Question:
Aerial Fire Alarm Cable. I have to run a fire alarm cable between two buildings about 15 ft apart. I have to do this aerial because there is no way to do it on the ground or buried. Are there any codes that I might not be aware of that I need to observe in the NEC? I have already spoken with the electrical inspectors and the AHJ.

Answer: -Fire alarms, when installed compliant to NFPA 72 (National Fire Alarm Code) will report failure of any and all circuits on open (resistance too high), short (resisitance too low), ground fault (resistance, when referenced to ground, too low). NEC (NFPA 70) may not address your concerns, but in our industry NFPA 72 does quite well.

-Actually my question was based more on a transient destructively through the alarm sensor. Would control panel detect a failed sensor? Simple way is to expect a 'heartbeat' from each sensor. Sensors in some factories were networked that way. No heartbeat meant no functioning sensor. Less reliable methods (exceesive resistance, short circuit, etc) apparently are acceptable according to your NFPA 72 summary. I thought those simpler methods were no longer acceptable. Unfortunately www.nfpa.org does not answer questions; only lists where to buy the answers - $120. Expensive answer if one only has one question.