In an old fire alarm system in an apartment building, with 4 wires to the initiating devices, someone disconnected the last two heat detectors on the farthest zone (disconnected behind a functioning horn in the hall) and installed an end-of-line resistor above a functioning smoke detector in the hall, so the system didn't show a trouble.
It was picked up on an annual inspection when the last two devices weren't on the circuit. The normal annual test probably doesn't include pulling all the devices, so it may have been this way for many years.
I traced the circuit, removed the incorrect end-of-line resistor and reconnected the heat detectors with their existing end-of-line resistor and the circuit was fine.
My assumption is that a different person disconnected the last detectors than the person who installed the extra end-of-line resistor or both things would be in the same box.
What are your thoughts about why someone would do this?
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On a different note, my favourite tool is now a telephone line toner. This system was installed many years ago and most of the conduits and #500 wiremold contained 8 wires (for 2 zones). All the wires were brown and blue. The boxes were too small and the wires were short or pulled through the boxes without a splice. It would have been a lot harder to trace the wires without a toner. I wonder what else a toner can be used for.
