Is it possible to blow a fuse on a micro oven? And where would I change it?

open and look for blow fuses

If you put in the correct size of fuse then what it needs is to go to a qualified service tech. What would be next requires removing the covers and if you do not know what you are doing you will fry yourself.

Most microwaves usually use 15 amp fuses and not 8's. If it keeps blowing fuses there is a short circuit somewhere and you would need to track that down to stop your problem. A frequent possibility might be one of the micro switches in the door circuit.

I guess the main plug fuse does not blow for the same reason it does not blow and you can wreck a PC, although not certain why that is. I have a feeling from past work on a Panasonic that there is an internal fuse as well. This may have blown with the power surge.

Be-safe, Un-plug your microwave oven ,

Open the microwave cover ,
Close and open door few times to check the door latch(es) and switch(es).
Door switch assembly may has one or more micro switches.( Most switches are black or grey and about 1,25 in long X 3/4 in wide X 5/6 in thick with two or three wire connections).
Making sure door latch close and open these micro-switches.

You can hear the switch "clicks" when small switch pin or lever is pressed.

Sometime these door micro-switches pin or lever get stuck or broken.

You can take couple pictures before remove wires or micro switches

You can buy these switches for about 3-7 dollars online. Some web sites have video showing how to check them. (Using Volt-Ohm meter)

(Fuse is a ceramic fast blow 20A Little Fuse 0314020 or Eton ABC-20) Melting I²t 631
If the Fuse blows when the door is opened. (not even energizing the microwave) The bottom micro switch (monitor micro switch) is normally closed, (open when the door is closed) however if it remains in the closed state when the door is open you will have a short circuit with the Primary Micro switch. The circuit diagram shows that one of the two switches must be open. I was able to test with an ohm meter. With a bad switch the reading was less than an ohm with the door open and 290 ohms with the door closed - Across the plug with a good fuse. With the new micro switch the resistance shouldn't change by much with the door open or closed.

Chek the H V fuse,Diode&Magnetron

You have a faulty interlock switch. This is one of two or three switches in every microwave that are operated by the door. The interlock switch is wired to blow the fuse if you try to run the oven with the door open. The switch may have gotten knocked out of adjustment (say by slamming the oven door) or its contacts stuck closed. If there are no other problems with the oven, a new switch should clear this up.

I am not an expert on Miocrowave ovens, but from past experience I know that they have a number of micro-switches on the door as safety devices. If these switches are faulty, the last safety feature is to short the supply and blow the fuse to stop the microwave from operating in an unsafe condition. Obviously the switches would have to be checked first before jumping to any conclusions and a number of other faults would probably cause the fuse to blow as well.

It is a safety fuse !but somthing has made it blow,and needs checking by microwave engineer.Possibly door interlock fault.Micros can kill even when UNPLUGGED be carefull. If you live in cheshire we can FIX IT Grandadfixer