Can A Microwave Spontaneously Combust?

Last night we narrowly missed having our house burned down. Our smoke alarm alerted us to the fire, which was in the utilty room. Our microwave was in flames, the room filled with smoke and everything in the room covered in a thick black film.

What I find odd is how much combustible material seems to be in a microwave, as I would have thought it was mostly metal.

We rarely use this microwave, but it was plugged in. Entire house was rewired 5 years ago. I'm wondering if anyone else has heard of such a thing, or had it happen to them. I'm nearly afraid to leave the fridge plugged in now.

Sounds very odd. I would imagine that the most likely cause was an electrical fault inside or leading to the appliance. I guess that it's technically possible for something like a firmware bug to cause the appliance to switch on spontaneously but that sounds very unlikely. Maybe check for details of that make/model in case there is some known problem with it? There probably are plenty of plastic parts in the microwave and it doesn't take much plastic to cause everything to be covered in residue. Somebody who I know had their cooker extractor hood spontaneously combust in a similar way causing substantial smoke damage to the whole house. It seem to have been due to an electrical fault and a build up of grease in the filter. The hood was switched off at the time, not used that often and the person was out of the house at the time which was good in one way (they were not affected by the fire/smoke) and bad in another (because there was nobody there the damage was more than if the incident had been tackled immediately).

Good to hear that at least your smoke alarms did the business. Must check ours more regularly!

Thanks for your reply, Clubman.

We had very bad lightning the previous day, somebody has suggested that it may have had something to do with it.

If I recall correctly, you pointed out on some other thread that it is dangerous to leave appliances switched on as there could be a fire risk. How right you are.

We always unplug the TV at night, as I grew up with a mother who was always warning us that " it could burst into flames ".She was of that generation for whom electricity was still a mysterious and dangerous thing.
Perhaps we have all become too blase about it.

Perhaps you could get your local fire officer (?) to give an opinion on why it happened? Not sure if you can pay them to perform this service or if they only do it at the scenes of fire accidents?

Bluebells said:

She was of that generation for whom electricity was still a mysterious and dangerous thing

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She was right! Certainly about the dangerous aspect.

The lightning sounds a likely root cause. No telling what it might have done. Fires can smoulder for days and not be noticed.

The same thing happened to the microwave in my home about 5 years ago. The microwave was about 7 years old at the time. It was a digital model. It was left plugged in overnight. It somehow activated itself and when I found it it the kitckhen was full of thick smoke and the microwave was burning. Scary! I dread to think what would have happened if I didn't catch it at that moment.
I would NEVER leave a microwave plugged in overnight after that incient.

Bluebells and pugwall - what make (and model if you know) were your microwave ovens? Did either of you ever have other electrical problems in the kitchen/house? pugwall - did you get anybody (e.g. fire or electrical expert) to look at things and hypothesise as to what exactly happened?

Is it sufficient to turn the socket switches to off rather than unplug all appliances?

Cheese said:

Is it sufficient to turn the socket switches to off rather than unplug all appliances?

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Yes, turning the socket switches off cuts the power to whatever is plugged into that circuit.

Cluman,
There was a reported power surge in the area. It was a Panasonic model but no fault on the manufacturer.