which is better 120 or 240

My new TS has the option of being 120 or 240 vt. Which is better?

Searcher1

Reply to
macyver
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Search on the google archives :-)

Reply to
Doug Winterburn

Power is proportional to the square of the voltage, so a 240v saw has four times the power of a 120v saw. It is a no-brainer.

Reply to
Toller

You just couldn't help yourself could you?

Reply to
Bruce

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
  1. I don't remember anyone arguing that 120 is better, so I always run 240.
  2. There are a whole bunch of other arguments that I forget because I already went with #3

I hope that this helps - Bob

Reply to
RWM

I have watched these too. I get that 240 is better but not enough better to spend a whole lot of money for it. If you have 240 and it is easy to hook up, do it.

Reply to
Greg

That is a great point! I have plenty of 240 available so there is no cost factor.

Reply to
RWM

Don't know which formula you are using but Power (Watts) = Current x Voltage or if you want to substitute I = V/R you get Power = V * V / R. However when you wire a motor from 110V to 220V you are changing two parallel windings to two windings in series, so you have the same current in each winding and therefore the SAME power from the motor. Where you do gain is from the wiring of the distibution box to the terminals on the motor, here you are dealing with a straight IR loss and as the R remains the same but the I halves you have less loss in the wiring and therefore more voltage to the motor.

Bernard R

Reply to
Bernard Randall

You have to read the OP more carefully. He didn't say anything about changing the wiring, but just using 240v or 120v. Since the wiring does not change, neither does the resistance. Four times the power!!!!!!!!!

Reply to
Toller

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

Reply to
Bernard Randall

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.

Reply to
Toller

This was the original post:

Which words don't you understand?

Bernard R

Reply to
Bernard Randall

At 240v the saw will use 1/2 the current compared to 120v, so the power is the same (V*I). However, lower current will mean less voltage drop in the feed wires, and less heating in the wires and motor. (This is also assuming that you're making the proper connection in the saw; if you run 240 with the saw at set 120, it will double the power, at least until the wires fry..)

That being said, I would agree with one of the other posters; if you don't have easy access to 240 already, stick with 120, assuming it's already there. If you're doing new wiring, wire both into the area and use 240 for the stuff that can take advantage of it and leave 120v outlets for everything else.

Mike O.

Reply to
Mike O.

split the difference and run it at 180

randy

Reply to
xrongor

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)

For a copy of my TrollFilter for NewsProxy/Nfilter, send email to autoresponder at filterinfo-at-milmac-dot-com

Reply to
Doug Miller

I'm approaching this from the supposition that the OP is a hobbyist in his own home.

I thought every home had 220 available to it through the fact that the drop from the utility pole is two hot leads and a neutral. The two hot leads each power a row of breakers in the service panel. A 220 breaker simply attaches to both leads.

When I got a tool that said to plug it in to 220, all I did was buy the neccessary electrical stuff (breaker, 12ga. wire, conduit, ect.) to make it happen. It was easy. It might have cost 20 or 30 bucks to do. I used the advise of people that know how and read over two different books on wiring a house for the subject of adding an outlet. I am not an electrician but can follow instructions.

Keep >

Reply to
Lazarus Long

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?

Reply to
Toller

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.

Reply to
Toller

It was worth it though. Two fish!

Reply to
Toller

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

Reply to
xrongor

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