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Spent 2 days chasing a ground loop on a 16 zone panel in Reno
Had a job in Reno last month where a 16 zone alarm panel kept showing a fault on zone 7. I re ran the wire twice, swapped the contact, and even replaced the resistor. Two full days of testing with a multimeter and the fault would come and go. Turned out the home owner had stapled a network cable right next to my zone wire in the attic, and the interference was tripping the panel. Moved the wire six inches away and the fault went away in 10 seconds. I felt like an idiot for not checking that first. How do you all handle cable separation on retrofits where you can't see the whole run?
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aaronfox1h ago
The network cable being the culprit is a solid find, but I'd push back a little on the interference angle. A staple through a cat5 or cat6 usually doesn't radiate enough to trip a zone on its own, even running parallel. What more likely happened is the staple nicked the jacket and shorted something, or the two cables were sharing a staple and the panel was seeing a ground reference issue through the shield. Zone faults that come and go with a wiggle test are usually a bad splice or a loose terminal somewhere in the run, not RF. I'd still check your zone 7 terminations before you call it closed, because if it was really just interference it'll probably come back the next time the AC kicks on.
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