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3-speed motor switch / wiring

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  • 3-speed motor switch / wiring

    Hi, I just bought a used ventilation fan for a dust collector I'm trying to build for my workshop. Its driven by a 1/4 hp 115 VAC Dayton 3-speed motor with a capacitor. Supposedly, it was a furnace fan. The unit does not have a switch but does have 4 wires: 1, common and one for each speed. I've been searching the web for days looking for a switch, finally finding a 4 position switch that appears to be the answer, but the supplier only sells wholesale!

    Can this thing be wired to run only on one speed via a regular switch? Is the common wire the same thing as neutral? Are there HVAC suppliers that I could contact for proper wiring instructions?

    Any suggestions?


  • #2
    A single phase 3 speed motor should have a white common wire, a red, blue and black wire for each speed. Also 2 brown wires for the capacitor. You do not need a special switch for this motor you can wire it as a single speed motor using the common wire as the neutral and which ever speed you want as the hot leg. Be sure to have the two brown wires hooked to the capacitor. Or just go to an electrical supply house and tell them you need a single pole triple throw switch. With this switch you can wire your hot leg to the common of the switch and each speed wire to one of the poles on the switch this will give you a speed selector.


    • #3
      Mike, thank you very much. I think I will try the single speed operating mode. Your rapid reply and sage advice is most appreciated.

      Steve Baker


      • #4

        It worked!

        Thanks again,