Before I sold my last house and after much goading from the wife, I thought it would be a good idea to finally install the attic fan that had been sitting in the box in the garage for about a year. [Linked Image]

Got the fan installed in the gable..no prob. However, there was no room to squeeze another wire into the existing chase down through the header/rafter above my panel (I wish I could choke the guy that wired my old house..but that's another story). I borrowed one of those long bits from a residential contractor friend down the street and got busy. Drilled hole. Climbed down to see where hole was. No hole. Hmmm.
Strange. You guessed it...the hole was in the living room. Cracked the drywall good too. I hate when that happens.

Last mistake that I remember (or will admit) at work was ordering a 500ft run of 500MCM CLX armored cable without the neutral. Ouch.