This greeted me when I opened the busbar chamber in a primary school just before the half term. Had started the periodic on thursday while school was in use, and then returned on the friday (inset day) when just caretaker was in for some shutdown testing.
Apparently head teacher was complaining to the caretaker about the disruption of the PIR (can't possibly fit every school in on half term), so the caretaker saved the burnt lugs I cut out to show her in order to demonstrate the reasons why PIRs are carried out ... when I returned after the half term for a couple of hours to tidy up a few loose ends she no longer had a problem with the the work I was doing ROTFWL