Disadvantages of Knob and Tube Wiring
• Insulation companies cannot insulate your home with knob & tube; It runs between between joists with air space to dissipate heat. When insulation, whether blow in insulation or standard pink insulation, surrounds the knob and tube wiring it can overheat and potentially cause a fire hazard.
• Knob and tube wiring was never meant to last more than 100 years. Homeowners sometimes take out the proper 15-amp or 20-amp fuses and install 30-amp fuses because they need more power. Yes, this will prevent the fuse from blowing but it creates a fire hazard. The knob and tube wiring that is now over-fused was not meant to carry such a high current and the wire insulation can begin to break down.
• Some insurance companies will not insure homes with existing knob and tube wiring, so it must be rewired
• Squirrels, mice and other critters seem to love the insulation on this knob and tube wiring style. These pests can can leave bare copper wire exposed.•
• Knob and tube wiring system does not incorporate a ground. The ground wire on any circuit is the most important wire, as it is there for safety. Also, some electronic equipment requires a ground to operate correctly.
• Switched neutrals. Electricians in the early 1900’s would switch the neutral feeding a ceiling light instead of the hot wire, which is today’s standard. Switching the neutral, would turn off the light, but live voltage potential would still be present at the fixture. Making a dangerous situation for a homeowner that is trying to change the light fixture.
• Insulation becomes very brittle and breaks down when heated too much. Older light fixtures had no insulation in them to prevent overheating. These older light fixtures were usually not marked with a maximum wattage for light bulbs. Homeowners could be installing 100 watt bulbs in fixtures that were never meant to have such a high wattage bulb, the wiring above the ceiling fixture could break down, and sometimes the insulation would disintegrate.
Want More Information?
A digital version of the Knob and Tube Wiring Guide is available for purchase on Amazon; that will take you through the entire knob and tube re-wiring. Click Here
