Knob and Tube Wiring: The Dangers, Why Home Insurance Won’t Cover It, and Why it Should Be Replaced

If you are buying or selling a home, or if you own an existing home that was built in the 1800’s to 1930’s, there’s a good chance the house is wired with knob and tube wiring. What is knob and tube wiring you ask? If you aren’t sure if your home has this type of wiring, take a look in your basement or attic. If you see wiring with ceramic/porcelain knobs and tubes connecting it, then you have knob and tube wiring. Review the images below for examples of this wiring so you can identify if your home has this in its basement and attic:

It’s important to note the dangers of knob and tube wiring and why most if not all home insurances won’t cover it. When passing inspection to sell a house with knob and tube wiring, no licensed electrician should sign off on this unless it is replaced with Romex wire because of the many dangers it poses. Again, almost all insurances will not cover this, and you will risk the sale of your home if it is not taken care of properly! Here are the reasons:


Dangers of Knob and Tube Wiring


  • Ungrounded

Knob and tube wiring consists of two wires (one hot, one neutral) instead of three, making this type of wiring NOT GROUNDED. This is very dangerous for a home to be ungrounded. Why? Because grounding prevents shock, fire, and many other electrical hazards with home appliances. To learn more about grounding and its importance, please visit our grounding blog.


  • Poorly Insulated

Knob and tube wiring uses a different type of insulation material than today’s wiring (Romex wire), which is known to deteriorate over time and exposes copper wiring. Because of how the wiring is put together, sagging and stretching are common issues that cause dangerous contact between the wires as well.


  • Fire Hazards

  1. Attic and basement insulation that covers this type of wiring causes heat build-up, which can result in fires.
  2. The electrical current passing through knob and tube wiring is too much for it to handle because of the amount of amperage an older home now uses. This type of wiring was good back in the 1800’s and 1900’s when families didn’t use many electrical appliances, but now it’s overloading the knob and tube system, which poses a heat and fire risk.
  3. Improper modifications to knob and tube wiring instead of rewiring the home have also caused fire concerns. While some homeowners have gone with splicing these wires and adding fuses to accommodate for the low amperage volume of the wires and high amount of blown fuses, this only creates overloading circuits which can cause the wires to heat up and catch fire.


Whether you plan on staying in a home with knob and tube wiring, or planning to buy or sell a home with knob and tube wiring, it’s important to know the risks and dangers and why most insurances won’t cover this. It can create headaches when trying to sell your house if you don’t get it rewired and up to code. All licensed electricians now should not “okay” this wiring to pass inspection. Knob and tube wiring is an old method of wiring a home; it’s ungrounded, poorly insulated, and causes many fire hazards. Licensed master electricians have come a long way in making sure houses are now properly wired to support all electrical aspects of your home to keep you and your family safe.