Cloth Wiring Sheathed Cables

Electrical Cloth Wiring Sheathed Cables

Cloth Wiring Sheathed Cables

The insulating material in this product was Vulcanized rubber covered with cloth fiber, often with an over-wrap of craft paper, all packaged neatly in more paper and cloth, then impregnated with paraffin wax or some sort of bituminous mixture. Can anyone say “light it up”?  Sounds a lot like a candle to me. Some electricians refer to it as “crumble wire” because after the rubber hardens and the cloth dry rots, the insulation falls off leaving the copper wire exposed. I’d say in most cases that happened about three decades ago.

The crumbly stuff burns nicely, too, and unlike modern wire insulation, it “supports combustion.” That means that once it lights up, it keeps burning provided it gets enough air. As an apprentice electrician, I remember the horror of balancing on the top of of a ladder to make up a live light fixture connection to this old stuff. The tiny ensuing spark ignited the “insulation.” I pondered the relative dangers of blowing on the flame to extinguish it: