The wiring inside your home provides the crucial infrastructure for all your modern appliances and devices to function. However, most homeowners give little thought to the wiring methods used in their houses. Examining wiring techniques from decades past can reveal clever and reliable approaches that could greatly enhance the capabilities and longevity of your home's electrical system.
Knob and Tube Wiring
This early form of electrical wiring was commonly used from about 1880 to the 1930s. It consists of insulated copper conductors run through the framing cavities.
Key Features
- Separate hot and neutral wires - This provides better isolation compared to modern NM cable that wraps hot and neutral together.
- Open air installation - With adequate space between conductors, knob and tube wiring stays cool and is less prone to damage.
- Heavy insulation - The thick rubber/cloth insulation resists breakdown over time.
- Silver-plated copper - This conducts electricity more efficiently than modern copper wire.
Benefits for Modern Homes
- Safety - The separated conductors are less likely to short or spark.
- Reliability - Properly maintained knob and tube can last over 100 years.
- Efficiency - Less resistance means lower energy usage for lighting and appliances.
Armored Cable (BX)
Introduced in the 1880s, BX cable has an overall metal sheath surrounding the internal insulated wires.
Key Attributes
- Flexible metal armor - Typically galvanized steel that resists damage.
- Separate grounds - Provides dedicated grounding path.
- Moisture resistance - Metal sheathing prevents water ingress.
Upgrading with BX
- Durability - Metal encased wiring won't be chewed by pests or damaged by contact.
- Safety - Armored cable prevents arcs, sparks, and electrical fires.
- Reduced EMI - Shielded wires block electromagnetic interference from appliances.
Conduit Wiring
Conduit wiring systems enclose conductors in rigid or flexible metal tubing.
Notable Features
- Interchangeable conductors - Wires can be easily replaced, upgraded, or removed.
- Flexible routes - Conduit can maneuver around obstacles and be re-routed.
- Range of materials - Available in low-cost steel or more durable stainless, aluminum etc.
Contemporary Applications
- Expandability - Conduit offers essentially unlimited capacity for additional circuits.
- Low voltage capabilities - Accommodates latest home automation systems.
- Element protection - Use watertight conduit in moisture prone areas.
Takeaway
While flashes of copper NM cable may look neat and tidy, the hidden electrical works of older homes had several advantages. By thoughtfully incorporating knob and tube wiring, armored cable, metallic conduit, and other past techniques, you can greatly enhance your home's electrical integrity, safety, efficiency, and capacity for generations to come. Talk to a qualified electrician about options for leveraging old and new wiring methods to create an optimally wired home.