As a homeowner, one of my biggest fears is my house catching on fire due to faulty electrical wiring. According to the National Fire Protection Association (NFPA), an estimated average of 44,800 home electrical wiring fires occur each year in the United States, causing 420 deaths, 1,570 injuries and $1.4 billion in property damage. However, looking back at the early history of electrical wiring, there were certain methods and innovations that could potentially have prevented many of these fires from happening if they had continued to be used today. In this article, I will explore some of the obscure early techniques used for home electrical wiring and how they surprisingly may have led to safer wiring than what we commonly use now.

Knob and Tube Wiring

One of the earliest forms of electrical wiring for homes in the late 1800s and early 1900s was known as knob and tube wiring. This consisted of individual electrical wires that were run through the wall cavities. Porcelain knobs spaced about every 3 feet supported the wires, keeping them separated and insulated from touching each other or the framing. Tubes made of porcelain were used to protect wires as they passed through joist and studs.

While knob and tube wiring may seem crude and potentially unsafe by today's standards, it actually had certain advantages:

If maintained properly, knob and tube wiring can theoretically last indefinitely. Although I don't recommend installing new knob and tube wiring nowadays, the fundamental design principles of separation, insulation and ventilation used in it could have prevented many modern wiring fires.

Armored Cable (AC) and Metal Clad Cable (MC)

As electricity demand increased in houses during the 1920s and 1930s, a faster wiring method was needed. This led to the development of armored cable (AC) and metal clad cable (MC). These consist of two or more insulated wires bundled together inside a flexible metal sheath. The most common types used a steel armor wrap and were known commercially as BX (Armored Cable) or MC (Metal Clad) cable.

The metal armor or sheathing of AC and MC cables provided several important safety advantages:

Because of these benefits, AC and MC cables became widely used for wiring lights, outlets and appliances in houses during the 1920s to 1950s era. Their usage began declining in the 1960s and 1970s as some types of AC cable were implicated in fires due to improper installation combined with aluminum wiring. However, if installed correctly, the armored shell design of AC and MC wiring likely could have prevented many electrical fires to this day.

Integrating Modern Safety Principles

While warranting certain improvements for performance, modern nonmetallic sheathed wiring offers less fire protection than obsolete knob and tube and armored cable methods. Plastic insulation and sheathing is more easily damaged by nails and heated by overloaded circuits or external fire. This contributes to the tens of thousands of home electrical fires that still occur each year.

However, some simple principles from old wiring methods could potentially be reintegrated:

By looking back at proven early wiring techniques and combining them with modern safety technology, the risk of electrical fires in homes could be substantially reduced. Knowledge from the past still holds lessons that could lead to a safer future.


While early electrical wiring methods may seem outdated or inferior, they possessed certain advantages that have been lost in modern wiring. Although we can't fully revert back to knob and tube or armored cable wiring, integrating some of the core safety principles from these techniques could potentially prevent many house fires. Simple steps like using insulated conduit, ample wire separation, arc-fault circuit breakers and fire-resistant insulation materials would go a long way. The obscure wiring methods used a hundred years ago still have much to teach us, and by learning from the past we can work towards a future of safer and more fire-resistant home electrical systems.