Is it Safe to Replace Knob and Tube Wiring?

Knob and Tube - Knob and Tube Wiring Safety graphic

Classical homes built from the late 1800s to the mid-1900s often featured electrical wiring. People refer to this type of wiring as knob and tube or K&T wiring. Unfortunately, while famous for its time, knob and tube wiring safety can’t compete with modern wiring safety standards.

Knob and tube wiring features many safety risks, including being a fire hazard when it contacts fiberglass insulation. These, among other safety risks, make K&T wiring replacement a necessity.

What Exactly Is Knob and Tube Wiring?

From around 1880 to the late 1950s, most homes used knob and tube wiring for electrical wiring. The setup consists of insulated copper wiring feeding through wooden beams via porcelain or ceramic knobs and tubes.

Workers place the tubes through drilled holes inside wooden joists. Meanwhile, the porcelain knobs run alongside the wooden beams. This process prevents wires from touching the frame.

Factors That Make Knob and Tube Wiring Dangerous

Despite its initial popularity, knob and tube wiring has largely fallen out of favor. There are many safety reminders when installing knob and tube wiring, including:


One knob and tube wiring safety issue stems from its age. Knob and tube wiring systems are outdated, with the newest installations happening in the 1970s. However, most installations predate this period, making a typical setup 60 years or older.

These systems quickly become brittle as wire coverings consist of cloth or rubber. Once they wear away, you have exposed wires.

Lack of Ground Wire

A knob and tubing system doesn’t feature ground wire. Instead of a third hole providing a place for extra electrical charges to retreat to, K&T systems only have two prongs. Modern-day systems generally feature three prongs.

While homeowners can use adapters, devices will remain ungrounded, increasing the likelihood of electrical shocks.

Incompatibility with Moisture

In general, electrical systems don’t go well with excessive moisture. However, modern wiring systems today have more safeguards in place. Manufacturers even design specific wiring systems and electrical outlets for moisture-abundant areas like bathrooms and kitchens.

K&T wiring isn’t rated to withstand moisture, making it particularly dangerous in wet areas.

Tendency to Be Overlooked

Insulation and building materials will often hide a K&T wiring system. Paired with the fact that these systems, by design, freely release heat, they often pose a fire hazard.

Insurance companies often don’t insure buildings using this type of wiring since they violate the National Electric Code (NEC). This code stipulates that K&T must stay away from insulation.

Frequent Improper Modifications

Homeowners often try DIY modifications that reduce knob and tube wiring safety standards. Some improper changes can include installing fuses with too much power or using Scotch tape instead of electrical tape.

How to Replace Knob and Tube Wiring

You can use strategies to maintain your knob and tube wiring system. However, these strategies are temporary solutions at best, and you’ll eventually need to replace your K&T systems—especially if there are any exposed wires.

You also can’t ground K&T systems, making it impossible to make them modern. For these reasons, it’s better to remove than replace these systems. Below are the following steps for doing so.

Start by calling a local electrical company to inspect your entire electrical system. The right team can expertly diagnose how much work is needed to replace your knob and tube wiring. Never attempt to replace your wiring yourself for the following reasons:

  • You can make incorrect modifications or improperly replace and install a new system.
  • You can damage yourself or create a fire hazard.
  • You likely won’t have the right tools and experience for the job.
  • You may void certain warranties for appliances like dishwashers and laundry machines.

After inspecting your wire setups, the company should give you an estimate, usually ranging from $5,000 to $15,000. Knowing the projected cost early on can help you budget.

Next, you’ll need to schedule a time that works for you. Then, prepare to be without electricity for a few days. Lastly, the electrical company will install your new wiring system, and you can rest easy knowing your electrical components are safe and up to code.

Frequently Asked Questions (FAQs) – Knob and Tube Wiring Replacement

How Much Does It Cost to Replace the Knob and Tube Wiring?

Unfortunately, replacing and installing new electrical wiring generally is a costly undertaking.

The final price tag depends on the size of your home and how many stories you have. But, generally speaking, homeowners can expect to pay between $5,000 to $15,000 for a K&T wiring replacement.

While this figure sounds high, homeowner’s insurance can sometimes cover the costs of rewiring a home. Many electrical companies also have payment plans in place.

Should I Be Worried About the Knob and Tube Wiring?

It’s easy to overlook the dangers of knob and tube wiring, especially if you’ve been living in a house for several years. However, knob and tube wiring can often be a ticking time bomb.

Knob and tube wiring safety risks include electrical fires. You can also quickly overload these systems using appliances higher than 12 circuits. So while the thought of rewiring your home sounds stressful, it’s worth it to avoid safety risks.

Is the Knob and Tube Wiring Out of Code?

While knob and tube wiring is “out of code” for new homes, replacing these electrical setups in older homes is not always necessary. However, while it’s not always 100% legally necessary to replace these systems, property owners can still run into issues.

Besides the inherent safety risks, insurance companies may outright refuse to insure a home until you rewire it. They may charge higher premiums if they do go through with coverage.

Call Attic Projects Today

Due to the many safety reminders when installing knob and tube wiring, experts consider these systems outdated.

However, with higher energy demands today, it’s essential that homeowners remove and replace these obsolete systems. Our Attic Projects team can expertly handle this process.

To learn more about knob and tube wiring safety, call Attic Projects today!

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