Homes built from the 1880’s through the 1930’s, and even the early 1940’s used knob and tube wiring. If in good condition, installed properly and no improper changes or connections have been made, then some electricians will say it is still functional and safe.
Over the years the insulation tends to deteriorate, the wires may sag and rodents may have damaged the insulation. Knob and tube systems are ungrounded systems and in general do not met the needs of modern day appliances and home owners requirements. Some building jurisdictions may require removal of knob and tube wiring under various circumstances.
Consult an electrician
Consulting with a qualified electrical contractor about the knob and tube wiring, as well as the condition and installation is wise, for at times there may be existing safety issues. Upgrading the electrical system should be seriously considered.
There are some insurance companies that will not insure homes with Knob and Tube wiring, while other insurance companies are happy to insure these homes. Checking with your insurance carrier or others will quickly identify which carriers are happy to insure your home.
Who to consult? Electrician.
Home buyers should consult an electrician when the home has knob and tube wiring. At times only a portion of the wiring is knob and tube and the rest of the home has up-dated wiring.