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Q & A: Should I Run My Tablesaw on 120 or 240 Volts?


Should I Run My Tablesaw on 120 or 240 Volts?



My contractor’s saw pops a breaker every once in a while, and that’s driving me crazy. I noticed that its motor can be wired for either 120 or 240 volts. I don’t have a 240 circuit in my shop yet. Do I have to install one or is there something else I should try first?


Rewiring your motor and upgrading the circuit to 240 volts will solve your breaker problem, improve the motor’s performance and extend its working life.However, it won’t increase the horsepower of your motor. Before you rewire your motor and shop make sure your saw is getting as much power as it can. Don’t run any other machines or lights on the same circuit as the saw. If your saw must be connected to an extension cord, replace the cord with one that’s shorter and made with heavier gauge wire. Finally, see if the amp draw of your motor exceeds the capacity of your 120-volt circuit.A sound rule of thumb is that the full-load amps (FLA) of your motor should be equal to or less than 80 percent of your circuit breaker rating,or 12 amps for a 15-amp circuit and 16 amps for a 20-amp circuit. (A motor’s FLA is written on its nameplate in a box marked Amps. FLA is generally two numbers, such as 12/6. The first number is the amp draw at 120 volts, the second at 240 volts.) If your motor exceeds this guideline, and popping your breaker is still a problem, your best bet is to rewire the motor to 240 volts. It may only involve switching a few wires inside the motor and replacing the plug.Then consult a licensed electrician about adding a 240-volt circuit to your shop.

This story originally appeared in American Woodworker September 2002, issue #95.

September 2002, issue #95

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