Electricians Help (Simple question)

[Allen Grimes]

Hi guys,

Are there any real benefits of 220v over 110v? I have 220 and I was wondering if there is a good reason that I should rewire my G0555 to 220 when it comes in.

My neighbor says it saves electricity, but I dont see how. I wouldn't mind doing it but its a PITA trying to find 220v plugs around here.

Im thinking that it has to have some kind of benefit for the motor, or it wouldn't even be an option, but then again my knowledge of these things is pretty minimal.

[Mike Henderson]

The big advantage of 220/240 volt over 110/120 volt for an electric motor is that the 220/240 service reduces the current in the wiring by half compared to the 110/120 volt service. The power, and therefore the cost of the electricity, is essentially the same. The only difference is that you may have smaller losses in the wiring because of the lower current in the 220/240 volt service.

My choice would be to go with the 220/240 volt service if the current is on the order of 7.5 amps or more at the 220/240 volt service level (at full load).

The disadvantage of the 220/240 volt service is that it's much more expensive to add GFCI to the circuit, and it generally requires that you add wiring to provide the power (most people don't have a lot of 220/240 volt circuits in their shop).

Good luck.

Mike

[Gary Howell]

It will save you money, and is easier on your motor as it will only draw about half of the current vs 110V. The more current a motor draws the hotter it will run for the same hp. 1 hp=746Watts. Power= Voltage X current. Hope this helps, If this is not enough info let me know, Gary

[Dev Emch]

First of all, it does not really save on power at all. Power is conserved and the nameplate rating is what your going to get in terms of ponies.

By going to 220 volts instead of say 110 volts, you reduced the current in the feeder or branch circuit running up to your motor by half. This allows you to use smaller gage wire. It also allows you to use cheaper plugs as you mentioned.

Once the voltage and current are inside your motor, things even out. Dual voltage motors use dual sets of windings in the stator. Please note that my comments here are extremely rudamentary. But in general, a dual voltage motor will have its coils in parallel for low voltage and in series for high voltage. This has the effect of delievering the same voltage and amps across each coil regardless of which incomming voltage you use. Under low voltage, the voltage across parallel coils remains the same but the current divides evenly which takes the low voltage current and divides it by half. Under high voltage, the coils are in series which means the current through each coil is the same and that would be the reduced nameplate current for the higher voltage or the lower voltage current divided by half. So you see, the current in the windings is the same. In series, the voltage drop accross each coil is the same making the voltage across the coils the same as that in the parallel case.

This then has the effect of producing the exact magnetic properties in the air gap regardless of which voltage you use.

Now I have heard that motors running at say 440 volts tend to jump to life almost instantly whereas motors running at 220 volts take a couple of more seconds. I cannot confirm this. The 220 case was a case driven by a phase converter whereas the 440 case is a dedicated incomming commercial service. The startup difference may well be attributed to issues in the converter not being large enough.

So in conclusion, dual voltage motors are often more an issue of installation convenience than anything else.

[Barry O'Mahony]

Allen,

Yes this is a simple question. It is therefore no surprse that Michael and Dev, both being engineers, answered it correctly. ;)

The G0555 motor isn't very big, and even wired for 120V, its current draw should be low enough that any properly-wired 120V branch circuit should handle it no problem.

[Dev Emch]

Allen,

Yes this is a simple question. It is therefore no surprse that Michael and Dev, both being engineers, answered it correctly. ;)

The G0555 motor isn't very big, and even wired for 120V, its current draw should be low enough that any properly-wired 120V branch circuit should handle it no problem.

Barry, I have to admit that I cheated.:rolleyes: Most engineers never get into the guts of electrical motors because that is beyond them. I learned lots from a couple of gray breaded old phogies who showed me the art of rebuilding this stuff. I have also rewound the louis allis DMD motor myself. That is more technician work than engineer work. So all you engineers give your local engineering tech a cookie and a pat on the back. They too work hard and deserve it. :D But glad you concure.

[Allen Grimes]

Thanks guys,

My brother-in-law and my neighbor are both "electricians", but I think that they do a lot more talking out of their backsides than anything else. I mean I appreciate the help, but I would rather somebody be honest and say that they dont know than give me bad information just to look smart.

So anyway, I'll probably rewire it anyway, just because, but not until I get my shop biggerized.

Thanks again guys.

By the way, I know this is off topic, but could anybody give me the names of some good books on electricity?

You can pm them to me so we dont take up board space on a non-woodworking topic.

[Barry O'Mahony]

So all you engineers give your local engineering tech a cookie and a pat on the back. They too work hard and deserve it. :D I absolutely agree with that one.

[Clem Wixted]

Thanks guys,

By the way, I know this is off topic, but could anybody give me the names of some good books on electricity?

You can pm them to me so we dont take up board space on a non-woodworking topic.

Allen,

Your question comes up frequently on woodworking and woodturning forums. If you do a google search you will get more information than you ever cared to have :)

Here is a good web site and there are some links at the bottom of the page.

http://home.earthlink.net/~mgoodall/happywoodworking/MotorWiring.html

Clem

[Howard Acheson]

>> My neighbor says it saves electricity,

I don't think this was addressed. Changing from 120 to 240 does not reduce your electical bill. You pay your bill based on Kilowatt Hours. Watts are calculated by multiplying the voltage times the amps. As an example, a 120 volt 10amp motor is 1200 watts. The same motor if converted to 240 volts will draw 1/2 the amps so the calculation is 240 volts times 5 amp which equals 1200 watts. In other words, the watts are the same, therefore the Kilowatt Hours are the same no matter how the motor is wired.

[Bryan Somers]

Michael , Dev , and Howard are correct. The only area where you save any money is in the wiring installation. You can use smaller guage wire, but having the choice I would wire for 220.

[Steve Stube]

I've heard the arguments 120 vs. 240 and avoid them but I do invite folks to experiment (test) a machine both ways to see if they experience a performance difference that would be beneficial to them. Myself I have machines that I am convinced do operate better on 240 volt. Snapping to attention when I throw the switch and no light dimming or flicker are positive attributes in my book so if I experience this on 120 volt and not on 240 volt - the machine gets wired 240 volt.

[Allen Grimes]

Allen,
If you do a google search you will get more information than you ever cared to have :)
That will never happen. I always want to learn more. I'm like Johnny 5, I need input.

To Howard Acheson,

Thanks for the explination, though the conclusion of that formula was the reason I wrote this in the first place. I was always under the assumption that 220 saved energy, therefore money because thats what I've always been told, by the "electricians" I know until one of them let me borrow one of their books with that formula in it.

With the use of the book and the application of logic, I not only figured out for myself that the energy consumption was the same with both set ups, but I also figured out that the "electricians" who I once trusted, didnt really know what they were talking about.

That is why I posted here, not to see if I would be saving money, but to see if there is a real benefit to rewire a machine that is already wired (plug included) for 110.

The only reason that I even that I even entertained that thought at all, was because, in the G0555 manula, it has instructions for rewiring the bandsaw to 220. So I just wanted to know, what is the point, if there is any point at all.

Steve,

You make a good point, I will probably rewire it eventually, but its not something that I will even worry about unless I I get light dimmage everytime I turn it on.

Once again, thanks to everybody who paricipated in this thread.

Oh one last thing. This is a 5 volume set that I am looking at, anybody know if its good or should I look at something else? http://www.amazon.com/gp/product/0790610418/ref=pd_kar_gw_1/102-3909764-8266540?n=283155

[Mike Henderson]

Just a comment, but if you're getting significant dimming of lights when you turn on a motor on a 15 amp circuit, you should really look at your wiring.

The reason you don't get dimming when you use a 220 volt circuit is that you install dedicated wiring for the 220 volt circuit back to the main box, and the current draw of the motor is not sufficient to drop the voltage at the main box.

You could get the same advantage if you installed a new 15 amp, 110 volt circuit back to the main box. If you did that, it's unlikely that you would see any dimming of the lights.

If your shop has the proper wiring for 110 volt circuits, I'd keep a band saw at 110 volts for convenience. One day you're going to want to re-arrange your tools and it'll be easier to do that if the saw is 110 volts than if you have to re-wire to put 220 volts where the saw moves to.

Additionally, it's much easier to add GFCI to 110 volt circuits, which could save your life one day.

The only advantage of 220 volts is the reduced current, which allows you to use smaller wiring to the outlet. I would only use 220 volts for high current draw equipment, like a 3 HP motor on a table saw.

Mike

[Allen Grimes]

Mike,

You make some pretty good points.

The good thing is, I will be building my shop in the near future and I will be able to do the whole thing the way I want. My current shop (14'x11') will be converted into my spray room. Instead of adding a sprayroom addition to my shop I will be adding a shop addition to my sprayroom:D.

EDIT: 2 things.

1) If the only advantage to 220 is like you said then to me it will not be an advantage at all since I will be using oversized wires anyway. Its just a personal prefference

2) If you notice any renegade commas in my posts, its because my finger habitually hits the comma key every so often

[Mike Henderson]

Allen, Yeah, I did the same thing when I wired my shop. I ran 220 service with big wire from my main box to a sub box at the shop, with a 50 amp breaker in the main box. Then I ran oversized wire to the outlets and put in a bunch of different circuits. While this is not code (Barry, don't flog me for this), I put 20 amp breakers in the sub box but used the standard 15 amp convenience outlets, and wired only a few outlets to each breaker (for the inspection, I had 15 amp breakers in the sub box). I also separated the outlets - that is, sequential outlets are always on different circuits, in an attempt to minimize the chance of using two tools at the same time on the same circuit. And I put in lots of outlets.

Since I work in the shop by myself, the peak load is the one tool that I'm using. The only time I have two tools running is when one of the neighborhood kids wants to do something (like sand something). I let them go at it while I continue my work. Otherwise, it's one tool at a time, so the 50 amp breaker to the sub box is plenty big.

Good luck on your wiring.

Mike

[Allen Grimes]

Thats how it will be for me for a while. I mean the one tool at a time thing. At least until I get a DC system. Though I do plan on hiring people to help me out in the future.

[Gil Jones]

This is a very good wiring manual!
http://www.amazon.com/gp/product/1561585270/002-0687830-5430433?v=glance&n=283155

[Allen Grimes]

Hey thanks Gil,

Thats not the kind of book that I had in mind when I was asking about electricity books, but now that you brought it to my attention it is definately a book that I want.

[Dev Emch]

>> My neighbor says it saves electricity,

I don't think this was addressed. Changing from 120 to 240 does not reduce your electical bill. You pay your bill based on Kilowatt Hours. Watts are calculated by multiplying the voltage times the amps. As an example, a 120 volt 10amp motor is 1200 watts. The same motor if converted to 240 volts will draw 1/2 the amps so the calculation is 240 volts times 5 amp which equals 1200 watts. In other words, the watts are the same, therefore the Kilowatt Hours are the same no matter how the motor is wired.

Twinkle twinkle little star.....

........... Power equals I squared R.....:D

[Dick Strauss]

Yes, you will save electricity. However, it will be a very small amount.

If memory serves me correctly it goes like this...

1. assume we need 1100W/1Ph power for a machine.
2. assume we need a 50ft wire run from the breaker to the machine
3. assume no heating of wire (20*C constant)
4. we can get 1100W by 10A/110V or 5A/220V
5. resistance for copper wire is roughly:
10g .00118/ft or 0.059ohms/50ft
12g .00187/ft or 0.094ohms/50ft
6. Power loss is I squared R (R from the wire only)
7. Power losses are roughly as follows:
10A/110V/10g...5.9W
5A/220V/10g...1.5W
10A/110V/12g...9.4W
5A/220V/12g...2.4W

So you'd save about 4.4W with a 10g wire and 7W with a 12g wire. I don't know about you but I wouldn't notice this small amount given our bills are always in kWH.

This is why power companies transmit power at such high voltages (500kV+) over long distances. Higher voltages mean less current and much less total power loss due to line resistances.

My numbers might not be exactly correct but they should be in the right ballpark...

[Stephen Dixon]

The motor uses exactly the same amount of electricity, however, there is some slight amount of extra power lost in the house wiring for 115 V circuits. This is VERY small though, and would take a very expensive meter to be able to read it, I doubt you would see the difference on your electric bill.
Steve

[Dev Emch]

The motor uses exactly the same amount of electricity, however, there is some slight amount of extra power lost in the house wiring for 115 V circuits. This is VERY small though, and would take a very expensive meter to be able to read it, I doubt you would see the difference on your electric bill.
Steve

And if I take that same wire and stuff it into a plastic, insulated conduit and fill that conduit with liquid nigrogen, then how much power will be expended by this highly efficient transmission line?

[Jim Dunn]

Dev, you building a ray gun there??

[Barry O'Mahony]

While this is not code (Barry, don't flog me for this), I put 20 amp breakers in the sub box but used the standard 15 amp convenience outlets, and wired only a few outlets to each breaker (for the inspection, I had 15 amp breakers in the sub box).
Mike, this is OK according to the NEC as long as you use 12 AWG wire, and there is more than just a single receptacle on the circuit; i.e., on a 20A branch, if there is just one single receptacle on it, it must be a 20A. If it is a standard tandem receptacle, or if there are multiple receptacles, then they may be either 15A or 20A.

Just don't put 14 AWG wire on a 20A branch! The bozo electrician my General Contractor hired on my house remodel did that in some places. I'm still finding and fixing mistakes that guy did; the GC doesn't use him anymore.

[Mike Henderson]

Yep, Barry, that's exactly what I did - I wired all the convenience outlets with 12 gauge wire, and I have multiple outlets on a single circuit.

Glad to know that I'm legal! Thanks for the code reading.

Mike