What is Knob and tube (K&T)?
The main safety feature of any electrical system is the insulation surrounding the wiring. This was present in even the earliest Knob and Tube wiring systems. When someone refers to knob and tube wiring they are really describing an insulation system.
The Knobs were porcelain spaces nailed into the wood used to keep the cloth-covered wires from touching the wood.
The tubes were porcelain cylinders used to line bore holes through the wood. The cloth-covered wire was threaded through the tubes to insulate the wire from the wood.
When doing an inspection we identify knob and tube wiring by the cloth covering the wire and not the literal Knobs and Tubes. We do this because we can not see into the hardware inside the walls. We look for old cloth wires that require the Knob and Tube hardware.
![](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/Here-for-the-Knob-and-Tube-inspection.png?lossy=0&strip=1&webp=1)
Who needs a K and T inspection?
Current home owner: Wire jacket is a safety feature. Inspections work best before failure. We generally advise homes to have yearly safety inspections. Homeowners with GEN3 maintenance plans have this type of inspection included.
New home Purchasers: When buying a new home it is advisable to have an electrical inspection. Home inspectors do not inspect electrical systems. They only report on surface issues and include exemptions in the fine print. Homes built before the 60s are likely to have outdated wiring. And if you think about that it makes sense. That would make the insulating materials 60+ years old. Inspections and replacement should occur before failure.
Selling a Home: When selling a home many homeowners want to take care of as many issues before going on the market. This is a good time to fix the problems. Surprises in the inspection period can be unpleasant. It can cause the sale to fall through.
![](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/Chared-wood.png?lossy=0&strip=1&webp=1)
![](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/Chared-wood.png?lossy=0&strip=1&webp=1)
![](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/Detail-of-Burnt-wires.png?lossy=0&strip=1&webp=1)
![](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/Detail-of-Burnt-wires.png?lossy=0&strip=1&webp=1)
![](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/Burn-in-the-wall.png?lossy=0&strip=1&webp=1)
![](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/Burn-in-the-wall.png?lossy=0&strip=1&webp=1)
Why do you need a Knob and Tube expert?
There are many ways old homes hide K&T. A home’s history can have honestly hidden this old wiring. Handymen and good-intentioned homeowners may of hidden outdated wires in their efforts to improve their homes.
![Three prong outlets were added to wire systems. This was a common practice. It is no longer allowed and can be dangerous. Knob and Tube systems are not grounded.](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/3-prong-putlet.png?lossy=0&strip=1&webp=1)
![Three prong outlets were added to wire systems. This was a common practice. It is no longer allowed and can be dangerous. Knob and Tube systems are not grounded.](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/3-prong-putlet.png?lossy=0&strip=1&webp=1)
An electrician may have needed to extend a wire during a renovation. Extention can hide the presence of knob and tube.
![](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/Wire-exstention.png?lossy=0&strip=1&webp=1)
![](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/Wire-exstention.png?lossy=0&strip=1&webp=1)
Other times contractors apply tricks on purpose to fool home inspectors and their testers. This can be a safety issue for the home and its occupants.
![Bootleg ground is done to fool an electrical tester. This will make it read as a 3-wire system and not a Kbob and Tube system](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/Bootleg-groung-to-hide-old-KT-wiring-1.png?lossy=0&strip=1&webp=1)
![Bootleg ground is done to fool an electrical tester. This will make it read as a 3-wire system and not a Kbob and Tube system](https://b3175653.smushcdn.com/3175653/wp-content/uploads/2023/08/Bootleg-groung-to-hide-old-KT-wiring-1.png?lossy=0&strip=1&webp=1)
Conclusion:
While inspections of knobs and tubes may seem daunting, these are relatively simple projects that can pay for themselves in home value, safety, and efficiency. A professional technician can access the condition of your knob and tube wiring system quickly, often within a matter of hours. With this knowledge, you’ll be able to make an informed decision about repairs or replacements to avoid potential dangers. And existing owners – it’s never too late to get one! So don’t delay-call GEN3 Electric and HVAC today for an old wire inspection before time runs out! Remember, an ounce of prevention goes a long way toward preventing dangerous accidents from happening throughout your home. Happy Home & Living!