Interconnecting Smoke Alarms, And Capacitive Coupling ?

[Robert11]

Hello:

Have been going around the circle with this, and would sure apprciate any
thoughts, or help.

Moved into a new house, and replaced some really old smoke detectors with 3
new Kidde AC wired-in ones. There is a three conductor (plus gnd wire)
running between them.

When hooked up as individual units, all is fine.

When interconnected via the red wire in the cable, they all just keep going
off.

To the best of my knowledge, there is absolutely nothing else on this line.
When the smoke detectors are not hooked to it, it is truly floating, I
believe.

But, with nothing on it, I measure about 2 to 4 volts AC, which is
apparently
enough to trigger them., when they are hooked to the line in interconnect
mode.

Voltage seems high, but others have told me that it is possible via
capacitive coupling.
True ?

A kidde engr told me that when NOT triggered, the interconnect line has 0
volts on it.
So, how can they ever work ?

Any thoughts on this, and hopefully suggestions on how to interconnect these
units without them always going off would be most appreciated.

Thanks,
Bob

 

[Robert Baer]

Robert11 wrote:

Hello:

Have been going around the circle with this, and would sure apprciate any
thoughts, or help.

Moved into a new house, and replaced some really old smoke detectors with 3
new Kidde AC wired-in ones. There is a three conductor (plus gnd wire)
running between them.

When hooked up as individual units, all is fine.

When interconnected via the red wire in the cable, they all just keep going
off.

To the best of my knowledge, there is absolutely nothing else on this line.
When the smoke detectors are not hooked to it, it is truly floating, I
believe.

But, with nothing on it, I measure about 2 to 4 volts AC, which is
apparently
enough to trigger them., when they are hooked to the line in interconnect
mode.

Voltage seems high, but others have told me that it is possible via
capacitive coupling.
True ?

A kidde engr told me that when NOT triggered, the interconnect line has 0
volts on it.
So, how can they ever work ?

Any thoughts on this, and hopefully suggestions on how to interconnect these
units without them always going off would be most appreciated.

Thanks,
Bob



See if you can, at minimum, get a wiring diagram for multiple units.

Look for a "termination device", as well as daisy chaining of that
red wire.

 

[Fred Bloggs]

Moved into a new house, and replaced some really old smoke detectors with 3
new Kidde AC wired-in ones. There is a three conductor (plus gnd wire)
running between them.

When hooked up as individual units, all is fine.

When interconnected via the red wire in the cable, they all just keep going
off.

To the best of my knowledge, there is absolutely nothing else on this line.
When the smoke detectors are not hooked to it, it is truly floating, I
believe.

But, with nothing on it, I measure about 2 to 4 volts AC, which is
apparently
enough to trigger them., when they are hooked to the line in interconnect
mode.

Voltage seems high, but others have told me that it is possible via
capacitive coupling.
True ?

A kidde engr told me that when NOT triggered, the interconnect line has 0
volts on it.
So, how can they ever work ?

Any thoughts on this, and hopefully suggestions on how to interconnect these
units without them always going off would be most appreciated.

Yeah- RTFB!- either you have a gross wiring error, different AC
circuits, or something else on the interconnect line. The
interconnection puts out 9VDC referenced to the incoming neutral line-
steady in smoke detect and pulsed in CO mode- so if your neutrals don't
match it will nusiance trip. http://www.kiddeus.com/bulletin1.rsf. Your
4VAC reading, measured with respect to neutral I assume, suggests that
there is some other load on the line/neutral circuit, remove it.