Lauterborn Electric receives calls all the time about Knob and Tube wiring. We always recommended replacement.
Dangers of Knob and Tube Wiring
We often see people running newer wire and connecting to the Knob and Tube and faking a ground. This process is called bootlegging. Outlets appear to be grounded with good wiring when tested by home inspectors. This is very dangerous because you are giving people the illusion that they have newer wire in their property.
Example of Bootlegging
The picture shows what we found in an attic recently. The new wire is spliced with the knob and tube and grounds are tied in with the neutral. The home owner bought the house thinking they had no knob and tube but now are trying to process that most of their 2nd and 3rd floor needs to be rewired.
For all your electrical needs contact your Philadelphia Electricians Lauterborn Electric.