builders have to work with are current costs of copper wire and the efficiency of motor selected at either voltage. Some posters have stated that motor efficiency is not affected by voltage; that is important to know, and should anyone wish to refute that, now would be a good time.

These are the issues (costs), I would like to see addressed in response to Glenn’s question.

Frank

[Hoa Dinh]

...(twice the voltage in 240 equals one half the resistance in comparison to 120),...

No, no. The voltage has nothing to do with the resistance. The resistance of the wire of a given material is inversely proportional to the cross section area and directly proportional to the length.

The energy dissipated (wasted) as heat in the wire (from the power source to the motor, not the wiring in the motor), however, is directly proportional to the square of the current through the wire (P = (I^^2)R).

For a given wattage, the current in a 240V is half of that in a 120V circuit, thus using 240V instead of 120V does reduce the heat dissipation in the wire, and saves some money. That is, if the wire has the same size and the same length in either case. But as noted, the saving in most common cases is negligible. If you already spend $100,000 on a car, it makes little difference whether a wiper blade is $4 or $2.


...Some posters have stated that motor efficiency is not affected by voltage;

That is correct. The windings in the motor can't tell if you are feeding the motor with 240V or 120V. So 240V or 120V, the difference in only between the power source and the connection box just outside the motor.

[chester stidham]

As long as you brakers are even on both bus bars no 220vshould cost the same. But if most of the brakers 110v are on one bus and you have an old meter you can save a little money by makeing the amp draw even across both sides. Don't ask? also some people say they get more power out of there motors but i have never had that hapen. but I run all my motors that will run 220v on 220v. seam to trip less brakers that way but only because most other tools, lights ect. run on 110v and only a few of my big tools run 220v and each has it'sowen 220 plug

[Hoa Dinh]

if most of the brakers 110v are on one bus and you have an old meter you can save a little money by makeing the amp draw even across both sides.
That's another myth.

[Mike Cutler]

Twinkle Twinkle little star. Power= I2R.

Watts are watts are watts. I Make the power. I put it on the grid at 345,000 volts. The utility charges you based on watts. Watts do not change. It will take the same amount of watts to saw through an 8/4 walnut board regardless of whether there is 115, or 220 running the saw. The blade thickness, tooth configuration, density of the wood, thickness of the wood etc, are the variables, independent of the motor efficiencies and losses based on the quality of the motor

The most compeling argument for 220 vs 115 is the increased availability of driving force. There is ultimately more "butt" available behind 220, but if your motor can be run at it's max off of 115 then it doesn't matter. Watts are watts. We're still going to charge you the same amount.

Size your wires, breakers, and receptacles properly to mitigate losses.

[Rick Christopherson]

To no one in specific:
This discussion has gone on way too long without substantiative information. The reason is that people keep repeating terms they hear others say without understanding what they actually mean.

The question was about cost, yet no one mentioned power-factor!! This has nothing to do with efficiency, as some have confused it, but deals with phase-shift between current and voltage. The result is that most inductive motors operate at almost zero-cost until they are loaded.

P = I-squared-R is NOT true when you forget that the current is nearly 90 degrees out of phase with the voltage!!! This is not how your residential meter socket operates.

If you are going to go off on these tangents, then make sure you have completed your vector analysis properly. If you don’t know what “vector analysis” means, then you should not be answering these questions with the type of answers that have been provided.

[Bob Aliano]

Since a 220V tool draws less current for a given wattage there will be less power lost to heating the tool, wires and connections. The loss will be greater as a 115V tool approaches the maximum breaker capacity, typically 15 amps, and often is noticable in the speed and torque developed by the tool.

[Mike Henderson]

To no one in specific:
This discussion has gone on way too long without substantiative information. The reason is that people keep repeating terms they hear others say without understanding what they actually mean.

The question was about cost, yet no one mentioned power-factor!! This has nothing to do with efficiency, as some have confused it, but deals with phase-shift between current and voltage. The result is that most inductive motors operate at almost zero-cost until they are loaded.

P = I-squared-R is NOT true when you forget that the current is nearly 90 degrees out of phase with the voltage!!! This is not how your residential meter socket operates.

If you are going to go off on these tangents, then make sure you have completed your vector analysis properly. If you don’t know what “vector analysis” means, then you should not be answering these questions with the type of answers that have been provided.
The power factor issue is the same for 110V and 220V. It won't have any effect on the difference in cost between operating on 110V or 220V. The only difference is what many people here have pointed out - if the tool is wired for 110V it will draw more current compared to operation on 220V and will have greater losses in the wire feeding the tool. Because of the way most motors are wired, there won't be greater resistance losses inside the motor when operating at 110V compared to 220V.
Mike

[Bruce Benjamin]

220...221...Whatever it takes.:cool:

Bruce

[Keith Hooks]

The reason I run my saw at 220v instead of 110v is that running at 110v potentially generates four times the amount of heat due to internal resistance of the motor windings. More heat means shorter life of the tool. Granted, the end result might be negligible, especially considering how much I use the saw.

You typically can't arbitrarily switch from running a tool at 110v or 220v without changing how it's wired.

[Mike Cutler]

To no one in specific:
This discussion has gone on way too long without substantiative information. The reason is that people keep repeating terms they hear others say without understanding what they actually mean.

The question was about cost, yet no one mentioned power-factor!! This has nothing to do with efficiency, as some have confused it, but deals with phase-shift between current and voltage. The result is that most inductive motors operate at almost zero-cost until they are loaded.

P = I-squared-R is NOT true when you forget that the current is nearly 90 degrees out of phase with the voltage!!! This is not how your residential meter socket operates.

If you are going to go off on these tangents, then make sure you have completed your vector analysis properly. If you don’t know what “vector analysis� means, then you should not be answering these questions with the type of answers that have been provided.

Hmm.... Should I be offended here? Lets see Vector analysis- Check. Polar Rectangular equations-Check. ZEQ equivalents-Check. AC, and DC circuits-check. SCR Controllers-Check. Right and left hand rules-Check. Grounded and ungrounded motor generators- Check. Harmonic frequencies of order-Check. Sometimes small motors throw me abit, I'll admit. I'm used to 6.9KV, 15,000 Hp motors that weigh 10 tons, and power pumps at 250,000gpm,or 3 phase scr controlled reactor control rod magnetic jack motor controllers. That's where the phase angle you refer to can be critical.

The Twinkle twinle little star ditty, was too lighten up the conversation. Your rebuttal is of no significance. You can't control the phase angles at home, they are what they are, ergo the comment had no value other than to bog down the discussion on an esoteric point of no relevance to the original post.

Such is the same with your second paragraph. If we're not discussing changing motors, it is a non entity, and is of no value. the variable will not change, and yes we can discuss PF, and eff until the cows come home.

The purpose of discussions like this thread is to help someone not trained in basic electricity to understand the concepts from a birdseye view, not to overwhelm them with concepts and principles that have no bearing unless we are discussing replacing any given motor. Again, Watts, is watts, is watts, and there is nothing the homeowner, or small shop can do about it. It is the only universal expression in discussions like these. It's the lowest common denominator, and it's how you are going to pay.

You're a very intelligent, and educated person Rick, that much is clearly obvious. You have an excellent webpage for information like this. I was really surprised that you didn't refer to your webpage. I've referred more than a few folks to your webpage when these discussions arise. I was also offended that you chose to criticize, and belittle Rob, and myself in a public forum. You have a lot of experience and knowledge to impart. Don't risk your audience and supporters.

[Glen Gunderson]

The reason I run my saw at 220v instead of 110v is that running at 110v potentially generates four times the amount of heat due to internal resistance of the motor windings. More heat means shorter life of the tool. Granted, the end result might be negligible, especially considering how much I use the saw.

You typically can't arbitrarily switch from running a tool at 110v or 220v without changing how it's wired.

As others have pointed out, the supply voltage has absolutely no bearing on the heat generated in the motor windings. The windings on 110V/220V motors run at 110V regardless of what the supply voltage is. I am really surprised at how much misinformation is spread around on what to me is a fairly simple topic.

[Larry James]

I've gotten conflicting info on this fairly straightforward question. If my TS draws 15amps at 110v and 7.5 amps at 220v does this equate to savings on my electric bill? MY TS and DC both will run either way. I'm just a hobbiest but, less money on juice = more money for wood!TIA.

"I've gotten conflicting info on this fairly straightforward question." That is an understatement.

My answer to Glenn in post #5: "Glenn, in general both use the same power. A 1 HP motor is a 1 HP motor - the motor requires the same power (read that $$$), regardless of voltage. ..."

Gee, you guys make it so complicated.

Larry

[Hoa Dinh]

"I've gotten conflicting info on this fairly straightforward question." That is an understatement.

My answer to Glenn in post #5: "Glenn, in general both use the same power. A 1 HP motor is a 1 HP motor - the motor requires the same power (read that $$$), regardless of voltage. ..."

Gee, you guys make it so complicated.

Larry

Larry, none of your replies include vector analysis. They are not sufficient :rolleyes:

[Bill Simmeth]

What a hoot! Three pages and two weeks. I thought (and seems Glenn did too) that the simple question got a simple (and correct) answer in reply #1.

[Larry James]

Larry, none of your replies include vector analysis. They are not sufficient :rolleyes:

Hoa, I checked the roster of members, I can't find Vector Analysis. Could he be in violation of TOS - using members real name? :rolleyes: :rolleyes:

Larry

[Keith Hooks]

As others have pointed out, the supply voltage has absolutely no bearing on the heat generated in the motor windings. The windings on 110V/220V motors run at 110V regardless of what the supply voltage is. I am really surprised at how much misinformation is spread around on what to me is a fairly simple topic.

If that's the case, then please educate me. Why would a manufacturer offer the option of running on 110v or 220v if there was no benefit to running on 220v? If thermal efficiency is not the answer, then what is?

At some level, I know the resistance of the motor as a whole must change to move from 110 to 220. Are you saying it's a case of going from two resistors in parallel to two resistors in series? But, I'm still using half the current (same power) on a 220v setup. Less current equals less heat. What am I missing here?

[Hoa Dinh]

To keep this simple, let's leave "vector analysis" out of this. If you disagree, skip.


If that's the case, then please educate me. Why would a manufacturer offer the option of running on 110v or 220v if there was no benefit to running on 220v?
So that you can use smaller wire (and switches, connectors, screws, ....) because for the same wattage, the current in the 240V circuit is only half of that in a 120V circuit.

There are cases in which the electrical components for a 120V hookup don't exist. My saw needs 13A @ 240V so I installed a 20A, 240V circuit for it. But if I were to rewire it for 120V, I would need breaker, wire, switches, outlet, and plug rated at 30A or 40A. They are difficult or impossible to find.

Are you saying it's a case of going from two resistors in parallel to two resistors in series?
Yes.

I'm still using half the current (same power) on a 220v setup. Less current equals less heat. What am I missing here?
What you're missing is the "half the current (same power) on a 220v setup" applies ONLY to the wiring from the power supply to the box just outside the motor. So the saving is miniscule.

Internally, the motor doesn't know what voltage you are feeding him.

[Bill Boehme]

I am a strong advocate of the placebo effect of a warm fuzzy:). I used to be like Hoa Dinh, Rick Christopherson, and others who have been trying to save the woodworking community from myths, folklore, and urban legends about electricity:confused:. I have come to realize that it is a lost cause so I now say, "if it gives you a warm fuzzy, then go for it." It makes life a lot easier and everybody is happy. And I won't be accused of being in cahoots with the power company.:D

Bill

[Hoa Dinh]

Thanks, Bill. I like your attitude. :)

After all, perception is everything.

[Bob Aliano]

Bill, I disagree. Running a power tool on 220V is more economical in the sense less power is wasted heating up the wire, connections and possibly the tool. The simple formula is power = current squared X resistance. So for a given length of wiring with a fixed resistance the amount of power wasted is proportional to the square of the current and the current required by the tool is considerably higher at 115V than at 220V. Why do you think there are wire guage requirements supplied with every power tool?

[Rick Christopherson]

Hmm.... Should I be offended here? Yes Mike, you should be offended, and others too.

I was in a hurry and I realized afterward that what I said was not what I was trying to say. Unfortunately, by the time I came back to read this, I was already quoted in someone else's post, so deleting my post was not an option.

I had confused some similar discussions in this thread (a long one at that) with a few emails I had just finished reading. It was too much information in too short of a time period, and I ended up attributing the wrong information to what I read in this thread.

As Bill put it, sometimes you need to just walk away. I knew I had information-overload when I made the post, but I was in too much of a hurry to be someplace, and clicked on send anyway. My appologies.

[Bill Boehme]

Now I find out after it is too late:(. After spending 32 years as an electrical engineer specializing in automatic control system design (this involves electric motors of various types, hydaraulic motors, pneumatic motors, hydrazine motors, etc., I finally learn that I really didn't know what I was doing, after all.:D Maybe I should have stayed on the farm.

Bill

[Mike Cutler]

Yes Mike, you should be offended, and others too.

I was in a hurry and I realized afterward that what I said was not what I was trying to say. Unfortunately, by the time I came back to read this, I was already quoted in someone else's post, so deleting my post was not an option.

I had confused some similar discussions in this thread (a long one at that) with a few emails I had just finished reading. It was too much information in too short of a time period, and I ended up attributing the wrong information to what I read in this thread.

No sweat bro'. I've been working 8:30 at nite to 7am lately, and I admit that I was a little reactionary. The response caught me a little off guard too. I've always found your posts, and responses on the subject to be well thought out,articulate, and accurate.

I've wondered at times if you would have the time and inclination to prepare, and submit an article for the Woodworking Articles and Reviews forum. I know that your webpage covers the subject, but having it condensed into a topic specific would be of great value.

This subject comes up alot on various forums, and inevitably ends up way too technical in nature for the original post(s). We begin to discuss motor eff, and PF. Thermal properties,and heat disapation of stranded and solid conductors. Cable insulation, and dialectric principles. Velocity propogation, etc. Mostly the original post(s) are asking a question much simpler than that. "How do I safely rewire a dual voltage motor?"and "what are the benefits?"

For Glen's original question. The answer is that he won't realize any tremendous savings swapping over the motor to 220. A safety argument can be made that the current in any single condutor, the wiring to the motor, and not the motor internal, will be less with 220. With properly sized conductors, internal wiring and breakers it becomes a non issue. The machine/motor is still operating inside of a safe envelope.