What is Knob and Tube wiring?
Knob and Tube wiring was an early standardized method of electrical wiring used from about 1880 to the 1940s. Knob an Tube wiring gets its name from the ceramic knob used to hold wires in place and the ceramic tubes that act as protective casings for wires running through wall studs or floor joists. The system is considered obsolete but many older homes can still have some evidence of knob and tube particularly if the electric has not been updated. The picture above was taken at a house I recently sold in Glen Ridge.
Why is Knob and Tube a concern?
Knob and Tube can be a safety hazard. According to Anderson Electric, the dangers from this system arise from its age, improper modifications, and situations where building insulation envelopes the wires. Insulation around the Knob and Tube wires will cause heat to build up, and this creates a fire hazard. It also has no ground wire and thus cannot service any three-pronged appliances. Wiring must be grounded in order to be used safely in wet locations such as kitchens, bathrooms, laundry rooms and outdoors.
Why is this important in a real estate transaction?
Other than the safety concerns noted above, the other complication of Knob and Tube wiring is the difficulty it can cause in obtaining home owners insurance. Many insurance companies will refuse to insure a house with Knob and Tube wiring. Others will command a higher premium or will insist the wiring be updated within a certain amount of time. Removing Knob and Tube wiring is also costly. According to Angie’s List, the cost is around $8000 to $15,000 to rewire a 1,500 to 3,000 square-foot home. In my experience it, can be even higher. This also does not take into account the repairs needed to fix the damage made to walls to remove the outdated wiring.
If you are planning on selling your home and know you have Knob and Tube, I recommend that you proactively remedy the situation. Don’t wait for the buyers’ inspector to find the issue and potentially lose a qualified buyer. If you are buying a home from this era, make sure you do a home inspection and hire a qualified and licensed home inspector who can look for evidence of Knob and Tube.
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