Does Your Home Have Knob & Tube Wiring?

One of the charms of living in New England is the large number of beautiful older homes here. When renovating or updating these homes however there are a number of age related issues you may run into. One of these is an old type of electrical wiring known as Knob and Tube wiring. With 35 years of experience working in these lovely older homes, Gibbons Electric has extensive knowledge of determining if your home has live Knob and Tube wiring and how best to rewire if you do. This has become a more common issue in recent years as people are taking advantage of incentive programs to install insulation, as Knob and Tube wiring cannot be covered by insulation. Insurance companies are also increasingly refusing to insure homes with this older wiring and requiring it be rewired prior to issuing a policy.


If your home was built prior to 1950 chances are you may have Knob and Tube wiring. Knob and Tube (K&T) wiring was developed in 1880 and used through the 1940’s. It consists of ceramic knobs that support the wire along its length and ceramic tubes that protect the wire where it passes through drill-holes in wall studs and floor joists. Where wires enter a device such as a switch or light fixture they are protected by a flexible cloth or rubber sleeve called a loom. Knob and Tube wiring uses only two wires, a hot and a neutral, with no grounding wire.

Some of the problems and disadvantages associated with Knob and Tube wiring include the following:

• Age & Deterioration

The cloth or rubber sleeve protecting the wire can deteriorate and become brittle due to age and heat. This can cause it to break off leaving the wire exposed causing a fire hazard.

• Ungrounded

Lack of a grounding wire means Knob and Tube wiring cannot be used for modern 3-prong outlets. Grounding conductors reduce the chance of electrical fire and damage to sensitive equipment. With ungrounded 2-prong outlets there is also increased risk of shock, especially near water as in kitchens and bathrooms.

• Unsafe Modifications

Over time most homes have had some renovations. Some of these modifications may have resulted in unsafe splices. It is also possible that newer wiring is connected to hidden Knob and Tube wiring within the walls.

• Building Insulation

Knob and Tube wiring is designed to dissipate heat into the air and cannot be covered by insulation. This would cause heat to build up and create a fire hazard. Many people are choosing to install insulation in the outside walls and attic of their older homes to reduce heating costs, especially where there are rebate programs in place to help defray the costs. It’s a great time to consider new insulation when you can take advantage of these programs. Your insulation contractor will require certification that you do not have any live Knob and Tube wiring in the areas being insulated before proceeding with the work.

• Limited Upgrades

Most existing residential Knob and Tube wiring lacks the capacity for today’s level of power use. At the time it was installed homeowners didn’t have the range of electrical devices we now commonly use. Existing systems have limited capacity for upgrades and additional circuits. Modification attempts made over the years to meet these increasing needs often leave the system vulnerable to overloading.

• Insurance

Most insurance companies are denying coverage of homes with Knob and Tube wiring due to the lack of a ground wire and increased risk of fire. If they do issue a policy the cost will likely be higher. When purchasing a home with active Knob and Tube wiring most insurance companies will require that the wiring be replaced either prior to closing or within 30 to 60 days after. Many are now refusing to renew policies for existing customers unless they have the Knob and Tube wiring replaced.

If you suspect you may have Knob and Tube wiring in your home we recommend having a licensed electrician determine if you do and if it is live. If so it’s best to have it disconnected and to rewire any circuits fed by the old wiring. As this wiring continues to age there will be increased risk of potential problems along with the need for increasing demand to power more and more devices. Where else in your home do you use anything developed in the 1880’s? Gibbons Electric has rewired many homes with Knob and Tube wiring. We’ve developed a consistent method for determining the extent of your existing Knob and Tube wiring and accurately estimating the best rewiring plan and cost.


During a Knob and Tube Survey, a technician from Gibbons Electric will perform a complete evaluation of the electrical service and all related equipment in your home. They will develop a detailed electrical floor plan identifying all existing wiring throughout your home as well as any safety or electrical code issues. Customers receive a report of the findings along with a detailed estimate if Knob and Tube wiring is found and needs to be rewired along with any other work needed. You will also receive a Certificate of Completion letter stating either no Knob and Tube was found or all Knob and Tube has been replaced if you choose to have us rewire. Having a survey done is a great way to protect your investment in your home and your family’s safety. A typical survey takes 1-2 hours for a single family home, 2-3 hours for a two family home and 3-4 hours for a three family home.


Download this valuable homeowners guide regarding knob and tube wiring and you will learn valuable information such as:
• What is knob and tube wiring
• Problems associated with this type of wiring
• Getting a knob and tube survey
Knob & Tube wiring can be a safety hazard in your home – download this guide to learn if you may have knob & tube wiring and what you should know.



Learn more about this type of wiring in your home, the safety issues and other facts that you should know. 


Contact us today to schedule a Knob and Tube survey of your home.


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