What is Knob and Tube wiring?
Knob and tube wiring was the go-to wiring method for buildings from the 1880s through to the 1940s. Many homes throughout Massachusetts, Connecticut and Rhode Island still have this kind of wiring and are considered out-of-date by today’s electrical code.
Can I Get Insurance?
Getting insurance for a home with knob and tube wiring can be difficult and may cost substantially more. If the wiring is determined to be active most insurance companies will require it to be removed either before or soon after the closing. If the wiring is thought to be inactive the insurance company may require certification of this fact by a licensed electrician.
Reasons Why Insurance Companies Don’t Like Knob and Tube Wiring.
Ground Wire: Knob and tube wiring does not have a third (ground) wire. The old knob and tube outlets are the two slot variety instead of the modern three slot outlets we have today. This can be a hazard especially in areas such as kitchens and baths where there is potential contact with water.
The Ravages of Rodents and Age: The cloth or rubber insulation called the loom surrounding the “hot wire” deteriorates over time. Wire insulation can dry out and crack leaving bare wires which is not uncommon considering the wires may be up to 140 years old in some cases. Also rodents tend to chew on insulation further exposing wires.
Home Insulation: The rule of thumb, if the home has active knob and tube wiring, the home should not be insulated. The National Electrical Code decreed in 1987 that it would not permit insulation contact with active knob and tube wiring. A licensed electrician can certify whether existing knob and tube wiring is active or inactive. The concern is that the wiring which is meant to stay cool by staying exposed can heat up and cause a fire if covered up. In a later blog we will talk more about the steps needed to convert a drafty, older home with knob and tube wiring into something more energy efficient and comfortable.
Amateur Modifications: According to the International Association of Certified Home Inspectors it is not uncommon to find that homeowners and even some electricians have made hazardous modifications to old wiring in an attempt to meet the new voltage demands of today’s modern households.