Got a tip from a commercial locksmith about resistor placement

An old timer who does bank vaults told me to always wire resistors right at the panel instead of the sensor loop, and after chasing a ground fault on a Panoramic job last Tuesday I think he might have been right but now I have to redo all my terminations, has anyone else had better luck with a different method?

2 comments

2 Comments

troymorgan13d ago

Wait, you mean he told you to put the resistor right at the panel instead of at the sensor? That goes against everything I was ever taught. I've been doing it at the sensor for years because that's how you're supposed to make sure the loop is supervised properly. Man, I can't believe a bank vault guy would say that. Those old school locksmiths usually have their own weird ways that work but this one sounds like it would cause nothing but trouble. I've seen so many service calls where the resistor placement was the issue and the panel was fine. I'm not saying he's wrong, I just can't wrap my head around it. Maybe there's something to it with certain panels or very long wire runs but I'd have to see some real proof before I changed my whole routine. You're braver than me for even trying it.

mitchell.mark12d ago

Actually, I read somewhere that some of the old Honeywell panels from the 90s actually PREFERRED the resistor at the panel because of how they handled the end-of-line supervision. Something about the internal circuit design. And yeah @troymorgan, I get your hesitation because I've been burned by that service call where you find a resistor shoved in the wrong spot too. But for REALLY long wire runs over 500 feet, I've seen guys say the voltage drop messes with the detection if the resistor is out at the sensor. The panel sees a different resistance value then. I tried it once on a warehouse job after a guy at a trade show swore by it and honestly, I didn't have a single false alarm out of that zone in two years. Still feels wrong in my gut though.