Smoke detector to trip RCD

fwor

Kernel_Sanders wrote: »

Could you not have isolated the battery by taking all the fuses out of the box (assuming they were accessible from inside the cabin)?

On some cars, that might be possible, but unfortunately the modern blade-type fuses can be extremely hard to remove with your fingers, because they often press in flush with the face of the fuse box.

And on many (most? all?) recent cars there will be some circuits that are not protected at the fuse box at all. There will probably be a high current fuse or fusible link next to the battery, but this will typically have such a high rating (so that for example the starter motor can run Ok through it) that a small wire within the wiring loom could get red hot without blowing it.

closed

fuses/trips/quickblows/plug fuses are there to stop electrical fires in the first place, same in cars, pulling the fuses would probably have removed power from the dashboard.

adriandilly

Kernel_Sanders wrote: »

Could you not have isolated the battery by taking all the fuses out of the box (assuming they were accessible from inside the cabin)? I'm not claiming I would have thought of this in your situation, even if I had known enough about car electrics to realize that a battery connection could thwart an extinguisher.

I would have popped the bonnet, got a spanner and disconnected the battery myself if I wasn't in a state of shock!

I think to make an electrical fault tripping device, as well as a smoke detector, the device could be programmed to monitor a nominal current and then trip if it sees a steady rise or fall in current (caused by insulation breaking down, conductors heating up or working loose) with a debounce timer to prevent nuisance tripping. The principle is used in industry whereby a thermistor is incorporated into a motor to cause a "Motor Over Temperature" fault and prevent damage

Kernel_Sanders

adriandilly wrote: »

I think to make an electrical fault tripping device, as well as a smoke detector, the device could be programmed to monitor a nominal current and then trip if it sees a steady rise or fall in current (caused by insulation breaking down, conductors heating up or working loose) with a debounce timer to prevent nuisance tripping. The principle is used in industry whereby a thermistor is incorporated into a motor to cause a "Motor Over Temperature" fault and prevent damage

No need for all that expense; I have thought of a fiendishly simple solution to your problem. In fact I can guarantee it would work in my own home, simply by using a couple of items I haven't used for years (I'm a hoarder, see!) But it does rely on your smoke detectors being linked together; is this the case?

adriandilly

Kernel_Sanders wrote: »

No need for all that expense; I have thought of a fiendishly simple solution to your problem. In fact I can guarantee it would work in my own home, simply by using a couple of items I haven't used for years (I'm a hoarder, see!) But it does rely on your smoke detectors being linked together; is this the case?

No. There is one mains powered detector in our place. The Mother-in-Law has connected smoke alarms though

Kernel_Sanders

adriandilly wrote: »

No. There is one mains powered detector in our place. The Mother-in-Law has connected smoke alarms though

What has she been connecting them to?

You state that smoldering is the main risk you want to counter but this may have to travel too far to activate anything before it bursts into flame. If however your main concern is just the dodgy fishtank then my idea would still work even with a single unlinked battery smoke alarm.
Intrigued?

adriandilly

Kernel_Sanders wrote: »

What has she been connecting them to?

You state that smoldering is the main risk you want to counter but this may have to travel too far to activate anything before it bursts into flame. If however your main concern is just the dodgy fishtank then my idea would still work even with a single unlinked battery smoke alarm.
Intrigued?

It seems you have a burning desire to tell me, so fire away

Kernel_Sanders

Hope this isn't just hot air...
I had a new single pole consumer unit fitted in February, and all circuits come under the RCD. I have a large, old (1980s) Creda microwave in GWO, but it now triggers the RCD after a few seconds use, every single time. My much loved oven is now unusable, but you can turn this unfortunate situation to your advantage! I have a noise-sensitive mains plug-in switcher (cost £3.99 from Aldi years ago, I think). All you need do is place this in a sound insulated box to deter triggering from everyday sounds (a trailing socket would be useful), with such an oven plugged into it and turned on (mine has dials). Smoldering from the fishtank will sound the smoke alarm placed just above it, the noise penetrating the insulation and starting the oven. Within 10 seconds, all RCD protected MCBs will be off. My electrician says this is a problem with some old appliances, so IDK if any old m/w oven would work. Same with the CU; mine's a Volex.
With a series of linked alarms, the contraption could be out of the way in the loft. In your case, you'd just have to use the oven as a stand for your fishtank :rotfl:

adriandilly

Fiendishly simple!