Everything You Need to Know About Replacing Knob and Tube Wiring

November 8, 2023
Knob and tube wiring services and installation

If you own an older home in Seattle, WA, updating its wiring system could be essential for supporting your modern devices and appliances. This is especially true if your home has knob and tube wiring. Introduced in the late 1880s, knob and tube wiring was the standard for residential electrical systems until the 1940s. It has a simple design, a unique look, and several highly enduring components. Although safe at installation, knob and tube wiring becomes hazardous as it ages. However, before pulling your knob and tube wiring out, there are several essential things to know about replacing it.

Wiring Removal and Replacement

Do-it-yourself (DIY) electrical repairs and replacements are always ill-advised. All electrical installations and upgrades require permits, and this work is only qualified for permitting when performed by licensed electricians. However, there are unique dangers that exist with knob and tube wiring that make DIY replacement an especially poor choice.

These systems are comprised of ceramic knobs and copper wiring with rubberized cloth insulation. Over time, exposure to heat causes this wiring’s insulation to crack and flake off. This frequently occurs at and around lighting fixtures and at other heat-generating elements. The result is often exposed live wires and a severe risk of electrocution.

Dramatic differences in how residential wiring systems are installed also pose a serious threat to homeowners who attempt to tackle these projects on their own. For instance, modern switch placement puts switch plates on hot wires. Many knob and tube installations put switch plates on neutral wires instead. Thus, even if you turn the circuit off, there could still be an active current with enough volts of electricity to cause serious physical harm or even death.

Hazards Introduced Throughout the Years

Many electricians assert that knob and tube wiring isn’t inherently unsafe. In fact, despite being ill-suited to modern appliances and devices, this type of wiring has several benefits that modern options don’t share. It’s less likely to be punctured by screws, staples, or nails because it isn’t directly attached to framing inside the wall. It also has a higher current carrying capacity than modern wiring of the same gauge.

However, in addition to age-related degradation, knob and tube wiring often has hazards that have been introduced throughout the years. If the wiring in your home has been around for more than five decades, there’s a good chance that several electricians have worked on it. Because knob and tube wiring hasn’t been the norm since the 1940s, not all electricians are skilled in working with it. Unfortunately, even a small, simple mistake made a long time ago could cause you injury when tampering with your electrical system.

Many homeowners who’ve hung onto their knob and tube wiring have paid for modest upgrades throughout the years. For instance, knob and tube wiring cannot accommodate three-pronged plugs because it lacks a grounding wire. By installing ground-fault circuit interrupter (GFCI) outlets, some electricians have provided a short-term solution. Unfortunately, this quick fix causes safety hazards because modern manufacturers do not design GFCIs to work with knob and tube wiring.

Knob and Tube Wiring and Home Insulation

Knob and tube wiring should never co-exist with modern insulation. If you’re interested in lowering your carbon footprint and reducing your home energy bills, the first and most important step is tightening your home’s envelope. This is best accomplished by upgrading windows and doors, installing weatherstripping, sealing air leaks, and adding to or improving building insulation.

Active knob and tube wiring poses a serious risk of fire when insulating materials are positioned too close to it. Even when knob and tube wires look fully intact, small areas of exposed wiring due to failing insulation often exist. The risk of electrical fires in these areas is so high that many roofing contractors refuse to install insulation in homes with knob and tube wiring until these wires have been inspected by licensed electricians and deemed inactive.

Home Insurance and Knob and Tube Wiring

Knob and tube wiring isn’t code-compliant. Although few municipalities require the complete removal of these wiring systems, they cannot be used as part of any new construction. These factors, along with the perceived risk of electrical malfunction, electrocution, and fire associated with outdated wiring, could make it challenging to get coverage for your property. Even if you find an insurance company that will cover a house with knob and tube wiring, your policy will likely come at a premium. This is one of many reasons to have it replaced as soon as possible.

What to Do if You Have Knob and Tube Wiring and BX Wiring

Knob and tube wiring was followed by BX wiring or armor-clad wiring. This wiring is a flexible metal conduit cable covered in thick plastic insulation. Introduced into the National Electric Code (NEC) in 1903, BX wiring became the primary wiring type in 1932 and was gradually phased out in the 1940s. As such, BX wiring systems are just as old as many knob and tube systems. Moreover, many Seattle homes have both wiring types.

Unlike knob and tube wiring, most BX wiring can safely co-exist with building insulation without posing a serious fire risk. Moreover, many home insurance companies will cover properties that have BX wiring even if they won’t cover homes that have knob and tube wiring. Notwithstanding these things, if you have both wiring types in your home, it’s best to have them replaced at the same time. BX wiring is just as outdated, and it’s just as likely to have hazards that were introduced over decades of electrical system repairs.

Ask for Separate Quotes

One way to determine whether or not replacing both BX wiring and knob and tube wiring is right for your home is by asking for separate quotes. You can get a breakdown of the costs for removing all knob and tube wires and a separate quote for removing all BX wiring. In most Seattle properties with both wiring types, replacing everything at once is the most cost-effective solution. These combination projects eliminate the need to open drywall or use other invasive techniques in low-access areas more than once. They also allow for seamless, fully updated, and safe electrical systems.

Boost the Value of Your Home and Support Your Modern Lifestyle

Replacing outdated knob and tube wiring will boost the value and marketability of your home and bring it up to all relevant building codes. Not only will this make it easier to attract qualified buyers if you ever choose to sell, but it will also ensure that your electrical system can pass all lender-required inspections.

Having all-new wiring will additionally allow you to fill your living space with all of the appliances and gadgets that are essential for supporting your modern lifestyle. With updated wiring, you can have a modern HVAC system, entertainment center, smart home features, and more. You can also take advantage of the latest options in whole-house surge protection.

Contact the Professionals

At Brennan Electric, we’ve proudly served Seattle, WA and the greater King County area since 1987. We offer top-rated electrical services and cutting-edge portable and standby generators. Our clients can turn to us for electrical panel replacement, hot tub wiring, RV plugins, advanced smoke and carbon monoxide detectors, and more. If you’re ready to have your BX or knob and tube wiring replaced, give Brennan Electric a call today!

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