Knob & Tube Wiring - Myths, Facts & Home Insurance

Most home purchasers will experience difficulty getting their home insured when Knob & Tube wiring is found to be present. The purpose of this article is to remove some of the myths surrounding this topic & share some facts.

Knob & Tube wiring or Open wiring as it is sometimes referred to, was the electrical system that was used in the first half of the 1900’s. It consist of two wires, live & neutral (no earth). Insulator knobs were used to keep the wires isolated & ceramic tubes used to line holes through wooden joists/studs. Insurance companies deem this older style of wiring to be unsafe & to be a fire hazard, however according to the Electrical Safety Authority, knob & tube wiring can be safe & functional.

It is recommended that a qualified electrician  inspect the wiring to determine its safety. With proper documentation from a certified electrician many insurance companies will insure a home with Knob & Tube. 

• You should be aware that there is no ground wire in a Knob & Tube wiring circuit, which may be an issue for today’s lifestyle, high electricity usage and technology. 
• Knob & Tube Wiring is only rated for 15 Amps, it should be protected by a 15 Amp fuse or circuit breaker. Devices rated for more than 15 Amps cannot be used with Knob & Tube wiring. 
• If three pin devices are to be used on a Knob & tube outlet, then it is recommended that a GFI be installed.
• Also, there are potential fire hazards with the break down of the insulation around the knob and tube wiring that comes with age, and should the black and white wires make contact.

Some home insurance companies will refuse to insure homes with knob and tube wiring. However, there are companies that continue to offer regular priced policies for homes with knob and tube wiring and others who ask a premium for this insurance. If you have any concerns about the safety of your knob and tube wiring, you can hire an electrician to update your home wiring. The average cost per room is approximately $800 to $1000 per room, expect to pay more for a two story home than a bungalow. Also ask if the quote covers all repairs to the walls, floors & ceilings. Keep the receipt to show prospective buyers when it comes time to sell.


If you purchase a home in the Toronto area where knob and tube wiring is still part of the electrical circuit, ask your realtor & your insurance company for advice on securing insurance before the deal firms up. Insurance companies will often ask you to estimate the percentage of knob & tube wiring that exists in the property before making a decision on insuring the property. This will help to mitigate any insurance problems when the closing date approaches.

Homeowners who are planning to modify their knob and tube wiring, or any other electrical wiring, should have the work performed by a licensed electrical contractor or electrician and arrange for an electrical inspection by Electrical Safety Authority.

Myths

• Knob & Tube wiring is unsafe.

• All knob and tube wiring must be disconnected and replaced.

• The Ontario Electrical Safety Code no longer recognizes knob and tube wiring as an acceptable wiring method.

Facts

• Knob & Tube wiring is safe, provided it is properly maintained by competent licensed people as outlined above.

• The Electrical Safety Authority as well as the Ontario Electrical Safety Code recognize and accept knob and tube wiring methods.

• The Ontario Electrical Safety Code 2002 edition contains rules that govern the installation of open type wiring methods (knob & tube). Rules 12-200 to 12-224 set out the minimum safety standards for the installation of open wiring, which may still be installed to this day.