Knob and Tube Wiring

Knob and Tube Wiring
Image from Wikipedia CC; realtor.com
  If you buy an older home in Delaware, Maryland or Washington, DC, your home inspector will probably find some old wiring. One of the common types of older wiring found is knob and tube wiring. It was commonly installed in homes from 1880 through the 1930s. Knob and tube wiring has white ceramic “knobs” and black “tubes” that cover the copper wiring carrying electricity through a house. While most wiring has been updated in a house by now, some can often be found in hard-to-reach places in a house, like crawl spaces and attics.

Is knob and tube wiring dangerous? Can it cause fires?

Depending on how it was installed, knob & tube wiring can be hazardous. Some insurance companies won’t cover homes with knob-and-tube wiring. K&T wiring lacks a ground wire. This extra wire is used to disperse extra electricity into the ground. The lack of a ground wire is what can cause problems with this type of wiring. If the wire is live and is overloaded there is an increase in the chance of a fire starting. If the knob and tube wiring is not overloaded, it’s can be safe depending on the quality of the wiring. However, there are a lot of variables that can go wrong. Knob and tube wiring should not be covered by insulation or contacting combustible material. It should have open space around it and be inspected for cracked knobs or sagging and frayed wiring. Sometimes, knob-and-tube wiring was tampered with by amateur electricians tapping into the power and this can cause dangerous fire hazards.

Replacing Knob and Tube Wiring

Taking out all the knob and tube wiring in a home can be expensive but is the safest choice. The cost can range from $5,000-$15,000 depending on the amount of wiring. There is no code that mandates its removal but many experts suggest it’s best to remove it from your home. To make the job more affordable, do it in chunks. First clear the knob-and-tube from the rooms that use the most electricity then move on to the less used rooms like the attic. Remove knob-and-tube wiring that is hidden in walls as well. This is a job best handled by an experienced electrician due to the complexity and should not be attempted by an amateur. Contact Bausum and Duckett for more information about knob-and-tube wiring and to get an estimate for removing it today.