Knob and tube wiring was commonly installed in homes built before 1950. While antiquated, this type of electrical wiring still lurks unseen in attics, walls, and ceilings across North America, threatening fire and electrocution. As a homeowner, I must educate myself on the risks of knob and tube wiring and options for upgrading to modern wiring.
What is Knob and Tube Wiring?
Knob and tube wiring consists of individual rubber or cloth-wrapped wires mounted on ceramic knobs and routed through porcelain tubes. Unlike modern wiring with a ground wire, knob and tube wiring has only a hot and neutral wire.
The insulation on old knob and tube wires often deteriorates over time, exposing bare copper wires. This can allow wires to arc, overheat, and ignite flammable materials in walls. Knob and tube circuits lack safety devices like circuit breakers, increasing fire risk.
Dangers and Risks of Knob and Tube Wiring
Knob and tube wiring poses the following risks:
- Fire hazard - Deteriorated insulation can overheat, ignite fires in walls. No circuit breakers to stop overloads.
- Shocks and electrocution - Exposed bare wires increase risk of shocks.
- Insufficient power - Cannot handle demands of modern appliances and electronics.
- Insurance issues - Many insurance companies won't cover houses with knob and tube wiring.
- Resale value - Houses with knob and tube wiring can be difficult to sell.
Fires blamed on faulty electrical wiring cause an estimated 51,000 home fires per year, resulting in 500 deaths and over $1.3 billion in property damage, according to the Electrical Safety Foundation International.
Warning Signs of Knob and Tube Wiring
Watch for the following signs that may indicate the presence of old knob and tube wiring:
- Ceramic knobs and tubes in attic or basement
- Wiring with cloth or rubber insulation
- Two-prong ungrounded outlets
- Blowing fuses from overloaded circuits
- Discolored or warm electrical outlets
- Lights dimming when other devices turned on
If I suspect my home has knob and tube wiring, I should contact a qualified electrician to inspect and evaluate my electrical system.
Options for Replacing Knob and Tube Wiring
Here are my options for replacing knob and tube wiring:
- Full rewire - Safest option is to remove all old wiring and install new wiring and circuit breaker panel. Cost: $8,000-$15,000.
- Targeted replacement - Replace wiring in high-risk areas like kitchens and bathrooms. Cost: $2,000-$5,000.
- Insulation retrofit - Install new wires and leave existing wires untouched. Cost: $1,500-$3,000.
Though expensive, I should strongly consider fully rewiring my home to eliminate fire and shock risks. My family's safety is well worth the investment. I can also check with my utility company for potential rebates to help offset rewiring costs.
Protecting My Family from Knob and Tube Wiring Hazards
Until I can rewire my home, I'll take precautions like:
- Having an electrician install GFCI outlets
- Not overloading circuits
- Examining cords/outlets for heat/discoloration
- Maintaining good housekeeping to avoid igniting fires
Replacing obsolete knob and tube wiring should be a top priority for homeowners seeking safety, peace of mind, and full use of their electrical system. With education and proper upgrades, we can protect our families from tragedies related to outdated wiring.