A Brief History of Residential Wiring in the United States

A Brief History of Residential Wiring in the United States

By Orr Lighting and Electric

When you flip a light switch or plug in your coffee maker, you’re relying on a system over a century in the making. The electrical wiring in American homes has evolved dramatically since the late 19th century—driven by advancements in technology, safety standards, and the increasing demand for power. This blog traces the major phases in residential wiring used in the U.S., explaining what was used, when, and why each step forward mattered.

1. Early Beginnings (1880s–1910s): Open-Wire Systems

The earliest home wiring consisted of open-wire systems, where wires were suspended along walls and ceilings using cleats or knobs. These were often bare copper wires with only a minimal cloth or rubber insulation, exposed to physical damage and moisture.

• Common Problems: Fire hazard, shock risk, lack of insulation.

• Typical Installation: Surface-mounted with no code oversight.

• Why It Changed: The fire risk and unsightliness led to rapid obsolescence.

2. Knob and Tube Wiring (1880s–1940s)

Knob and tube (K&T) wiring became the first standardized method in the U.S. It used separately run hot and neutral wires, supported by ceramic knobs and passed through ceramic tubes to protect wires through wood framing. The conductors were insulated with rubber and cloth.

• Pros (at the time): Simple, effective air insulation; better than open wire.

• Cons: No ground wire, insulation deterioration, overloaded by modern standards.

• Current Status: Still found in some old homes, but deemed unsafe and outdated.

3. Armored Cable (1920s–1950s): BX Cable

As demand for safer, more durable wiring increased, BX cable (short for “Bronx cable,” where it originated) was introduced. It featured two or three conductors wrapped in flexible steel armor, offering physical protection.

• Advantages: Better protection, longer lifespan, partial grounding via sheath.

• Drawbacks: Still limited by rubber insulation, difficult to work with in tight spaces.

• Modern Use: Still used in some commercial applications, but mostly replaced in homes.

4. Non-Metallic Sheathed Cable (1950s–Today): Romex

Romex (a brand name for NM cable) changed residential wiring forever. Introduced in the 1950s, it consists of two or more insulated conductors plus a bare ground wire, all bundled in a flexible plastic (PVC) sheath.

• Why It Took Over: Easier and faster to install, cheaper than BX, grounded.

• Modern Versions: Include NM-B cable with heat-resistant insulation (90°C/194°F).

• Today’s Standard: Romex is now the most common wiring in residential work.

5. Aluminum Wiring (1965–1973): A Dangerous Detour

Due to a copper shortage in the 1960s, builders turned to aluminum wiring for branch circuits. While cheaper, aluminum has different physical properties—it expands and contracts more than copper, leading to loose connections, overheating, and fire risk.

• Modern Code: Allows aluminum wiring only under strict conditions and typically only for large appliances or service feeders.

• If You Have It: Professional evaluation and replacement or retrofitting is highly recommended.

6. Today’s Innovations: Smart Wiring and Future-Ready Systems

Modern homes are seeing a surge in low-voltage systems, Cat6 Ethernet, smart home hubs, and dedicated circuits for EV chargers, solar panels, and backup generators. Residential electrical systems now include load centers, surge protection, and energy monitoring integrated into smart panels.

• What’s Next: Expect more demand for high-capacity, modular systems and AI-integrated circuit management in the next decade.

Conclusion: The Wiring Tells a Story

Your home’s wiring reflects the era it was built in—from open wires nailed to the wall to smart home-ready circuits. If your wiring hasn’t been updated in decades, it’s worth a professional inspection. Outdated systems not only pose safety hazards, but they also can’t keep up with today’s tech-heavy homes.

At Orr Lighting and Electric, we have the expertise to evaluate, upgrade, and future-proof your electrical system with code-compliant, energy-efficient solutions that last.

Thinking about a service upgrade or rewiring?

📞 Contact us today for a consultation—and let’s bring your home up to speed with today’s standards.