Fire supression systems basically run their own electrical code.
At one of my previous workplaces I learned a bit about our local firecode in relation to electrical code. Mostly that firecode supersedes electrical code. The fire alarm is running of a 230V line (standard) without grounding (non-standard) via a special line from the upstream power transformer that has higher amperage tolerance.
All the fire detectors are powered and wired from this at 40-70V, no ground or if there is a ground, it's grounded at the control panel of the fire alarm system.
In the event of a fire, the entire system is rated about 10X over it's standard ratings. The wires that are allowed to handle 1 Amp before are now allowed to go to 10 Amps, just in case there is a short this might burn it out and allow other equipment to operate.
I've seen some systems that are "optionally fused", they have an internal relais that's held by external power and if the fused lines fail, it automatically switches to unfused power, where the alarm system can evaluate the condition and decide to go back to the fused line if power returns. That's on top of having it's own backup batteries. Some of the more modern systems have watchdogs systems built in so that in case the fire alarm computer is on fire, it won't switch to the unfused line once the computer is no longer operational.
I think you will find that those circuits use isolation transformers and have no path to earth normally -- if you touch active and normal building earth there is no circuit.
At to amperage ratings, don't you just mean that they have a 10x safety factor? Probably using current limiting supplies that can handle a short circuit. Fire circuits (and the feed from the main panel) should use fire rated cabling -- generally mineral insulated copper sheathed cables. Most of the standards (NFPA 75/76) are moving away from being prescriptive to being risk or performance based though, so it is possible they used normal conduit if the overall risk was small.
Incidentally, hospitals also make extensive use of isolation transformers for wet areas (like emergency / ICU), to provide a local point for resetting breakers (electronically), identifying which point is tripping, etc, see IEEE 602-2007. Much better filtering for medical equipment too. You also tend to see positive retention plugs (in the US, green dot UL 817).
The cables have fairly high ratings but in the even of a short circuit, the ratings have a safety margin of about 10x that the cable can last about 6 hours under, above the normal rating under standard conditions (ie, not fire).
At one of my previous workplaces I learned a bit about our local firecode in relation to electrical code. Mostly that firecode supersedes electrical code. The fire alarm is running of a 230V line (standard) without grounding (non-standard) via a special line from the upstream power transformer that has higher amperage tolerance.
All the fire detectors are powered and wired from this at 40-70V, no ground or if there is a ground, it's grounded at the control panel of the fire alarm system.
In the event of a fire, the entire system is rated about 10X over it's standard ratings. The wires that are allowed to handle 1 Amp before are now allowed to go to 10 Amps, just in case there is a short this might burn it out and allow other equipment to operate.
I've seen some systems that are "optionally fused", they have an internal relais that's held by external power and if the fused lines fail, it automatically switches to unfused power, where the alarm system can evaluate the condition and decide to go back to the fused line if power returns. That's on top of having it's own backup batteries. Some of the more modern systems have watchdogs systems built in so that in case the fire alarm computer is on fire, it won't switch to the unfused line once the computer is no longer operational.