How to Safely Replace Old Knob and Tube Wiring

Introduction

Replacing old knob and tube wiring can seem like a daunting task, but with proper planning and safety precautions, it can be done safely by a homeowner. Knob and tube wiring was an early method of electrical wiring used in homes in the late 19th and early 20th centuries. While it was safe when initially installed, it can become hazardous over time as insulation breaks down. Replacing it completely should be a top priority for homeowners with knob and tube wiring. In this article, I will provide a step-by-step guide on how to safely replace knob and tube wiring as a DIY project.

Dangers of Knob and Tube Wiring

Before beginning any work, it's important to understand the potential dangers of knob and tube wiring:

• Fire hazard - the old, brittle insulation can crack and expose wires, leading to arcing and sparks. This can easily ignite surrounding combustible materials.

• Shock hazard - exposed wires can energize metal components like ducts and pipes, posing a serious shock hazard.

• Overload - knob and tube wiring lacks safety devices like circuit breakers. Connected devices can overload the system and cause overheating.

• Insurance issues - many insurance companies won't insure a home with knob and tube wiring due to safety concerns.

These risks demonstrate why replacement is so important. Never take shortcuts or delay when dealing with knob and tube wiring.

Getting Professional Guidance

While a DIY replacement is possible, it's wise to consult an electrician early in the process. An electrician can:

• Evaluate the scope of the project
• Identify any special issues or considerations
• Provide technical guidance on the replacement
• Obtain necessary permits
• Ensure the new wiring meets electrical codes

If the home still has the original electrical service panel, the electrician may recommend an upgrade to the entire electrical system.

Planning the New Wiring System

When planning the project, there are several factors to consider:

• New wire gauge - #12 or #14 AWG copper wire is recommended
• Circuit mapping - document which circuits connect to which outlets/devices
• New circuit design - decide how many circuits are needed and their amperage
• Safety devices - integrate circuit breakers, AFCIs, and GFCIs as needed

Take time to carefully design the new wiring system on paper before purchasing any materials.

Obtaining Necessary Permits

Most jurisdictions require permits for home electrical work. The general process is:

• Contact the local building department and fill out an electrical permit application
• Provide details about the scope of work to be performed
• Pay the required permit fee (often based on number of circuits)
• The inspector will visit at certain stages of the project

Having the permit ensures code compliance. The inspector will also need to perform a final inspection before signing off.

Staging the Project

With proper planning, the project can be executed systematically:

1. Purchase all required materials

This includes:

• New nonmetallicsheathed cable (romex)
• Circuit breakers and electrical boxes
• Conduit and fittings as needed

2. Reroute a single circuit

As a trial run, replace just one knob and tube circuit initially. This allows you to understand the full process start to finish.

3. Replace circuits incrementally

With the learnings from the first circuit, continue replacing the remaining knob and tube circuits one by one. Avoid trying to replace everything at once.

4. Remove old wiring at the end

Only remove original knob and tube wiring after each circuit has been replaced and tested. Attempting to remove too much at once can create safety issues.

Key Safety Measures

When dealing with live electrical wiring, safety should be the top focus:

• Turn off power - the circuit breaker corresponding to the working circuit must remain OFF. Verify with a non-contact voltage tester.

• Personal protective equipment - always wear rubber-soled shoes, gloves, long sleeves and safety goggles.

• Use caution - when working in the breaker box, avoid contact with live bus bars. Remove only one wire at a time.

• Connect new ground wires - new grounding provides shock protection. This should be done immediately after installing each new circuit.

• Inspect work thoroughly - double check all electrical connections are tight and fully insulated before re-energizing.

By following proper safety protocols, you can upgrade from hazardous knob and tube wiring to a modern electrical system meeting current safety standards. Paying close attention to planning and safety will lead to success on this critical DIY project.