A week and a half ago I went to turn on the rangehood light and got a huge fright when I heard and saw heavy arcing, blue light instead of the usual white, followed by a pop and the circuit breaker cutting out.

After cautiously checking everything over and not seeing anything unusual - just one slightly blackened bulb, I turned it all back on and it was all working again, sans said blackened bulb. "Oh," thought I, "must have just been a very loudly blowing bulb". Shrugged and didn't think much more of it. One bulb was still working.

I've just turned it on again and - BZZZ.... POP - same thing again. This time I removed both bulbs and found something I can't explain easily: they are E14 (Small Edison Screw) and the screw thread on both has been completely vaporised in parts:





Any ideas what could have caused both bulbs to fail so spectacularly, so close together? Clearly there's an internal short there: bad batch? Poor construction? Oil or moisture ingress? I've seen a lot of blown bulbs and never seen anything like this before.