Can we talk about how a 25 year vet changed my mind on zone wiring?
I used to be a home run guy all day long. Every sensor got its own wire back to the panel, no exceptions, because that is how I was taught in my first year. Last spring I was doing a 4200 sq ft house in Chandler and the client wanted every window and door covered, which came out to 34 zones. I was standing in the attic sweating through my shirt when the guy I was subbing for, Ray, walked up and asked why I was pulling 34 separate runs. I told him that is just how it is done. He laughed and said "you are going to burn a whole day on wire, watch this," then showed me how he zones rooms together and installs a single 4 conductor to a group of 6 windows with a resistor at the end of line. We still met code, the panel was clean, and I finished the rough in a day and a half early. I have been mixing zones on bigger residential jobs ever since, though I still home run anything on the perimeter doors. What is your cutoff for when you stop running individual zones? Do you zone by room or by wall?
Wait, he put a resistor at the end of line on a group of 6 windows? That part is wild to me (I get why it works, but still, wrapping my head around one resistor covering that many contacts took me a minute). I always thought each device needed its own way to tell the panel it was still alive, but the end of line resistor just watches the whole loop, so if any wire in that run gets cut the zone trips. That is actually really clever for fixed windows that never open. For me the cutoff is somewhere around 20 zones, once I hit that I start grouping by room, and I keep the perimeter doors and anything the client actually uses as their main entry on its own run. By wall makes more sense to me than by room though, since you can fish one run along a wall and pick up everything on that side instead of doubling back.