One of the oldest inventions in the field of electrical wiring is the knob and tube wiring in Toronto. It was a common type of wiring in buildings in the early 20th century. The system consists of copper conductors running within wall and ceiling cavities. The copper conductors are insulated with tubes made of porcelain. Each tube carries a single conductor for maximum safety. This reduces the chances of short circuiting to almost zero. The wires in the system are twisted together for better mechanical stability and coated with rubber or asphalt cotton cloth. The stability of the wires is further increased by soldering them together after twisting.
The insulated tubes in knob and tube wiring in Toronto are supported along the length using properly insulated knobs. The knobs nail down the tubes without breaking them due to their shock absorbing capability. Most versions of the knob were made using porcelain and covered with a soft piece of cloth for improved shock absorbing properties. There are two basic types of knobs used in knob and tube technology. These are the single and double sided knobs. The single sided knobs have a single cylindrical hole that is used to hold a single conductor at a time. The double sided on the other hand has two cylindrical holes on either side of the nailing hole used to hold a complete circuit with two conducting wires.
The cost of installing knob and tube wiring in Toronto is extremely high as compared to that of the normal interior wiring systems with simple cables. Most countries have banned this type of technology since it is quite uneconomical. However, some few states have allowed their citizens to use the technology under specified provisions. The few instances under which the system can be used are stipulated in the national electrical code. Some of the common areas of application include the agricultural and industrial environments.