Updating Your Home's Knob-and-Tube Wiring to Meet Modern Safety Standards

What is Knob-and-Tube Wiring?

Knob-and-tube wiring was an early standardized method of electrical wiring used in buildings in North America from about 1880 to the 1940s. It consisted of single insulated copper conductors run within wall or ceiling cavities, passing through joist and stud drill-holes via protective porcelain insulating tubes, and supported on nailed-down porcelain knob insulators.

This old wiring system lacks grounding wires and the insulation around the wires becomes brittle with age, leading to breaks in the wiring and fire hazards. While knob-and-tube wiring was safe when it was installed correctly and has served many homes well for decades, it does not meet today's electrical safety standards and should be updated.

Why Upgrade from Knob-and-Tube Wiring?

There are several important reasons to update old knob-and-tube wiring:

• Safety - Knob-and-tube lacks grounding which protects against shocks and allows faults to trip breakers. The degradation of insulation raises fire risks. Upgrading removes these hazards.

• Reliability - New wiring is less prone to shorts, faults, and voltage drops that can cause flickering lights and loss of power to circuits.

• Capacity - Knob-and-tube was not designed to handle the power needs of modern homes with more appliances and electronics. Upgrading allows for more circuits and outlets.

• Insurance - Many insurance companies won't issue policies for homes with knob-and-tube wiring due to fire risks, or will require an expensive rider. Upgrading may lower costs.

• Resale value - Updated wiring makes a home more attractive to buyers and easier to finance and insure. Many banks won't offer mortgages on homes with knob-and-tube.

How to Upgrade Knob-and-Tube Wiring

Replacing knob-and-tube wiring throughout a home is a major project that requires planning and licensed electricians. Here is an overview of the process:

Hire a Licensed Electrician

• Only licensed electricians should perform wiring work in a home. Get quotes from several to compare.

Plan the New Wiring System

• The electrician will design a new circuit plan optimizing safety, capacity, and convenience. Evaluate needs for more outlets, switches, lighting, appliances, and electronics.

Install New Wiring and Components

• The old wiring is disconnected and new wires run through walls and ceilings to each outlet and switch. New breaker panels, meters, and grounding are added.

Remove Old Wiring

• Once the new system is installed, tested, and operational, the old knob-and-tube wiring is removed. Holes are patched and surfaces repaired.

Obtain Inspections and Documentation

• The work will require permits and inspections. Get copies of paperwork to document the upgraded electrical system.

Costs of Replacing Knob-and-Tube Wiring

Upgrading home wiring is a major investment, with costs influenced by:

• Home size - More wiring is needed for larger homes.

• Accessibility - Ease of running wires through walls, attics, and basements impacts labor time.

• Rewiring extent - Whole home rewires cost more than partial upgrades.

• Special needs - Upgrades like adding air conditioning require additional work.

• Local rates - Costs vary by region and electrician rates.

Typical range: $8,000 to $15,000 for a full rewire of a 2,000 sq ft home, but costs can be much higher. Get multiple quotes.

Is it Worth It?

The costs are substantial, but the benefits for safety, reliability, resale value, insurance, and peace of mind often make wiring upgrades a smart investment. Many homeowners schedule upgrades when doing major renovations or before selling their home.

Prioritize hazardous knob-and-tube circuits like those near water or supplying major appliances first. A phased approach spreads costs over time. Seek rebates, tax credits, or financing options to help fund major wiring projects.

Upgrading old knob-and-tube wiring improves safety and prepares a home for modern electrical needs. Planning carefully and hiring professional electricians ensures the project goes smoothly.