Reno:
OK, I see your point within the scenario you suspect.
Yes, there are causes from improper electrical work/installs, as you indicate may have been the case.
My point is that there is a 'box' that is checked often as the 'cause' being 'electrical'. No details.
Yes, nine lives were lost.
I have seen quite a few 'overcrowded' SFDs, one which had ten (10) 'boarders'!! Luck, it was 'found' and vacated, before the possibility of an issue. (There were NO working smoke detectors).
