How to Replace Knob and Tube Wiring in a Historic Home

Introduction

Replacing knob and tube wiring in a historic home can be challenging, but with proper planning and care it can be accomplished while maintaining the historic integrity of the home. As the homeowner, I walk through the key steps I took to replace the outdated and potentially hazardous knob and tube wiring in my 1920s craftsman bungalow.

Evaluate the Existing Knob and Tube Wiring

Hire an experienced electrician to inspect the knob and tube wiring and provide a professional assessment. They can test the wires and connections for safety and determine which circuits need to be replaced first.
Consider having an insulation company perform an insulation evaluation. Blown-in insulation can often not be added to walls containing knob and tube without risking overheating the wires. They can determine if insulation can be added safely.
Identify all locations of knob and tube wiring and which circuits they supply. Mark locations on floor plans for reference during rewiring.
Determine if the knob and tube wiring can be disconnected and new wiring added without demolition, or if walls/ceilings must be opened.

Develop a Rewiring Plan

Consult with the electrician and a general contractor experienced in historic homes to develop a rewiring plan tailored to your home.
Prioritize which circuits need to be replaced first for safety. Bedrooms, kitchens, and bathrooms may take priority.
Determine if any wiring is inaccessible and would require destruction of historic architectural details. Consider alternative routes.
Decide if you will completely rewire the entire home or just replace the knob and tube over time. Phasing the work can spread out costs.
Apply for any necessary building permits for electrical and construction work.

Protect Historic Elements During Rewiring

Have contractors carefully remove and preserve trim work, molding, plasterwork, etc during demolition to access wiring.
Protect exposed wood framing from incidental damage during electrical fishing by contractors.
For exposed conduit runs, have electrician take care to route along existing lines of building for minimal visibility.
Where walls are opened, have contractor conserve and clean any historic wallpaper or unique plaster for reuse/reinstallation.

Repair and Restore After Rewiring

Properly reinstall any removed historic lighting fixtures and devices. If missing, replace with period-appropriate fixtures.
Repair and patch opened walls and ceilings using techniques to match historic finishes. Plaster repair or drywall skim coating help achieve original look.
Touch up paint on repaired walls using paint matched to existing colors. Original paint colors can also be matched.
Refinish any damaged wood architectural details by restoring the original profile, sanding, and restaining/refinishing.

Key Takeaways

Full knob and tube replacement in a historic home takes careful planning and coordination between homeowner, electrician, and contractor.
Rewiring must balance safety upgrades with preserving historic integrity and architectural details of the home. Patience is required.
Phased approach allows for replacing worst hazards first while spreading costs over time.
Restoration efforts after rewiring completes the process and helps restore original historic look and feel.