Knob and tube wiring was in common use until the 1950s and consists of two wires (black/hot and white/neutral), separated by ceramic knobs and ceramic tubes.

Insurance Issues

Insurers consider knob and tube wiring to be higher risk than other types of electrical installations because there is no third ground wire, and the wires can be exposed through wear and tear over many years of use, thereby creating a potential fire hazard. Also, the accessibilty of knob and tube wiring makes it easy for amateurs to make repairs and/or upgrades. It is not uncommon to see poorly joined connections or exposed wires where amateur work has been done.

Tip

If you are considering purchasing an older home, you should consult your insurance broker to see what kind upgrades may be required before obtaining homeowners insurance coverage. You will be able to factor the upgrades into your offer price and you will avoid any unpleasant surprises later on.