I just fitted a sump pump in anticipation of Gabrielle.

I was congratulating myself on a job well done when I realised that if the power goes out I'm going to have to start bailing.

But if it happens in the middle of the night I'm not going to know.

Finding a mains failure alarm is proving more difficult than I expected - aliexpress has loads, but they aren't going to arrive on time.

Does anyone have any ideas where I can get one, or any clever workarounds?