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Thread: Replacement 3 phase On/Off Safety Switch

  1. #1

    Replacement 3 phase On/Off Safety Switch

    We have a 10" 3 Hp 3 Phase Powermatic cabinet saw where I work. Currently the saw does not have the proper disconnect power protection nor does it have an off/on switch that has a large OFF button. We are looking for a Safety type on/off switch to put on this saw. Has anyone replaced their factory on off switch on a three phase saw?
    Lee Schierer - McKean, PA

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  2. #2
    Join Date
    Jul 2007
    Location
    Forest Grove, OR
    Posts
    1,167
    You will need to determine the kind of contactor the saw uses. The on/off switch is generally a remote control for the magnetic contactor for the saw. If it is in a commercial environment, it may require a licensed electrician to do it, and that person will know what you need.

  3. #3
    Our electrician is the one that discovered the improper protection starter. He is not familiar with tables saw safety switches.
    Lee Schierer - McKean, PA

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Contribute

  4. #4
    Join Date
    Nov 2007
    Location
    Mid Missouri (Brazito/Henley)
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    2,761
    A disconnect is easy enough to add between the saw and the power source. Your 3hp, 3-phase saw would need at least a 20A 3-pole knife switch. Some disconnects also include fuses on each leg, sized to protect the motor. Depending on code, disconnects are usually added when machinery is *hard-wired* to a circuit, with no plug and receptacle.

    Depending on how old, your PM should have a magnetic Furnas or Gould starter switch with overload heaters to protect the motor. The pushbuttons make or break current to the starter coil which starts/stops the motor. Of course, some other type of switch without overload protection could have been added, OR the heaters could have been replaced by only a jumper. A Pic would tell what kind of starter is installed on the saw.

    IF the starter is magnetic type, any momentary on/off pushbutton station (with big mushroom stop button) can be wired into it, and attached to the saw where most convenient.
    Last edited by Chip Lindley; 03-31-2010 at 4:14 AM.
    Necessisity is the Mother of Invention, But If it Ain't Broke don't Fix It !!

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