What was knob and tube wiring?

Knob and tube wiring was an early standardized method of electrical wiring used in buildings in the United States from about 1880 to the 1940s. It consisted of single insulated copper conductors run within wall cavities, passing through joist and stud drill-holes via protective porcelain insulating tubes, and supported on nailed-down porcelain knob insulators.

While knob and tube wiring provided useful and safe electrical service for many decades, it lacks many features standard in more modern electrical systems, such as grounded metallic conductor sheathing and multiple circuits. It has largely been replaced due to the cost of servicing and upgrading, and safety concerns. However, some existing older buildings still contain functional knob and tube systems.

What caused the Great Chicago Fire of 1871?

The Great Chicago Fire was a catastrophic blaze that burned from October 8 to October 10, 1871, and destroyed thousands of buildings across Chicago. While the exact cause is still unknown, the main theories are:

Could knob and tube wiring have prevented the fire?

It is extremely unlikely that knob and tube wiring could have prevented or significantly mitigated the damage caused by the Great Chicago Fire. While knob and tube provided an effective early standardized wiring method, it was still vulnerable to fire spread in the following ways:

Overall, while knob and tube wiring provided important early electrical standards, it likely had negligible impact on the initiation and spread of the Great Chicago Fire. The fire was fundamentally fueled by extreme conditions, prevalent wood construction, and an urban layout vulnerable to rapidly spreading flames.