Like smoke detectors have been blowing off the ceilings with all those transients.

Load of nonsense SPD,s

Being physically blown off the ceiling is rather the extreme end of the scale - I suspect more often it's some tiny but vital electronic component that's stressed to the point of going phut (either short or open circuit) - the results not necessarily being visible to the naked eye (other than the damn thing doesn't work any more).

Over the last 10 years or so I've had a number of electronic devices stop working at home - one boiler PCB, a connector to the gas valve/igniter (also electronic) (twice), one PCB in the induction hob, a CO detector, a TV aerial amplifier and the ballasts of far too many LED lights. Of course I can't tell what the cause of each was - it might equally have been poor manufacturing or some other external influence or just natural end of life, or even an accumulation of several different events.  But if surges that could have been mitigated by SPDs were responsible for even a quarter of them, economically it would have been a no-brainer to fit SPDs and would have saved a huge amount of inconvenience as well. Granted actual evidence is lacking (or isn't well presented), but I'm still willing to keep an open mind.

   - Andy.

In the BEAMA surge protection guide they point out that one mode of failure from transients is that it will cause a brief arc between two close air-gapped components, such as adjacent tracks on a PCB. This won't of itself destroy the component, but may cause slight carbonisation. The next time, arcing will be slightly easier (i.e. with a lower transient voltage), and cause more carbonisation. Eventually there will be enough carbon such that the peak of a normal AC supply will arc, leading to rapid destruction of the device. That final failure may be months or years after the initial thunderstorm, and with nothing obvious happening to have triggered it.

In the BEAMA surge protection guide they point out that one mode of failure from transients is that it will cause a brief arc between two close air-gapped components, such as adjacent tracks on a PCB. This won't of itself destroy the component, but may cause slight carbonisation. The next time, arcing will be slightly easier (i.e. with a lower transient voltage), and cause more carbonisation. Eventually there will be enough carbon such that the peak of a normal AC supply will arc, leading to rapid destruction of the device. That final failure may be months or years after the initial thunderstorm, and with nothing obvious happening to have triggered it.