I have an old Westinghouse motor with a missing wiring diagram. It runs but is slow to start and sometime needs help. The terminal block has four connections, two labeled as line. I've measured resistance across all terminals and it is nearly the same. The data tag call out a capacitor size but I'm not sure were to connect it. enter image description hereenter image description here

  • \$\begingroup\$ Do you have a part number? What's the nameplate say? \$\endgroup\$
    – Hearth
    May 5, 2018 at 20:58
  • \$\begingroup\$ Can you hear an audible click when it stops? If so, it has a centrifugal switch, which opens at speed to disconnect a start capacitor. \$\endgroup\$
    – user16324
    May 5, 2018 at 21:13
  • \$\begingroup\$ It's a 56y frame. S# 1465028k SER EZ. \$\endgroup\$
    – rdbates1
    May 5, 2018 at 21:32
  • \$\begingroup\$ I don't hear a click when it stops \$\endgroup\$
    – rdbates1
    May 5, 2018 at 21:33
  • \$\begingroup\$ Does "two labeled line" mean the word line is written on the labels? Are the other two terminals not labelled at all? Is the resistance between each terminal and every other terminal the same? How much difference in resistance can your meter measure? Can you provide all of the information written on the data tag including the capacitor value. \$\endgroup\$
    – user80875
    May 5, 2018 at 23:03

1 Answer 1


You need to start by properly identifying the type of single phase motor you have.

Is there one "hump" on the motor like this? enter image description here

Or are there two humps like this? enter image description here

Or no humps at all?

One hump = Capacitor Start / Induction Run (CSIR) type motor

Two humps = Capacitor Start / Capacitor Run (CSCR) type motor

CSIR or CSCR versions will have a slightly different wiring diagram, but from one mfr to another, most single phase single voltage motors are going to use the same basic wiring, so if you find a diagram for one brand, it will work for this one too. I suspect you have a CSIR motor (because the nameplate only mentions one capacitor size).

No humps usually means it is CSIR but for an external capacitor, often done with submersible pumps or for machines where space for the motor is too tight. For this type of motor there may not be an internal centrifugal switch so you would use an external "potential relay" to switch the capacitor out of the circuit. that means the wiring diagram would be different yet again.


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