"It's never the right time to see if the backup generators can take the building load. " How about a test outside normal working hours? It is possible, to mea

"It's never the right time to see if the backup generators can take the building load. " How about a test outside normal working hours? It is possible, to meassure the power output before and then plug in enough stuff, that draws roughly the same. But yes, it is more convenient to not do it and continue buisness as usual and hope for the best. My point is, that in most cases, you can test and fix critical stuff and also fix problems created by your fixes, if you make it an important issue and plan accordingly. However, I did not say it is necessarily easy.