Help needed: 12/2 or 12/3 for 220 receptacle

Old 05-10-05, 04:24 PM
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Help needed: 12/2 or 12/3 for 220 receptacle

I am trying to wire a dedicated branch circuit from a sub panel to a receptacle for a table saw. The saw requires 220 volts without a neutral wire so there are two hot leads and a ground.

I plan to run NM cable to the receptacle. Since I do not need a neutral, is it best to use 12/2 cable, re-label the white wire red, and use it as one of the conducting wires? Or is is better to use 12/3 cable, use the red and black for conducting wires and cap the white wire in the receptacle box? If I go the route of 12/3, should I connect the white wire to the neutral buss bar in the sub panel or also just cap it.
Old 05-10-05, 04:38 PM
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The choice is yours. Neither is a better solution. The 12/3 solution costs more, but allows greater freedom for expansion in the future. The 12/2 is cheaper, but doesn't offer flexibility in the future.

If the wiring is all exposed, I would probably run 12/2, but if the wiring were going to be covered by walls then I might run the 12/3.

If you run 12/3, I wouldn't connect the extra wire in the panel. I would leave it long enough to connect, but disconnected.
Old 05-10-05, 10:04 PM
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Check the full load current of the saw FIRST

I would also suggest that you check the nameplate on the saw to make sure 12 AWG wiring is suitable for the load. Take the Full Load Amps (FLA) off of the nameplate on the motor and mutiply time 1.25. If it is greater than 16 you should run 10/2 wg or if you prefer 10/3 wg this circuit would be good for 24 amps if a 30 amp circuit breaker is used. Some of the larger saws have a 3 or more hp motor and require a larger circuit.
Old 05-11-05, 06:57 AM
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I'd recommend you use 12/2. It is the "normal" way to do it, and deviating from "normal" can lead to future confusion.

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