Introduction
Rewiring a home can be an intimidating task, but it doesn't have to be if you use some tried and true obsolete and forgotten methods. Before the age of Romex and PVC conduits, electricians had to be much more creative in how they ran wiring. Although modern electrical codes restrict the use of some of these outdated techniques, they can still be handy for DIYers looking to avoid opening up walls and ceilings. In this article, I'll walk through some of the fascinating obsolete and forgotten rewiring methods that you can actually still use today if done safely.
Knob and Tube Wiring
Knob and tube wiring was commonly installed in homes in the early 20th century. It consists of individual rubber or cloth insulated wires run through porcelain knobs attached to structural framing. The wires were also threaded through porcelain tubes when passing through open spaces:
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Advantages
- Allows open air ventilation of wires
- Wires are spaced safely apart
Disadvantages
- Rigid and inflexible
- Cannot handle high amperages of modern appliances
- Fire and electrocution risk if insulation degrades
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Although knob and tube doesn't meet modern codes, it can be reused in some cases for low power lighting circuits. Any circuits over 60 amps should be replaced.
Gas Pipe Wiring
From the 1890s to the 1930s, a popular obsolete wiring method was to run electrical wires through existing gas pipes no longer used for gas lighting:
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Advantages
- Uses existing metal conduits through walls
Disadvantages
- Safety hazard if gas leaks into pipes
- Can only handle low voltage lighting circuits
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This thrift method can still be used safely in some cases, but great care must be taken to ensure gas piping is intact with no leaks. Always run new wiring when possible.
Metal Molding Raceways
Metal wire molding was the precursor to modern plastic raceways for surface mounted wiring. It provides an attractive finished look for visible cables. Two main types are:
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Two-piece molding - Has a backing plate and snap on cover
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One-piece molding - Wires lay directly on the metal surface
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Advantages
- Aesthetically pleasing surface wiring
- Easy installation
Disadvantages
- Rigid, so can't make smooth bends
- Prone to corrosion over time
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Reusing old metal molding is an acceptable practice, but watch for corrosion issues around connections.
Cloth-Covered Wiring
Early electrical wiring from the 1880s to 1930s used cloth insulation saturated with rubber or tar:
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Advantages
- More flexible than rubber insulation
Disadvantages
- Prone to deterioration over time
- Fire and shock risks if insulation frays
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While cloth-covered wiring does not meet modern code, it can potentially be reused for small low-voltage circuits if the insulation is intact. Any fraying or cracks warrant full replacement.
Splicing Methods
Rewiring also requires making safe and reliable connections. Obsolete splicing methods include:
- Twist/tape splices - Bare wires twisted together with electrical tape
- Western Union splices - Wires knotted together with solder
- Rat tail splices - Stiff bare copper wires interwoven and soldered
These are inferior to modern splicing due to higher resistances and tendencies to come loose over time. Use wire nuts, crimp connectors, orterminal blocks for any new splices.
Conclusion
While modern electrical codes restrict many early wiring techniques, some can still be reused in certain low-voltage applications. Always prioritize safety and be prepared to fully upgrade any deteriorated or insufficient wiring. With care and common sense, integrating some obsolete and forgotten methods can preserve the heritage of your vintage home. Let me know if you have any other questions!