Thanks for all the replies.
Well, in the end after a lot of thinking, I came up with this lot:
Total is £34 inc VAT and postage. I already have a box to house it in.
Timer switches ON after 10 mins, triggering latching relay to BREAK the circuit.
The problems is resolves are:
Someone leaving...
< £30
VERY interesting chart of relay functions - never knew there were so many! I think I found the one, but the Schneider on is £40+VAT. Now I know what I'm looking for I'll dig further - thanks!
Timer should be unrelated to float switch. Thanks for all the ideas - I'm going to let this bounce around in my head over the weekend and I'll let you know what dribbles out next week...
Thanks - well, I don't want a DIN mount, so this looks close https://uk.rs-online.com/web/p/latching-relays/9143963/
But... useless datasheet. I'll give them a call later!
Thanks for the fast replies - sorry, I was away yesterday!
Thanks for that - would this suit for the delay-on timer? The voltage, price and functionality seem right!
https://quasarelectronics.co.uk/Item/cebek-i-137-230vac-delayed-on-timer-relay-module-2-45-minute
The only thing I'm unsure of...
Well if, for the sake of £10-£20 I could do a drop-in replacement of a relay without a timeout relay, that just adds another level of protection.
It's like saying "why have an RCD? What if it fails? Why put a seatbelt on? What if it fails"?
Belt and braces?
Yeah, I can find loads of off-delay relays. The trick is finding one which locks-out until manually reset, if the delay is reached.
In other words, if the float switch is still apparently requesting water more than 10 minutes after it was first triggered, then something is wrong.
I just thought...
Thanks both. Good ideas there.
Well, I do in fact have an RCD, but what made you think that from the pics, given it's about 30 feet away on the dist. board? It did indeed trip when the light fittings started dripping, however, the lighting circuit is separate so didn't cut the pump. Not too good...
D'oh! That's so simple! I think that would do - I just liked the idea of a third line of defence - mechanical (switch), plumbical (overflow) and electrical (timeout relay)
I would like to replace the relay which triggers a water pump, with a relay which times out after, say, 10 minutes. And if it times out, it stays locked out until reset.
Needs to be 230v AC on both sides of the relay.
If it doesn't time out, the next time it's triggered it should come on...
Came home to find the kitchen flooding and water pouring through the ceilings between the loft and the kitchen, via the bathroom.
Turns out the float switch, which controls the pump that brings water from the well, had stuck, AND the overflow pipe had the remains of some kind of nest in the end...
Thanks - got a reply by chat: "For this model number the buttons and mechanisms behind come as part of the interface, here is a link to the part -Interface"
It's out of stock and £80 anyway - I'll take you advice and bodge it myself :)