How to Safely Replace Your Old Knob and Tube Wiring

Introduction

Replacing old knob and tube wiring in your home can significantly improve safety and allow you to upgrade to modern electrical capacity. However, working with electrical wiring can be extremely dangerous if proper precautions are not taken. In this guide, I will walk you through the complete process of safely replacing knob and tube wiring, from planning and preparation to wiring methods and best practices.

Dangers of Knob and Tube Wiring

Knob and tube wiring was commonly installed in homes built before the 1950s. This outdated wiring system presents several safety hazards:

• Fire risk - Knob and tube wiring lacks grounding, has brittle insulation, and overheats easily, making it a major fire hazard. Electrical fires cause over 40,000 home fires every year in the US.

• Shocks and electrocution - Without proper grounding, knob and tube wiring puts you at risk of electrical shocks and electrocution. Faulty wiring is responsible for over 30,000 home electrocutions per year.

• Insufficient capacity - Knob and tube wiring was not designed to handle the power demands of modern appliances and electronics. Overloaded circuits can overheat, arc, and cause fires.

Replacing knob and tube wiring as soon as possible greatly reduces these risks and prevents potential tragedy. The project does require working carefully around live electrical wires, so safety should be your top priority.

Preparing for a Rewiring Project

Careful planning and preparation will ensure your wiring project goes smoothly and safely. Here are some important steps to take before replacing knob and tube wiring:

Assess Scope of Work

• Carefully survey your home to identify all areas with knob and tube wiring. Attics, basements, and crawlspaces are common places to find it.

• Determine if you will fully rewire your home or only replace individual circuits. Rewiring the whole home provides maximum safety.

• Decide if you will upgrade your electrical service panel as part of the project. Upgrades provide increased capacity.

Hire a Licensed Electrician

• Only hire a licensed electrician experienced with replacing knob and tube wiring. Proper training and expertise are essential.

• Get multiple quotes to find the best electrician at a fair price. Ask about their specific experience with rewiring projects.

• Verify they carry proper licenses and insurance coverage. This protects you in case of accidents.

Purchase Materials and Shut Off Power

• The electrician will provide a list of necessary wiring, conduits, junction boxes, and other materials. Purchase everything ahead of time.

• Shut off power at the main electrical service panel before starting work. The electrician will demonstrate proper lockout/tagout procedures to avoid electrocution.

• Important: Check that all power is off with a non-contact voltage tester. Do not start work until power is confirmed off.

Safe Wiring Methods

Your electrician should adhere to the following safe wiring methods throughout the rewiring process:

Install New Conduits

• Rigid metal conduits provide maximum protection for wiring in basements, crawlspaces, and attics.

• Non-metallic flexible conduits can be used for shorter runs in less exposed areas.

• Conduits should be anchored every 5 feet for stability.

Run Copper Wiring

• New wiring circuits should be run using copper wiring. Copper provides safety and capacity that outdated knob and tube wiring lacks.

• Use 12 AWG or 14 AWG copper wires for 15 amp and 20 amp branch circuits. This depends on circuit load.

• Carefully pull wires through conduits without exceeding manufacturer bend radius limits.

Update Electrical Boxes

• Replace any old switch, outlet, and junction boxes with new approved electrical boxes.

• Use metal electrical boxes for fire safety. Plastic boxes should only be used in finished walls and ceilings.

• Properly ground all outlets and switches by connecting copper ground wires.

Label New Circuits

• Clearly label each new circuit at the service panel identifying the area served, the wire gauge, and maximum amps.

• Create an accurate diagram of the location and labeling of all new circuits for reference.

• Thorough labeling reduces confusion and makes future electrical work easier and safer.

Final Safety Checks and Closeout

Before closing up finished walls, the electrician should complete several safety checks and closeout tasks:

• Use a megohmmeter to test insulation resistance on all wiring. This ensures insulation is intact.

• Pressure test conduits to verify no leaks are present. Fix any identified leaks.

• Ensure all junction boxes are properly covered and closed.

• Check ground continuity on all outlets using a circuit tester.

• Measure voltage on all circuits to confirm proper operation.

• Discuss recommended GFCI and AFCI circuit breaker upgrades for additional safety.

Finally, have the completed work thoroughly inspected by your local building department to receive an approved final permit. Only operate the new wiring after successfully passing inspection.

Replacing antique knob and tube wiring requires care, expertise, and adherence to safety standards. But eliminating the fire and shock risks of old wiring greatly improves the safety of your home and everyone in it. Stay diligent throughout the project planning and rewiring process to protect your most valuable investment - your home and family.