In my home, I have a hard-wired smoke detector / fire alarm (https://www.lowes.com/pd/First-Alert-Wireless-Interconnect-AC-Hardwired-120-Volt-Photoelectric-Sensor-Smoke-Detector/1000456469) that is linkable to another smoke detector down the line. It is connected with 12-2 or 14-2 but it needs 12-3 or 14-3 normally to link the smoke detector together. I do not have any 12-3 or 14-3 wire on hand and I am wondering if you can use another individual wire to link them together. It is my understanding that the linking wire only sends about 3-9 volts down the wire to the other smoke detector to make it alarm. Could I use a 14 AWG or 16 AWG? Trying to avoid re-wiring the whole thing but if it is the right thing to do I will do it.
Would wire like this work? https://www.lowes.com/pd/Southwire-100-ft-14-AWG-Stranded-Red-Copper-THHN-Wire-By-the-Roll/1000777296