How to Safely Replace Knob and Tube Wiring in Old Homes

Introduction

Replacing old knob and tube wiring in your home 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 commonly installed in homes built before 1950 and lacks many of the safety features of modern electrical systems. Upgrading to modern wiring brings your home up to current code and reduces fire risks. In this guide, I'll walk you through the complete process of replacing knob and tube wiring in an old home.

Dangers of Knob and Tube Wiring

Before starting any electrical project, it's important to understand why knob and tube wiring can be dangerous:

• No grounding - Knob and tube systems have no ground wire, increasing the risk of shocks. Modern wiring grounds the system to prevent shocks.

• Insulation deterioration - The insulation on old wiring dries out over time, exposing bare conductors and increasing fire risk.

• Overloaded circuits - Knob and tube wiring wasn't designed to handle the power demands of modern appliances and electronics. This can lead to overloaded circuits and fires.

• Exposed splices - Splicing wires without a junction box also increases fire hazard.

Replacing knob and tube wiring eliminates these risks and brings the home up to modern safety standards.

Planning the Replacement Project

Careful planning is crucial when taking on an electrical project. Follow these planning steps before touching any wiring:

Consult an Electrician

• While a homeowner can legally replace wiring, consult an electrician first. An electrician can evaluate your specific electrical needs, provide guidance on the project, and handle any complex wiring.

Research Permit Requirements

• Many municipalities require permits for electrical work. Research permit requirements in your area and obtain any required permits. Failing to get a permit can cause issues when selling the home.

Create a Wiring Diagram

• Draw out a wiring diagram mapping all the existing wiring and outlets. This helps you understand how the existing system is wired and allows you to plan the new circuit routes.

Label Circuit Breakers

• With the power still on, label each circuit breaker according to which outlets it controls. This allows you to work on one circuit at a time.

Purchase Supplies

• Buy all required supplies before starting, including new breakers, wiring, boxes, and outlets. Having materials ready avoids dangerous delays.

Safety Tips for the Project

When dealing with electrical wiring, safety should be your top concern. Follow these precautions:

Turn Off Power at the Breaker

• Before touching any wires, shut off the main breaker and all individual breakers. Verify power is off by testing outlets with a multimeter or voltage tester.

Work on One Circuit at a Time

• Focus your replacement efforts on one circuit at a time to avoid confusion. Label wires as you disconnect them.

Wear Protective Equipment

• Wear rubber-soled shoes, eye protection, gloves, and long sleeves when handling wiring. Never work on wiring with wet hands.

Use a Voltage Tester

• Test wires with a non-contact voltage tester before grasping them to confirm power is off. Even with the breakers off, live wires can be dangerous.

Check for Hidden Knob and Tube

• Scan walls, attics, and basements with a voltage tester to find any hidden knob and tube wires that didn't get disconnected.

Step-by-Step Replacement Process

With proper planning and safety preparations completed, you're ready to replace the old wiring. Follow these key steps:

1. Disconnect Knob and Tube at Outlets and Junctions

• Starting at one outlet, disconnect the knob and tube wires from the outlet and splice junctions. Cap wires and label, "Not in Use" so they aren't confused for new wiring.

2. Run New Wiring to Each Box

• Working one circuit at a time, run new wires from the service panel to each outlet/junction box. Follow local codes for wire gauge and installation method. Avoid contact with old wiring.

3. Connect New Wiring at Service Panel

• At the service panel, connect the new wiring to the proper overcurrent protection device (breaker or fuse). Consult your wiring diagram to connect new circuits properly.

4. Connect New Wiring at Outlets and Junctions

• Following your wiring diagram, connect the new wiring to each outlet, switch, and junction. Install boxes where old splices existed without a proper junction box.

5. Label New Circuits

• For safety, label each new circuit clearly at the service panel. This allows for quick shutdown of circuits for future electrical work.

6. Update Permit and Electrical Inspection

• Call your municipality to schedule an electrical inspection. Provide any updated permit paperwork to get your new wiring approved.

Once approved, turn the main power back on and test all outlets to ensure proper function. With the old knob and tube fully replaced, you can rest easy knowing your home's electrical system is safe and meets modern code. Be sure to take precautions anytime electrical work is needed in the future.

Common Questions about Replacing Knob and Tube Wiring

Is it required to replace knob and tube wiring?

• In most areas, it is not legally required but highly recommended for safety. Many insurance companies and lenders also require replacement.

Can I just abandon knob and tube wiring in place?

• Abandoned wiring is still a hazard if energized accidentally. It's best to fully remove it.

How difficult is it for a homeowner to replace wiring?

• The work is manageable for a homeowner if proper safety precautions are followed, but an electrician should handle complex wiring.

Does all wiring need to be replaced at once?

• It's usually best to replace all old wiring, but you can phase the work by rewiring one circuit at a time.

How much does a full rewiring job typically cost?

• Depending on home size, the total cost can range anywhere from $3,000 to $15,000. Get contractor estimates.

Conclusion

While rewiring an old home takes time and diligence, it greatly improves home safety and functionality. By planning the project thoroughly, remembering crucial safety steps, and methodically replacing the old wiring, a homeowner can successfully convert their electrical system from hazardous knob and tube to modern code-compliant wiring. Proper electrical wiring ensures safe operation of modern lights and appliances.