My 82 year old house still has lots of knob and tube wiring, which looks to be in excellent shape according to my electrician. He recently upgraded our service to 200 amp (it was still 60)and installed a bunch of new, grounded circuits (the PO were running a washing machine, a dryer etc. mostly on the K+T circuits!) I asked him to give an estimate for replacing it all, and he suggested that not only would it be mostly impossible, but also unnecessary, as long as those circuits are not overloaded. For grounded applications, he's going to install a bunch of new circuits around the house (total bill so far about $3500). Claims that K+T has an undeservedly bad rap, that ours is in excellent shape, and that other types of wiring (first generation sheathed electrical cable and BX, of which we have some also) have been far more truoblesome and dangerous in his experience. However, insurance companies will tell you that houses with K+T are practically doomed to fiery deaths. Who do I believe? I feel like if he can run new circuits all over the house, he should be able to disconnect the K+T and effectively rewire the house, even if the old wire is physically left in place. He claims that he could never get to it all without ripping up some significant amount of plaster.
We'd like to have insulation blown into the walls, but I've heard that it's not wise with functional K+T in place. Who do we believe? Should we talk to another electrican? This one's been great so far, and it's hard to believe that he'd be giving us wrong advice when he could stand to make a serious buck by doing the replacement job.
Sorry for the long post, and thanks for your answers!