The summer of 2010, I installed a new AC/heat pump system in the place we were living. The system came with a set of emergency heat coils for those times when the weather got really low and the heat pump needed help supplying heat to the home. Well, I didn't wire it up right away because "I'll get to it later". Fast forward to January 2011 and the temperature dropped down to 0* that night. I was working graveyard shift, and when I got home, it was 40 something degrees inside the house, and the family was freezing. I could hear the system running, but no heat was coming in. Then I remembered the wiring job I didn't finish, so I went outside and connected that one wire to get the emergency heat strip to come on. Yeah, I was miserable out there doing that, and my poor family was cold all night long.