How to Keep Your Home's Knob-and-Tube Wiring Safe and Operational

Knob-and-tube wiring was commonly installed in homes built before 1950. This old electrical system can be concerning for homeowners today, as it may seem unsafe or outdated compared to modern wiring methods. However, with proper maintenance and safety precautions, knob-and-tube wiring can remain functional for decades to come.

What is Knob-and-Tube Wiring?

Knob-and-tube wiring consists of individual wires that are run through open air, supported by ceramic knobs and tube insulators. This type of wiring was the standard method of electrical wiring in homes prior to 1930.

Some key features of knob-and-tube wiring:

• Two or more wires - There is a hot and neutral wire, without a ground wire.
• Open air - The wires are separated and not bundled together or inside a sheath.
• Knobs - Wires are supported along their length by ceramic knobs.
• Tubes - Where wires pass through framing, they are protected by a ceramic tube.

While out-of-date, knob-and-tube can be perfectly safe if properly maintained. Many homes function with this original wiring to this day.

Dangers and Risks of Knob-and-Tube Wiring

While knob-and-tube can work just fine, there are some risks to be aware of:

• Insulation deterioration - The old insulation can crack over time, exposing bare wires. This can cause shorts, fires, or shocks.
• Overloading circuits - The wiring may not be adequate for high wattage modern appliances. Overloads can cause heat buildup.
• Lack of grounding - Without a ground wire, risk of electrocution is higher if an appliance shorts out.
• Loose connections - Vibrations over decades can loosen wire connections, causing drops in power.

These risks are manageable with diligent maintenance and common sense. Do not let the age of the wiring itself scare you.

Inspecting Your Knob-and-Tube Wiring

The first step is to thoroughly inspect your home's knob-and-tube wiring:

• Check for cracked, brittle, or damaged insulation on wires. Exposed copper can be hazardous.
• Look for loose or improper connections at switches, outlets, or splices. These can overheat.
• Verify wires are not pinched by framing, or resting against sharp edges that can damage insulation.
• Confirm no improper modifications were made, such as tapping new wires into old ones.
• Evaluate if any spaces have inadequate ventilation around wires. Heat cannot dissipate.

Use a licensed electrician if you have concerns beyond your comfort level. Safety is paramount.

Basic Repairs and Improvements

Here are some basic upgrades you can make to maintain and improve knob-and-tube wiring:

• Replace damaged sections - If insulation is cracked or wires exposed, install new wiring for that portion.
• Add junction boxes - Enclose splices and connections in junction boxes for protection.
• Update outlets - Swap outdated outlets for modern, grounded ones with safety shutters.
• Add GFCIs - Installing GFCI outlets provides greater protection from shocks.
• Add insulation - Only use insulation designed for retrofits, to not disturb old wiring.

Target high risk areas first, and always hire an electrician for any significant repairs.

Best Practices for Living with Knob-and-Tube Wiring

You can take steps to safely coexist with knob-and-tube wiring:

• Never overload circuits - Be aware of wattages, don't use extension cords, replace fuses with identical ones.
• Do not conceal wiring - Leave access for inspection, do not build walls over it or add insulation on top.
• Check for hot spots - Monitor for warm spots along wires which may indicate problems.
• Hire an electrician when needed - Have them make repairs beyond your skill level.
• Shut off power before any work. Never handle live wires yourself.
• Consider upgrades - If feasible down the road, upgrading certain circuits can improve safety.

Exercise caution and common sense, and knob-and-tube wiring can last surprisingly long. Do not let its age alone intimidate you. With prudent maintenance, it can supply electricity safely.