Increasingly insurance companies will not insure homes with antiquated fuse boxes and knob & tube wiring. Also some bank loans are declined due to the presence of knob & tube wiring.
Knob & tube wiring is the original wire that was installed when the home was built, it offers no ground wire. Grounding is important for the protection from shocking hazards to both the appliance being used and more importantly the person using the appliance!
Another consideration is the insulation on the knob & tube conductors, it becomes brittle with age and begins to separate from the copper conductors. Also in an old home, junction boxes were not used at some locations, leaving open splices against a combustible material.
Please take a look at the hyperlink below from Bob Villa.
Below are some of the grand old homes we rewired.
Drs. Raymond and Edwina Benza, Squirrel Hill, PA.,
Drs. Joyce & John Warwick, Squirrel Hill, PA.,
Larry Walsh, Oakland, Pa.
Fred Fowler & Linda Falorio, Pittsburgh, PA