How to Rewire Your Home Using Obsolete and Rarely Seen Historical Electrical Methods

Introduction

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:

• A brief history
• How the wiring system works
• The tools and materials needed
• Step-by-step installation instructions
• Safety considerations
• Pros and cons

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:

• Invented in the late 1800s to provide an alternative to risky open-wire systems
• Used cloth or rubber insulation on wires instead of only air insulation
• Wires are separated by air space, reducing risk of shorts
• Knobs keep wires from contacting wood framing
• Tubes protect wires where they pass through framing
• Allowed for first practical interior electrical systems
• Phased out by armored cable and nonmetallic sheathed cables

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:

• No ground wire - relies on metal conduit system
• Wires spliced together with porcelaincaps
• Multiple circuits required separate runs of wire
• Light and outlet boxes have their own knob tubes

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:

• Vintage rubber-insulated wiring with cloth braiding
• Ceramic knobs with nails for attaching to framing
• Tubes and bushings for running wires through holes
• Porcelain wire nuts
• Vintage light and outlet boxes
• Vintage switches and receptacles
• Wire running tools - fish tape, pull cord, pulleys
• Hammer, wire cutters, needle-nose pliers, screwdriver

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:

• Maintain 1 inch spacing between hot and neutral wires
• Keep wires away from plumbing or chimneys
• Only splice in junction boxes, not open air
• Pull wires gently to avoid damage to old insulation

Safety Considerations

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

• Condition of wire insulation - look for cracked rubber or cloth
• Any improper modifications or ungrounded outlets
• Presence of insulation in contact with wires

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

Some other precautions:

• Don't run circuits above their rated amperage
• Don't conceal knob and tube behind new walls
• Use GFCI outlets for added protection
• Combine with circuit breakers or vintage fuses

Pros and Cons of Knob and Tube Wiring

Pros:

• Historically accurate for old homes
• Maintains antique look of switches and outlets
• Wires are very durable if insulation is good

Cons:

• No grounding - GFCI required for outlets
• Difficult to run new circuits in filled walls
• Insulation decreases effectiveness of air gap
• Rubber insulation has finite lifespan

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:

• Invented as an alternative to risky open wiring
• Used stiff copper armor to protect wires
• Allowed a single cable to carry multiple circuits
• Quickly adopted for industrial buildings and homes
• Phased out by nonmetallic sheathed cables in 1950s

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:

• Two rubber-insulated wires wrapped in copper or aluminum
• Wires come pre-bundled in reels for faster installation
• Armor is flexible to bend around corners
• Interior channels separate wiring for multi-circuit runs
• Connects to metal junction boxes and fixtures

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:

• Vintage BX cable reels in various conductor counts
• Antique BX connectors and clamps
• Metal junction and outlet boxes
• Vintage light switches and receptacles
• Armored cable staples
• Hacksaw, crimpers, screwdrivers, fish tape
• Voltmeter, wire cutters, needle-nose pliers

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:

• Be gentle bending cable - don't kink armor
• Make clean cuts to avoid damaging conductors
• Armored cable is sturdy - it can be stepped on

Safety Precautions

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

• Armor continuity from panel to all boxes
• Good connections with clamps and connectors
• No ungrounded receptacles or reverse polarity
• GFCI protection for all outlets

Also watch for:

• Cracked or damaged wire insulation
• Overheating at high current loads
• Any exposed copper conductors

I recommend an electrical inspection to ensure safety.

Pros and Cons of Armored Cable

Pros:

• Allows multi-wire circuits in one cable
• Armor protects against physical damage
• Can directly embed into plaster walls
• Doesn't easily overheat

Cons:

• Not compatible with standard wiring
• Hard to pull through small holes
• Inflexible compared to modern cable
• Old insulation has limited lifespan

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:

• One of the earliest plastic-insulated wiring systems
• Allowed wiring full buildings from a single spool
• Developed as a cheaper, flexible alternative to BX
• Used cloth or cambric insulation rather than rubber
• Later versions had PVC or polyethylene sheaths
• Ushered in the age of plastic insulation

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:

• Individual wires with cloth or plastic insulation
• All wires contained within a fibrous sheath
• Can bundle multiple circuits into one cable
• Sheath protects against damage
• Flexible for pulling through walls and ceilings
• Sheath must be firmly anchored to boxes

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

Tools and Materials

For my kitchen rewire I used:

• Vintage 2-wire and 3-wire Romex
• Early plastic wire nuts and connectors
• Vintage light switches and receptacles
• Electrical tape and cable staples
• Fish tape, hacksaw, needle-nose pliers
• Wire stripper, voltage tester, crimpers

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:

• Carefully pull cables to avoid tearing sheath
• Make clean sheath slits using sharp razor
• Use cable lubricant for difficult pulls

Safety Considerations

To safely use early Romex:

• Inspect insulation for damage or wear
• Ensure sheath makes good contact with boxes
• Use GFCI outlets if ground wire is absent
• Don't overload circuits beyond rating
• Properly anchor cable to prevent strain

Also watch for:

• Poor termination of wires at boxes
• Loose staples allowing cables to sag
• Any exposed copper conductors

Pros and Cons of Early Romex

Pros:

• Easier, faster installation compared to BX
• More flexible than modern NM cables
• Sheath protects against physical damage
• Allows wiring entire buildings quickly

Cons:

• Cloth insulation is less reliable than rubber
• No ground wire in some early versions
• Sheath hardens and cracks over time
• Rat chews are common in old insulation

Conclusion

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.