table saw motor - Woodworking Talk

yimmortal · 08-14-2007, 06:12 PM

i've got a sears table saw with a 1 3/4 hp motor

it can be wired 110 or 220

right now i have it for 110 if i switch it to 220 will that make it stronger for cutting??

what are the advantages of 220

skymaster · 08-14-2007, 08:02 PM

Yes it will. Runs better by far. Also half the amps ( a tad cheaper )
A motor that is 110/220 capable that takes 15A at 110 takes 7.5 amps at 220V and techinically gets a tad more power :}:}:}:} .
My Delta is rated at 1.5 hp @ 110 and 2.0 at 220
JackM

**TexasTimbers** · 08-14-2007, 10:06 PM

You will never want another 110V table saw again. The power increase will bring an instant smile to your face.

Peter Bosse · 08-23-2007, 08:25 AM

You probably don't want to hear this, but:

First, the internal windings of "small" electric motors run on 110V even when 220V is supplied to the motor's wiring plate.

Also, it's a common misconception that a motor running on 220V use less current and will generate more power than the same motor running on 110V. It won't.

While it's true that the motor will draw 15A at 110V and 7.5A at 220V, that 7.5A is per leg, and there are two legs (two hot wires), therefore it still uses the same 15A. At 110V there is only one leg (one hot wire), hence the 15A.

As to power, Power = Volts x Amps. So at 110V and 15A, the power is 1,650 Watts, or roughly 2 HP. Given that the houose voltage is probably not a constant 110 volts, and in fact can did as low as 90-odd volts, the voltage supplied to the sub-panel will also be less than 110V. Couple that with any small IR drop in the wire, outlet, cord, etc., you can see how the voltage could be significantly less than 110V, and so the "power in" would be lower also (and the output power cannot be more than the input power).

For 220V Power still = Volts x Amps. Double the Voltage and halve the Amperage and you still have the same P = Volts x Amps, or 1,650 Watts, and the same roughly 2 horesepower. You can't increase a motor's power by rewiring it to run on 220V.

To sum it all up:

1. The motor's power will be the same whether wired for 110V or 220V.

2. Using 220V allows the use of a smaller wire (not a significant cost saving).

3. 220V can be wired from a single douoble pole breaker. Note that I said double pole, not two pole. There is a difference.

4. There may be a tiny reduction in total circuit amperage, which will give a tiny reduction in Watts as recorded by the electric meter on your house, but it not even be measurable or noticeable on your bill.

edp · 08-23-2007, 10:58 AM

One thing you will notice is that the blade comes to speed immediately which will reduce the start up energy draw but like Peter said, the energy costs are not reduced and the horsepower is not increased. 1½ HO is the same regardless of the power supply except in relation to voltage drops that will reduce your available horsepower. So, think of HP as the maximum developed when all incoming power conditions are as expected.

Ed

rob.hough · 08-23-2007, 01:28 PM

I had always heard that running at 220 didn't generate as much heat so your motor life would last longer and that it didn't get "bogged" down by a lack of draw from the power source. Beats - I figure there's a reason why you have the option though.

Peter Bosse · 08-23-2007, 02:00 PM

That's another misconception. If the power stays the same (and it absolutely does) the heat generated will be the same. Again, it's voltage times current.

~ Peter

**TexasTimbers** · 08-23-2007, 04:36 PM

I was thinking a 220 motor had more startup torque and was going to tout this as a response but before I made a fool of myself I asked my dad who shot that down in flames.

PB is right there is no real power advantage of 220 over 110 even in the startup it is a myth to which I have fallen prey for many years.

I would rather be publicly enlighted than to remain silently ignorant thanks Peter.

rob.hough · 08-23-2007, 05:34 PM

so is there any real reason to use 220 over 110?

Stick · 08-24-2007, 06:15 PM

Quote:

Originally Posted by rob.hough

so is there any real reason to use 220 over 110?

I'm new here and in the confusing stages of looking at table saws and am very interested in this question. Furthermore, is there a saw out there that will run in the US (110/60hz) and in Europe (230/50hz)? That would be very interesting to me as I am in the military and bounce between Europe and the US as much as possible.

Peter Bosse · 08-26-2007, 07:14 AM

Generally speaking a motor of 1 to about 2 or 3 hp can be switched from 110V to 220V, but motors are designed to run at either 50 hz or 60 Hz only.

I would check with some saw manufacturers that you're interested in.

~ peter

Peter Bosse · 08-26-2007, 07:40 AM

The advantages from using 220V rather than 110V are:

1. the double pole breaker can occupy a single space in the service panel and still cut out both 240V hot wires; and

2. Because the power is split between the two hot wires a smaller gauge wire can be used.

3. It is possible to get two 110V feeds from a 220V line in a work box.

Peter

Travelin Bill · 09-07-2007, 11:01 PM

having usedtable saws for yrs I have ripped 2x4s on t.s.'s with both 220 and 110 on the same saw by switching the wiring the saww didn't bog down with the 220 but did with the 110 why?