Originally Posted by markrubin
these use only 2 wires for the AC: the third yellow communications wire that connects to all the other detectors in the house (by code in my town) is not used since the Nest interconnects by WiFI
Yeah, that little tidbit is the reason I'm holding off... I'd really like a couple of these, but no way am I replacing the ~11 detectors in my house with Nest units. And having one go off without the rest defeats the purpose of adding one of the Nest units in my case.
There have been some statements by Nest that a version that could "integrate with security systems" is coming early next year - i'm hoping that means they'll have a model with the interconnect enabled. I assume the current model doesn't support it for code / certification / regulatory reasons - and they dropped the feature to get it out the door.