Electric Power & Utilities/Toggle Switch Wiring


I have a KR Tools 6 inch bench grinder in which the previous owner removed the switch and wired it to power on by plugging grinder in.  I purchased a basic on/off toggle switch which has 2 posts to connect the wires.  The power cord has 3 wires (red, black, green) The red and black in the cord are currently connected to each other and the green is grounded to the housing.  There are 2 red wires coming from the motor which are connected to each other as well.  So, my current power button is to plug and unplug the grinder.  What should the wire configuration be in order to use the toggle switch I purchased?

You say the red and black are connected together on the cord? This can't be right, as it would be a direct short when you plug it in. Also, if you have only two leads coming from the motor, and they are together, the motor cannot run. To wire the switch, connect the black from the cord to one terminal of the switch. Connect one of the reds from the motor to the other switch terminal. Connect the other two remaining red leads and insulate.  

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Charles C. Jones


Let Me help you with your problems with single phase and three phase electric motors. I can tell you how to troubleshoot your motor problems. From simple testing of capacitors, how to test your windings, replacing bearings, and general maintenance. Before we go any further, remember these words of advice: Disconnect the power before you do anything! Please limit your questions to electric motors and there immediate components. I review each question, and if I can answer or help, then I will. If you receive a rejection, it means it is out of my expertise, and just do not have the answer. I'll be waiting for your question.


I have 40 years experience in the repair of electric motors and related equipment. I am a master machinist in the field of motor repair. I was employed with my company for 35 years, but retired in May of 2013. The downside to that is I lost access to a lot of technical data. I will still try to give you the most accurate advice that I can.

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