220 vs. 110 question.

[Monroe Brown]

Now that I have 220 in my shop, I was wondering if there is any advantage to changing my 2HP General TS from 110 to 220. It can do either and has run fine on 110. Will it run "stronger"? Is 220 easier on the motor?

Any thoughts?

Thanks,

MB

[Art Mann]

The only way you will gain any increase in power from converting to 240V would be if there was a problem with the 120V circuit to start with.

[Tom Veatch]

Now that I have 220 in my shop, I was wondering if there is any advantage to changing my 2HP General TS from 110 to 220. It can do either and has run fine on 110. Will it run "stronger"? Is 220 easier on the motor?

Any thoughts?

Thanks,

MB

The only way you would benefit from the change is if there is something about your wiring installation that would benefit from reduced amperage. As far as the motor in your saw is concerned, in the vast majority of cases, it won't notice the difference.

[Jim Becker]

In general, there is no "stronger" using 240v unless you have a specially wound motor that has different HP when run on 240v.

[Dennis Miller]

I did some calculations assuming 100 ft of #12 wire for 110 and 220. Calculating the voltage drop for each leg of the wire run Vdrop=I*R where I=current draw of the motor and R is the wire resistance which is about .16 ohms/100ft for #12 wire. Remember there are two legs (one wire to motor, one wire from motor) and each leg will have a voltage drop relative to the 110v or 220v at the panel.

And the results are...

Wire Size---Ohms for 100 ft---Amps---Nominal Voltage---Volts at Motor---% of Nominal Voltage
---#12-----------0.16-----------20-----------110----------------103.6----------------94
---#12-----------0.16-----------10-----------220----------------216.8----------------99

So, using this scenario there is a 5% difference in nominal (design) voltage...at the motor.

[Greg Funk]

So, using this scenario there is a 5% difference in nominal (design) voltage...at the motor.
The only thing I would add is that during startup the motor can draw up to 6x its rated current so the voltage drop can be noticeable.

Greg

[Wayne Cannon]

Ignoring the voltage drop in the wiring, the power is the same. At 240 V, it only draws half the current. There is a voltage drop along the wire which is a function of the current being drawn, so a 240 V device will cause only half the voltage drop of a 120 V device. If your wire run to the breaker panel is short (e.g., less than 25 feet), it will probably be inconsequential. 50 feet will probably be hardly noticeable.

Where you will see the difference is under load (and at startup), when the motor draws the most current. For example, a motor wired for 240 V will "sag" less under load -- more and more noticeable as the wiring run is longer and longer.

[Rick Christopherson]

You are new to the forum, so I assume you probably don't know my reputation. I am one of the strongest opponents to rewiring a motor when there is no reason to do so. As was stated already, there is no net gain by going to 240 volts.

However, a 2 hp motor is right on the edge of what a 120 volt circuit can provide. I oppose rewiring smaller motors for 240 volts, but I generally do not question it when the motor is 2 hp, because the current draw from the circuit can reach its maximum limit when the motor is at full-load. If you are not noticing any existing problems, then leave the motor alone. If you are noticing problems, then this motor is a candidate for rewiring.

Oh, just to reiterate; no, the motor will not have more power, nor will it be easier on the motor, nor will the motor run cooler, nor any of the other common mis-beliefs that are often stated.

[Art Mann]

Dennis, just a minor comment on your post. The voltage at my house, and in most places that I know of, is 120V and 240V nominally. I have seen the voltage drop to as low as 112 at my house on a very hot summer day when the demand was at its peak. I'm not exactly sure where the 110/220 numbers came from. They have been around for a long time. But, they are more like worst case than nominal. That really has nothing to do with the point of your post, though.

[Mike Henderson]

One reason often given for going to 220/240 volts is that the motor will have greater startup torque. Since the motor draws more current during startup, the voltage drop is greatest at that time so it is true that a 240 volt circuit will often provided a smaller percentage voltage drop during startup - and thus a bit better startup torque.

But the whole issue of startup torque for woodworking applications is mostly a red herring. Very few woodworking applications have large inerta loads, or require very quick startup time. If high startup torque was really an issue, we'd have different kinds of motors in our equipment. For example, a Replusion/Induction motor has much greater starup torque than a capacitor start induction motor but you don't see RI motors in modern woodworking equipment.

My belief is that most of the time when people say they get much better performance out of a motor when they operate it at 240 volts, it's because the circuit which was feeding it at 120 volts was too small and could not provide rated voltage at the motor's rated current.

There's nothing wrong with operating a motor at 240 volts, provided the motor will accept it, but you now have to always have a 240 volt circuit to feed it - which may limit your ability to reorganize your shop.

I agree with Rick C. If your motor is small - say 1.5Hp or less - leave it on 120 volts. It'll be more convenient for you.

Mike

[Robert foster]

And don't forget if you have a magnetic switch on your saw you will probably have to change it also. It least check with the manual before making any changes.

Bob

[Dave MacArthur]

I'm interested in Rick C's post, and wondering folk's opinions on this:

I rewired my 1.5 HP Delta 50-760 dust collector to 220 (was just 3 screws). My thoughts on doing this were that my new garage wire-up has plenty of 220 receptacles everywhere, but is only a 70A total feed off the main panel. Since the DC would effectively always be on, I wanted to only have a 7.5 A load vs. 15A reduction before turning any other tool on. Additionally, it allows me to move the thing around the shop a bit more because the lower 7.5 A opens up "sharing" circuits such as my jointer, while the 15A would max out any circuit on 110 I tried to share. I do have plenty of circuits (9) and a well planned layout. But since it was just a 3 screw operation, it seemed all good with no downside; and the motor and instructions are clearly diagrammed for both 110 and 220, it just happened to come set for 110.
Thoughts?

[Rick Christopherson]

... but is only a 70A total feed......................:eek::eek::eek: ONLY 70 amps? :confused: That is far more power than you will ever come close to using in your garage. That's 70 amps at 240 volts, but its also equivalent to 140 amps at 120 volts. A 2-pole breaker provides 70 amps on each phase, and since you have two separate phases for 120 volt circuits, that's 140 amps of power (or a combination thereof). You have enough power in your garage to simultaneously operate 6 Unisaws at maximum load. You could buy 12 more dust collectors, and not run out of power.:D

Some people have switched a tool to 240 volts for load balancing on an undersized service, but yours is not one of those situations.:)

[Dennis Miller]

Art,
Regarding 110/120 and 220/240, I agree...I was just using the numbers quoted in the original post.
Dennis

[Rob Will]

Yes, a true 2 hp table saw will perform better and last longer on 230V.
All of the "electrical theory" presented here is correct but your saw does not operate in a theoretical world.
One of the weakest links when running anything substantial on 115V is the plug and receptacle. It is really hard to apply electrical theory to things like a weak receptacle or cord end.

Pay no attention to all of the theory and go ahead and change it to 230V.

Rob

[Pete Bradley]

It is really hard to apply electrical theory to things like a weak receptacle or cord end.


I'll probably regret this, but I'll bite. Rob, what do you mean by a "weak receptacle or cord end", and why do you believe higher voltage will help that?

Pete

[Mike Henderson]

Seems that if you had "a weak receptacle or cord end" it would be cheaper and faster to repair or replace the "weak receptacle or cord end" rather than convert the voltage.

Mike

[Rob Will]

I'll probably regret this, but I'll bite. Rob, what do you mean by a "weak receptacle or cord end", and why do you believe higher voltage will help that?

Pete

Each point of contact carries 1/2 as many amps.
Runs cooler, lasts longer.

Weak: By design, marginally able to carry the required load or a device that is not in perfect condition.

Rob

[Rob Will]

Seems that if you had "a weak receptacle or cord end" it would be cheaper and faster to repair or replace the "weak receptacle or cord end" rather than convert the voltage.

Mike

That is assuming you know it is weak.

I say switch to 230V and your typical device has more "headroom".

Rob

[Rick Christopherson]

All of the "electrical theory" presented here is correct but your saw does not operate in a theoretical world......... Pay no attention to all of the theory .....A sure way to raise my hackles is to state something like this. When I read something like this, in my mind the person is saying, "Well, since I can't understand it, then it must not be true."

It isn't Theory just because you don't understand it. There is nothing theoretical about this information. It is factual information. The only people that view this as theoretical are those that don't understand it.

I don't know how to play the piano, so does that mean that a piano only makes noise "in theory"? That's pretty much what you are saying. When you make a statement such as yours, you actually insulted yourself, but just didn't realize it yet.

[Mike Henderson]

That is assuming you know it is weak.

I say switch to 230V and your typical device has more "headroom".

Rob
There are many things which can be wrong in the world but we don't go around changing things because of that.

If your motor is working fine, you don't start changing things because something might be wrong and you don't know about it. If your motor is not working fine, you try to find out what's wrong, rather than assuming the solution is to increase the voltage.

Plugs and receptacles are designed to carry certain amounts of current without excessive voltage loss - that's true for both 120 volt plugs and receptacles and for 240 volt plugs and receptacles. As long as your "plug and receptacle" is working correctly, you don't need any more headroom.

Mike

[Rob Will]

A sure way to raise my hackles is to state something like this. When I read something like this, in my mind the person is saying, "Well, since I can't understand it, then it must not be true."

It isn't Theory just because you don't understand it. There is nothing theoretical about this information. It is factual information. The only people that view this as theoretical are those that don't understand it.

I don't know how to play the piano, so does that mean that a piano only makes noise "in theory"? That's pretty much what you are saying. When you make a statement such as yours, you actually insulted yourself, but just didn't realize it yet.

No Rick, I have understood this level of electrical theory since high school. It is not complicated at all. In fact, I think everybody here understands it very well.

My point is that most of the time, when dealing with conductors in the real world, it is better to have some "headroom" rather than take devices to their theoretical limit.

Case in point: Electric heaters often have amperage requirements that are well within the "rated" capacity of the cord and plug. Having said that, a lot of house fires would have been avoided if the amperage was cut in half.

Your assertions about electrical theory are absolutely true but automatically telling everyone to run 2 hp tools on 115V:eek: is not good advice.

Rob

[Rob Will]

There are many things which can be wrong in the world but we don't go around changing things because of that.

If your motor is working fine, you don't start changing things because something might be wrong and you don't know about it. If your motor is not working fine, you try to find out what's wrong, rather than assuming the solution is to increase the voltage.

Plugs and receptacles are designed to carry certain amounts of current without excessive voltage loss - that's true for both 120 volt plugs and receptacles and for 240 volt plugs and receptacles. As long as your "plug and receptacle" is working correctly, you don't need any more headroom.

Mike

No Mike, I believe a 2 hp motor running on any 115V cord and plug would be better off with more "headroom".

Rob

[Rob Will]

I did some calculations assuming 100 ft of #12 wire for 110 and 220. Calculating the voltage drop for each leg of the wire run Vdrop=I*R where I=current draw of the motor and R is the wire resistance which is about .16 ohms/100ft for #12 wire. Remember there are two legs (one wire to motor, one wire from motor) and each leg will have a voltage drop relative to the 110v or 220v at the panel.

And the results are...

Wire Size---Ohms for 100 ft---Amps---Nominal Voltage---Volts at Motor---% of Nominal Voltage
---#12-----------0.16-----------20-----------110----------------103.6----------------94
---#12-----------0.16-----------10-----------220----------------216.8----------------99

So, using this scenario there is a 5% difference in nominal (design) voltage...at the motor.

Dennis is absolutely right!
In motor circuits when voltage goes down - amperage goes up.
Now let's say that we have something in the circuit that is operating at max capacity (a cord, a plug etc.)
Not only would switching to 230V cut the amps in half, it would also improve the voltage drop situation - and that in itself would save a few amps. Headroom is a good thing.

Rob

[Rick Christopherson]

Your assertions about electrical theory are absolutely true but automatically telling everyone to run 2 hp tools on 115V:eek: is not good advice.Gee, not only could you use a few lessons in electrical information, but you could use a few reading lessons too. (since things don't seem to sink in all that well, that was a hint to go back and reread my original posting.)

As for "headroom", that's already built into the devices. The cross-sectional square area of the bus bars in an electrical outlet are far larger than any other component in the electrical circuit. The heating is caused by a poor connection in a worn out receptacle, where the compression fitting results in a high resistance connection.

But that is all a moot point. By your rationale all devices should be reduced in capacity by 50%. So you better rip out the NEMA 10-50 plug behind your stove and replace it with a 100 amp pin and sleeve connector. If you don't, then surely your house will burn down tomorrow.

http://www.onestopbuy.com/productimages/cd-4100b12w.jpg

[Mike Henderson]

No Mike, I believe a 2 hp motor running on any 115V cord and plug would be better off with more "headroom".

Rob
I guess I don't understand what you mean. If a motor is working fine with a certain plug and receptacle, what good does this "headroom" do? Does it make the motor more powerful, run cooler, or what?

I think what you mean is that at 2HP you might have a significant voltage drop in the plug and receptacle at 120 volts. I would maintain that if plug and receptacle are designed to carry the current, the motor will work fine (given that the rest of the circuit is proper). The voltage drop will not be excessive as long as its working within its current (amperage) design limits.

But in the final analysis, the proof is in the operation. If the motor is not working well, you need to find out what's wrong. It may be that the circuit, or the plug, or the receptacle is not proper for the operation of the motor, or the plug or receptacle is excessively worn. If so, the solution is to fix the problem.

If the motor is working well - leave it alone and do some woodworking.

Mike

[Rick Christopherson]

In motor circuits when voltage goes down - amperage goes up.No Rob, it doesn't. This is a typical misconception from those that do not fully understand how motors work. Current goes up when the motor rpm drops. As long as the motor is operating at its normal slip speed, then the current and voltage will be proportional.

[Rob Will]

......The heating is caused by a poor connection in a worn out receptacle, where the compression fitting results in a high resistance connection.....

Very good observation.
And it happens all the time when people run big power tools on 115V circuits.

Rob

[Mike Henderson]

Very good observation.
And it happens all the time when people run big power tools on 115V circuits.

Rob
Well, I don't want to get between two guys having so much fun, but the usual reason a receptacle wears out is because of use (many plugs and unplugs) and not because of the amount of current passing through the circuit.

Mike

[Rob Will]

No Rob, it doesn't. This is a typical misconception from those that do not fully understand how motors work. Current goes up when the motor rpm drops. As long as the motor is operating at its normal slip speed, then the current and voltage will be proportional.

I suppose that is why our electric motor shop sees so many motors destroyed by low voltage?

If the voltage drops, the ability of the motor to maintain RPM under load is reduced (yep, it is slipping and getting hot)

So if low voltage causes slip....
and slip increases amps......
and amps increases heat.....
then low voltage increases amps and heat.

Rob

[Rob Will]

Well, I don't want to get between two guys having so much fun, but the usual reason a receptacle wears out is because of use (many plugs and unplugs) and not because of the amount of current passing through the circuit.

Mike

Mike, I agree with that 100%

This is also why my electric range plug is working so well - I never unplug it or run over the cord in the driveway:eek:.

We are just having some fun here.

Rob

[Tom Veatch]

...I don't know how to play the piano, so does that mean that a piano only makes noise "in theory"? ....

It sure makes noise when I touch it. 'though some folks can make some pretty nice sounding stuff come out. With me, just noise.:D

[Rick Christopherson]

Mike, I agree with that 100%

This is also why my electric range plug is working so well - I never unplug it or run over the cord in the driveway:eek:.

We are just having some fun here.

RobBut don't confuse one problem for another. If the outlet is a problem, fix the outlet, not the motor. I design and build test equipment that specifically tests electrical plugs and cables, and unless the receptacle is faulty, it will not have an appreciable voltage drop even if the circuit is fully maximized. If you are getting a voltage drop at the outlet, then it is time to replace the outlet. This is true regardless what the voltage is.

Fix the problem, not the symptom.

[Rick Christopherson]

It sure makes noise when I touch it. 'though some folks can make some pretty nice sounding stuff come out. With me, just noise.:DOk, but if you are "tone deaf" does that mean that you can only hear sounds that don't have a tone?

[Mike Cutler]

Now that I have 220 in my shop, I was wondering if there is any advantage to changing my 2HP General TS from 110 to 220. It can do either and has run fine on 110. Will it run "stronger"? Is 220 easier on the motor?

Any thoughts?

Thanks,

MB

Monroe

I have the General, Model 50-220, 2HP, Hybrid saw. It has been running just fine for 2 years on the 120 it came with pre- wired .
I've put 8/4 Jatoba, Bubinga,Wenge, Orange Osage. 4/4 Macassar Ebony, African Blackwood, Qsawn Oak, Maple. Basically some pretty hard, dense, oily, tropical hardwoods. It's handled all of them. I don't baby machines.

I can talk motor theory and wiring all day long.(I do it for the day job.) The saw just works, as is, out of the box.
I strongly suspect that it is not a "true" 2HP either, probably closer to 1 1/2 HP because it came with a molded 15 amp plug and a UL Sticker on it. I also noticed that the instruction manual gave no motor amperage info, or direction to convert it to 240. The instruction diagram is on the inside of the motor connection box.
Like Rick Christopherson stated; When it becomes an issue, I'll change it.

[Rob Will]

But don't confuse one problem for another. If the outlet is a problem, fix the outlet, not the motor. I design and build test equipment that specifically tests electrical plugs and cables, and unless the receptacle is faulty, it will not have an appreciable voltage drop even if the circuit is fully maximized. If you are getting a voltage drop at the outlet, then it is time to replace the outlet. This is true regardless what the voltage is.

Fix the problem, not the symptom.

I think we are all really saying the same thing. We all advocate doing what it takes to get proper voltage to the motor.

If there is any difference of opinion here, I am leaning toward 230V because I would rather have some headroom as opposed to a fully loaded 115V circuit.

In my shop that is easy because all heavy machines and the DC are hard wired to dedicated 3-phase circuits. In addition to that, I have a general purpose 3-phase outlet about every 6 feet:D.

I realize that it is not so easy for everyone to access 230V outlets anywhere in the shop.

In the old shop we did our share of plugging 1 hp tools into 115V extension cords. Not my favorite thing to do.

Nowdays, anything 1 hp and over - I use 230V or the full 3 ph.

Rob

[Art Mann]

It is no use guys. Give it up. The moment someone says "That is alright in theory, but . . ." the conversation should be over right then. It is not possible to educate or even discuss things of a technical nature with such people.

[Rick Christopherson]

..... because all heavy machines and the DC are hard wired to dedicated 3-phase circuits. ..........Nowdays, anything 1 hp and over - I use 230V or the full 3 ph.Oh My. :eek::eek::eek: I hate to say it, but unless you have a center-tapped Delta 3-phase system, you are actually doing more harm rewiring your tools for 240 volt operation. If this is a commercial facility with a 3-phase wye system, you are only giving the tools 208 volts instead of the 240 they would prefer.

Light industrial areas will be more likely to have the 120/240 center-tapped Delta, but heavier industrial areas will have the 120/208 Wye system. If you have the Delta system, then you are good-to-go. If you have the Wye system, then you actually want to rewire ALL of your dual voltage motors back to 120 volts. :p

After the previous discussion, you have really piqued my curiosity about this. What is your phase-to-phase voltage?

http://www.waterfront-woods.com/tempgraphics/SystemTypes-lo.jpg

[Rob Will]

Light industrial areas will be more likely to have the 120/240 center-tapped Delta, but heavier industrial areas will have the 120/208 Wye system.

Rick,

Yes, I have a 120/240 open Delta.
But I can't figure out why my lightbulbs are so bright on this one particular phase.
Just kidding;).

Excellent graphic by the way.

Rob

[Brian Walter]

I don't follow this board real close, but I will offer my 2 cents worth anyhow. I think Rick and Rob both understand exactly what's going on, only they disagree slightly as to when it become advantageous to switch from 120 to 240 v. If you go back and read one of Rick's first responses you will see that he did indicate that with a 2 hp motor you were right at the edge of where you should consider switching over to 240 v.

I suspect that both Rick and Rob would agree that the only time you might notice a difference between the 120 v and 240 wiring is when you are loading the motor so that you are drawing close to the maximum power from the motor. I would suggest that if you are doing this on a regular basis then you should switch to 240 v, and while you are at it, switch to a motor with more HP as well.

I would also like to add that another big reason for heat generation in power chords is oxidation of the both the plug and outlet.

I'll go back to my lurking mode now.

Brian Walter

[Rick Christopherson]

I don't follow this board real close...

Brian WalterWow! My first reaction was to think, "For a newbie you are pretty astute!" ................

And then two things hit me mid-thought: First off, you are not a newbie (just a lurker) and secondly, you live within 1-1/4 miles of me! Wow! I am just past Lexington and Westcott from you.

So, do you want to be the first person in the state to see what a Festool Kapex looks like? (I don't have to worry about you stealing it because it is wired for 240 volts. :D)

[Brian Walter]

Hi Rick, Wescott and Lexington is really close, we'll have to get together sometime. I haven't been following Festools new products much, is the Kapex the new power miter saw? I doubt if I'd be getting one, but I always like to look at new tools. By the way, I do have 240 in my shop, so the Kapex might not be safe.

Brian Walter

[Monroe Brown]

Well now, that was some thread.

Thanks for the input,

MB

[Wayne Cannon]

I have to agree with Rick that there's no reason to change to 240 V, especially if there is the additional expense of replacing a magnetic switch that someone mentioned, unless you find that your saw bogs down noticeably on heavy cuts, or that something else on the same circuit is affected when your saw is cutting. At the same time, there's no harm in switching to 240 V either. I run every tool at 240 V that can, even though as an electrical engineer I know it most likely doesn't matter.

If your saw does bog down during heavy cuts, there are two ways to determine if the problem is voltage drop on that circuit. (1) Switch to 240 V and see if your saw sags less. (2) Measure the voltage at the saw AND at the service panel during a heavy cut. If it is significantly lower (e.g., I'd say, more than 2 V lower) at the saw than at the panel, then you will benefit from 240 V, otherwise the problem lies elsewhere and changing the saw's circuit to 240 V won't help.

[Dave MacArthur]

Ah HA! Another thread just reminded me the main reason I re-wired my 1.5HP 50-760 DC from 110 to 220: I wanted to run it on a ShopFox remote switch, but the 110V version is maxed out at 1.5 HP; the 220V version lets you get up to 3HP. I didn't want any problems, and having tripped my 15A circuit on startup numerous times due to that thing having a big startup draw, I was worried. So sometimes there are other factors in the 220vs. 110 v motor wiring decision.

[Wade Lippman]

All those answers!

How many amps is the motor? (hp doesn't matter, the HF DC is 2hp...)
What size wire is the circuit?
How long is the circuit?

Without that information a meaningful answer is impossible.
240v is always kinder to a motor on startup, but the difference may or may not be enough to matter.

[Marcus Ward]

The NAZI (http://en.wikipedia.org/wiki/Godwin%27s_law)s rewired everything for 220, it's a known fact.