Converting a Table Saw to Higher Voltage

The considerations include switch setup, coil capacity, and wiring. October 30, 2005

I recently purchased a General table saw which is prewired for 110 volt. The motor is capable of 220 volt operation and a diagram on the motor cover shows the wiring diagram to convert it. Can I use the existing 110 volt wiring and On/Off switch on the saw to carry 220 volt load?

Forum Responses
(WOODnetWORK Forum)
From contributor C:
Wire size is determined by amps, not volts. Since you're doubling the voltage, the amps will be cut 50%, so wire size shouldn't be at issue.

From contributor K:
Aside from changing the wiring in the motor, and changing the cord, you may want to check on the voltage of the coil in the switch. If it is 110V and you convert the neutral leg to 120, you may be running 220V through it, which may fry it. You may want to check back with General if you don't know how to read the wiring diagram and follow the wires in the starter.

From contributor B:
The responses above are correct. By going up 220v, you are decreasing the current draw and the existing wiring (if it was correct for 110v) will be fine for 220v.

If the saw has a magnetic starter switch, then that would have come with a 110v coil if the saw came from the factory set at 110v. This would need to be changed out to a 220v coil or, as suggested above, the coil will burn out immediately. If you can't find a replacement coil, then you need a new magnetic starter.

If the saw came without a magnetic starter, then you will want to make sure it has a double pole/single throw switch. This will open both legs of the 220v line when the saw is turned off. A single pole switch only opening one leg will work, but isn't a good idea.

From contributor K:
There is another way. It would require you to bring a 4 wire cord into the starter. The energy for the coil comes in through the start/stop button, through the coil, then through both heaters if there are two, then to the other lead which was neutral, but is now hot. If you know how to find where that last wire goes back to complete the circuit, it can be led back into the new neutral and have the same protection as before, without changing the coil. General should be able to tell you how to do this if you don't understand what I just described.

From contributor B:
Contributor K, you're right... I should have suggested replacing the 3 conductor cord with a 4 conductor as an option. That way, you still have a neutral coming into the system.

From the original questioner:
Thanks for your posts. The On/Off switch looks like it breaks both wires.