I wouldn't typically use #14 on a shared circuit because I am #12 kind of guy. So for me to use 14-3-G, the circuit would have to be dedicated to really small stuff.
Considering the Xc, the smaller gage may be superior too, especially at 75+'. Have to see what Scott says about that. I don't have any instructions handy.
It's not that I didn't read them ever. I think I oversized to #18 solid for strength from what was required.
The signal is very low voltage and limited DC current. I hope it would be hard to make it illegal. When dealing with small, multi-family dwellings, each unit has its own electric service and pays for the energy used by its own smoke detectors. The signal wire runs through the attic or basement to interconnect all the units.
Yes, I've used a #18 THHN and never gotten any grief over it or even an argument (until now). It is pretty obvious that this small, yellow, standalone wire is not 120 V and is not completing a circuit. I label it "fire alarm interconnect" at appropriate places.
What would you cite me for (besides not reviewing the installation directions within the past year)?
