John...
At a brand new Albertsons grocery store, a trooper was using 4" flat head screws -- very high strength -- to anchor door stops so as to prevent wall damage at the handle height.
He found good purchase, he drilled deep into the bussing of a 200A three phase panel -- taking out two breakers. (Perfect aim)
The damage was mitigated because I always test for bolted shorts before powering up alien work. (stuff I have not installed myself.)
Upon first inspection, I thought that some conducting material had fallen behind the bussing and caused the short. My attempt to shift the bussing -- pulling it forward -- was for naught.
It was at that point I walked to the other side of the wall. BTW, backing that honking screw out really put a strain on my drill motor.
Even to this day I'm puzzled as to his expectation. Was blocking installed all over the job to await his rubber bumper installation?
