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Knob and tube wiring

Knob and tube wiring What is knob and tube wiring?

Knob and tube wiring was installed in houses in North America in the early 1900s to 1940s. This system consists of two wires, one black or hot wire and the other white or neutral to create a circuit. There is no ground wire. These two single wires are held in place with ceramic knobs and tubes. Knobs are used to clamp the wire to the structural member, while tubes are placed in holes in the structural members to prevent the wire from chafing.
These wires are connected by being soldered together and wrapped in electrical tape. After time, this tape either falls off or deteriorates. There are some concerns with this system. The rubber and cloth insulation around the knob and tube wiring breaks down over time creating a potential for shorts.

How knob and tube wiring can be dangerous?

Knob and tube wiring, on its own, is not inherently dangerous. It can become a problem when it is abused. The type of insulation used has a tendency of drying out and falling off the wires, especially in areas for lights, switches and receptacles.

Here are some explanations associated with the dangers of knob and tube wiring and how we as a company we address the situation:

  • Many homeowners we’ve met use wrong size fuses by replacing a 15 amp with a 20 or 30 amp fuses. Overloading the circuit is commonly seen on older outdated fuse panel. It can cause fires. This is why strongly we recommend our customers to replace the fuse panel to new circuit breaker panel to eliminate potentially dangerous situation.
  • Some customers we’ve worked with were using extension cords as a permanent alternative to adding receptacles. When we come across this we automatically add receptacles where is needed. Even though, we are only required to replace and rewire what is existing and it will simply pass the ESA inspection, such as a bedroom that only has one receptacle instead of having 3 or 4 receptacles. Yes, we take these extra steps and the reason is quite simple: Get rid of improper extension cords that are in direct violation of the electrical safety code.
  • Improper connections are done by adding receptacles/outlets on existing circuits or improperly connecting to the knob and tube wiring circuit. Quite often, we receive calls regarding installing new lights, receptacles or adding new appliances, etc in a house with existing knob and tube wiring. As a company, we DO NOT perform any upgrades until the knob and tube wiring are removed. 
  • Ground pins on power bars or electrical equipment should NOT be removed to accommodate the two pin receptacles used in knob and tube wiring because it’s less safe. Installing a GFI receptacle is a solution acceptable by the ESA. GFI receptacles replacement is just “band-aid” fixes that will not work in some circumstances where the neutral is shared. As a company, we believe that knob and tube wiring needs to be totally cleaned up.

    using extension cordstwo and three pin receptacles

What is the cost of replacing knob and tube wiring?

As each home is unique, it is important to do a careful assessment as to the exact plan of action that is best suit for your specific situation. The cost can range from $3000 to $25000+. In most cases, this job may take a few days, one week or more depending on the size of the home and complexity of the task. Some factors to be considered are: 

  • Type of home (bungalow, 2 story house or more).
  • The amount of Knob and tube wiring.
  • Unfinished or finished basement.
  • Access to attic (some homes don’t have attic).
    and the approach taken…..

    There are two ways to replace knob and tube wiring. The fastest, more messy, more damage, and more repairs for a cheaper price or the slower, cleaner, time consuming which means more expensive way.

    Then there is our way…fastest and cleaner and cheaper!! We have our own technique we use when installing potlights in homes with NO damage. We use long bits when drilling through joist to fish wires. With our technique we barely break any holes (rarely done) and if we do, we patch it up for you. 

How do we deal with the insurance companies? 

If you have such wiring, it would be wise to have the system evaluated by a licensed electrical contractor. If necessary, it should be upgraded to modern wire. Some insurance companies require periodic evaluation and most of them are reluctant to renew policies to homes with knob and tube wiring due to the risk of fire. Home's buyers with knob and tube wiring may find it difficult if not impossible to get insurance coverage.

When the job is complete, we will write a letter for the insurance to confirm that all the knob and tube wiring removal was completed and replaced with new copper wiring. It will be signed by the master electrician and attached with the ESA certificate of inspection.


Rewiring your home is an investment which adds substantial value to your home. It is the only solution that correctly addresses unsafe knob and tube wiring. We provide all electrical services for residential, including knob and tube removal. Our electricians are knob and tube removal experts. For more information call us at 637-344-3320 or email at:

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