Replacement 3 phase On/Off Safety Switch

[Lee Schierer]

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?

[Josiah Bartlett]

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.

[Lee Schierer]

Our electrician is the one that discovered the improper protection starter. He is not familiar with tables saw safety switches.

[Chip Lindley]

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 Of course, some other type of switch without overload protection could have been added, OR the heaters could have been replaced by only a jumper.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.