What is knob and tube wiring?

Knob and Tube Wiring

Photo by: Laura Scudder

Knob and Tube wiring, also known as K&T, used to be the standard for wiring houses and buildings. Way back in the 1880s, electricians would run single-insulated copper conductors through holes drilled in joists and studs. Knob and Tube wiring installation was eventually abandoned due to high cost of insulation, and fear of possible risks associated with knob and tube.

What good would knob and tube wiring be? New installation of knob and tube wiring is severely limited in the US for specific situations, nowadays, but back in the 1900s, K&T was the least expensive method to supply power to a building.

Dangerous Wiring

K&T had some strange wiring layouts, which included having supply and return lines separated. K&T can be dangerous in some circumstances because of the way neutral fusing was used. This included the use of separate fuses, which meant that if the neutral fuse failed and cut power to a circuit, the hot conductor could remain hot in regards to the ground. Modern electrical codes do not require neutral fuses, eliminating this potentially fatal position.

Knob and Tube wiring also never included safety ground conductors. K&T also cannot be covered by insulation, due to the release of heat by knob and tube wiring systems. Some systems can generate a lot of heat, which can in turn cause fire problems with insulation or even the wood studs the wiring is fed through. Regardless, most modern homebuyers find that K&T systems lack the capacity for power for today’s needs.

No Insurance, No Mortgage

Insurance companies may even deny coverage if your building has knob and tube wiring, or may refuse to write new homeowner policies at all due to the increased risk of hazard.

No insurance = no mortgage! In many cases, a homeowner who is interested in selling their home that has K&T wiring cannot find applicable buyers because a bank will not loan out due to the risk of hazard associated with knob and tube wiring. Even if an electrician clears the building as being up to code, an insurance company can deny even partial coverage for these types of buildings.

If you are looking to purchase a home that you have found has knob and tube, you may want to consider bargaining with the seller for funds to be able to replace the knob and tube system. Sometimes, certain knob and tube installations can also fail an inspection. It is important to let a seller know that if you can’t insure the property, or it won’t pass inspection, you can’t purchase it.

What Can I Do?

What can you do with a knob and tube wired building? The best suggestion would be to remove and replace old knob and tube wiring with safer, updated electrical wiring. You can also partially upgrade the system for usage, although this may or may not be acceptable for insurance policies or financial institutions.

If you have knob and tube wiring and are interested in upgrading, give us a call at Cote Electric LLC today. We can help figure out the cost and best methods for you. (603) 836-4488