What is Knob and Tube Wiring?
Knob and Tube was a method of electrical wiring, seen in North America from the 1880’s to the 1940s. It consisted of single-insulated copper wire run in wall or ceilings. 2 wires had to be laid for each circuit. It used insulated porcelain tubes to get through joists. Along the wire, porcelain knobs insulators provided support. Where the wire went into a device or into a wall it was protected by LOOM, a flexible cloth insulating sleeving.
At first the insulation was asphalt-filled cotton cloth. Later rubber replaced cotton. Connections were twisted together and soldered. The connection was then protected with rubber insulating tape and friction tape (asphalt saturated cloth). Sometimes metal junction boxes were used. Because it was very labour intensive Knob and Tube was replaced with wires that had 2 insulated wires inside. Safety was NOT the driving factor.
Is Knob and Tube Safe?
The problem is that over the years many things could have happened to the wiring. Any number of squirrels, mice or rats could have chewed or nested around the wiring and insulation. Debris and sagging or rotten walls could have pushed wires together. The insulation most certainly will have deteriorated and become brittle. The constant small expansion and contractions will have worn through it in some spots. More-often unskilled renovators and homeowners could have added to and modified the wiring without the safeguards essential to make Knob and Tube safe.
To make matters worse, the old Knob and Tube, which was adequate for power requirements when it was installed, is simply not up to the task of powering the modern home. We use much more electricity than before. Think Air Conditioners, countless appliances, and power tools. Because Knob and Tube only has 2 wires it cannot be grounded. This also adds another level of potential danger.
Can I get Insurance on Knob and Tube?
Many homeowners were surprised to get notifications informing them they would no longer be insured unless they replaced the Knob and Tube. Notices were alarmingly short. There was not a sudden epidemic of knob and tube fires. Just reduced profit margins.
There is no regulation that prevents Insurance companies from insuring Knob and Tube. They are simply unwilling to do so because of increased risk. Although I have heard of very rare exceptions being made, premiums were always significantly higher, AND coverage reduced. This means that there is no saving in getting insurance on Knob and Tube as opposed to upgrading the wiring.
What can I do?
More commonly, an insurance company will insure a home with Knob and Tube as long as the wire is scheduled to be replaced very quickly. Make sure you know before you close by having a Home inspection done.
Call Ring Electric Inc. at 613-299-8239 for expert advice and free quote on your older wiring.