How to Safely Repair an Old Knob and Tube Wiring System

Introduction

Repairing an old knob and tube wiring system can seem daunting, but with proper precautions it can be done safely. Knob and tube wiring was commonly installed in homes built before 1950. While it can last for decades, the insulation often breaks down over time, creating potential fire and shock hazards. However, with care and caution, you can repair and even completely rewire your home without incident. This guide will walk through the key steps for safely repairing knob and tube wiring.

Evaluate the Existing Wiring

Before doing any repairs, you'll want to thoroughly examine the existing knob and tube wiring to assess its condition.

• Look for cracked or damaged insulation on the wiring. Any exposed copper conductors can create a dangerous short circuit or shock hazard.

• Check for loose connections at the porcelain knobs, tubes, and junction boxes. This can lead to arcing and overheating.

• Verify that circuits are properly fused. Overfusing can allow dangerous overcurrent conditions.

• Consider hiring an experienced electrician to evaluate the system if you have any concerns about its safety or condition. They may recommend partial or complete rewiring.

Repair Individual Components

Once you have determined the wiring is stable enough for DIY repair, you can work on fixing individual components as needed.

• Replace any cracked or damaged insulation. Carefully wrap new electrical tape around any exposed sections of copper conductor.

-Tighten any loose connections at knobs, tubes, splices, and switches. Turn off power before working on connections.

• Replace fused links with modern circuit breakers. Fuses only protect against overloads and not short circuits.

• Consider replacing cloth-insulated wiring in high risk areas like kitchens or bathrooms. Use modern NM cable.

Always turn off the power at the main breaker before doing any hands-on electrical work. Test wires before touching to confirm power is off.

Add GFCI Outlets for Protection

While repairing the existing wiring can help, knob and tube systems lack modern safety features. Installing GFCI outlets provides important protection from shocks.

• Install GFCIs in bathrooms, kitchens, laundry, and other areas prone to moisture.

• Ensure you connect both the hot and neutral wires to the GFCI outlets for full protection.

• Test GFCIs monthly by pressing the "Test" button to confirm they trip off. Reset button when done.

• Consider adding AFCI breakers to protect against arcing faults which can start fires. Combination AFCI/GFCIs provide maximum safety.

Consider Full Rewiring

For older, extensively damaged, or inadequately protected knob and tube wiring, complete rewiring may be needed. This will provide modern safety and performance.

• Consult electricians on options like running new NM cables through walls and ceilings vs surface-mounted conduits.

• Rewiring is disruptive, so consider a phased approach starting with high priority areas.

• When rewiring, ensure adequate grounding and install GFCI and AFCI protection.

• Remove all old knob and tube wiring once new system is installed to prevent confusion. Cap unused wires.

While seemingly complex, with proper planning and caution knob and tube wiring can usually be repaired or upgraded safely by a diligent DIYer. Always err on the side of caution by consulting experts when needed. Take things slow and double check your work.