My second-hand 1300 W microwave oven worked fine for years, but a few weeks ago, while running, it blew a fuse (with nothing else turned on on the same circuit). Landlord replaced it, I tried the microwave again, and it worked fine.
Continued using it normally for a few weeks, and then yesterday while running it, sparks and burning smell came out of the back, presumably from the outlet itself, since I don't see burn marks anywhere else, and plug is slightly melted.
Is this just because the outlet is old and not making good contact with the prongs, causing arcs when high current is flowing and the connection breaks? (But why would that blow a fuse?) Or could there be something wrong with the microwave itself?
I replaced the melty plug, connected it to a different outlet with a Kill-A-Watt in between, and cautiously tried to heat some water. The microwave sounded a little weird, and the current ramped up to 16.7 A and the Kill-A-Watt started beeping.
Soooo I guess it's time for a new microwave.
The brand-new microwave also draws 16.7 A, voltage drooping to 114 VAC. 😒
Similar discussion: "Panasonic inverter microwave drawing more current than it should"
I found manuals for both, and they say:
The oven must be plugged into at least a 20 A, 120 V, 60 Hz GROUNDED OUTLET.
I don't understand how they are allowed to use a 15 A plug for a device that draws 16.7 A, while claiming it requires a 20 A outlet. Shouldn't they be required to use a 20 A plug? Maybe because the power level is selectable?
This FCC document says
7. EQUIPMENT SPECIFICATIONS:
Electrical Power Requirement: 120V, 60Hz, 12.7A
REPORT OF MEASUREMENTS
Supply Voltage: 120 Volts, 60Hz, 16.7A
But I guess the FCC only cares about emissions, not power draw.