How to Fix Faulty Knob-and-Tube Wiring in Your Old House

Knob-and-tube wiring was commonly installed in homes built before the 1950s. While it can still be functional, it does pose some safety concerns compared to modern electrical systems. Fixing faulty knob-and-tube wiring in an old house requires care and expertise to avoid potential hazards. Here is a comprehensive guide on addressing knob-and-tube wiring problems.

Evaluating the Existing System

The first step is to thoroughly evaluate the existing knob-and-tube wiring to identify any issues or deficiencies.

Inspecting for Visible Damage

• Carefully examine where wiring is visible, like in the attic or basement. Look for cracked or damaged insulation, exposed wires, loose connections, or signs of overheating. These can indicate faulty or dangerous conditions.

Testing Circuits and Outlets

• Use a voltage tester to check for hot-neutral reversals or other wiring errors. Verify grounding with a ground wire tester.
• Check outlets for loose connections by plugging in a lamp and wiggling the cord. Flickering indicates a faulty outlet.
• Tripped breakers, dimming lights, or flickering can point to wiring issues.

Considering an Electrical Assessment

• For a thorough evaluation, hire a qualified electrician to assess the entire system. They can identify any safety hazards missed through visual inspection.

Repairing Faulty Wiring

Once problems are identified, repairs or replacements may be necessary for safety.

Splicing Damaged Wiring

• Use wire nuts to splice and cap any exposed or damaged wiring. Match wire gauge and type.
• Wrap electrical tape around splices for additional insulation.

Replacing Bad Outlets and Switches

• Upgrade outdated outlets and switches with modern, grounded replacements. Use GFCI outlets in bathrooms, kitchens, etc.

Rerouting Unsafe Circuits

• For wiring running across floor joists or near insulation, reroute through metal or PVC conduit for protection.

Removing Dead Knob-and-Tube

• Consult an electrician about fully removing non-essential knob-and-tube to simplify the system.

Upgrading from Knob-and-Tube

In some cases, completely upgrading the electrical system may be preferable for full modern safety and capacity.

Installing New Grounded Wiring

• For new grounded wiring, an electrician will run new cables through walls and ceilings back to the main panel. Very labor intensive.

Using Armored Cable

• Type AC cable (BX cable) can be retrofitted through existing walls more easily as an upgrade. Contains grounds.

Converting to Circuit Breakers

• Replace any old fuse boxes with modern circuit breakers. Allows easier expansion later.

Adding GFCI Protection

• Adding GFCI outlets provides protection from electrocution even on ungrounded wiring. Especially useful in kitchens, bathrooms and basements.

Working Safely with Knob-and-Tube

Always exercise caution when dealing with old electrical systems.

• Turn off power at the main panel before any repairs or replacements.
• Never run extension cords long term on old wiring as it poses overloading risks.
• Use LED bulbs or lower wattage bulbs to reduce loading.
• Avoid overloading circuits which are often only 15-20 amps.
• Have an electrician handle any major repairs or upgrades for safety.

While knob-and-tube wiring does not necessarily need complete replacement, it is smart to have any issues addressed for peace of mind and the safety of your home. With proper repairs and precautions, knob-and-tube can be maintained safely.