An Overview of Knob and Tube Wiring

September 1, 2021

knob and tube wiring residential

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Knob and tube wiring was the standard for electrical wiring in homes built between the 1880s and 1940s. The system consists of copper wiring that passes through porcelain-protected tubes throughout holes drilled into support beams. The wiring is supported by porcelain knobs and covered by flexible cloth or rubber insulation. 

Knob and tube wiring has acquired an unfortunate reputation for being somewhat unsafe. However, this criticism doesn’t represent the complete story about the wiring system. In fact, those who installed this type of wiring had to have a great deal of knowledge and expertise, and the system itself was reasonably safe for the electrical needs of the era in which it was popular. 

However, safety issues tend to arise in a wiring system as old as knob and tube wiring, often augmented by improper modifications made over the years by improperly trained homeowners. In addition, this wiring system has no ground wire, making it inappropriate for many of our modern appliances and for areas in which GFCI outlets are required by code.

Code Requirements and Homeowners Insurance

Building codes can vary significantly by state and locality, meaning there is no hard and fast rule about knob and tube wiring. In some locations, this form of electrical wiring may be disallowed entirely, where others may require it to be certified as safe by an electrical inspector. In any case, the presence of knob and tube wiring means that a homeowner (or potential buyer) will need to take a few extra steps. 

Homeowners should also be aware that most insurance companies will refuse to cover a home with knob and tube wiring. In most cases, if you are buying a home with this type of wiring, you will need to agree to replace it within 60 days to obtain your insurance. Insurance companies who do cover homes with this particular wiring will generally charge a higher rate. 

Replacing Knob and Tube Wiring

If you have a home with knob and tube wiring, you should consider replacing it with a better alternative. If you choose not to replace it entirely, you will probably want to rewire or add additional wiring to parts of your home to support three-pronged appliances and reduce the risk of electrical shocks. In general, you will need to ensure that you have GFCI outlets in your kitchen and bathrooms to meet code requirements. If you choose not to replace your wiring, you should at least have it inspected for potential problems to ensure your safety. 

Right Electrical in Raleigh, NC

It is essential to hire an electrician who has the skills and knowledge to perform the job correctly and safely. If you live in or around Raleigh, NC, Right Electrical Services has the trained professionals you need. 

In addition to electrical repair and electric panel upgrades, Right Electrical provides electrical work for remodels, emergency services, security system wiring, home generator installations, and many other services. At Right Electrical Services, all electricians are licensed and insured to ensure your project receives the highest quality workmanship.


This article was a guest post supplied by We thank them for their contribution.

Renee is a freelance copywriter and blogger known for her expertise surrounding topics like marketing, freelancing, mental health, and more. She has written for hundreds of small business websites and is the Marketing Director here at Right Electrical Services, LLC. Renee believes that when a business prioritizes entertaining, engaging, and informational content for their readers, they can expect a loyal following that trusts their company.

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