Microwave trips the household breaker or blows a fuse when starting a cook cycle.

Safety Warning: Repeatedly resetting a tripped breaker can be dangerous. Unplug the microwave and do not continue to attempt operation until the fault is found.

User-level checks:

• Verify the microwave is on a dedicated circuit as recommended by Insignia.
• Inspect the power cord for visible damage, cuts, or burns.

Technician-level steps:

• With the unit unplugged, remove the cabinet and discharge the capacitor.
• Inspect wiring for burns or melted insulation.
• Test the high-voltage capacitor, diode, and magnetron for shorts.
• Check the line filter board and power cord connections for shorts to chassis.

Because this involves high current and high voltage, professional diagnosis is strongly recommended.