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Knob and Tube Wiring

By Jane Leo, PMAR Governmental Affairs Director
February 2012

Buyers of homes with knob and tube electrical wiring may experience difficulty in securing insurance for the home. Recently, some insurance companies have announced they will not issue an insurance binder on a home with knob and tube wiring. What has driven some insurance companies to take a hard line position on this type of an electrical system is the result of internal policy. [At the present time, there is no State of Oregon law or regulation forbidding the use of knob and tube electrical.]

Should the buyer of a home containing knob and tube electrical wiring be unable to insurance the house with one company, the best advice you can give them is to, “Try another.” From my research, not all insurance companies are saying “no.”

Knob and tube was a standardized method of electrical wiring used in construction from the 1880s until the 1930s. It consists of single-insulated copper conductors run within walls or ceiling cavities, through joists and studs via protective porcelain insulated tubes with the wire supported by porcelain knobs. According to the National Electrical Codes, only in a few very specific situations is knob and tube permissible.

Oregon Building Code does require specific practices be met should insulation be added to a home with knob and tube. If insulating the older home is what your clients are thinking about, it’s advisable they seek the services of a certified and bonded contractor familiar with this type of wiring.