Most all microwave ovens have an internal fuse, as this is such a high power electrical device which could have a catastrophic electrical explosion of wiring/components if the magnetron shorted out. Since these are installed in mostly modern wiring with branch circuit breakers, and internal equipment fuses you never seem to hear about these explosions happening.
You might do a search on You Tube on replacing the internal fuse in your brand/model microwave. Most of them I have taken apart have the fuse mounted on or near the magnetron, and are noticeable in size.
When I was a kid in the 1950's 1960's it was a common thing to read about accidental electrocution accidents in the news. Then GFI circuit protection came into being, and it is a rare thing to hear of these accidents happening any more. The same with the elimination of cholera and typhoid epidemics due to the widespread use of chlorination in public potable water supplies. All are results of a modern scientific public health effort that goes pretty much unrecognized or appreciated. Electrical safety legislation is part of the public health effort.
