Trouble light on ESL 1500

I have a 20-year-old ESL 1500 panel in the basement of my condo unit. A few months ago, the orange trouble light went on for the zone marked “Floor 2”. I called an electrician who recommended it was a good idea to swap out all of the smoke detectors since they were old anyway. He did that and it fixed the problem for a few weeks, but then the same problem happened again. He checked his work and admitted that he’d left the old end-of-line resistor in one of the detectors on the 2nd floor. He replaced it and the trouble light went away for a week, but now it’s back on again.

Any theories on what it might be? Anything I can diagnose on my own? This is starting to turn into a money pit. Do you think it might be weather-related since it’s getting colder/wetter outside?

Thank you in advance!

Your best best is to get a fire tech out to troubleshoot the problem. Some electricians have a decent idea with fire systems if they work around them enough, but their information can be misleading.

There could be numerous reasons for a trouble.

Loose wires, water in a device, bad smoke head (or other device such as pullstations etc), voltage or resistance problems, and the list goes on.

It seems his guess on it being smoke detector related could be off. Troubleshooting needs to be done to find the problem.

Yes smoke heads can go bad, but this problem (if it fixed) ultimately could’ve been a single smoke detector which would’ve saved you money.

It may or may not be related to those detectors at this point.

If you want to do it yourself for starters - put the system on test and remove each smoke head individually - then go back to the panel to see if it cleared the trouble. (Don’t remove all - just one at a time and keep going back to the panel).

While doing that - check the wires are secure, and each device has fully clicked in to place so you know the contacts are touching.

If you have a meter and know how to use it, check the voltage and resistance of each device. There could be a possible break on the wire and it’s shorting out sending a trouble to the panel. This also helps pinpoint where a bad device could be.

Are you sure it’s smokes on that zone? Are there any other devices connected to the floor 2 loop?

My advice - seek out a fire alarm company and have them troubleshoot for you. Not an electrician.

Agreed- I would call the fire alarm company that services your system to find out the problem. Are there heat detectors in units? Most times I get problems like this, someone in their unit has messed with a heat detector or mini horn.