reply to post by budski
With asbestos, it has to be consistantly, periodically checked because it deteriorates relatively fast. However, when asbestos was banned for use,
they no longer had to do much checking or replenishing of it.
However, you are right that the buildings were shut down periodically for other maintenance and repair. Not long prior to 9/11, there was a shutdown
complete with shutting down all security cameras. When they have to repair electric, they shut all electric off at the main breakers once they locate
the problem.
It would be nothing to manually cause a failure in even one part of a building, knowing the main breakers have to be shut off to fix that problem.
That means no security cameras and no generators kicking in.
The same goes for the plumbing being shut off at the main water intake valve(s).