Introduction
In the early 20th century, as electricity was becoming commonplace in homes across the United States, the wiring methods and materials used often proved inadequate and dangerous. Frayed and deteriorated insulation, overloaded circuits, and improperly installed connections were among the primary causes of electrical fires during this period. A simple change to require more durable wiring insulation and inclusion of safety devices could have prevented many of these fires and saved numerous lives.
Early Electrical Wiring Methods
In the late 1800s and early 1900s, electricity was still a relatively new technology in most homes. The wiring methods and materials available at the time were primitive compared to modern standards.
Knob and Tube Wiring
The most common early wiring system was known as knob and tube wiring. This consisted of individual rubber or cloth-insulated wires running through ceramic knobs mounted to walls and joists. They were often connected by twist-on connectors or wrapped around terminal screws.
While this system worked adequately at first, the insulation tended to dry out and crack over time. Exposed copper conductors could then make contact, arcing and sparking fires. The tubes provided protection where wires passed through walls and studs but did little to prevent damage elsewhere.
Cloth-Covered Wiring
Another early wiring method involved cloth-covered cables with rubber insulation around the individual wires. The cloth jacket helped protect against abrasion damage but still allowed deterioration of the insulating rubber underneath over decades of use.
With both knob-and-tube and cloth-covered wiring, copper conductors were typically small gauge by modern standards. This increased resistance and heating, contributing to fire risk.
Dangers of Early Wiring Systems
These early 20th century wiring systems posed numerous fire hazards that could have been reduced through simple improvements.
Deteriorating Insulation
The biggest issue was the tendency for the rubber and cloth insulation to deteriorate over many years of use. As cracks and dried out spots developed, bare copper wires could make contact, causing shorts and sparking arcs. This ignited surrounding combustible materials.
Overloaded Circuits
Homes originally wired for lighting loads only often had excessive loads added from appliances over time. Small gauge conductors overheated easily when circuits were overloaded. This could ignite surrounding wood framing and insulation.
Poor Connections
Twist-on connectors and loosely wrapped terminal screws also contributed to loose connections and overheating. These hot spots readily ignited surrounding materials.
Improvements That Could Have Prevented Fires
Simple upgrades to materials and inclusion of safety devices could have prevented most of these electrical fires.
More Durable Insulation
Requiring more durable insulating materials like modern rubberized thermoset plastics would have prevented the deterioration and cracking that led to shorts and sparking arcs. This insulation remains flexible and robust for decades.
Overcurrent Protection
The inclusion of fuses or circuit breakers to shut off power in overloaded branch circuits would have prevented overheating of conductors. This became standard practice much later.
Reduced Copper Gauge
Increasing conductor size reduces resistance and heating. Larger wire gauges may have prevented overheating of overloaded circuits.
Improved Connections
Using screw-tightened receptacles and junction boxes avoids loose connections associated with early twist-on connectors and wrapped terminals. This reduces heating at connections.
Grounding
Grounding conductors provide a safe path for fault currents and prevent housing materials from becoming energized. Their use could have saved homes and lives.
Conclusion
Many devastating home fires in the early 20th century could have been easily prevented through simple upgrades like more durable wiring insulation and inclusion of safety devices like fuses and circuit breakers. These oversights by the electrical industry led to the loss of many lives and properties over several decades. With modest increases in material requirements and installation methods, much of this damage could have been avoided. It serves as an important lesson as new electrical technologies emerge even today.