Knob and Tube Wiring

What is knob-and-tube wiring?
Knob-and-tube wiring, most common among homes built before 1950, is named after it’s ceramic knob support and ceramic tube protection. Knob-and-tube wiring is insulated with rubber, which often breaks down and becomes brittle over time. Additionally, this type of wiring has two wires, instead of the modern three wires which includes a grounding wire.
Should knob-and-tube wiring be replaced?

Knob-and-tube wiring has been deemed dangerous by most insurance companies and electricians alike because it does not have a ground wire. Insurance companies will often require that you remove and replace or deactivate this wiring before they will insure your home, no matter the condition. While it is not impossible, it is very unlikely that you will be able to insure your home with this type of wiring in place.In addition to the lack of insurance options, there are the very real possibilities of short circuits, overheating, shock, and fires.

Knob and Tube WiringBelow are a few of the top reasons knob-and-tube wiring has been deemed dangerous:

  • Ground Wire: Knob-and-tube wiring uses no ground wire and therefore lacks protection from electrical error.
  • Insulation: The rubber insulation used in knob-and-tube breaks down and becomes brittle over time, exposing the home to bare wiring.
  • Wiring: The wiring system is outdated for modern technology. The wiring, meant to withstand only 15 amps of electrical current, are often carrying much more than it can handle. Additionally, these systems use two-prong vessels that restrict use of technology and appliances.

How do I know if I have knob-and-tube wiring?

As previously mentioned, knob-and-tube is very common among homes built before 1950–if your home was built during this time, it is very likely you have it.

Knob and Tube Electrical Wiring You can confirm this by inspecting visible wiring to see if it fits the description of knob-and-tube; this wiring is largely found in the basement and attic. In your attic, you can find the wiring often under insulation; in your basement, it is often found above, under the floorboards of the home. Though the attic and basement are not the only places that knob-and-tube will appear, they are the most easily accessible without a licensed technician.

The most efficient way to find out if your home contains knob-and-tube wiring is to call Brilliant Electric of Redwood City for an inspection. After the inspection, our highly trained electricians will present you with your replacement options, as well as give you a price quote for replacing your wiring with new, safe, and modern circuits and wiring.

How do I replace the knob-and-tube wiring in my home?

We always suggest that this work be done by a licensed, expert electrician; The best time to do this work is while you are remodeling your home, as the walls are readily exposed which will save time and cost less. However it is possible to rewire a home with little damage to the existing wall and ceiling.