I have a ton of UPSs and never had any "fire-related" issues. But on the other hand I've also had a lot of UPS that fail, so sometimes it is the UPS itself that causes a problem, even when there is no outage. Also, they tend to run out of energy in the face of an extended outage, so you often need a generator backup that you can switch to. So if power is normally stable where you're at, a UPS probably won't help much anyways.