To ensure long-term reliable operation of Molded Case Circuit Breakers (MCCBs), follow strict maintenance protocols: Before work, disconnect power and verify de-energization while wearing insulated gear. Inspect housing for cracks/discoloration in dry conditions; tighten terminals to manufacturer specs with torque wrench. Operate handle 5+ times to verify smooth switching/trip reset. Test insulation (≥1MΩ dry/≥0.5MΩ damp) and contact resistance (≤50μΩ; replace if exceeded), calibrate protection settings. Clean arc chambers and test shunt trip. Maintain annually (normal) or every 6 months (humid/dusty areas), with immediate post-fault checks. Record all data vs historical benchmarks.