Knob and Tube Wiring

Have you ever wondered, does my home contain knob and tube wiring? and is it safe?

Knob and tube wiring was a method of bringing electricity to homes and businesses in the years between 1880 to 1940, seeing how St. John's, NL is North America's Oldest City you can be guaranteed there are many homes and businesses on the Avalon peninsula that are riddled with it.

The installation consisted of insulated conductors ran through walls, joists, and attic spaces and protected by porcelain "knobs and tubes". They entered boxes or devices they were then wrapped in a material called loom, and splices were done either in a box or free air and twisted together, soldered and eventually wrapped in a cloth asphalt tape.

At the time of installation this was a sophisticated method and regarded as a luxury, but with new wiring available it has become outdated and in many cases a fire or electrocution hazard.

The hazards associated with knob and tube wiring are as follows:

- Deteriorating insulation on wiring causing conductors to come in contact with adjacent materials (some combustible).

- Renovations over the years and new wiring spliced into existing wiring causing possible circuit overloading and arcing in bad splices.

- Knob and tube wiring was meant to be ran free-air except where ran through insulators (knobs and tubes), so as insulation in homes' attics and walls became more popular this created a hazardous situation as the conductors cannot disperse heat properly to the surrounding air causing heat build up in the wiring.

- Knob and Tube wiring is based on a 2-wire system meaning there is no ground wire, which is what prevents most electrocutions from occurring.

Many insurance companies may not insure a home or business with knob and tube wiring and require it to be disconnected and new wiring installed.

If you suspect or know of Knob and Tube wiring in your home you should contact a licensed and qualified electrician to do a thorough inspection of your homes wiring to ensure the safety of your family or business.