No, it is not normal for the interior bottom/floor of a microwave to get super hot. While it is normal for certain parts of a microwave, such as the walls and ceiling, to get warm during operation due to the heat generated by the magnetron (the component that generates the microwaves), the interior bottom should not become excessively hot.
If you notice that the bottom of your microwave is getting extremely hot, it may indicate a potential issue with the appliance. There are a few reasons why this could be happening:
Malfunctioning turntable: The turntable is designed to rotate the food to ensure even cooking. If it's not functioning correctly or if you're using the microwave without the turntable in place, certain spots might be exposed to excessive microwave radiation, leading to localized overheating.
Uneven or improper loading: If you place food or containers directly on the microwave's bottom without using a microwave-safe dish or plate, it can cause the bottom to become excessively hot.
Defective or damaged microwave components: There might be a problem with the microwave's internal components, such as the magnetron or the thermal cutoff switch, causing irregular heating patterns and localized overheating.
Insufficient ventilation: Microwaves require proper ventilation to dissipate heat. If the vents or air circulation inside the microwave are obstructed, it could lead to the interior overheating.
Dirty or damaged waveguide cover: The waveguide cover is a metal or plastic sheet that covers the microwave's opening where the microwaves enter the cooking area. If this cover is damaged or dirty, it can cause arcing and localized overheating.
If you encounter this issue, it's essential to stop using the microwave immediately and have it checked by a qualified technician. Continuing to use a microwave that overheats could lead to further damage or even pose a safety risk. Remember to always follow the manufacturer's guidelines for proper use and maintenance of your microwave.