I would assume Tom, that the explosives would be replaced periodically and the automatic firing systems tested as part of building maintenance, just as smoke and heat sensors and sprinkler systems are checked and as far as is practicle, tested.
With regard to the explosives going off in a fire (a catastrophic event,) that’s kind of the point. But apart from being very well protected they are placed in low risk areas and the set up is designed so that there would be plenty of time to evacuate before the automatic firing system was triggered. They are placed to ensure the building collapses in its own footprint, just like an expert demolition job on one of these tall buildings.
To be honest I never thought about the topic much until I saw the way the WTC towers came down. Then certain experts who were not on the government payroll (and a few that were,) started to question how the towers hit randomly could collapse as if explosives had been placed by professionals.
If it is true it still proves nothing about culpability of course.