# 220V vs. 110V for my new used saw?



## Valid8r (Nov 8, 2008)

I just bought a used contractors saw (Delta). The motor is wired as a 2HP 220V but can be obviously rewired to be used as a 1.5HP. I've read various posts elsewhere about whether there really is a big difference or not. I would prefer not to use up another circuit in my panel to use the 220V, but if it makes a big difference, then I will.

Thoughts?

Thanks,
Jon


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## sweensdv (Mar 3, 2008)

Where did you get the idea that you'll get more HP at 220V than at 115V? There is really no difference in performance if you power your saw with 110 or 220. Usually if 220V is used the saw will be on a dedicated circuit and at 110V will likely share the line with other items. This "sharing" of power might cause the saw to start up a little slower than it would on a dedicated circuit but after that there will be no difference. There also would be no difference in the operating cost of one over the other.


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## clarionflyer (Apr 27, 2008)

I keep reading that there is no difference. Maybe scientifically, but I found a *huge* difference. 

When I went to 220v it came straight from the box, and not from the house wiring. That could be the difference.

When I went to 220v, it was like a whole different saw. Instant start up. And my saw pushes through hard wood easily. Never any problems.

Before the switch (110). The saw would pull hard on start up (you know, lights dim... wife's mad), and - science will tell you different- but the saw pulls and drags along... 

I'm all for science but my saw runs completely different on 220v.
They can tell me the moon's made of cheese, but I can surely tell a difference with 220v.


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## user4178 (Apr 18, 2008)

If the lights dim at start up, thats a sure sign the motor isn't geting enough power at start up and under a heavy load. I had the same problem on my Contractors saw that had running on a 120V shared circuit, then switched to 240V, made a big difference. Sween is right about a 120V dedicated circuit working also, but I do think that 240V is easier on the motor. As far as takeing up another spot in your breaker box, depending on the brand of your breaker box, you may be able to get a 240V breaker that only takes up one slot in your breaker box. I guess in a nut shell, you should add another breaker regardless if it's 120V or 240V and dedicate it to one outlet for your tablesaw, personally I'd keep it at 220V.


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## knotscott (Nov 8, 2007)

AFAIK, some of the older Delta contractor saws did have extra windings that are utilized when wired for 220v, thus going from 1.5 to 2hp, but in general the power output is the same on other induction motors.

Whether or not 220v makes an improvement really depends on the individual circuit and the draw that a particular motor puts on it. I wired my GI 2hp contractor saw for 220v and noticed very little difference. I wired my 1-3/4hp Craftsman hybrid for 220v and it made a noticeable difference. There tends to be less voltage drop with a 220v line, especially on start up and during recovery from bogging, but an adequate 120v circuit should give roughly the same results.


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## Tony B (Jul 30, 2008)

*Science is correct*

You just have to plug in all of the parameters. 
There are lots of reasons that 220v may be better than 110v, but this all depends on your house wiring. Generally speaking, it wont be worse than 110V.
Your shop line may be on same line as other operating equipment such as lights and coffee and TV etc which is causing a voltage drop. 
But disregarding that, lets consider a particular tool draws a certain amount of power. Power = volts X amps. That mean that if you double the voltage, you will be halfing the current (amps). Amps = heat. Heat generated from wire is a power loss which shows as a voltage drop. So, if we run half the current on a 220v line through a given size wire we will have less voltage drop and the tools will perform better. As wires get hotter, their electrical resistance goes up. Resisrance causes a voltage drop across the wire itself. Again, this all depends on your particulal wiring. Some people will experience no noticable difference while others will experience a drastic difference. I have always have experienced a drastic difference. 
I use to wire all my 220 plugs for a clothes dryer receptacle.


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## user4178 (Apr 18, 2008)

Tony B said:


> I use to wire all my 220 plugs for a clothes dryer receptacle.


Tony, why use such a heavy plug ? That seems like overkill and more costly than it needs to be. I use the smaller 240V plug and receptacles.


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## Tony B (Jul 30, 2008)

*Woodchuck*

One of my shops at one time was in my home and I used the dryer plug because it was there. LOL
You are right. Thanks for correcting my poor choice. I was too fixated on a dryer plug, one of our dryers out here died last night.
Anyway, it is way overkill and a waste of good money if you were to have several 220V tools. 
I need to get back on land and get a life.


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## Ed'sGarage (Aug 16, 2007)

*Amps cost $$$*

All that you have mentioned is correct, but, in addition, if I'm not mistaken we pay our electrical bill by amps and 220 V uses half the amps that 110 uses; therefore lower electric bills. At least that's what I understand.


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## user4178 (Apr 18, 2008)

Not true Ed, lets say you have a motor that uses 15 amps at 120V. At 240V it uses 7.5 amps per hot leed. Since 240V has two hot leeds, your still useing a total of 15 amps. At startup or under a heavy load it will actually use a couple more total amps.


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## Tony B (Jul 30, 2008)

*Ed, another way to look at it is...*

you pay by the KW (Kilowatt Hour) which is roughly 10 cents per 1000 watts used in an hour.
Power is measured in watts. Watts = Volts X Amps
Therefore 220V x 7.5 amps = 1650 watts. 
and 110V X 15 Amps = 1650 watts. 
Power consumption should be the same from a practical standpoint.


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## skymaster (Oct 30, 2006)

220,220,220,220,220,220, rules :laughing::yes: mo power, mo faster start,mo better cutting, mo better:icon_smile::shifty: All mine 220, all mine mo better


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## Ed'sGarage (Aug 16, 2007)

*220 vs 110*

Thanks guys for clarifying the amp issue on 220! I learned something new today. 
Ed


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## Kenbo (Sep 16, 2008)

Speaking as a liscenced electrician, I recommend that the saw be wired at the 240 volt level based solely on personal experience. Without getting into ohm's law and all kinds of technical mumbo jumbo, the saw will, perform at a higher level, with less "stalling" on larger stock. Quicker response on start-up and less heat buildup in the motor windings are other bonuses. Care should be taken to ensure that the startup switch is one that is rated for 240 VAC. A lot of table saws that come with dual voltage motors, only come with single voltage startup switches. Over heating of these switches is a hazzard that can be extemely dangerous. As far as the kilowatt hour charges that are imposed on us by our local utilities, the cost of operation between 120 VAC and 240 VAC is insignificant and not even enough to bother mentioning.
Just the opinion of a guy with his electrical C of Q, that's all.
Ken


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## GeorgeC (Jul 30, 2008)

Ed'sGarage said:


> All that you have mentioned is correct, but, in addition, if I'm not mistaken we pay our electrical bill by amps and 220 V uses half the amps that 110 uses; therefore lower electric bills. At least that's what I understand.


You have it 1/2 correct. The 220 is using only half of the amperage, but twice the voltage. Therefore the power bill will be essentially the same.

Tony B stated it correctly.

George


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## Gerry KIERNAN (Apr 20, 2007)

The last time I started looking at electrical outlets and plugs I nticed a huge difference in price between the various types, voltages, and amp ratings of the outlets and plugs. Basically, the common everyday 110/120 volt 15 amp plugs and outlets were the least expensive, probably because they are mass produced, and most common. When you got into 240 volt outlets and plugs the dryer plugs and outlets were among the cheapest. Why? Because they are very commonly used. Some of the 240 volt outlets, of the less common variety, are upwards of $50 each, and more up here. 

So, I would say there is a good case for using dryer outlets and plugs. Of course, you have to have the wiring and breakers to support them as well.

Gerry


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## user4178 (Apr 18, 2008)

At $50 each I think your geting into Hospital grade outlets and plugs.


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## Gerry KIERNAN (Apr 20, 2007)

Woodchuck1957 said:


> At $50 each I think your geting into Hospital grade outlets and plugs.


No, I think these are just standard grade plugs and outlets, but it seems that because they are not so common they charge an ear and a right hand for them.
If I remeber correctly, the one that caugt my attention in particular was either a 20 or 30 amp 240 volt plug and outlet. I was wanting to run a line for my table saw which has a 1-1/2 hp motor, and can be wired for 240 volt. I keep killing the lights on 120.:thumbdown:

Gerry


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## skymaster (Oct 30, 2006)

commercial grade male and female 220 15A cost me less than 20 bucks for the pair. Somebody is ripping you


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## TexasTimbers (Oct 17, 2006)

GeorgeC said:


> You have it 1/2 correct. The 220 is using only half of the amperage, but twice the voltage. Therefore the power bill will be essentially the same.
> 
> Tony B stated it correctly.
> 
> George


I know better than to enter this thread filled with experts and engineers and master electricians (I am but a lowly Journeyman Electrician so just ignore me) but can't stand it any more. BUT, no one is correcting your mis-perception George and I know you don't want to stay that way. A 15 amp table saw motor wired for 240v does not use half the power that a 15amp 120v motor will. 

Loads do not use voltage per se anyway, and your bill is not figured by how much voltage is present during the running of a load. Although this is not exactly how simple it is, for all intents and purposes amperage used is the determining factor regarding how fast your meter will spin. 

It is a common myth that 240v (almost always incorrectly referred to as "220v" even in some literature and on some appliances) uses half the amperage of 120v ( I see that you do understand this part is a myth). A table saw wired to a 120v circuit will use the same amperage as one wired to a 240v circuit, and thus spin the meter at the same speed. There are some things that will cause the 120v to use a hair more amperage such as a 120v motor will get a little hotter than a 240v, and can be a hair more resistance in the windings of a 120v motor but for all practical purposes they use the same amount of amperage. 

With a 120v circuit, all the amperage (let's say 15 amps) will be carried on L1 (a.k.a "hot" leg). 

The 240v circuit distributes the current over two legs instead of one. 7.5 and 7.5, or 7 on one or 8, or 6.9 and 8.1 or any combo thereof etc. the more balanced the load the better but that's all another subject too.

I better stop here. The more I say, the more someone is going to feel the need to correct me i.e "Hey man the power company doesn't charge you by how many amps you use they charge you by how many watts you use!" and then someone will say "No man they charge by how many kwh you use!" and someone else will say "No man, they charge by how many times you fip a switch on and off!' :laughing:


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## GeorgeC (Jul 30, 2008)

Texas, let me refer you to this article.

http://www.kevinsbrady.net/motors.pdf

The Numbers Game:
A Primer on Single-Phase A.C. Electric Motor Horsepower Ratings
Kevin S. Brady, Esq., Minneapolis, Minnesota

In particular please note the table on page 4. For some reason I could not get that table to copy so I could paste here. It looks to me that this gentleman knows that about which he is writing because I could verify all of his statements.

What you are saying is correct IF the motor you are describing is rated at let us say 2hp at 120 volt and 4hp at 240 volt. Then the current stays approximately the same. 

If I am misunderstanding what you are saying, please forgive me.

George


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## skymaster (Oct 30, 2006)

TT; ROFLMFAO it really is about how many mices ya got on the treadmill and whether they are fed American white or Mild Cheddar.
In my shop I gots 240 mices and they eat Cheddar. Way gooder than those American white 120 mice models LOL LOL

George C; For what it is worth on my Delta the motor ratings are: 1 1/2 hp @ 120 2 hp @ 240


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## user4178 (Apr 18, 2008)

GeorgeC said:


> What you are saying is correct IF the motor you are describing is rated at let us say *2hp at 120 volt and 4hp at 240 volt*. Then the current stays approximately the same.


:confused1: WHAT ? :wallbash:


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## user4178 (Apr 18, 2008)

GeorgeC said:


> You have it 1/2 correct. *The 220 is using only half of the amperage, but twice the voltage.* Therefore the power bill will be essentially the same.


 Not to pick on you George, but, again I gotta say, WHAT ? :confused1: I'm going to try this once more. At 120V there is one hot leed that supplies 15 amps or whatever the motor requires, for arguements sake we will say it needs 15 amps. At 240V there are two hot leeds, each leed supplies aproximatly half the amps required, which would be 7.5 amps. So two x 7.5 amps = 15 amps. To sum it up, no matter what voltage your useing on a particular motor, 120V or 220V your still useing the same amount of amps.


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## GeorgeC (Jul 30, 2008)

Woodchuck1957 said:


> Not to pick on you George, but, again I gotta say, WHAT ? :confused1: I'm going to try this once more. At 120V there is one hot leed that supplies 15 amps or whatever the motor requires, for arguements sake we will say it needs 15 amps. At 240V there are two hot leeds, each leed supplies aproximatly half the amps required, which would be 7.5 amps. So two x 7.5 amps = 15 amps. To sum it up, no matter what voltage your useing on a particular motor, 120V or 220V your still useing the same amount of amps.


Woodchuck, did you bother reading the article and looking at the table?

What you are describing is a motor that is designed to be twice the horsepower when the voltage is doubled. Skymaster said his motor was designed to be 2 hp vs 1 1/2hp when run on 220/230/240 vs 110/115/120. (pick whichever convention you like as to the magnitude of the voltage) In his case the amperage at 230 volt is more than half of the 115 volt. (1/3 more horsepower so therefore it needs sufficient amperage to feed that extra horsepower)

In your example, the correct amperage on each leg would be approximately 3.75 amps.

You have to understand the relationship between horsepower, voltage and amperage. The article I referenced gave a good explanation of that. Then at the end they provided a table that listed the current draws for motors of between 1 and 5 hp running on 115 volts and 230 volts at various efficiencies.

That article is a good primer. Read it and then you will understand the various relationships. Remember that the basic power formula is POWER EQUALS CURRENT TIMES VOLTAGE.

George


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## user4178 (Apr 18, 2008)

Ok George, maybe this will make more sense. I don't know how else to explain it, and quite frankly I give up. I don't know what it says on Sky's motor plate for amps at 120V and 240V. I only know what it says on the Delta motor I have on my saw. Volts 115/230, Amps 12.8/6.4, 1 1/2 hp.


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## skymaster (Oct 30, 2006)

OK both you guys have done it now!!!!!!!!!:laughing: My head hurts trying to stay with ya. HOWEVER I was FORCED to go down to my saw and here is the data on the plate:
Delta motor 62-044
12.8A @ 115 vac
8.6 @ 230
So somehow my saw does NOT conform to the theory of the same amps regardless of voltage :}:}:} 
From what I understand then my saw should really take 17.2 amps @230 since it should be 8.6 PER leg NOT the 4.3 it really does.
Am totally in "shock" ( devil made me do it ) :laughing::yes:


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## GeorgeC (Jul 30, 2008)

skymaster said:


> OK both you guys have done it now!!!!!!!!!:laughing: My head hurts trying to stay with ya. HOWEVER I was FORCED to go down to my saw and here is the data on the plate:
> Delta motor 62-044
> 12.8A @ 115 vac
> 8.6 @ 230
> ...


I would say your saw is just about what the article says it should be. The small difference from theory can easily be explained by inefficiencies in the real world.

12.8 amp divided by 2 equals 6.4amp if the power were to remain the same. 

Your saw is 1/3 more powerful on 230 than 115 volt.

So 6.4 times 1.33 equals 8.51amp theoretical vs 8,6 listed on the plate.

Pretty close.

Thanks for the real life demonstration and assistance.

George


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## skymaster (Oct 30, 2006)

George C: Yeah ok what ever you say ROFLMAO I followed that article, actually read the table and actually did the math. OW My head really hurts now LOL LOL.
IF I have it understood: than my saw at 115 vac is approx 65% efficient
At 220v it actually is better runs approx 75% efficient
this is using the table in the article:
Man and I thought all I ever needed to know was E=IR 
E= OWWWWWWWWWWWWWWWWW :laughing::laughing::yes::icon_smile:
Jack

Howdy Chuck:}:}

OK now I dare ask this: Then I DO USE LESS electricity on 220 YES?


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## user4178 (Apr 18, 2008)

No, you use more at 230V, thats why your hp increases at 230V. :thumbsup: Howdy Sky. :bangin:


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## skymaster (Oct 30, 2006)

DAMN!!!!!!!!!!!! LOL nothing is free LOL LOL It runs sooooooooooo much better tho. Beats the crap outta my friends mailbox tho :}:}:} Power and light ran 12,500 volts thru it on Monday :laughing:
It didnt run at all just burned up and melted LOL LOL LOL. Nobody hurt but man what a mess!!!!! Just like your oxy torch cut right thru it, melted the rocks,dirt, burned big holes thru the concrete.


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## user4178 (Apr 18, 2008)

Hmmmmm, how many amps was it ? Maybe we can figure out how many horses trampled over it. :smartass:


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## GeorgeC (Jul 30, 2008)

Skymaster asked " OK now I dare ask this: Then I DO USE LESS electricity on 220 YES?"

The answer is actually no. For a motor that is rated at the same horsepower at each voltage there is no difference in POWER(P = IV). In the case of your specific motor, it is rated at a higher horsepower on 230 volts and therefore draws more current that when wired to operate on 115 volts.

That is why a theoretical 1 hp machine operating on 230 volts uses 1/2 the amperage of a 1 hp machine operating on 115 volts. The current drawn for any motor is strictly governed by the old Power equals Current times Voltage equation(P = IV).

In real life it is not normal to find that a given motor that is designed to operate on eithe 115 volt or 230 would have the same horse power rating. Your motor is the example. It is 33% more "powerful" on 230 volts. Therefore it has to draw a like additional amount of current to power that increased horse power.

Luckily to the woodworker it does not matter as long as you know what the current rating is of your motor and ensure that you have adequate wiring for that current. Well, maybe it does matter as far as you knowing to read the hp rating on a motor you are buying to know how the rating differs between voltages. That may help lead you to the decision of which voltage hookup to use.

George

George


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## Gerry KIERNAN (Apr 20, 2007)

This is all very interesting, but, the bottom line is really: Will the saw run better on 240 volt? Probably will. Easier start up, less bogging down, lights don't go out. This is assuming a dedicated circuit.
Are you willing to pay for the extra wiring and outlet/s? Yes?
Then, the answer is simple ! Do It. I know all us dedicated wood butchers are willing to cough up a few extra sheckles for the power, if we have to. If there is any extra power cost it will be insignificant compared to the aggravation of trying to run a heavy saw on an inadequate power supply. As one member put it "More Gooder"

Amps X Volts equals Watts. Our meters record in increments of 1000 Watt hours [Kilowatt hours]
We pay for the number of kilowatt hours we use.

Oh yeah, there ain't nuthin free. Same up here.

Gerry


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## TexasTimbers (Oct 17, 2006)

:laughing:

George this is why I "usually" stay out of this 240 vs 120 threads - everyone wants to be right and there are SO many ways to change the data. 

I did preface my statement that I was comparing apples to apples i.e both motors were rated at 15 amps. You can throw HP or anything else in the equation you want but as I said (I think you missed this part in my post) a motor rated for 15 amps and 120v, and a 15 amp 240v motor will spin the meter at virtually the same rate. 

I am not trying to make any other point really. :smile:


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## GeorgeC (Jul 30, 2008)

Gerry KIERNAN said:


> This is all very interesting, but, the bottom line is really: Will the saw run better on 240 volt? Probably will. Easier start up, less bogging down, lights don't go out. This is assuming a dedicated circuit.
> Are you willing to pay for the extra wiring and outlet/s? Yes?
> Then, the answer is simple ! Do It. I know all us dedicated wood butchers are willing to cough up a few extra sheckles for the power, if we have to. If there is any extra power cost it will be insignificant compared to the aggravation of trying to run a heavy saw on an inadequate power supply. As one member put it "More Gooder"
> 
> ...


I agree.

G


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## user4178 (Apr 18, 2008)

Well as I stated before, but probably not too well, as I seem to have a problem describing things to people so they understand. So I'll try again. There is probably little to gain at useing 220V,230V,240V unless you have a motor like Sky does. But either way if you gain something it's better than nothing. A motor at 110V,115V,120V should run just as strong if it's using the same amount of watts at either voltages. Where people get into trouble at 110V,115V,120V is when they have the saw runing off a circuit breaker that is running more than one outlet and or lights, reducing the available power from the breaker. A 110V,115V,120V breaker with only one outlet hooked to it should give you all the power you need to run the saw provided you use the correct amperage breaker. If you have a saw motor that is 15 amps at 120V, a 20 amp breaker would be in order. A 15 amp breaker probably wouldn't provide enough at startup or under a heavy load. Extension cords are another thing to consider when looking for a loss in power, length and gauge are also a factor. For me, my saw is wired for 240V, so is my compressor, edge sander and dust collector. I had an electrician wire my shop and we discussed it all and decided 240V was the way to go for those tools. Did I gain alot ? probably not, but I think I gained some advantage, and I've got peace of mind knowing that it all works the best it possibly can. I know your thinking that a 220V,230V,240V, 15 amp breaker, outlet and plug would be an extra cost, but so is heavier gauge wire that would be required for a 110V,115V,120V, 20 amp breaker. Depending on how much wire you need to run, it could run about the same in cost either way. Thats my story and I'm stickin to it. :glare:


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## mics_54 (Oct 28, 2008)

Look at all the money yall are saving while debating the thread topic instead of running that saw. Unless of course you surf and saw at the same time. 
I'm no expert electrician..but..seems to me that 220 volt is supposed to be easier on the equipment and requires smaller wire to power the same loads. There are many variables one being the initial cost of circuitry. Another is how much the equipment is used. It all equates to dollars. Voltage drop, ambient temprature, load, wire size all effect the bottom line. Either 220 equipment is more cost effective over the span of service life or it aint. If it ain't..somebody has been lying.


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## skymaster (Oct 30, 2006)

WAY GOODER
RULES!!!!!!!!! :laughing::yes::thumbsup:arty:


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## clarionflyer (Apr 27, 2008)

GOOD GOD, MAN (diagrams hurt my tiny brain)!!!!

If you're willing to throw down a couple hundred bucks to wire the 240... do it! I think your saw (and other future equipment, will work better). If you're not willing... don't! But don't worry about the light bill.
The only way the bill will change much, is with a production shop, changing phases, and all that! PERIOD!

If you want the 240. Study up, run the wire yourself, and have someone who knows what they're doing hook it up. Unless you're going a mile, the wire and hook-up will be worth the work.

Good Luck.


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## user4178 (Apr 18, 2008)

clarionflyer said:


> GOOD GOD, MAN (diagrams hurt my tiny brain)!!!!


Sorry, but I didn't know how to explain it anymore, or easier. You think your brain hurts ?


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## GeorgeC (Jul 30, 2008)

clarionflyer said:


> GOOD GOD, MAN (diagrams hurt my tiny brain)!!!!
> 
> If you're willing to throw down a couple hundred bucks to wire the 240... do it! I think your saw (and other future equipment, will work better). If you're not willing... don't! But don't worry about the light bill.
> The only way the bill will change much, is with a production shop, changing phases, and all that! PERIOD!
> ...


Good comment. The average home woodworker would like never notice any difference in their power bill just because they set up a table saw to run on 220/230/240 (call it whatever you want)volt. 

Most saws will probably run a little more efficiently and stronger on 220 and that is the bonus.

Good cutting.

George

G


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## Kenbo (Sep 16, 2008)

I'm getting electrical trade school flashbacks................head hurts!!:blink:


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## Tony B (Jul 30, 2008)

*George C's last comment simplifies it.*

.........."The average home woodworker would like never notice any difference in their power bill just because they set up a table saw to run on 220/230/240 (call it whatever you want)volt. 
Most saws will probably run a little more efficiently and stronger on 220 and that is the bonus."

I agree 100%. 
Just want to add one thing. They will also most likely start faster also.

BTW: the best way to explain this is in mostly math with every little text. And there are several different ways to apply the formulas and if done correctly all of the answers will come out exactly the same.


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## user4178 (Apr 18, 2008)

GeorgeC said:


> The average home woodworker would like never notice any difference in their power bill just because they set up a table saw to run on 220/230/240 (call it whatever you want)volt.
> 
> Most saws will probably run a little more efficiently and stronger on 220 and that is the bonus.


Why would there be a difference for ANYONE in the power bill if both voltages eatup the same amount of watts ? And how would the motor run stronger ? The vast majority of electric motors to my knowledge are not like Sky's and should not be considered the norm.


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## Tony B (Jul 30, 2008)

*I promised that I would leave this alone. LOL*

Woodchuck made me do it

I have not read any of the articles posted but here is what I think is happening.
First off, there should not be any noticable change in the power bill.
Power (WATTS) = Volt X Amps.
There are several forces at play here. 
No. 1. Whether you have 110V or 220V there are 2 main voltage drops. One is across the tool and one is across the wires themselves. 
Normally the wiring voltage drop is negligable but I will have to throw it in here.
No. 2) Voltage drop is determined by electrical resistance. E=I X R.
E = Voltage I = Current in amps R= Resistance in ohms.
I am going to make up numbers here for demonstration purposes.
No. 3) Normally, electrical resistance in wire is determined by its diameter. The skinnier the wire, the more the resistance. The more resistance in the wire, the more it takes voltage away from the tool. 
Lets say your 110V is 20A circuit breaker on *12 gage* wire. Your 220V ckt breaker is probably on a 30A breaker with *10 gage* wire.

So, the first thing we notice is that if we use the 220V outlet we have thicker wire which is less resistance. Lets assume we did the formulas and we determine that the 220V is split between 215V for the tool ann 5 volts for the wire. We still have a total 220 V and say the tool draws 15 amps. that is 3300 watts.

Now if we use the same tool on 110V we have a higher resistance in the wire. Remember Power = Volts X amps. We have theoretically twice the amps on the tool on a 110V line. So we apply the P= 110V X 30 Amps and we get the same 3300 watts. Same power consumption which means same electrical bill.

But........The 110V line has more electric resistance in the wiring so the tool may have 104 volts across it tool and the wire may have 6 volts across it. Also when the wire has current running through it, it heats up and that also increases the resistance and in turn increases the voltage drop. 

Again these are exaggerated figures. But we will use them. 

On the 220V circuit we have tool voltage 215 Volts for the tool and 15 amps running through it. 

Tool Power = 215V X 15amps = 3225 watts of elec power drawn
Wire Power = 5 V X 15 amps = 75 watts of power lost in heat due to wire resistance.
We still have a total of 3300 watts of electrical power used.

On the 110V line we have 104V drop across the tool and 6 volt drop avross the wire.

Tool Power = 104V X 30amps = 3120 watts of elec power drawn/
Wire Power = 6V X 30 Amps = 180 watts of power lost in heat due to wire resistance.
We still have the same total of 3300 watts. So our elec. bill is the same.

OK , lets use these numbers on more time"

The 110V circuit is providing the tool with 3120 watts
The 220V circuit is providing the tool with 3225 watts.

There is 746 watts per horsepower (Theoretical)

The 110V tool with 3120 watts divided by 746 = 4.182 HP
The 220V tool with 3225 watts divided by 746 = 4.323 HP

So, you get more HP with 220V and still burn the same exact amount of electricity. The main factor is in the size of the wire.
With the 110V circuit you lose more power in the form of heat because the wires are thinner and warmer. 
This is assuming there are *NO* appliances attached to the same 110V line

I aint even going to proof read this. My freaking head is spinning.

Thanks Woodchuck , you owe me. LOL


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## user4178 (Apr 18, 2008)

Tony B said:


> Lets say your 110V is 20A circuit breaker on *12 gage* wire. Your 220V ckt breaker is probably on a 30A breaker with *10 gage* wire.


Well I'll go along with the fact that there is resistance in wire. But, where your geting confused I think is, you don't need to run a 220V double 30 amp breaker on 10 gauge wire for a tool that ran on a 110V single 20 amp breaker and 12 gauge wire. Remember, when you converting that motor to 220V your only useing half the amps per hot leed. So a 110V motor that was on a 20 amp breaker useing 12 gauge wire would be run on a 220V double 15 amp breaker and you could use 14 gauge wire. Ofcourse in both instances the wire gauge to be used also depends on the length of the wire used, just like an extension cord, the longer the cord, the heavier gauge you want. Who owes who ? :icon_cheesygrin:


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## knotscott (Nov 8, 2007)

Woodchuck1957 said:


> Well I'll go along with the fact that there is resistance in wire. But, where your geting confused I think is, you don't need to run a 220V double 30 amp breaker on 10 gauge wire for a tool that ran on a 110V single 20 amp breaker and 12 gauge wire. Remember, when you converting that motor to 220V your only useing half the amps per hot leed. So a 110V motor that was on a 20 amp breaker useing 12 gauge wire would be run on a 220V double 15 amp breaker and you could use 14 gauge wire. Ofcourse in both instances the wire gauge to be used also depends on the length of the wire used, just like an extension cord, the longer the cord, the heavier gauge you want. Who owes who ? :icon_cheesygrin:


This describes the type of scenario that very often makes 220v an attractive choice when you have an existing 110v circuit that's not quite meeting the demand. Let's say a long 110v circuit has 12 awg wire and is having trouble supplying full power to meet the demands. You can use the same 12 awg wiring, change the circuit to 220v, and end up with sufficient power being supplied due to lower losses. It's basically the equivalent of adding heavier wire to the 110v circuit but is usually easier and less expensive.


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## Tony B (Jul 30, 2008)

*I give up. LOL*

I knew I should have used a 50 Amp breaker for my model, LMAO.
OK how does this sound. 

Given the same diameter wire with the same electrical resistance. 
The 110v at twice the current will heat the wire more and thus increase the resistance of the wire which in turn will increase the voltage drop across the 110V house wiring which will in turn will dropthe available voltage across the tool and it will run less efficient.


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## user4178 (Apr 18, 2008)

Yes Tony, especially if your running multiple outlets and or lights on that 110V circuit. However, a dedicated 110V circuit, meaning only one outlet, nothing else on a single 110V breaker can work also with the correct size breaker and wire size. Scott is correct also. One thing I'd like to add is if your useing lets say 10-2, 12-2, 14-2 wireing, a hot ( black ), a nuetral ( white ) and a ground ( usually bare copper or green coated ) for 220V, the white wire inside the breaker box and the outlet box you will want to mark as black since your useing both the white and black wires as a hot. You can do that by either wraping the white wire with black electrical tape, or what I like to use, black shrink tubeing. I feel the shrink tubeing is less messy, easier to apply, and is more permanent. That way if anyone opens that box they will know both leeds are hot. It's probably code too.


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## Wachsmuth (Feb 11, 2009)

It is always better to run your tool at highline voltage, i.e. 240 Vac vs. low-line voltage, i.e. 120 Vac, even if both configurations produce the same horsepower. The reason is: at 240Vac the input current is lower and therefore heat generation is lower. Motors are built with electrical insulation systems rated for certain temperatures. The more heat the insulation system receives, the faster the insulation system will degrade and the windings will short. How long does this take for 120V vs 240V???? I don't know. What I do know is that if the motor is certified for safety by an agency such as Underwriters Laboratories at both 120Vac and 240Vac, the insulation system is sufficient for both 120Vac and 240Vac. The fact still is that running identical motors side-by-side, one at 120Vac and the other at 240Vac, the motor running at 120Vac will fail first.


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## WDChew (Aug 31, 2007)

Woodchuck1957 said:


> As far as takeing up another spot in your breaker box, depending on the brand of your breaker box, you may be able to get a 240V breaker that only takes up one slot in your breaker box. I guess in a nut shell, you should add another breaker regardless if it's 120V or 240V and dedicate it to one outlet for your tablesaw, personally I'd keep it at 220V.


Minor amendment to woodchuck's comment:
A 240v breaker is really a 2 breakers ganged togther that fits in adjacent slots in the panel. Every other slot is on the same leg (110v), adjacent slots are on opposite legs, thus 240v between them. The mini breakers that double up in one slot will still be 110v unless you straddle 2 slots. That would still take up another whole slot using half it's space.


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