Question about a weird false alarm loop that took me 6 hours to figure out

Yesterday I had a job in a townhouse complex near Denver where every single wired zone on a DSC panel kept tripping at random. I swapped the panel, checked grounds, even ran new wire to one zone (which took forever). Turned out the builder had used this really cheap 22/4 cable and the insulation was breaking down inside the walls, causing cross-talk between zones. Has anyone else run into bad cable causing phantom alarms like this?

3 comments

3 Comments

charles_young921mo ago

Holy crap, insulation breaking down inside the wall? That's wild (and honestly scary to think about for future service calls).

thomas_sanchez1mo agoMost Upvoted

I had a call back in 2018 where a homeowner in Phoenix thought they had mice in the walls, but it turned out the old fiberglass insulation had basically turned to dust and was clogging up their AC vents. You gotta watch for this especially in houses from the 70s and 80s where the insulation wasn't always rated for high heat. If you're doing service calls, invest in a good borescope so you can spot the deterioration without cutting into drywall. Also, if you smell something weird or see dust collecting around vents more than usual, that's a red flag worth checking.

amy_west1mo ago

Dude that's like insulation giving you the middle finger from inside the wall. I bet the builder got a bulk deal on that 22/4 cable from the clearance bin at a fire sale. Next time I'll just stick my head in the attic and yell "hello" to see if my zones respond before I start ripping drywall.