Knob and tube wiring – Knob and tube wiring is 2 strand with a neutral wire only and a hot wire. Also uses no ground wire. There is really no protection when a fault occurs. Result from the faults caused by knob and tube wiring can easily make Shocks and fires. Second, for insulation, this is uses sheathing. And they are easily to disintegrate. The problem is increase since buildings that contain this type of wiring are old.
Much better insulation materials that are much safer use at modern knob and tube wiring types. Third, for the older electrical system, the wire is fuse with 15 amps and uses a 60 amp service. So, leading to excessive heat and possible fire. Because that more current is flowing through the wire than it is meant to handle. Extra loads cause the insulation to become brittle.
This is because of the older electrical systems didn’t carry high ampacity loads. So, exposing bare wire and the capacity to overheat which can cause fires. The last, the older systems using 2 prong receptacles. Also using knob and tube wiring. Because increased chance of injury and shock, since no ground wire. Especially around areas where water is prevalent. Kitchens and bathrooms are especially at risk.