u/Zebah

We moved into a newly bought home from 1920 and have so far found 2 active circuits of knob and tube. Not sure of the full extent but our knob and tube has some kind of sheathing or lining on it on it. Anyone familiar with this as I thought it had to be open air to cool? Some of it is going through vermiculite in the attic which I’m getting tested as well but hoping it’s early enough to not have abspestos. Nothing is running to the panel itself and seems to have been left in place mostly for light switches to fixtures in addition to limited outlets.