110V table saw now 240

Well now it's in a permanent spot in the shop so I switched it to 240 and WOW, what a difference! It'll rip a 2X4 about as fast as the blade will take it and when it does pull down it has guts. This is a Craftsman motor, and I know almost nothing about electric motors so I don't know if other brands of motors would show the same response or not, but this one really jumped into action when it was given the extra juice. Jim

In my case I wanted the shop at the opposite end of a 40 x 60 tin building from the 200 amp panel. It was wired decently with 12 gauge wire and 20 amp breakers. And I wanted to start a shop vac at the same time as the radial arm saw (Sears 10", dating from about 1986). Starting both on about 100' of 12 gauge wire, the voltage would sag to about 92 volts and it would take 5 seconds for them to get up to speed.

I tried a 10 gauge extension cord the length of the building. It was better but not much.

The problem is that an AC motor requires the same watts whether its supplied with 90 or 125 volts, because the AC motor speed is set primarily by the frequency and so the shaft load is constant and to get the power it has to draw the watts. When the line voltage is down 10%, the line current is up 10%. When the line voltage is down 30%, the current is up 30% and that increase is really good at dropping the line voltage in what would ordinarily be good wiring.

I have a 240 volt 50 amp 4 wire welding outlet at the west end of the barn (shop area), so I made up a second panel. It has a 4 wire 50 amp range cord plugged into that welding outlet, then switched outlouts along one side. I know the phase of each outlet so adjacent outlets I know are on opposite phases. For the last 20', I shortened pieces of that 10 gauge extension cord so I have #6 from main to second panel, and 10 to the saw. I set up a relay with a switch box to control saw and shop vac at the same time with a convenient rocker switch, but with them on opposite phases. Now the radial arm saw has TORQUE and starts quick, and the shop vac keeps it clean. And the minimum voltage the saw sees is 115 volts.

Its all in limiting the voltage drop in the power wires and going to 240 volt motor wiring cuts the current in half.

Remember while starting the motor current will be 5 or 6 times running current and that's where the voltage drop is the worst. You went 240, I went STURDY wires, we both won.

Gerald J.

If you have two windings and connect them in series and apply 240 volts across the series connection, each individual winding only drops 120 volts buttttt ttttt t if you wire them in paralell, each sees the full applied voltage but each only draws 1/2 of the total current.

Hope this helps yall

John T

By the way, you might want to take another look at that nameplate. 13 amps sounds about right for a 1.5 hp motor on 120, but it should be around 6.5 amps on 240. And it's the lower current that makes 240 work: less current equals less voltage drop. Less voltage drop means higher motor speed. Higher motor speed means less current!

I just did a voltage check in the shop and it's currently 120.Thanks for the response. Jim

The WATTS used remain the same, and "WATTS over time" (kilowatt hours) is what your meter measures, and what you pay for, and the "KWH used" will be more or less the same, whichever voltage the motor is running on. There's NO such thing as a "free lunch"!

John T

John T

I do know how a 220 wired motor acts on 110, and this thing had more power than that. Like I said, I know almost nothing about motors, but this motor seems kinda small physically for 1 1/2 horse. Anybody know who made Craftsman motors fifteen years ago?Jim