The knob and tube wiring are also known as open wiring or K&T. Homeowners started to use this type of wiring at the end of the 1800s and this trend continued until the 1930s. If your house was built during that period, then you may have this kind of setup.
This is an older form of electrical distribution that consists of two long wires which are wrapped in a rubber insulator. These run along the beams of a house and are wrapped around a tube made of ceramic at the joints in order to prevent chafing.
Most insurance companies will refuse to insure your home if it has a knob and tube electrical system because this old system may be worn out and cause electrical problems.
How Much Does Knob and Tube Wiring Replacement Cost?
The price of knob and tube wiring replacement will be influenced by a series of factors such as the electrician performing this job, the size of the house, the geographical area, the number of floors, and the amount of wiring that has to be replaced. However, the average cost for knob and tube wiring replacement would start at around $550 and go up to more than $1,600 per room.
According to some members of the Zillow forum, you should expect to spend around $5,800 for a 1,200 square foot home, if you want to replace the whole wiring system, resulting in an average cost of $4,8 per square foot.
From an article on the Angie’s List website, we found that you should plan on spending anywhere between $8,500 and $15,500 for a 1,500 to 3,000 square foot home if you want to replace the entire knob and tube wiring system. Also, in the same article, you are recommended to upgrade the service of your home to 100 amps at a minimum. Though, the majority of the electricians recommend 200 amps.
A member of the Reddit forum said that he bought a three-story house with a basement and had to pay around $10,500 for the knob and tube wiring replacement. The house is located in the Chicago area, and this is known to be the most expensive area in the United States. Also, the replacement included a new second breaker on the second floor.
According to a member of the City-data.com forum, the cost for knob and tube wiring replacement at a 3,200 square foot house is around $4,500.
Knob and Tube Wiring Replacement details
The cost estimates that we presented above should include the expenses with the necessary parts to complete the job and the labor costs. Most of the time, a reputable electrician will have you sign a contract before, where it is clearly noted what you will have included with the offer. Usually, these estimates will contain the expenses of disconnecting the old system, running the new wires, installing a new junction box, filling any holes made, updating any electrical components or outlets, and replacing fuses.
You have two options when replacing the knob and tube wiring, according to Speare’s Electric website. You can choose to run the wires in a fast and short way by destroying the ceiling and the walls of the house. This method is known to be the cheapest. In case you choose the second method you will have to look for other ways to fish the wiring through the ceilings and the walls.
No matter which method you choose keep in mind that electricity will be shut off while the electrician will work on this project.
What are the extra costs?
You may need to put up insulation in preparation for any type of work you intend to do with your ceiling and walls, depending on which area of the house you will be working on.
In case the electrician will have to open up the walls and/or the ceiling and the patching will not be included in their price offer, then you will have to plan on spending on patching and painting the walls.
If the house doesn’t have attic access, a crawl space, or has more than one floor, then the costs will increase.
In most cases, you will have to replace the panel as well and this may or may not be included in the initial price offer.
Important things to consider
Depending on how complex the replacement job will be, you may have to tear down the ceilings and the walls in order to have access to the higher floors of the house and install a new electrical system.
In case the distribution panel was never updated at a house that has a knob and wiring, then this old house may have other problems as well, such as burst or/and frozen leas water pipes and untreated asbestos insulation. So, you should consider the cost of fixing these problems as well.
Be aware that when you are replacing the knob and tube wiring with aluminum wiring some problems may appear if it is installed with the wrong electrical outlets and/or light switches.
Analyze the advantages and disadvantages of every type of replacement you can make. Even if the first type of replacement which involves tearing down the walls may cost you less, the expenses of repairing the damaged walls may lead to a higher cost. Talk with the electrician about the complexity of the damage and then decide which option is better for you.
According to Mr. Electric, the knob and tube wiring is dangerous because it is two-stranded which means that there is no ground wire, it uses a sheathing that can wear along time. Also, it uses a two-prong receptacle and this restricts the use of small appliances; plus this doesn’t carry high ampacity loads.
How can I save money?
Make sure you get at least three quotes before deciding which electrician to choose to replace the knob and tube wiring at your house. The majority of the contractors will be more than happy to make a price offer for free.