For most of our owning the house, I believed that except for one tiny corner of the garage, the knob-and-tube wiring had been replaced with some early Romex-like product. Especially based on what the wiring underneath the house looked like. I was wrong.
On Christmas weekend 2012, we started to replace the wiring above the garage, and realized that the whole upstairs lighting circuit was knob-and-tube underneath blow-in insulation. There's a special place in hell for whoever did this...
Anyway, we got 3 of the 10 fixtures rewired on Christmas Eve and Christmas Day, and my hope is that we're starting to get the process down so that we can knock out the remaining ones much faster as we move forward.
