Dec 16, 2021
The truth behind knob and tube electrical
Did you find out your home has knob and tube wiring?
If you are considering buying an older home, it is crucial to understand how to identify knob and tube (K&T) wiring. This outdated type of wiring can pose a serious fire hazard. Still, it can be classified as safe if installed and maintained properly. But is it worth it?
Some consumer reports show that this type of electrical wiring is not a deal breaker for selling their property. According to Toronto Realty Blog, a realtor sold a $1,350,000 house that had knob and tube wiring estimated to cost $15,000 to remove and got a full-priced offer after only two days on the market.
If your current property or future home has K&T wiring, you need to consider the pros and cons. In this blog, you will learn about the current challenges and safety issues with this type of home electrical system and how it can impact your Ontario home insurance.
What is knob and tube wiring?
In the early 1900s and 1940s, knob and tube wiring were less expensive than other methods of electricity in homes. The name comes from the ceramic insulators that support the wires around bends and beams around the house. It is also more common in buildings with 60-amp service.
There may be wires running through porcelain cylinders, or tubes, inserted in holes along wooden floor joists. Porcelain knobs help keep the wires secure and prevent wires from touching. The wires are insulated with a piece of rubberized cloth fabric versus today’s wires insulated with plastic.
The main difference between modern wiring and K&T is that there is no grounding wire, and it can’t power today’s appliances and electronics. Modern wires have black, white, and ground wires enclosed in a single cable, but knob and tube electrical all run separately.
No law in Canada’s building code states that knob and tube are illegal or need to be removed, but it is considered a hazard and can’t be used in new construction.
Is knob and tube wiring safe?
Knob and tube wiring is an obsolete method in today’s buildings. Until the Second World War, homes were built with K&T – keep in mind they did not use the number of electronics and appliances we do now, which is where the danger lies. This increase of electrical load can cause strain on the wires, resulting in a fire hazard.
Other dangers of knob and tube wiring include :
- Wear and tear : The rubberized cloth that wraps around the tube wires becomes brittle, cracks, and falls off. This leaves wires exposed which can lead to water leaks, and the wires are even more exposed to being a shock and fire hazard.
- Ceramic knobs : These knobs and tubes can crack.
- No ground wire : This exists in modern circuits that use copper wiring. Knob and tube only has a hot wire and a neutral wire. This lack of grounding poses a huge risk for appliances and your home.
- Improper connections : Many homeowners believe they can change the wiring on their own, however improper connections and splices can comprise safety. Taping and soldering additions without junction boxes are a huge risk. Many of these modifications are not permitted by the Ontario Electrical Safety Code.
- Fire hazard : Contact between the black and white wires can overheat and cause a fire.
- Insulation : The insulation in attics and walls can lead to the overheating of K&T wires – they were initially designed to remain suspended in the open air.
- Appliances : Modern technology and appliances exceed the original electricity supply. The old wiring simply cannot handle the amount of power we use in the 21st century.
If your home happens to have K&T, you should :
- Get an inspection from a licensed electrician to verify the switches, wires, connections, and fuses.
- Replace all the bad circuits that are damaged, incorrectly modified, or covered with insulation.
- Install a ground fault protection (GFCI) and an arc fault (AFCI) protection to enhance safety.
Even making the above points does not guarantee your home can get insured with knob and tube electrical. Taking the proper precautions to ensure the wiring is correctly installed can make it safer, but updating is recommended.
How does knob and tube wiring work?
Knob and tube wiring is made of copper, one hot and one neutral, that runs through porcelain knobs and tubes. It is covered in insulation, and the knobs hold the wire in place, generally in contact with wooden beams of the house. The tubes are designed to protect the wire from being in contact with wood or drywall and fraying.
What is the cost to replace knob and tube wiring?
Replacing knob and tube wiring can cost between $5,000 to upwards of $10,000. The cost depends on how big your home is, how much of the wiring exists, and assuming there are no major issues found during the renovation. Most of the work involves removing or replacing drywall and ceilings, pulling out the old wiring, and installing the new receptacles and wiring. All work needs to be inspected by a licensed electrical inspector.
How to tell if you have knob and tube wiring
Just because you can’t see it doesn’t mean you don’t have it. Knob and tube electrical are still present in many older homes, and it is quite easy to identity. You can usually find it in your basement or attic. It is identified by white ceramic, spool-like tubes and knobs. You can make holes in walls or send a tiny camera inside to take a look.
Can I get insurance with knob and tube wiring?
Did you know that if your home is over 30 years old, your insurer may require you to upgrade the wiring in your home before providing or renewing your policy?
It can be challenging to get coverage with knob and tube wiring. If they do approve K&T wiring, your costs will be much higher. This type of wiring is the most dangerous and is associated with increased safety hazards.
Depending on your provider, you may be able to get coverage after a licensed electrician inspects it. You may also be able to get coverage from a specialty insurer.
What companies insure knob and tube wiring?
It depends - policies vary, and they may or may not cover knob and tube wiring. Talk with an expert to compare your options for getting coverage if you have knob and tube electrical.
How to maintain knob and tube electrical
If you have knob and tube wiring in your house, here is what you can do to keep your home safe :
- Have the full system inspected by a qualified electrician – only they can confirm it is safe or what needs to be fixed.
- Don’t run an excessive amount of appliances and electronics at once.
- Replace outlets with ground fault circuit interrupter (GFCI) outlets.
- Replace any cracked or brittle wiring.
- Remove from the kitchen, bathrooms, laundry room, or outdoors – these areas are prone to water damage which can lead to a higher risk of electrical damage with the old wiring.
- Remove insulation surrounding wires.
- Consider the cost of replacing K&T wiring to make your home safer.
Knob and tube wiring FAQs
Yes – you should disclose knob and tube wiring to your insurer. If you need to make a home insurance claim and the cause was from the wiring, your claim could be denied.
Since knob and tube wiring does not have ground wiring, it is incompatible with many modern appliances. It increases the risk of electrical shock. The wiring also poses a fire risk if they contact each other or become over insulated.
Knob and tube wiring is legal in Ontario; however, it needs to meet Ontario home insurance requirements and must be inspected by a certified electrician.
Knob and tube wiring stopped being used in homes around the 1950s to 1960s.
Knob and tube wiring can last years, but not as long as copper can. Copper wiring can last up to 100 years and has fewer issues.
Old-fashioned knob and tube electrical is a heated modern-day topic
Although some types of electrical can be safe as long as they are certified and installed properly, it’s important to make sure you have the correct home replacement cost and coverage in case something happens.
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