How to Safely Replace Old Knob and Tube Wiring

Overview of Knob and Tube Wiring

Knob and tube wiring was commonly installed in homes built before 1950. It features:

Wires encased in cloth insulation rather than plastic or rubber
Wires run through ceramic knobs attached to beams or joists
Wires connected by porcelain tubes at junction boxes

While knob and tube can still function safely if undisturbed, it does pose risks like:

Fire hazard from degraded insulation cracking and exposing wires
Insufficient capacity for high wattage appliances and electronics
Lack of grounding to prevent shocks and equipment damage

So replacing knob and tube wiring is recommended to protect your safety and allow modern electrical capacity.

Dangers of DIY Knob and Tube Wiring Replacement

I do not recommend homeowners attempt to replace knob and tube wiring themselves. Risks include:

Electrocution from working with live wires
Fire if wires are damaged or improperly connected
Legal liability if work doesn't meet local building codes

Proper knob and tube replacement requires:

Turning power off at the main panel before working
Using appropriate materials like UL-approved wiring
Installing new boxes and conduits to route wires
Making secure connections and avoiding wire damage
Testing circuits to ensure good functionality

Only a licensed electrician has the expertise to safely replace old wiring. Homeowner repairs to knob and tube can endanger your household.

Overview of Full Knob and Tube Replacement Process

Replacing knob and tube wiring completely in a home involves:

Inspection to identify all existing wiring to be replaced
Permit application with required drawings and documentation
Turning off power and testing that it's de-energized
Removing old wiring from knobs, tubes, boxes, and conduits
Installing new wiring circuits per code with boxes and conduits
Making connections at main and subpanels and devices
Testing circuits to confirm good connections and no shorts
Final inspection by the town to approve finished work

This extensive process demonstrates why you need a licensed electrician rather than attempting DIY repairs.

Questions to Ask Potential Electricians

When selecting an electrician for knob and tube replacement, important questions to ask include:

Are you licensed in this area?
How much experience do you have with knob and tube replacement?
Will you provide computer generated load calculations?
Do you handle securing the necessary permits?
What safety precautions do you take?
Do you have references from recent similar jobs?
What is the timeline for completing the work?
What warranties do you provide on parts and labor?

The electrician should be forthcoming with detailed answers assuring their expertise and professionalism.

Cost Factors for Knob and Tube Replacement

Cost for complete knob and tube rewiring will depend on factors like:

Home size - more square footage means more wiring required
Accessibility - easier attic access lowers labor time
Permit fees - costs vary by municipality
Scope - replacing knob and tube for just problematic circuits or full rewire
Additional updates - if you want to add circuits, lights, or devices
Electrician rates - pricing varies, get multiple quotes

According to HomeAdvisor, the average national cost for a full knob and tube replacement is $8,000 to $15,000, but can go as high as $25,000 for larger homes.

Improving Electrical Safety

Replacing obsolete knob and tube wiring improves safety by:

Reducing fire risk from exposed, cracked wire insulation
Allowing proper grounding to prevent shocks
Handling modern electricity demand from appliances and devices
Ensuring consistent power flow to electronics without flickering
Meeting current code requirements for box fill capacity and wire ratings
Boosting home value with a safer electrical system

As homes age, it is crucial to evaluate electrical systems and make needed upgrades. Replacing original knob and tube wiring is often an essential investment in protecting your most valuable asset - your family.