How to Safely Rewire Your Home with Obsolete Knob and Tube Wiring
Rewiring a home with obsolete knob and tube wiring can seem daunting, but it is possible to do safely if you take the proper precautions. Knob and tube wiring was common in homes built before the 1940s, but it can present fire and shock hazards if left in place. In this guide, I will walk through the key steps I took to rewire my 1920s home, focusing on safety and avoiding common pitfalls.
Dangers of Knob and Tube Wiring
Before rewiring, it's important to understand why knob and tube wiring is problematic:
Fire hazard - The insulation on old wiring becomes brittle and cracks over time, exposing bare wires that can arc and spark. This can ignite nearby combustible materials.
Overloading circuits - Knob and tube circuits are rarely grounded and often max out at 15 or 20 amps. Plugging in too many modern appliances can overload the wiring.
Lack of grounding - Ungrounded systems do not provide a safe path for faults or surges to travel. This increases the risk of shocks.
Insurance issues - Many insurance companies won't cover homes with knob and tube wiring, due to the risks.
Thorough preparation is crucial for a smooth and safe rewiring project. Here are the key steps I took:
Consult an electrician - Have a licensed electrician evaluate your existing wiring and provide rewiring recommendations. They can identify any particular hazards or challenges.
Research permits - Check with your local building department about required permits and inspections for rewiring projects. Failing to get proper permits can cause issues with inspections or future home sales.
Consider professional help - Rewiring is complicated, and mistakes can be dangerous. If you don't have electrical experience, consider hiring an electrician to do the job safely.
Create a plan - Map out a detailed plan for which circuits need to be rewired and how you'll route the new wiring. Planning meticulously will avoid surprises mid-project.
Test for live wires - Use a non-contact voltage tester to identify any live wires that need to be shut off at the main panel before working.
When you're ready to start rewiring, follow these tips to maximize safety:
Turn off power - Turn off the main breaker and verify power is off with a voltage tester before touching any wiring.
Work one circuit at a time - Focus on one full circuit replacement before moving to the next. Avoid leaving partial circuits unfinished.
Use the proper gauge wire - Follow the electrical code requirements for wire gauge based on your home's amperage. This avoids overheating wires.
Install GFCI outlets - Upgrade to modern grounded outlets with GFCI protection for added safety, especially in kitchens, bathrooms and basements.
Label meticulously - Label each wire clearly and keep detailed notes on which wire goes where. Good labeling avoids confusion later.
Inspect work frequently - Have the electrician inspect your progress after finishing each circuit. They can catch any errors or issues.
Final Safety Checks
Before turning the power back on, conduct these final safety checks:
- Verify all unused wires are properly capped off
- Check that all circuits have the correct size overcurrent protection
- Confirm all outlets and devices are wired correctly
- Ensure no wires have any loose, exposed or damaged connections
- Test GFCI outlets to ensure proper function
- Double check the main panel connects to the utility feed correctly
Only restore power once you've confirmed through close visual inspection and testing that everything is safe and ready for service.
While rewiring a home with knob and tube wiring has its hazards, taking proper safety precautions at every step allows the project to be completed safely. Following the tips outlined here for thorough preparation, careful execution, and double-checking your work can help avoid fires, shocks or other dangerous mishaps. With adequate care and caution, that obsolete wiring can be updated to modern standards.