A look at whether the knob and the tube wiring is safe or not

The knob and tube wiring is one of the old forms of electrical wiring that many new homeowners find issues to use. The use of the knob and the tube wiring started from the late 1800s to 1940’s. The electricians used the porcelain knobs in order to anchor the wires to the studs and the floor joists and the insulated tubes in order to pass the wires through the walls and the other types of obstacles. The main aim of this arrangement was to make sure that the hot wire and the neutral wires are separated from each other. If you want to know more about whether this arrangement of the electrical wires are safe or not, then you have definitely come to the right place. This article will take a look at whether the knob and the tube wiring are safe or not.

Is the knob and tube wiring safe or not?

The knob and the tube wiring doesn’t include the ground wire and this makes it very dangerous for the appliances which require a three prong outlet and it also increase the chances of fire.

This system of wiring dominated in the olden days when there was less use of electricity and power load. In any modern homes now days, one can expect to power up the entertainment system, dishwasher, air conditioners etc. and these increases the power load that the home uses. The real issue with this particular arrangement of wiring stems when people try to retrofit it and does it in the incorrect way. It is common with unsafe K&T wiring and this is why one should first check whether the arrangement is done safely or not.


At the present times, any homeowner generally adds insulation to the house, in order to improve the energy efficiency of the home, and when they are adding insulation, they are mistakenly hiding the knob and wire wiring with the blow in insulation. This creates a fire hazard in the home. When it gets in contact with the insulation which can cause the wire to overheat and catch a serious fire in the house.


The 2008, National electric code strictly prohibits this arrangement of wiring in the hollow wall spaces, ceilings and the attic. This is because these places are insulated by loose and rolled or any other arrangement of the insulating material.


For the modern homes, where insulation is used, one should and must avoid this arrangement of wiring.
One should make sure to get a licensed electrician to check out the wiring arrangements of the home and before insulation to be safe. In case, the house uses this method and arrangement of wiring, one should avoid insulation and make sure to replace this for the modern and safer arrangement for the home, which will definitely have more advantages and is safer. Even though it may be expensive, it is definitely worth for long term and safety comes first. 

There are some more facts that one should remember about the K&T wiring and these are:

The K&T are not considered as illegal and there are no certain requirements to replace them exclusively. There are various safety issues with the K&T wiring and it can also potentially cause fire in the home, when it is worn down or hidden by the layers of insulation. As the modern homes use a huge amount of electricity and there are a variety of electrical devices used, it is best advised to remove this electrical system as it will not be able to handle the huge electricity flow and catch fire easily if it overheats.

There are no electrical grounds provided with this electrical wiring. This is one reason why this electrical system is considered as very dangerous compared to the modern electrical wiring system. The modern electrical wiring systems come with ground wire, which is capable of protecting the user when using the electrical devices; otherwise, there is a good amount of risk of getting an electrical shock, which can be avoided with the use of the ground wire.


The wiring of the old electrical system is more prone to breaking and wearing out. As mentioned, this system of wiring was used before 1950’s and after which safer and better wiring systems were introduced, which can accommodate the extra electricity flow. Other reasons of breaking down are: leakage or the rodents chewing the rubber protection of the wire, which will expose the wire and this, will increase the chance to catch fire.


One should never make any amateur attempt to fix this wiring system as doing so will cause more issues and after fixing it, when using it, there is a greater chance of facing more issues, such as: catching fire. If one is looking to fix this old wiring system, then they should definitely opt for a more experienced and for someone who knows about the old wiring system. Although not mandatory, it is best to get this old electrical wiring system out of the house and replace it with the modern electrical wiring system. As mentioned earlier, it is prohibited recently. It is best to replace the old wiring system when changing the house or when renovating the house, as this will make sure that one is spending less amount of money with the replacement, unlike replacing it after moving into the house, which would require the furniture to be shifted and walls to be exposed, increasing the overall cost.


In case if any one finds out that the ceramic portion is cracked or the wires are hanging in clusters from the attic roof unprotected, then it is definitely the best time to place this old wiring system. If the conductor is hung using a nail, then it is also best to replace this old wiring system, which otherwise can cause disastrous results if it is either not maintained or replaced.