Electric Power & Utilities/Boat Lift Motor Replacement


QUESTION: I am replacing a Magnatec/Century 3/4hp 1725rpm motor running on 120v used on a boat lift with a Furnas drum switch. The replacement motor I have is a AO Smith/Century C655 with the same specs. I set the replacement motor to run on 120v but can't figure out the proper connections for the switch wires. Both motors have the same connections, 1 through 6, but the AO Smith motor doesn't have any terminal in the #2 position. The original motor was wired (from the switch) #1- black, #2- red, #5-white, and #6-orange. Is the switch compatible with this motor? Thanks for your time.

ANSWER: There is nothing standard about the connection plates between manufactures. The only standard is the number and color codes of the leads. Wiring a reversing switch can be a puzzle sometimes. Without knowing how the motor leads are connected to the plate, it would be impossible to explain how to connect. And many times, it requires disassemble of the rear endbell to accomplish this. The following is a diagram of how to connect a reversing switch to the motor, and the color and numbering system

http://www.flickr.com/photos/charles_jones149/466646785/  Substitute L1 for P2

http://www.flickr.com/photos/charles_jones149/253735324/  NEMA standards for color and number codes.

I hope this may help you, and if you have problems, let me know

---------- FOLLOW-UP ----------

QUESTION: Thanks for the response. I'll try to explain the wire locations on the 2 plates. On the original motor the internal wires are # 1- orange and blue,#2- red, #3- none, #4- black, #5- none, #6-yellow and white. The switch wires were black to 1, red to 2, white to 5, orange to 6. On the new motor the internal wires are #1- blue, #2- no lug, #3- none, #4- red, #5- orange, #6- black, white and yellow. There is a brown jumper wire going from #1 to #5. I checked the wires from the switch and I have power on the black and red wires and the orange to common in the up position and power on the orange and red wires and black to common in the down position. The # 1 and 6 position on the new motor have screw lugs so I was going to put the black and orange wires from the switch on these and thought the red wire wasn't used because of the brown jumper going to the centrifugal switch but that still left the white wire. Hope this helps clarify things. I really need to get the boat out of the water. Thanks again. Lew

ANSWER: Lew, I need to know what color wires are connected to which terminal on the reversing switch including the lines coming from the power source. And also verify that the switch makes up in the drawing i supplied.


         1          2

         3          4

         5          6

With this info, It will help me to correctly advise you, without frying your new motor!  


---------- FOLLOW-UP ----------

QUESTION: I checked the switch and the 6 wires are in a circular pattern. The upper left is marked L1 and has the black power-in wire. The lower right is marked L2 and is the white power-in wire. None of the others are marked. The upper right wire is red, the center right wire is orange, the lower left wire is white and the center left wire is black. Hope this info helps.

I'm not familiar with this type switch. What I'm giving you is my best guess. It may not work. Remove the red and black from the motor. From the switch, connect the orange wire to the orange on the motor. Connect the white wire to the white and yellow on the motor. Connect the red to the red from the motor, and the black center to the black from the motor. I cannot be sure this will work, but it is the only way, without knowing how the switch makes up, that i can offer.

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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.

Former member EASA

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