Rewiring a home can be an intimidating task. Most electricians today use modern wiring methods that meet current safety codes and standards. However, prior to the late 19th century, electrical wiring was much more rudimentary and experimental. Although obsolete by modern standards, learning about these earlier techniques provides fascinating insights into the history of electrical wiring. While not recommended for actual use, understanding the methods our ancestors used to bring electricity into their homes is an enlightening historical journey.
In this article, I will comprehensively cover various primitive techniques used for home wiring in the late 1800s and early 1900s. We will explore fascinating obsolete and forgotten wiring methods used during the pioneering days of residential electricity.
Knob and Tube Wiring
Knob and tube wiring was commonly used in North American homes from about 1880 to the 1930s. This early wiring system consists of insulated copper conductors run through porcelain knobs attached to structural framing.
Here is how knob and tube wiring works:
- Wires are either single conductor solid or stranded copper with insulation made of rubber, cloth, or asbestos.
- Knobs made of porcelain hold the wires in place and prevent contact with framing. They attach to joists, studs, and rafters.
- Wires are spaced apart from each other and anything flammable by air gaps. This prevents overheating.
- At splices and wall boxes, wires are connected by twisting and soldering.
- Where wires enter wall boxes and fixtures, they pass through porcelain tubes to protect the insulation.
While effective for the time, knob and tube wiring is considered obsolete and hazardous compared to modern systems. It lacks grounding, suffers degradation over time, and has fire risks. However, some homes still have original knob and tube wiring functioning.
Benefits of Knob and Tube Wiring
- Simple, inexpensive parts and installation
- Open air circulation helps prevent overheating
- Porcelain is more durable than modern plastic
Drawbacks of Knob and Tube Wiring
- No grounding - Shock and fire hazard
- Insulation deteriorates over time
- Soldered splices can loosen
- Difficult to modify around new fixtures
Gas Pipe and Tube Wiring
From about 1890 to the 1920s, gas piping was sometimes adapted for electrical wiring, utilizing existing gas lines to pull wire through. This unusual technique is called gas pipe and tube wiring.
Here is how gas pipe and tube wiring works:
- Existing iron gas pipes throughout the home are used.
- The pipes have insulated wires pulled through them.
- Wires enter and exit pipes through openings cut into porcelain tubes.
- At fixtures, wires are spliced to sockets and lamps.
This technique allowed homes already plumbed for gas lighting to add retrofit electrical lighting without new wiring installation. However, gas pipe wiring carries risks of electrocution and fire. Grounded metal gas pipes in close proximity to wiring can become energized.
Benefits of Gas Pipe and Tube Wiring
- Allows retrofitting electricity in gas-piped homes
- Reuses existing iron pipe network
- Provides physical protection for contained wires
Drawbacks of Gas Pipe and Tube Wiring
- Gas pipes may become electrically energized
- Difficult routing around bends and joints
- Inaccessible for maintenance and upgrades
- Metal pipe provides no wire insulation
Armored Cable Wiring
Armored cable consists of insulated wires wrapped in metal armor, providing both conductor protection and electromagnetic shielding. It was used from about 1900 to the 1950s for wiring homes and commercial buildings.
Here is how armored cable wiring works:
- Insulated copper conductors are bundled together
- Conductors are wrapped in metal tape providing armor
- Lead sheath or varnish cambric add further insulation
- Wires route to boxes and fixtures through bushings
Armored cable offered important improvements over knob and tube wiring:
- Metal armor protects against damage
- Improved conductor insulation
However, it still lacked grounding and had fire risks from degradation over time. Armored cable has been replaced by more modern wiring methods, though some legacy installations still exist.
Benefits of Armored Cable
- Metal tape armor protects wires
- Compact, flexible installation
- Varnish cambric insulation resists moisture
Drawbacks of Armored Cable
- No grounding conductor
- Insulation breaks down over decades
- Difficult to modify after initial installation
- Bushings required at openings
Rewiring a home with obsolete historical methods like knob and tube, gas pipe, and armored cable wiring provides a fascinating look into the early days of residential electrification. While these techniques powered homes for decades, they are now considered outdated and hazardous compared to modern wiring. Still, understanding how our ancestors brought the wonder of electricity into their daily lives is an enlightening journey into the past. For actual home wiring projects, always use approved modern wiring methods that meet current electrical codes and safety standards.