Checking for DC on the signal line, I get functionally nothing. 20ma DC at most, and even that's something I'm picking up out of noise floor shift rather than direct measurement.

My _thought_ was that if the signal line was somehow floating in whole number volts (for whatever reason) than maybe somehow the right RF noise could kick it over.

The problem with _that_ is that I can now _also_ confirm that non-detecting units go off _exactly as long_ as a detecting device keeps saying it's detecting by putting voltage on the signal line. If that voltage goes away, so do the satellite alarms - and immediately.

And that's not what happens. We have to manually intervene and shut the alarms off ourselves.

(2/n)

#electronics #SmokeDetectors #why

The reason I paid meaningfully more than baseline for this particular set is that they report exactly which detector went off and why. That way, if it were the signal line somehow triggering the alarms, none of them would claim to be the originating unit; they'd all report it came from the signal backbone.

But they don't. There's always a unit claiming to be the active detector and it's always smoke (and there is *never* actually smoke), and none of them shut up until we shut off that unit, which sometimes seems to require removing it from power.

So today's afternoon check was basically just another way of confirming what we already knew, and I guess I've done that now, but...

(3/n)

#electronics #SmokeDetectors #why

All _that_ does is get us right back to where we started, which is, "we have alarm after alarm after alarm of different makes, methods (ionisation, photodetector), and models which just in this house are determined to go off randomly, usually but not always at night, for absolutely no detectable fucking reason, and then pass self-test just fine afterwards."

And no, regular cleaning - even weekly cleaning - does not help. I do _all the things_. None of it stops the problem.

(4/?)

#electronics #SmokeDetectors #why

If you're new to this adventure, I have heard this exact same story from _many other people_ at this point - though nobody I've talked to has said they've literally taken metres to the signal wires to verify that way.

Regardless, I know it is not just us.

What I've been told from others who deal with this is to RMA individual units that trigger randomly one at a time until you end up with a set that doesn't. And I guess that's what I'm gonna do, but

holy shit, team

holy shit

(5/6)

#electronics #SmokeDetectors #why

this is the opposite of fire safety

this is the opposite of how anything like this should ever work, I mean

what if all the RMAs are getting you are a set that won't go off even when they should?

but whelp

guess i'm gonna find out

'cause this sure ain't workin'.

(6/6 fin)

#electronics #SmokeDetectors #why

Well, the good news is that _unlike_ the makers of the previous smoke detectors we've had who refused to honour their warranties, BRK/FirstAlert gave absolutely no pushback on this. They don't even want the original unit mailed back, they told me I could just toss it out.

(Since it's optical, I can recycle it cleanly.)

#SmokeDetectors

@moira .......

does your area have shallow bedrock and your house has a deep basement?

@RueNahcMohr Our house is on glacial till. Insofar as we _have_ bedrock, which we do not, it's far, far below. xD We are on relatively _stable_ fill, however - by our standards it's quite firm.

The house is _very_ underground, _sort of_. It's built into the side of a hill. Three and a half storeys (five levels if you count the halves), and in front the bottom level is even with ground, and in back without the giant retaining wall only the _top_ floor would be above ground. _With_ the giant retaining wall, the second-from-top level is 2/3rds above ground in back.