White countertop microwave on a kitchen counter
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Microwave trips the house breaker or GFCI

Separate a supply problem (shared or undersized circuit, GFCI nuisance trips) from an internal short. Internal shorts in the HV section usually blow the internal fuse; a trip on start can also come from a shorted HV component.

Single source ~60 min advancedBrands: All

Before you start

  • DANGER: the HV capacitor can hold a lethal charge after the microwave is unplugged
  • Homeowners must not open the cabinet; internal steps are for trained techs only
  • Trained techs: unplug or breaker off, discharge the HV capacitor with an insulated tool, verify 0 V before touching internal parts
  • Never run the oven with the cabinet off or with interlocks bypassed
  • Do not upsize a breaker to stop trips

Diagnostic steps

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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Microwave trips the house breaker or GFCI · OnCall Tech