Contactor contacts that are badly pitted can cause the motor to burn out.

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Wear on contactor contacts affects how cleanly and efficiently power is delivered to a motor. When the contacts are badly pitted, the effective contact area is reduced, raising the resistance in the path of the current. This extra resistance causes heat to build up at the contact point and increases arcing when the contact opens and closes. The heat and arcing gradually wear the contacts, sometimes causing welding or sticking, which leads to unreliable switching. With degraded contacts, the motor may receive less than full voltage or experience unstable current surges, stressing windings and insulation and raising the risk of overheating and burnout. Keeping contacts smooth and clean minimizes voltage drop and arcing, protecting the motor from damage.