Practical Techniques to Locate Wire Breaks

Detecting Break Points in Frequently Damaged Cables (e.g., water pumps, extension power strips)

Set the multimeter to the low AC voltage range.
After powering the cable, slide the probe along the outer surface of the wire insulation.

You will notice the induced voltage reading change along the cable.
The location where the voltage suddenly drops or changes significantly is generally the point where the conductor inside is broken.