How to Replace Old Knob and Tube Wiring

Introduction

Replacing old knob and tube wiring in your home can seem like a daunting task, but with proper planning and by following safety precautions, it is quite doable as a DIY project. Knob and tube wiring was commonly installed in homes built before the 1940s. While it can still be functional, it presents safety hazards due to lack of grounding, insulation, and capacity for electricity needs in modern homes. Replacing it completely should provide peace of mind and allow for easier upgrades.

Reasons to Replace Knob and Tube Wiring

There are several important reasons why I should replace old knob and tube wiring in my home:

Fire hazard - The old cloth-covered wiring is brittle and prone to cracking over time, increasing fire risks. New wiring has plastic/rubber insulation less prone to deterioration.
Insufficient grounding - Knob and tube systems are 2-wire systems without a ground wire. This can lead to electrical shock risks. Modern wiring is 3-wire grounded.
Lack of capacity - Knob and tube wiring was not designed to handle the electricity needs of modern appliances and devices. Replacing with modern wiring allows for safer electrical capacity.
Difficulty with insurance/resale - Homes with knob and tube may face challenges getting homeowners insurance policies or lower offers during resale due to safety concerns.
Peace of mind - Overall, replacing old wiring provides safety and peace of mind knowing my home's electrical system is updated to modern standards.

Preparing for the Replacement Project

Before beginning the wiring replacement project, I need to make sure I complete certain preparations:

Gather Supplies and Tools Needed

Wiring - Use 12 or 14 gauge NM (nonmetallic) electrical cable with ground. Calculate the amount needed.
Circuit breakers - Match the amperage rating of the wiring; 15A or 20A are common.
Wire nuts - To connect and cap wires.
Conduit and boxes - If replacing wiring in walls, use electrical boxes and conduit as needed.
Voltage tester - To safely check if wires are live before working on them.
Basic tools - Wire strippers, pliers, screwdrivers, hammer, drywall saw, drill, ladder.

Take Safety Precautions

Shut off power - Turn off all power at the main electrical panel before starting work.
Work safely - Wear safety goggles, gloves, long sleeves, etc. Use fiberglass ladder when needed.
Inspect attic wiring first - Attic wiring is often more accessible. Shut off power and visually inspect before attempting replacement.
Get professional help if needed - If the project is too complex, hire a licensed electrician.

Create a Plan and Get Permits

Make a plan for the order in which wiring will be replaced. Prioritize high usage areas first.
Check local permit requirements. A permit may be required and inspections needed.

Step-by-Step Knob and Tube Replacement Process

Here is an overview of the typical end-to-end process I will need to follow:

1. Turn Off Power and Disconnect Old Wiring

Shut off power at the main panel and use a voltage tester to verify it is off.
Disconnect the old knob and tube wires from any outlets, switches and junction boxes they are attached to.

2. Install New Wiring Pathways

Drill holes through joists and studs to create a path for new wiring. Use conduit if required by code.
Fish the new wires through the paths. Pull cables through with fish tape.

3. Connect the New Wiring to Circuits

Connect the new wiring to the appropriate circuit breaker in the main panel.
Connect wires to any existing grounded outlet or switch. This grounds the system.

4. Connect New Wiring to Outlets and Fixtures

Attach the new wiring to any outlets and switches, replacing devices as needed.
Attach new wiring to light fixtures, appliances and equipment.

5. Update Electrical Boxes and Fixtures

Replace any outdated electrical boxes with modern grounded boxes.
Install modern light fixtures, outlets, and switches as needed.

6. Close Up and Patch Finished Areas

Use junction boxes to cap any unused knob and tube wires for safety.
Patch walls, ceilings, and floors from any drilling/cutting needed for installation.

7. Turn Power Back On and Test

Turn power back on at the main panel and verify lights and outlets function properly.
Test outlets/circuits with a voltage tester and check grounding.

Hiring a Professional Electrician

While a DIY replacement of knob and tube wiring is possible in many cases, some homeowners opt to hire a professional electrician to take care of the project. Here are some benefits of hiring a pro:

Experience and expertise - They have extensive knowledge of electrical codes and safety practices.
Efficiency - They have the right tools and workforce to complete the project faster.
Permit handling - The electrician can pull any required permits and schedule inspections.
Liability - Using a licensed electrician means any liability falls to their business, not to me.

While a professional wiring replacement costs more upfront, it provides peace of mind knowing the job was done safely and correctly by a licensed electrician. I should get quotes from at least 3 local electricians and check reviews before choosing one.

Conclusion

Replacing outdated and potentially hazardous knob and tube wiring provides significant safety and functionality benefits for my home. By carefully planning the project, taking safety precautions, following local electrical codes, and getting help from an electrician if needed, I can successfully upgrade my home's electrical system and gain peace of mind. While somewhat tedious, replacing the old wiring is a valuable investment in my home's safety and modernization.