Knob & Tube wiring is not inherently dangerous as an installation. Where we experience the danger is in the following areas:

• Due to its age, the insulation is typically brittle, broken, cracked and/or missing.
•  The system is typically added to over the years with dangerous wiring methods, typically a mix of old and new wire.
• It has no ground wire and thus cannot service any three-pronged appliances.
• It is often modified by do-it-yourselfers, or unqualified technicians, resulting in poor connections.
• It is often overlooked. Knob and tube is designed to dissipate heat by being in free-air. It is often covered in insulation over the years, putting home with it at risk of a fire. 

Five Reasons You Need to Rewire:

Knob and tube wiring, also referred to as cloth wiring, was a standard in homes built from the late 1800s through the 1940s, but now it’s an outdated hazard. While it served its purpose in a time of lesser electrical needs, modern homeowners face significant risks when relying on this aging system. Whether you’re renovating an older home or have concerns about your current wiring, understanding the dangers of knob and tube wiring is crucial for maintaining safety. At Mirsky Electric, we specialize in safely upgrading old electrical systems with knob and tube rewiring, ensuring your home is up to code and ready for today’s electrical demands. Dimmer switches, such as Lutron or Leviton, rely on new wiring to function correctly. 

What is Knob and Tube Wiring?

Knob and tube wiring is an early method of electrical wiring used in homes from the late 1800s through the 1940s. The system gets its name from the ceramic knobs that hold the wires in place and the ceramic tubes that protect the wires as they pass through wooden framing. Hot and neutral wires are run individually and spaced apart to prevent contact. This system was commonly used in homes during a time when electrical usage was much lower than it is today.

The Top 5 Dangers of Knob and Tube Wiring

While knob and tube wiring served its purpose in the past, it poses several significant risks to modern homes:

1. Risk of Electrical Shock Due to Lack of Grounding

Knob and tube wiring systems lack ground wire, which is a critical safety feature in modern electrical systems. Without grounding, there’s no  path for the energized circuit to trip a circuit breaker, increasing the risk of electrical shock. Leviton, Pass and Seymour,  Lutron, and other brands receptacles are required to have a ground connection.

2. Exposed Live Wires from Aging Insulation

Knob and tube wiring was typically covered by cloth or rubber insulation, both of which degrade over time. The insulation can flake off and expose live wires as they become brittle and deteriorate, leading to bare wires and dangerous conditions such as short circuits or accidental contact with live electrical parts.

3. Fire Hazards from Overheating

When added to homes with cloth-insulated wiring, modern insulation materials can trap heat around the wires, causing them to overheat. Additionally, knob and tube systems were not designed to carry the electrical load of today’s homes, making them prone to overheating and increasing the risk of electrical fires.

4. Overloaded Circuits Due to Limited Capacity

Knob and tube wiring systems were designed to handle the electrical loads of early 20th-century homes. As modern appliances, HVAC systems, and electronics became a staple in today’s modern home, old circuits began to fail due to the added loads. This leads to  frequent tripped breakers or damaged cabling. 

5. Damaged Wiring from Pests

The exposed and unshielded nature of knob and tube wiring makes it particularly vulnerable to pests like rodents. Rodents can chew through the wires, causing damage that leads to electrical faults, power failures, or even fires. This pest-related damage is difficult to detect without professional inspection and repair.

Common Warning Signs of Knob and Tube Wiring Issues

Homeowners with knob and tube wiring may notice several warning signs that indicate potential problems. Some of the most common signs include:

• Flickering Lights: Lights that flicker or dim frequently could signal your knob and tube wiring is struggling to handle the electrical load.
• Burning Smells: A persistent burning smell near outlets, switches, or electrical fixtures is a serious red flag and a sign of overheating or malfunctioning. Leviton, Pass & Seymour, Lutron and other brands have warning signs on how to properly wire their devices.
• Frequent Breaker Trips: If your circuit breakers trip regularly, it could be due to knob and tube wiring being overloaded by modern electrical appliances, receptacles, or lighting.
• Visible Damage: If you see brittle or cracked insulation, exposed wires, or other signs of wear and tear, it’s a definite sign your knob and tube wiring needs to be replaced.
• Sizzling or Buzzing Sounds: Unusual sounds like sizzling or buzzing coming from outlets or walls could be a sign of electrical arcing, a dangerous occurrence with outdated wiring systems.
• Warm or Hot Switches/Outlets: If outlets,  switches, or dimmers feel warm or hot to the touch, it could mean the wiring behind them is overheating.
• Non-Grounded, Two-Prong Outlets: Homes with knob and tube wiring often have outdated two-prong outlets, which is a sign the system lacks proper grounding.

Knob and Tube Wiring Leads to Loss of Home Insurance Coverage and Denied Claims

Many insurance companies refuse to cover homes with knob and tube wiring due to the increased risks it poses. Even if your home is insured, your insurance policy may not cover damages caused by electrical issues or fires linked to outdated wiring systems. Some policies have exclusions for known risks, and if knob and tube wiring is found to be a contributing factor, the insurance company will likely deny the claim. Failing to disclose the presence of knob and tube wiring will also result in a denied claim.

Exceptions are sometimes made for houses where an electrical contractor has deemed the system to be safe.

Knob and tube wiring may lead to electrical code violations

Knob and tube wiring fails to meet the electrical code because this wiring system doesn’t support modern electrical loads, lacks grounding, and can pose a significant fire hazard. Knob and tube wiring is flagged during home inspections. This can cause additional costs if you’re trying to sell or renovate your home. Buyers and contractors will require upgrading the wiring to meet current codes. Failing to replace knob and tube wiring with modern wiring could lead to costly delays.

Risks of DIY Fixes or Inaction

Attempting to fix or modify knob and tube wiring on your own can lead to serious electrical hazards. This outdated system requires expertise to handle safely, and improper repairs can result in electrical shocks, short circuits, or fires. Even minor DIY rewiring projects can increase the risk of malfunction and create code violations. Doing nothing, on the other hand, allows the risks to grow over time as the system ages further, increasing the likelihood of an electrical failure. For your safety, it’s essential to have knob and tube wiring inspected and replaced by licensed professionals.

Advice for those with Knob & Tube Wiring

• Have the system evaluated by a qualified electrician. Only an expert can confirm that the system was installed and modified correctly. 
• Do not run an excessive amount of appliances in the home, as this can cause a fire.
• Where the wiring is brittle or cracked, it should be replaced. Proper maintenance is crucial.
• K&T wiring should not be used in kitchens, bathrooms, laundry rooms or outdoors. Wiring must be grounded in order to be used safely in these locations.
• Rewiring a house can take weeks and cost thousands of dollars, but unsafe wiring can cause fires, complicate estate transactions, and make insurers skittish.
• The homeowner or an electrician should carefully remove any insulation that is found surrounding K&T wires.
• Prospective home buyers should get an estimate of the cost of replacing K&T wiring. They can use this amount to negotiate a cheaper price for the house.

In summary, knob-and-tube wiring is likely to be a safety hazard due to improper modifications and the addition of building insulation. 

If your home still relies on knob and tube wiring, it’s essential to address these risks sooner rather than later. Contact Mirsky Electric to schedule a free quote today and ensure your home’s electrical system is safe, reliable, and up to modern standards.