Only copper conductors can be used for fire alarm systems. You can use conductors of sizes 18 AWG and 16 AWG (installed in a raceway, enclosure, or listed cable) if they do not supply a load that exceeds the ampacities given in 402.5.

Basically, Class E buildings that are over 100 feet high must provide a fire alarm system with characteristics including: An electrically supervised direct wire or radio fire alarm signal system and voice communication system or a combination of the two. Audible and visual annunciation of fire alarm signals.

FR PVC insulation has better fire retardant properties than normal PVC. FRLS PVC insulation provides better fire retardant properties then normal PVC & also emits Low Smoke, in case of fire.

Either a 15-amp circuit (wired with 14-gauge wire) or a 20-amp circuit (wired with 12-gauge cable) is acceptable for powering hardwired smoke detectors. Wiring the smoke detectors is fairly straightforward for an experienced DIYer or a professional electrician.

According to the National Fire Protection Association (NFPA) regulations and National Electric Code (NEC) articles, any wiring that exists in non-accessible areas or below seven feet must be installed in metallic conduit.

300V

The 2019 edition of the National Fire Alarm® and Signaling Code NFPA 72 was recently approved. The approved code contains revisions to sections relating to use of metallic cable wiring methods. AFC Cable offers Dual Rated Type MC/FPLP Fire Alarm® Control Cables to meet various fire alarm wiring needs.

Class A Loop wiring uses both a primary wire path, and a redundant secondary wire path. When a wire breaks, by using both paths, devices are still able to communicate with the fire panel.

It’s acceptable to leave wire in the walls. The only thing you need to do is leave the ends exposed in boxes and wire nut and tape the to legs together. That will indicate to an electrician what’s going on, and if someone does try to tie into them in the future it will just pop the breaker.