OT: UK 3-pin mains plug

[Dave Plowman (News)]

Yes.

That's exactly what happens these days. All (new) flexes are capable of blowing a 13 amp fuse under fault conditions.

[Andrew Gabriel]

What did you check?

One of the door interlock microswitches deliberately shorted out the supply, because the two microswitches disagreed on the door being open or closed, so the interlock failed. There can't be "nothing wrong with it". It may seem to just work by replacing the fuse, but that's not good enough. There's still the original fault to find, and there's possibly a second fault now due to the microswitches having been used to crowbar the supply, rendering one or both microswitches inoperative. These two faults can appear to cancel each other out, but they don't - it means the door interlock failed, and you've possibly now also lost the redundancy checking on the door interlock so it can't detect the interlock failed.

That's partly why it says "No user serviceable parts".

Interlock failure can be caused by one of the microswitches not working, or the catch mechanism or door hinge wearing out, or the oven being bashed or bent so the door is out of true with risk of microwave leakage. In the case of wearing out, it might first show itself either when closing the door very slowly, or when slamming it.

[Brian Gaff]

I had a philips microwave that rusted through on the bottom lip of the drop down door, it almost fell off the hinge. The paint covered up the rust! Brian

[Andrew Gabriel]

Microwave oven cavities rusting through the bottom due to spillage and/or condensation can be an issue, and is something to be checked when inspecting/testing them.

[Adam Funk]

Is that going to blow the fuse? ;-)

[Andrew Gabriel]

No (unless it affects the door position or door catches).

Can cause arcing and high heating at the site, as well as microwave leakage of course.