The method is easy, the resistance between common and staring will greater than the Resistance between the common and run wire.So you identify the common wire, so the next step to finding out which one is 'start' and 'run' wire.If you find out that two-wire have greater resistance between one another then it's mean that these are 'start' and 'run' and the 3rd one is common.Then check resistance between wire to wire in 3 wires.First of all, set your multimeter on ohm testing.However, to completely understand, follow the below step by step guide And if you find out that two wires have a high value of resistance showing on multimeter or ohmmeter in three-wire then it means that these two wires are 'start' and 'run' connection and the other one is common. In the single phase 3 wire motor we have a high resistance between the start and run connection or wire. Use a Multimeter You can easily identify the common, starting, and running connection of a single-phase motor.

And if you did not find any guide about the connection then follow the below step.

So the better and easy option to find out the run, start, and common wire or connection to read the connection plate diagram or chart. But is not important that the connection will come in the same colors. In someone phase motor the common wire comes with a black color wire, run as red, and start as white color. To find out the common, start, and run wires or connections first read the connection plate diagram and notes to find out which one is common, which one is running, and starting. Which we know with the name of common, start, and run connection.

In a single-phase motor we have three wires which come from both stating and running winding. (Basically to identify starting and running winding is just to find out the start, run, and common connection.) But this Identification can be done when you open the motor but what you will do if don't want the motor and just want to find out starting and running winding from the main connection plate or connection point. the thick wire gauge winding is the main winding and the thin wire gauge winding is the starting winding. If you open the single-phase motor, you will find out that your motor has two types of winding of which one is made from thick wire gauge and one thin. How to Identify starting and running winding in a single-phase motor

Electric motor winding types