Fire Alarm Fire
I recently had a fire engineer that came and serviced and tested my fire panel. Whilst he was fiddling around inside the panel, the panel caught fire. I was informed that the battery was faulty and we were lucky we hadn't had a power cut as the battery would have caught fire.
A few weeks later, another company came to instruct the staff with their annual fire prevention lecture, video and extinguishers. This engineer claimed that it was unlikely to have caused a fire. He claimed that it would be more likely to have caught fire because it had been wired incorrectly.
Which is more likely?
I received this enquiry to day any observations.
I presume that we are talking about a SLA battery.
I have never known these to catch fire themselves. Even those that have been overcharging. But anything is possible, I suppose. Was the battery damaged by the flames? Did the battery end up with a hole in it somewhere? (This is what I'd expect to see in something that caught alight internally)
Because you say that the incident happened whilst someone was fiddling about in the panel and that the panel caught fire, I would more likely believe that the battery supply was shorted and caused enough heat to create a fire in the panel wiring or components.
Even a wimpy-sounding 12V 7AH capacity can supply a hefty old current in a short-circuit scenario. Battery circuits are normally fused to prevent such short-circuits but if you short the wrong side of the fuse then expect sparks to fly.
A demonstration of this power would be to drop a spanner across the terminals of a 12V car battery* - the spanner is likely to melt!
* I strongly recommend only trying the above under proper test conditions with all appropriste safety protections and clothing available. Actually, I don't recommend it at all unless you know what you are doing!