Is it safe?
Perhaps you might ask: is knob and tube wiring Toronto very safe? If this particular system will remain unaltered, carefully maintained and that all repairs are being made by an electrician who is knowledgeable, this wiring method will still be very safe for use today. However, this is almost not the case. As the system deteriorates and ages, the porcelain knobs and tubes usually break or crack, old wires fray and sag and the sheathing will turn brittle and eventually falls off thereby exposing the live wires. Homeowners will improvise their own repairs as the replacement parts will not be easily available which then results in very dangerous modifications.
The owners of these properties unknowingly create a very perilous situation when household insulation will be installed over the wires. The rubber or cloth sheathing surrounding the wires will not be approved for contact with the insulation as it requires that there should be unrestricted airspace surrounding it in order to dissipate any heat buildup. Add this particular picture to the unsafe modification practices made to sophisticated appliance cords in order to allow them to be compatible with the outdated and old 2 prong receptacles, power bards and extensive use of the extension cords in gleaning more power than the aging electrical system and you will have a potentially serious problem which can be catastrophic.
What you will find in older homes today is a combination of the knob and tube wiring with modern wiring twist in them. If this work has been done by someone who is not familiar with the unique requirements needed by the knob and tube wiring, the potential for disaster is very much present. The tinder dry beams would instantly fuel spark from the dangerous wiring combination old and new wiring systems. In many cases, updating is not really visible in the basement or attic.