# which is better 120 or 240

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• posted on April 3, 2004, 4:52 am

not
Four times the power where - I agree if its into a dead short; but he did ask whether to wire his TS 120 or 240, so unless you're telling him to connect his 120V wired motor directly to 240V without changing the taps then he's going to get the same motor power plus a small fraction depending on how long his cable run is. Of course if he wires his 120 motor to 240 he will get four times the power for about 30 seconds before either the motor burns out or the breaker trips.
Bernard R
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• posted on April 3, 2004, 5:20 am

Nope, he didn't say anything like that. No chance it would last 30 seconds. Many many many years ago I plugged my 120v razor into a 240v outlet and it went up in a puff of blue smoke in less than a second. I don't think a table saw motor would last much longer.
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• posted on April 3, 2004, 5:55 am

<snip>
This was the original post:

Which words don't you understand?
Bernard R
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• posted on April 3, 2004, 2:24 pm

The ones that aren't there; the part about "but he did ask whether to wire his TS 120 or 240". No he didn't. What words are you hallucinating?
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• posted on April 3, 2004, 12:22 pm

Try again.
Power is the product of the voltage and the current, not the square of the voltage.
When a dual-voltage motor is connected to run on 240, it draws half the current that it draws at 120, thus the power remains the same. (There's a slight increase in available power, due to lower losses at the higher voltage, but the difference is minor.)

So it would seem.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
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• posted on April 3, 2004, 2:29 pm
wrote:

four
voltage,
Damn you people are dense. When you change the voltage from 120v to 240v, you DOUBLE the current, not halve it. V=IR. Since P=VI, and both V and I double, then P goes up by 4.
Sure, if you change things so that the winding are connected in series rather than parallel everything changes, but the OP said nothing at all about doing that; he simply refered to using 240v rather than 120v. Do not make assumptions.
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• posted on April 3, 2004, 3:25 pm

the
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its less expensive to run your motor at 220 instead of 110. less losses in the wire (as you say, 4 times less all other things being equal). however unless your power supply runs are say 50' or longer, and you are actually using enough power to notice it on your bill, its irrelevant.
for a shop with a tool running 16 hours a day, this will also help the motor last longer because there are less losses in the motor itself. 3 phase power would be even better. for the average guy who turns his table saw on for 4 hours a week, it probably makes none.
in short, for the average home shop guy, it doesnt matter. wire it to what you got there already.
my 2 cents.
randy
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• posted on April 3, 2004, 3:54 pm
Sorry Randy, your approach is much too straight forward and simple. :-)

motor
on
what
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• posted on April 3, 2004, 6:49 pm
wrote:

Realize that the supply run is from the electrical panel. My garage/shop is 24' wide. It is 10' tall. The panel is on the opposite wall from where I am installing my shop tools. I need 8' of wire up to the ceiling, 24' to cross the building, 5' down to where the outlets will be and about 12' along the wall to where I want the saw outlet. That totals 49 feet. Add the 20' cord on the saw and you are starting to talk about measurable voltage drop on a 120V circuit. In many cases you will have a lot more distance. It is amazing how fast it adds up.

The other place where it matters is in the efficiency of the motor. Even after re-wiring my previous shop to feed my saw with #10 wire at 120V it bogged badly, it is an 18A motor and draws about 24A on startup. I would routinely blow a 20A breaker if the blade was a bit dull or the saw was otherwise loaded. After converting to 240V it clearly runs better. It starts faster, never bogs down and I suspect that the RPMs are a bit higher, since it seems to "sing" a tone higher.
I might even add that a lot of places are wired with #14 wire on 15A circuits - and that is not heavy enough to run any useful table saw. So my feeling is that the only drawback to going with 240V is the cost of wiring and there are many benefits while there are really no benefits to staying on 120V other than the savings of wiring costs. Of course I do my own wiring, so it only takes about \$30 to add a 240V circuit with appropriate breaker, wire and receptacle.
YMMV
Tim Douglass
http://www.DouglassClan.com
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• posted on April 4, 2004, 2:26 am
Thats what I was thinking, the less amps I am drawing the less money I give to my local electric company.
Searcher1

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• posted on April 4, 2004, 2:33 am

The power company measures watts, not amps. 240V at 10A is the same power consumption as 120V at 20A.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
For a copy of my TrollFilter for NewsProxy/Nfilter, send email to autoresponder at filterinfo-at-milmac-dot-com
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• posted on April 3, 2004, 6:46 pm

Invert that, buddy. You don't understand what you're talking about here.

False.
That would be true *if* the resistance were the same. But it's not.

.. which is exactly what happens when you re-jumper a dual voltage motor to operate at 240V instead of 120V.

You're the one making assumptions, the primary one being the assumption that you understand how dual-voltage motors work. You don't.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
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• posted on April 3, 2004, 6:59 pm

the
a
not
to
not
that
I make no assumptions at all. He is proposing connecting his saw to 240v rather than 120v. Reread the OP, that is ALL he says. Making no assumptions at all, current will double and power will quadruple.
If YOU make the ASSUMPTION that he "re-jumpers" the motor, then everything changes, but then you are ignoring the OP and giving out potentially dangerous misinformation. If he was going to change the wiring, don't you think he would have given details?
When you are wrong you should just admit it; cause now you are just sounding stupid.
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• posted on April 3, 2004, 7:08 pm
wrote:

-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
For a copy of my TrollFilter for NewsProxy/Nfilter, send email to autoresponder at filterinfo-at-milmac-dot-com
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• posted on April 3, 2004, 7:31 pm

<snip>
sounding
Doug,
No use taking this any further, the guy obviously doesn't understand English, if he actually reads the OP, repeated below it does say it has the OPTION of being either voltage, it doesn't say, as our friend seems to imply, that it can be pluged in unaltered to either.

There are four levels in learing any new skill, guess which one he belongs to:
Unconcious Incompetent: Doesn't know he doesn't know. Concious Incompetent: Knows he doesn't know. Concious Competent: Knows that he knows. Unconcious Competent: Knows that he knows without having to think about it.
Bernard R
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• posted on April 3, 2004, 8:45 pm

the
Since it doesn't say anything about alteration, you assume it WILL be altered, instead of that it WON'T. Geez, that is moronic. What does pluge (an acronym for "Picture Line Up Generation Equipment") have to do with it.
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• posted on April 3, 2004, 10:16 pm

have
But nowhere near as moronic as saying he would get four times the power by using 240V, which is patently false no matter how you try and justify it.
I believe that, as the OP had enough sense to discover that the TS was dual voltage capable, he also has the ability to see what is necessary to do to achieve that change. Unless someone shows that they are moronic, which is how I will regard you for here on, I give them the benefit of having reasonable intelligence. In any case I don't give misleading or false information as you did in this case.
We all get fed up with answering the same question almost every other day, but you always have the option to ignore it, reference it off or try and give a sensible answer.
This guy asked a reasonable simple question, he deserved a simple straight answer.
Rant, rave as much as you like, as far as I'm concerned this is the last you'll hear from me.
Bernard R
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• posted on April 4, 2004, 12:42 pm

come on dude. im sure even you know something is gonna get switched in the saw if he uses 220 v 110. arguing the point further does indeed make you look... well.. like you just want to argue.
randy
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• posted on April 3, 2004, 8:07 pm
No assumptions being made. Fact: you're an idiot. Plonk.
> Do not

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• posted on April 3, 2004, 3:20 am

This is one of the most discussed topics in this newsgroup over the years. You should find lots of information by searching the archives. My executive summary:
1. Some people argue that electricity is electricity, and that the motor runs the same on either.
2. Some people argue that motors run cooler on 120 vs. 240, or 110/220, or 115/230, and cooler is better
3. I don't remember anyone arguing that 120 is better, so I always run 240.
4. There are a whole bunch of other arguments that I forget because I already went with #3
I hope that this helps - Bob