I have an older home built in the 1920s that still has the original knob and tube wiring. This type of electrical wiring was common in homes built in the early 1900s but is now considered obsolete and even dangerous. As the homeowner, I need to fully rewire my house to make it safer and up to code. Here is an in-depth guide on how I plan to rewire my home to replace the outdated knob and tube wiring.
Understanding Knob and Tube Wiring
Knob and tube wiring consists of single black rubber insulated wires run through ceramic knobs, with air gaps between the wires. It was the standard wiring method in North America from about 1880 to the 1930s.
Some key facts about knob and tube wiring:
- Used ceramic knobs attached to joists or studs to hold the wires in place
- Wires are separated by air instead of bundled together
- No ground wires
- Cloth insulation on wires instead of plastic
- Only designed to handle about 30-60 amps total
The lack of a ground wire and the cloth insulation makes knob and tube wiring a fire hazard by modern electrical standards. The wiring degrades over time, increasing the risk of arcing and ignition within wood framing.
Dangers of Knob and Tube Wiring
There are several dangers associated with obsolete knob and tube wiring:
- Fire hazard - degraded insulation can lead to arcing and sparks
- Shocks - no grounding means risk of shocks
- Overload - not designed for today's power consumption
- Insulation problems - wiring running through walls can cause cold spots and condensation
In fact, many homeowners insurance companies will not insure a home with knob and tube wiring due to the risk. Replacing the outdated wiring makes the home significantly safer.
Planning the Rewiring Project
Rewiring my entire home is a big project that requires planning and preparation. Here are the key steps I will take:
Consult an electrician - I will hire a licensed electrician to ensure the new wiring meets building codes.
Check permitting requirements - My municipality likely requires permits for rewiring a home.
Schedule inspections - I will coordinate with the town building inspector to inspect the work.
Determine scope - The electrician will help me determine which parts of the home to rewire. At minimum, I need all living areas and kitchen rewired.
Choose wiring method - New wiring will be single conductor copper wiring with plastic insulation and a ground wire.
Create a budget - I will get quotes from 3 electricians and factor in costs like materials and walls repairs. Rewiring a whole home could cost $8,000-$15,000.
Safely Removing Knob and Tube Wiring
Once I have a rewiring plan in place, I can start the process of removing the old knob and tube wiring. This involves:
Turn off power - I will shut off all power at the breaker box before removing any old wiring.
Inspect knob condition - Some knobs degrade over time. I'll check for any that are crumbling or deteriorating.
Remove knobs and tubes - I'll take care extracting the old wiring from the knobs and tubes. Ceramic pieces could fall into walls.
Cap abandoned wires - Any inactive knob and tube wires must be properly capped off with wire nuts or electrical tape.
Dispose properly - Knob and tube wiring is typically considered hazardous waste and cannot go to a landfill. I will bring it to a hazardous waste facility.
Rerouting and Installing New Wiring
Once the knob and tube wiring is removed, I can start routing the new wiring:
Map electrical plan - The electrician will determine the required wiring runs and circuits.
Drill holes through studs - New holes will give access for wiring between rooms.
Run cables - Modern NM cables with ground wires will be run from the panel through walls and ceilings.
Install boxes and fixtures - Electrical boxes bring power to devices and fixtures.
Connect devices - Light switches, outlets, appliances and fixtures get connected to the new wiring.
Inspect - The building inspector checks that the new wiring meets code requirements before walls get closed up.
Tips for DIYing Some of the Rewiring
While I will hire an electrician to oversee the major rewiring work, there are some parts of the project I can do myself as a homeowner to save on labor costs:
- Safely remove old knob and tube wiring
- Open up holes in walls and ceilings for new wire routing
- Fish some of the new cables through walls
- Hang light fixtures and install switches/outlets once wiring is complete
- Patch, spackle, and repaint walls after electrical work is inspected
By doing thishands-on work under the supervision of the electrical contractor, I can reduce the total rewiring costs by 15-25%.
Final Checks and Completing the Project
Once the new wiring is installed throughout my home, there are a few final steps to wrap up the rewiring project:
Install wall coverings - Patching, painting, insulation and drywall get replaced throughout the home.
Confirm functioning circuits - I will plug in devices and test lights in each room to ensure all new wiring is working correctly.
Electric meter check - The power company will assess the new electrical load and upgrade my home's meter if needed.
Certification - I will obtain an electrical certificate of compliance from the town indicating the home is now up to code.
Inform insurance - Finally, I will provide the wiring certification to my homeowner's insurance to show the old hazardous wiring has been replaced.
While rewiring an entire house is a major undertaking, it is absolutely necessary in homes with original knob and tube wiring to prevent fires and make the home safe. Following this comprehensive guide will allow me to successfully rewire my home.