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Knob & Tube Wiring: A Guide

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If your North Carolina home was built between 1880 and 1950, there’s a good chance it has knob and tube wiring. While not a problem in and of itself, this type of wiring is no longer permitted in new home construction. Most insurance companies consider the older wiring dangerous. Many homeowners aren’t even aware they have knob and tube wiring until they’re remodeling or an electrical issue exposes it.

Blanton’s Air, Plumbing & Electric provides comprehensive electrical solutions, including wiring repair and rewiring homes with knob and tube wiring. We manage the entire rewiring process, including obtaining permits and approvals if necessary. If your Raleigh-, Durham-, or Fayetteville-area home needs expert knob and tube wiring services, contact us today.

What Is Knob & Tube Wiring, and How Does It Work?

Installed in homes from the 1920s to the mid-1960s, knob and tube wiring was considered a state-of-the-art electrical solution. As the name suggests, it uses a combination of porcelain knobs and tubes as insulators. Basic characteristics include:

  • No ground wires are used — one hot and one neutral wire is used, with no ground conductor.
  • The wires are encased in fiber insulation or a rubberized cloth. It wasn’t uncommon for a second rubber or fiber insulator to be installed over the first.
  • Splices and connections are made outside the junction box.

Also known as “spider webbing,” knob and tube wiring is easy to identify if you can see it! Its white spool-like ceramic knobs with electrical wires winding through them are often visible in the attic or basement, nailed to joists and protected by the tubes.

It’s common for knobs and tubes to be hidden in a home’s walls, whether intentionally or otherwise. Finding it usually requires opening or making some holes in a wall. However, that discovery sometimes doesn’t tell the whole tale. That’s because when something went wrong, homeowners often had the older wiring in a switch or socket replaced, running the new wiring the height of the wall and leaving knob and tube in the ceiling and beyond.

Issues Related to Knob & Tube Wiring

Though knob and tube is generally considered a superior electrical installation, the consensus is that it’s inherently more hazardous than modern wiring. Common problems with knob and tube wiring are:

  • Its lack of a ground wire means it is not protected from shocks and fires that can occur when a fault is present.
  • Its insulating sheathings disintegrate over time. They’re also a favorite meal for rodents!
  • It’s fused with 15 amps, but the system is 60-amp. This means more current flows through the wire than it’s designed to handle, leading to excessive heat and, in some cases, fire.
  • It’s not equipped for modern extra loads, so it becomes brittle, exposing bare wire.
  • It’s meant to air cool. If your home has blown-in insulation in the attic, it could make it impossible for heat to escape.
  • Its two-prong receptacle isn’t compatible with many modern appliances. The lack of a ground wire also increases the chance of shock and injury, especially in water-related areas like kitchens, bathrooms, and laundry rooms.

Extra circuits can be another problem, as the original knob and tube installations only allowed for 12 circuits. Over the years, homeowners would add additional circuits to the panel or splice into the existing wire, both of which present a risk of overloading the electrical system.

Upgrade Your Wiring: Replacing Knob & Tube Wiring

Local codes vary for knob and tube wiring, and replacing it isn’t typically required by law. However, most homeowner insurance policies now contain specific language regarding knob and tube, with some requiring its removal or charging a higher premium.

If your home has knob and tube wiring, it’s recommended to have it regularly inspected. You might also want to consider replacing it. While a whole-house rewriting can require a significant investment, it’s usually a once-in-a-lifetime home expense that protects the safety of your home and family.

Choose Blanton’s To Rewire Your Home

Blanton’s has been delivering trust electrical services to North Carolina families since 1951, including whole-home rewiring. To learn more about knob and tube wiring or to schedule an installation, call (910) 822-2866 in Fayetteville or (919) 298-2105 in the Triangle.

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We make the process easy in multiple ways but you can always expect the same, easy way when you work with us:

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We don't schedule in those 4 hour windows - you won’t have to wait around for us.

Instant Updates on Arrivals

We call you and give you updates. We provide a 30 minute heads up phone call.

You’ll Know Who Your Technician Is

When you book, you get a welcome email that shows your technician's photo and some of their recent customer reviews.

We Provide real time tracking

When your tech is dispatched, we provide a link where you can track them en route.

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