My Wiring 3 Kidde Smokes Together Problem

["Robert11" <rgsrose@xxxxxxxxx>]

Hi,

This relates to the problem I've been having in getting 3 new Kidde PI 2000
smoke dectors to talk to each other.  They replaced 3 very old detectors
which were apparently wired together also. As described in a previous post,
when my new ones were hooked up to
the third wire (red) they all just cycle on and off.

So, I guess there are two main possibilities, as folks have mentioned:

a. that there is perhaps another detector on the line somewhere that I am
not
aware of.  But, I really looked all over, including the attic, and cannot
find any other.
Still, it is just about impossible to trace the wires, and maybe there is
one that was plastered over, or... ?
30 yr old house, so anything is possible.

b.  I disconnected the red wires from each detector to the red interconnect
wire interconnecting the 3 new detectors, and measured the voltage appearing
between the interconnect wire and the white neutral.
Couldn't believe it.  Seems there is about 2 volts AC appearing.

Of all the weird voltages, this is a tough one.

It certainly isn't inductive coupling, but might be "leakage" from
"something"

Was wondering if any one might have any thoughts on this.
What uses 2 V AC ?

Sure has me stumped.  Becoming an intellectual challenge by now.

Haven't looked into this yet, but just had the thought that perhaps the
thermal safety
cutout (that little downward facing wheel coming out of a 4" gang boxy the
furnace) on the power to the gas forced hot air furnace we have, is
connected back to the alarms to indicate if it is ever tripped.
Perhaps leakage thru this if wired in to the detectors ?  Anyone here ever
run across anything like this ?

Is this something, or a wiring scheme, they may have used way-back-when,
or not very likely ?

Thanks,
Bob