Should You Buy a House with Knob and Tube Wiring?

Should You Buy a House with Knob and Tube Wiring?

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Many home buyers ask us if they can buy a house with knob and tube wiring or if they should get it replaced first. It’s important for home buyers to understand that knob and tube wiring itself is not unsafe. In fact, the necessary drilling, soldering, wrapping, and splicing during the original installation required great deal of skill, since the wiring was meant to last. However, home buyers may have a problem getting insurance for a home with knob and tube wiring.

What is Knob and Tube Wiring?

Homes in the U.S. built from around 1880 to the 1940s often still have knob and tube electrical wiring. This is where electrical wires anchored by ceramic insulating knobs pass through tubes placed inside holes drilled in the joists of the house.

Here are pictures of what knob and tube wiring looks like in the home:

Knob and Tube WiringKnob and Tube WiringKnob and Tube Wiring

Some Issues with Knob and Tube Wiring

When you are buying a home with knob and tube wiring, there are a few issues to be aware of.  For instance, insulation cannot touch the wires, as the heat from the wires cannot dissipate. Knob and tube wiring also does not provide a third wire for grounding. Even if two-slot outlets are replaced with three prong outlets (for devices that require them, such as kitchen appliances) there is still no third wire which protects against electric shock. One of the most common issues with knob and tube wiring is with incorrect modifications. Because it is easily accessible, some homeowners make their own repairs and do not splice the wire correctly or they make inadequate, unsafe modifications. Always hire a licensed electrician to make changes or updates to knob and tube wiring.

Knob and tube wiring is no longer used in homes because it doesn’t carry the same capacity for electricity that modern homes require. Modern households tend to use much higher loads of electricity than the wiring was originally designed for (usually 60 amps). Homeowners should not install higher amp fuses to match the increase in electricity use as this will cause the wires to overheat.

Financing a Home with Knob and Tube Wiring

The Department of Housing and Urban Development (HUD) states that home appraisers should examine the electrical box to ensure there are no broken or frayed wires. They don’t usually examine whether the home has knob and tube wiring.

Major selling guides (Fannie Mae, Freddie Mac & FHA) are ok with knob and tube wiring as long as it functions, is safe, in good condition and is a minimum of 60 amps.

Getting Insurance for a Home with Knob and Tube Wiring

Though you may be able to get financing for a home with knob and tube wiring, getting insurance for it can be difficult and the cost will likely be more than double. If the knob and tube wiring is active, most insurance companies will require that it be removed prior to closing or 30 days after closing.

If the system is inactive, an insurance company might agree to write a policy.  The company may either require that the wiring be removed first or in some cases will allow from 30 to 60 days after policy inception to have it professionally removed.  If the home buyers can’t take it out, or are unable to do it within a certain time frame, or if it is active, they can still get insurance through the Massachusetts Property Insurance Underwriting Association (MPIUA).  The MPIUA provides basic property insurance on eligible property for applicants who have been unable to gain insurance through the voluntary market.  Keep in mind rates for MPIUA tend to be higher (between 30-60%) higher than a standard insurance company in Massachusetts.

When buying a home with knob and tube wiring you should have a licensed electrician look the system over to determine the overall condition of the wiring. Any circuits that has been modified, damaged, or covered with insulation should be replaced.



  1. I have knob and tube, the question never came up from my mortgage inspector or from my insurance agent. If I have a fire, will they cover my losses? How do I ask the question without having my insurance cancelled? To rewire the house would be too expensive right now.

    • The problem with knob and tube is two fold.. there is no ground which is how a fault (short) is cleared and the insulation basically falls off after many years. I know how expensive it is to replace, having been a licensed electrician since 78. Do a piece at a time. At the very least make sure that the fuse or circuit breaker is rated for the proper size. As a general rule most general use circuits were of the 15 amp size back in the day. Also many times home owners would install additional devices to the existing knob and tube wiring such as receptacles or switches and would have them improperly connected to the existing wiring because the color marking on the wire had faded due to age which leads to a reverse polarity and a dangerous condition. Not trying to scare just educate.


  2. Hi Walter,

    You’ll have to ask your insurance company about the specifics of your policy.

  3. Hello-
    I am trying to sell my grandmother’s home. The home was built in 1923 and originally had knob and tube wiring. 95% of the knob and tube has been totally replaced with new approved wiring. However, some hard to reach places in the attic and behind two walls in the bedrooms has been deactivated and the receptable rewired using romex and Wiremold. My real estate agent tells me that some banks will not finance a home with knob and tube even if it is deactivated and abandoned in place. My grandmother has lived in this home mortgage free for 75 years and just recently took out a small home equity line of credit and the bank never questioned at all the wiring. Can you give me any feedback on this?I obviously don’t want to go to the expense of ripping down walls and removing deactivated knob and tube if I don’t have to.

    Thank you.

    • Hi Kathy,

      We can’t make recommendations since we are not an insurance company. However, our colleague at Stanton Insurance Agency in Waltham has told us that even if the system is inactive, insurance will be difficult to get. If you are in Massachusetts, you may be able to get insurance through the Massachusetts Property Insurance Underwriting Association (MPIUA).