The Myths and Facts about Knob and Tube Wiring
01 Mar, 2020 / Comments: Comments Off on The Myths and Facts about Knob and Tube Wiring / By Corey Haywood
You have come here for information on knob and tube wiring. You have concerns, and they are probably valid. There are specific types of wiring in older houses that are so dangerous they can cause a fire. Yes, knob and tub, also known as K&T, is one you should be concerned with. However, each case is situational, and you should have a local electrician evaluate the wiring in your home.
What Exactly is Knob and Tube Wiring?
In many of the houses built before 1950 used a type of wiring called knob and tube. The name derives from the tubs and knobs used while installing the wiring. The wires are exposed and are meant to dissipate the heat in the open.
The tubes were made out of ceramic and used in areas that went through wood or to protect areas where cross wires or pipes may be present. The knobs are anchored to the wood framing of the house. Knob and tube are easy to identify as you will see the wiring run from the knobs and through the tubes. Both the knobs and tubes are generally white, and the wires are spaced apart.
Why is Knob and Tube Wiring Dangerous?
The first thing to understand is that not all knob and tube wiring is a fire danger or needs to be replaced. There are plenty of cases where it can be safe. A professional electrician should perform a home electrical safety inspection to determine the condition of your wiring. With that being said, here are the reasons why knob and tube can be harmful.
• No Ground Wire
• Insulation is a Fire Hazard
• Stretching and Sagging
• Electrical Add-ons
• No GFCI
No Ground Wire – A ground wire is essential, and all modern-day homes are built with a grounding system. Many older homes lack a grounding system. You can quickly identify if your home is grounded by the type of electrical outlets you have. Homes with a three-prong outlet are grounded. Knob and tube wiring does not have a ground wire, and because of that, it could cause electrical shock or fire. Also, most significant appliances need a three-prong plug to operate correctly.
Insulation & Fire Hazard – Knob and tube are meant to be cooled by the air around it. If your home’s insulation is near the wires, this can cause a severe fire hazard. This is true for both insulations in your walls and the attic.
Stretching or Sagging – The most severe problem with knob and tube wiring is over time it stretches out or sags. This usually isn’t a problem with a vertical run; however, in a horizontal electrical run, it can cause serious issues. When a horizontal wires sag, it can come into contact with your plumbing, framing, and other wiring.
Electrical Add-ons – Over the years, an older home may have needed new outlets or some electrical work done. Often these add-ons were made by handyman, homeowners, or even before the National Electrical Code was established. If someone spliced in a new circuit, there is a chance it wasn’t done correctly. Some specific codes and procedures must be followed to ensure the home stays safe. Lighting fixtures require a new junction box to transition from knob and tube to the new Romex wiring. This isn’t always the case and can lead to serious electrical issues.
No GFCI or AFCI – The electrical outlets with knob and tub in your kitchen and bathrooms aren’t adequately protected against moisture and liquids. This can create a real hazard and cause electrical shock should the outlets or electrical devices become wet.
Fire Hazard Statistics
The statistics below are not specific to knob and tube wiring. These numbers apply to all residential home fires in the United States between 2014 and 2016 and are from the United States Fire Administration, which is a division of the FEMA.
• 12,000 Electrical Fires per Year
• 155 Deaths per Year
• 425 Injuries per Year
• 43% of Residential Electrical Fires were Electrical Malfunction
• 23% of Residential Electrical Fires were from Short-Circuit Arc
• 11% of Residential Electrical Fires were from Worn Insulation
• 32% of Residential Electrical Fires Happen in Winter Months
• 30% of Residential Electrical Fires Start in Wiring
• 12% of Residential Electrical Fires Start in an Outlet
Will Insurance Companies Cover K&T Wiring?
If you are purchasing a home with knob and tube wiring, you will soon learn that it can be challenging to insure. Many of the significant homeowner’s insurance policies will not underwrite a home with this type of wiring. It can be too risky for them to insure homes with 70+ years old wiring that is common to have issues.
Alternatively, you may even find it hard for mortgage companies to approve of the loan if the home has knob and tube wiring. In some cases, an electrical inspection must be performed by a licensed electrician and written documentation provided stating that the house as no immediate issues.
On 2/24/20, we contacted a few insurance companies to find out if they would insure knob and tube wiring. Please note these are their answers at that time, and you should check with the specific insurance company to see if their policies have changed.
“We have received your inquiry about knob and tube wiring, and unfortunately this is not eligible for our home product. However, the risk may be acceptable in our Foremost product as long as the Knob and Tube wiring is not servicing the home (electricity is not flowing through the Knob and Tube wiring). If the wiring has been updated in the house and the Knob and Tube wiring has been disconnected but has not been physically removed, it may be acceptable. If this applies to your home and you would like to explore this option please call our Foremost customer service line at 1-855-679-5886.”
“We work as an agency with a number of underwriters. While most of them do not accept knob and tube wiring, we do have one that will insure knob and tube in some cases. For your convenience please visit our website. Once we have your general information, I’ll be able to help you finalize your online quote.”
Nationwide Insurance Company
“A home’s eligibility for coverage with knob and tube wiring is dependent on underwriting approval. An electrical inspection would be required to determine the condition and functionality of the wiring before a decision could be made. We are unable to generically state through this email if a home with knob and tube wiring could be insured.”
*Poor customer service and couldn’t be bothered to help us via email.
Cost to Rewire a House
The cost of rewiring a home depends on several factors, including the square footage, location, city permit fees, and current electrical panel. In some cases, the electrical service may need upgrading or moving underground. In California, you will find the cost to rewire a home to range from $4,000 to $12,000 on average. You can expect the process to take anywhere from 3-14 days.
Pricing of a rewire depends on much more than just square footage. The second most significant influence on pricing is accessibility. In some older homes, the electricians will need to cut extra access points into the walls to complete the wiring. If the house has an attic or basement, it can be easier for the electricians who will lower the cost.
Electrical Panel Upgrades
Older homes will probably need an upgrade to the electrical panel, also known as the breaker box. Homes built 70 years ago or more needed fewer amps back then. Today’s modern electronics need larger electrical panels to handle modern electronics safely. Many of these older homes have 100 amp electrical panels but should be upgraded to the minimum standard 200 amp panels.
The cost of upgrading your electrical panels can vary from $1,800 to $4,200. Just like the home rewire, the cost will depend on location, accessibility, and city permit fees.