To clean the contacts on a magnetic starter, use a crocus cloth.

• A. Sandpaper
• B. Emery Cloth
• C. Crocus Cloth
• D. Wire Brush

Answer: (C)

Cleaning electrical contacts needs to remove the oxide film without roughening or damaging the metal surface. Crocus cloth is a very fine abrasive cloth that lightly firms up, sweeps away oxidation, and leaves a smooth surface ideal for good conductivity. Sandpaper and emery cloth are rougher and can scratch the contacts or leave abrasive particles behind, which can cause arcing or accelerated wear. A wire brush can gouge the surface and create burrs or shed metal, degrading contact reliability. So crocus cloth cleanly restores the contact surface with minimal material removal, making it the best choice.