Glossary · Fire & electrical safety
Knob-and-tube wiring
Also called: knob-and-tube · K&T wiring
An early type of house wiring that runs separate wires on porcelain knobs and through porcelain tubes, with no ground wire; insulation must not cover it.
What it means
It's found in many older homes, often still live in attics and walls. NRCan warns never to let insulation touch old knob-and-tube wiring, because it can pose a fire hazard. Have a licensed electrician assess it before anyone air seals or insulates the attic or walls.
Why it matters in an audit
Finding knob-and-tube changes the order of work: the wiring has to be assessed, and often replaced, before attic or wall insulation can go in.
Typical numbers
Reference values with their sources. Your energy advisor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| NRCan insulation safety rule | Never let insulation contact old knob-and-tube wiring, a chimney or a combustion vent | natural-resources.canada.ca ↗ |