Rewiring a home can be a daunting task, but for those with an interest in antique electrical systems, it can also be an exciting opportunity to incorporate obsolete or rarely seen historical wiring methods. As someone who enjoys tinkering with electrical projects, I decided to rewire my 1920s craftsman using some of the authentic techniques from that era.

In this guide, I will walk through the historical rewiring methods I employed room-by-room. My goal is to provide a comprehensive overview of obsolete electrical systems, focusing on knob and tube wiring, armored cable (aka BX wiring), and early prototypes of Romex wiring. For each method, I will cover:

I'll also share some of the challenges I faced along the way as well as tips and tricks I learned. Whether you want to rewire an old house using period-accurate methods or simply learn about antiquated electrical systems, this guide will give you an in-depth look at the lost art of historical home rewiring. Let's get started!

Rewiring the Attic and Walls with Knob and Tube Wiring

A Brief History of Knob and Tube Wiring

Knob and tube (K&T) wiring was commonly used in American homes from about 1880 to the 1930s. It consists of individual rubber-insulated wires either run through ceramic knobs attached to framing or fished through holes in framing members.

Here are some key facts about knob and tube wiring:

How Knob and Tube Wiring Works

The key to knob and tube wiring is that hot and neutral wires are run through the building framing separately, spaced apart by about one inch. The air between them acts as insulation. Wires pass through ceramic knobs attached to the framing or through bored holes.

Some other important features:

This clever air insulation system allowed interior residential wiring well before rubber and plastic insulated cables.

Tools and Materials Needed

Rewiring with knob and tube requires a few specialized tools and materials:

Step-by-Step Installation

Here are the basic steps for installing knob and tube wiring:

  1. Plan the wiring runs - mark knob, hole, and box locations
  2. Install knobs at proper intervals using nails
  3. Run wires through holes using protective tubes
  4. Use pliers to make "J" hooks when wires need to reverse direction
  5. Splice wires together with porcelain caps and tape
  6. Attach wires to light and outlet boxes using tube bushings
  7. Install switches, receptacles, lights, and fixtures
  8. Leave excess knob and tube intact for historical accuracy

Some key tips:

Safety Considerations

While knob and tube can still be safe, it's vital to evaluate:

I advise having an electrician inspect and sign off on any installed knob and tube wiring.

Some other precautions:

Pros and Cons of Knob and Tube Wiring



Rewiring the Basement with Armored Cable

History of Armored Cable

Armored cable, sometimes called BX cable, arrived in the late 1880s as an early version of metal-clad wiring. It consists of two rubber-insulated wires wrapped in a metal armor.

Here's some background on armored cable:

Armored cable was a rugged predecessor to modern NM, MC, and AC cable. The metal armor grounded the system while allowing multiple circuits.

How Armored Cable Works

The armor of BX cable acts as the ground while insulating the internal wires. Key features include:

By using the armor as a ground, separate ground wires were unnecessary. The metal sheathing also protected against physical damage.

Tools and Materials

Installing armored cable requires:

Finding original BX supplies can be challenging but gives an authentic look.

Installation Steps

Here is how I installed armored cable in my basement:

  1. Plan wiring runs from the panel to boxes
  2. Mount metal boxes allowing 6-8 inches of cable
  3. Run BX through holes in framing using fish tape
  4. Secure cable with antique staples every 4-5 feet
  5. Cut cable using hacksaw, leaving 6 inches in boxes
  6. Attach connectors to box knockout holes
  7. Thread cable through connectors into boxes
  8. Attach grounds to boxes using clamps
  9. Splice wires together with ceramic nuts
  10. Install switches, outlets, lights and test circuits

Tips for working with old BX:

Safety Precautions

Because armored cable relies on its metal sheathing for grounding, it's important to verify:

Also watch for:

I recommend an electrical inspection to ensure safety.

Pros and Cons of Armored Cable



Rewiring the Kitchen using an Early Form of Romex Cable

History of Early Nonmetallic Sheathed Cables

The first Romex cables emerged in the 1920s as an alternative to armored cable and knob and tube wiring. They consisted of rubber-insulated wires with a protective fiber wrap, rather than metal.

Key historical facts:

These early Romex prototypes revolutionized wiring by replacing metal and air insulation with plastic.

How Romex Wiring Works

Early Romex contains individiual hot and neutral wires sheathed in a protective fiber wrap. Key features:

The bundled cables and sheathing simplified wiring by eliminating the need for conduits.

Tools and Materials

For my kitchen rewire I used:

Finding original Romex can be difficult. Reproduction cables capture the vintage look.

Installation Steps

Here are the steps I followed to install early Romex:

  1. Plan cable runs from the panel to each box
  2. Drill holes through joists and studs for cable
  3. Use fish tape to pull cables through holes
  4. Staple cable every 1-2 feet for support
  5. Leave 6-8 inches of cable at boxes
  6. Anchor sheath to box using clamps
  7. Remove sheath and trim conductors
  8. Attach grounds if present; splice wires
  9. Secure receptacles and switches
  10. Test operation of all newly wired circuits

Tips for working with vintage Romex:

Safety Considerations

To safely use early Romex:

Also watch for:

Pros and Cons of Early Romex




Rewiring my home using obsolete electrical methods was an enjoyable trip back in time. While challenging at times, the end result is a house wired just like the 1920s with period-authentic switches, outlets, and fixtures.

If you have an old home, I encourage you to consider a vintage rewiring project. Not only will you get safer, modern electrical capacity, but you'll preserve a bit of technological history. Just be sure to do your research, take all proper safety precautions, and consult an expert electrician if needed.

While knob and tube, armored cable, and early Romex lack some of the refinements of modern wiring, these methods established the foundation of practical residential electricity. Understanding where we've come from provides insight into how far electrical systems have progressed. With the right knowledge and care, these antique wiring techniques can be adapted to work safely and reliably, even a century later.