converting a unisaw 1.5hp motor from 115 volt to 220 volt

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Forum topic by Beginningwoodworker posted 04-16-2013 12:05 AM 5509 views 0 times favorited 22 replies Add to Favorites Watch
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13345 posts in 3669 days

04-16-2013 12:05 AM

I been thinking converting my Unisaw 1.5hp motor from 115 volt to 220 volt, I am wondering how do you do that? I hear you get more hp with 220 volt current?

22 replies so far

View JustJoe's profile


1554 posts in 2034 days

#1 posted 04-16-2013 12:09 AM

No you don’t get any extra power. The motor just draws less amps. If your motor is switchable there should be a wiring diagram on the side or on the inside of the capacitor cover. You can get a new cord and a 220V plug to match your 220V outlet from any electrical supply store for under $5.

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13603 posts in 3337 days

#2 posted 04-16-2013 12:10 AM

take the cover off where the wires go into the motor
it should have a wiring diagram there
for the conversion
(the wires are numbered
and just go to different places then)
then get the right plug for the power
(you got advice on your other post for that)

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

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13345 posts in 3669 days

#3 posted 04-16-2013 12:15 AM

Ok thanks!

View Shawn Masterson's profile

Shawn Masterson

1325 posts in 1945 days

#4 posted 04-16-2013 12:46 AM

a lot of people think it draws less amps. This is not exactly true. If a motor draws X amps on 110 (1 leg) then it draws 1/2 the amps on 220 (2 legs). What I mean by “leg” is when you look at the wire 110 has 1 hot wire 1 neutral and 1 ground , 220 has 2 hot wires and a ground, some have a neutral. A 220 motor draws its amps from each side of the panel using the same amount of amps in total it just draws it from 2 legs not 1. It is better to run 220 because the motor runs cooler, and starts easier/faster. The wiring diagram for changing it over should be on the motor some where, and the cord will work as long as you change the plug. The plug will cost some where around $5 and the cord you have on the machine now is sized for 110 so changing to 220 the cord will be oversized. If your wanting to make the cord longer it is cheaper to buy a #12 extension cord and cut the ends off and put a 220 plug on it than to buy the wire alone. the only thing not mentioned is to make sure the starter switch is rated/setup for 220.

View JamesT's profile


102 posts in 1908 days

#5 posted 04-16-2013 12:52 AM

There will NO difference in the power of the saw at 110v or 220V. Most 1-1/2HP motors are rated at about 12 amps at 110V and would be 6 amps at 220V. 110X12=1320 watts 220X6=1320 watts. The power of the motor is the same. If the 110V circuit is sized correctly you will accomplish nothing by changing to 220.

-- Jim from Doniphan

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13345 posts in 3669 days

#6 posted 04-16-2013 01:05 AM

Thats what I tought. My motor is rated at 115 volt at 19.2 amps I think. Well I was running the motor on a 100ft exentsion cord so thats why I was losing power. In the new 12×20 garage I am going to build it will be wire.

View knotscott's profile


8011 posts in 3372 days

#7 posted 04-16-2013 01:09 AM

It’s very common for 110v circuits to suffer from voltage loss during peak demand, and starve the motor for amperage. 220v is much less likely to suffer from voltage loss, so the motor tends to start faster, and recover faster from lugging….it also tends to run cooler. If your 110v circuit is at all suspect, you might find that 220v makes a noticeable difference….not more horsepower, but faster starts and faster recovery can make it seem like it had it’s Wheaties. 220v can be handy to have for bigger motors, even if you don’t notice a difference on your TS.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View Beginningwoodworker's profile


13345 posts in 3669 days

#8 posted 04-16-2013 01:12 AM

Maybe, but I was running my saw on a 100ft extension cord.

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5 posts in 1879 days

#9 posted 04-16-2013 01:13 AM

Try it and see

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85 posts in 3705 days

#10 posted 04-16-2013 03:38 AM

Here’s a metaphor for you.

Imagine a 5 gal bucket. You fill it with the garden hose and it takes 1 min. Now image that you take your hose and a hose from the neighbor’s house and use them both to fill the bucket. Of course, it takes half the time.

The windings of your motor are just like that bucket. They have to fill up with electricity to turn the motor. 220v allows them to fill faster, thus improving performance. In almost every situation it will help.

Also, most table saws draw enough current that using a 100ft cord is not recommended. Unless that cord is 10 gauge or bigger.

View Woodknack's profile


11613 posts in 2376 days

#11 posted 04-16-2013 03:58 AM

I’ve been meaning to convert my saw to 220 and just haven’t gotten round to it the last 15 years or so… I’ll just hardwire it though.

-- Rick M,

View TorxNut's profile


58 posts in 1893 days

#12 posted 04-16-2013 04:03 AM

A few years ago I converted my Ridgid 3660 table saw and Sears RAS from 120 to 240 volts. I figured the motors would start faster and maybe give a little more power. It made absolutely no difference. I even recorded the sound of the machines starting up before and after – no difference.

In this case the supply circuit was 12 gauge wire on a 20A breaker for both the 120 and the 220. Because the 120V circuit was a fairly short run with 12 gauge wire, the motors were getting all the power they needed to run properly on the lower voltage.

A 100 foot extension cord, as mentioned above, is a bad idea.


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13345 posts in 3669 days

#13 posted 04-16-2013 04:05 AM

I been using a 12 guage!

View JamesT's profile


102 posts in 1908 days

#14 posted 04-16-2013 01:56 PM

I repeat. If the 110 circuit is sized correctly it will make no difference using 110 or 220. A 100 ft. cord is not the way to go, way to much voltage drop. Also re-check the motor, hard to believe a 1-1/2HP is rated 19.2 amps. That kind of current draw (watts more than 2300) is more like a 3HP.
If you are indeed drawing 19.2 amps @ 110 volts on a #12, 100 ft. cord (wiring in saw may be #14) the voltage drop may be as much as 7%-8%. The voltage reading at the saw may be 100 volts or less. Before you rewire the motor, you need an electrician to look at the entire set-up. (Just my 2 cents)

-- Jim from Doniphan

View REO's profile


928 posts in 2070 days

#15 posted 04-16-2013 06:25 PM

people have a tendency to think of electricity like water in a hose. often people will use the analogy and oversimplify an explanation but it is misguiding. The simple hose story leaves out resistance to flow, pressure, hose diameter etc. To get right down to it, a motor is designed to use a certain amount of electricity. it can only pass a given amount of water (HP or work) At a given pressure (110 volts) if you feed it with one hose (110) it will require a bigger hose to allow enough flow to satisfy the draw. if you split it up into two supplies (220 peak to peak 110 per leg, less if you use RMS because they are 180 out of phase.) you can use a smaller diameter hose. The total volume in the bucket over a given amount of time is still the same. smaller hoses are easier to run and

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