On Monday, March 27, 2017 at 8:30:32 PM UTC-4, wrote:
On Mon, 27 Mar 2017 23:58:54 -0000 (UTC), Doug Miller
wrote:

trader_4 wrote in news:9fcff8f8-fe61-4543-9a3a-
:

IDK. But smoke detectors are not necessarily required to be in the
actual bedroom.

No; in fact, they should *not* be in the bedroom unless there is an expected source of ignition
in the bedroom (e.g. an idiot who habitually smokes in bed).

Smoke detectors should always be *outside* the bedrooms: if a fire arises elsewhere in the
house, by the time a detector *inside* the bedroom alerts to the smoke, at best, precious time
has been lost -- and at worst, the sleepers are already dead of smoke inhalation.

That is why they are supposed to be interconnected. If you are really
doing this right, the smoke going off anywhere will set off all of the
bedroom smokes.
Prior to the interconnection rule, the smoke was required to be in the
hall outside the sleeping rooms ... and it still is.
Now you need a smoke in each sleeping room, one outside the sleeping
rooms and at least one on every other floor.

That's what they do with new construction here. Which solves the
problem Doug is talking about, ie whether one inside the bedroom
or one just outside, may miss early detection. Given how many fires
start from smoking in bed, requiring one inside the bedroom seems like
a very good idea to me. And like you say, the interconnection is a
big plus, a fire starting in the basement you'd get alerted long before
smoke reaches a second floor bedroom.

Still, from casual observation of the news, it seems that probably 95%+
of the protection comes from just having a working, unconnected alarm
near or inside a bedroom. All the fatal fires I can recall reading
about, there were either no smoke detectors, broken ones, disconnected
ones, dead batteries, etc. But getting an early warning from interconnected
alarms, multiple alarms, etc can also lessen the fire damage or avoid
an actual fire, by getting to whatever is going on before it's too late.