Motor hums but does not start – what to check first

What the symptom means

When the motor hums but does not rotate, there is an electrical or mechanical cause preventing startup.

Possible causes

• Phase loss in a three-phase motor.
• Low voltage.
• Blocked shaft or load.
• Capacitor failure in a single-phase motor.

Check

First, check the voltages, fuses, and whether the shaft moves freely while ensuring safe isolation of the power supply.