Houses built before the 1950s have knob-and-tube wiring, also known as K&T wiring. They have a simple design with a unique look and highly durable components. However, they don’t have a grounding wire, which poses a risk of shocks and fires. Also, as they age, they become more hazardous. So, it is better to get rid of it and replace the old knob and tube wiring system.
In this blog, you will read about how to replace knob and tube wiring to support modern electronic devices and appliances.
Why to Replace Knob & Tube Wiring?
Safety Concern
Knob&Tube wiring poses serious safety hazards. Modern wiring systems feature grounded conductors and GFCI (Ground Fault Circuit Interrupter) protection, which are not present in K&T systems. Moreover, the insulation around the K&T wires can cause electrical fire and deteriorate with time. Hence, it is advisable to replace K&T wiring with modern options and have a safe home.
Not Suited for Modern Equipment
The knob&tube wiring was designed for an ancient era because of the lower usage of electricity. However, with advancements in technology and the power demands, K&T wiring cannot handle the power load. You may have to rethink when installing new electrical appliances, such as - larger televisions, HVAC, etc.
Cost Efficiency
Finding replacement parts for K&T wiring can be challenging and costly because of its outdated technology. So, switching to a more modern wiring system lowers the cost of maintenance and repairs.
Insurance and Code Compliance
Most insurance companies do not insure homes with old K&T wiring. They also don’t adhere to the requirements of local building codes, making the homes difficult to sell or renovate. Moreover, homes with K&T have a low market or resale value, as prospective buyers are aware of the possible safety risks and the expense of replacing the wires.
Tools and Materials Required
Make sure you are well-equipped with the following tools and supplies -
| Tools | Materials |
|
|
How to Replace Knob and Tube Wiring?
Here’s how to replace knob and tube wiring -
Switch Off the Breaker and Find the Damaged Wire
The knob and tube wiring is a black-colored cable wrapped in white or gray knobs or posts that runs through the same colored tubes. When inspecting the wires, ensure that the breaker is turned off. It is also advised not to touch the wire barehanded. Check for damages such as exposed wiring, cracks along the knob and tubes, wire fraying and disintegration, etc.
Ensure There’s No Insulation Around the K&T Wiring
In addition to checking for damaged wires, it is important to ensure there’s no insulation near the wiring. However, if you do find insulation around the K&T wires, make sure to keep the breaker off until your local electrician arrives. K&T wiring, when surrounded by insulation, is one of the major risks of fire accidents at home. This is because the insulation causes the wire to overheat, which easily catches fire.
Disconnect the Items Connected to K&T Wiring
The devices we use today consume more electricity and require an electrical system that can support these needs. The traditional electrical panels were around 60 amps for knob and tube wiring. On the other hand, modern electrical systems consist of at least 100 amps to support modern devices’ requirements for electricity. The K&T wiring cannot handle the electricity pull required for items such as large appliances and may pose a risk of short or overheating. Thus making the replacement a necessity.
Remove Existing K&T Wiring
It is advisable not to remove the K&T wires on your own if you’re not an experienced electrician. Without proper knowledge, working on the K&T electric wiring system can cause damage to the home and even injury or even death. Hence, restrain yourself from working on electrical systems and hire a professional.
Here’s how you can remove existing knobs and tubes wiring -
Use Voltmeter to Check the Lines
The electrician uses a voltage meter or voltmeter to monitor the lines and verify whether the power has been turned off. The lines are considered dead if the voltmeter does not stay lit or show any signs of being electrified. Moreover, it is advisable not to check the wires by hand or touch them.
Cutting Down Wires
The electrician then cuts the wiring with a wire or bolt cutter. Before proceeding with removing the knob, they may cut on the side of a porcelain knob.
Removal of Knobs
Next, the electrician will remove the knobs using a hammer, prybar or a screwdriver. The type of tool used will be based on how the items are attached to the wood framing. This ensures there’s no breaking or cracking of porcelain.
Pulling Wire Through Tube
The electrician then reaches the tube and pulls the wire through it easily. However, they recommend whether to remove the tubes or leave them in place.
Why Hire a Professional?
Knob and Tube wiring consist of ceramic knobs and copper wiring with rubber cloth insulation. The insulation gets damaged (crack and flake off) due to exposure to the heat, which mostly occurs when there are other lights and fixtures around. It may also cause electrocution. Also, the mechanism of wiring system installation also poses serious risk to homeowners who want to take up the DIY project.
Several K&T wiring have switch plates on neutral wires. This means that even when the circuit breaker is turned off, there may be an active current with enough volts of electricity to cause severe physical harm or even death.
Hence, it is required to call a professional to do the electrical work, as they understand the dangers and take precautions beforehand. Additionally, electric upgrades and installation require permits, which are only offered to a qualified electrician.
Cost for Knob&Tube Replacement
The cost of knob and tube wiring replacement can range between $4,000 to $8,000. The cost may differ depending on the service provider, location, and scale, in addition to the season. The labor cost may also differ, but given the current cost of supplies, $4,000 would hardly cover the materials required for the replacement.
Two major factors that affect the cost are -
-
The accessibility of the circuits.
-
Conditional methods to maintain existing finishes.
Working with a professional electrician will help you understand the cost of replacement. They give you an upfront quotation to make a sound decision. A reputed electrician won’t hesitate to answer cost-related questions. The cost may be somewhat reduced by leaving some of the current knob and tube in place, but the materials and labor time needed for boxing and splicing do add up to the cost.
Conclusion
The decision to change or remove Knob&Tube wiring will not only keep the house safe but also increase the market value of your home. Though many homeowners may think they can replace the K&T wiring, it is recommended to seek help from a professional. This is because modern wiring systems are safer and more secure.
