HGINS - How Old Knob and Tube Wiring Can Impact Home Insurance

Buying An Older Home? Old Knob and Tube Wiring Can Impact Home Insurance

Looking to buy a vintage home? Check the electrical! If it has knob and tube wiring, there could be complications both for safety and home insurance

The idea of purchasing a vintage home is a dream for many of us. A home with a long history that has a unique character and individuality that you just can’t find in newer construction is super appealing.

The practicalities on the other hand can pose some serious challenges. The electrical wiring is chief among them. If it’s a home that was built before 1940, there’s a good likelihood that it was wired with old-school knob and tube wiring.

What’s wrong with knob and tube? Well, simply, it can pose a fire hazard and pose problems when you try to insure the home. If this is an investment property and you are the landlord, the same goes – insuring the home could be a challenge if you’ve got knob and tube wiring.

Understanding knob and tube wiring

Between the late 19th century and the late 1930s, the knob and tube wiring system was the industry standard for electrical wiring in homes and buildings. It consists of a series of copper conductors that run through walls and ceilings via an insulating tube made of porcelain. The wiring is nailed down and supported by white porcelain knobs.

Two copper wires – one hot and one neutral – pass through insulating knobs and tubes. The knobs hold the wiring in place. The tubes prevent the wires from fraying or unravelling and coming into contact with nearby surfaces such as wood or other flammable materials that could ignite if overheated.

To power switches, lamps, and other electrical fixtures, the conductors were fed into them, protected by an insulating cloth known as loom.

How is it different from modern electrical? The old knob and tube wiring has no ground wire. There is very little protection against shock if you touch it and there’s also a greater likelihood that it will cause a fire.

However, during the years it was in use, early in the era of electricity technology, knob and tube wiring was the best way of providing electricity to homes and buildings.

When Did They Stop Using Knob and Tube Wiring?

Expensive to install, knob and tube wiring slowly phased out of use, particularly as more modern electrical systems and technologies were put into place across North America. By the 1940s, it was slowly replaced with electrical wiring systems that bundled hot and neutral cables. The new systems also provided a new level of safety: grounding.

As a result, it’s hard to find a home built after 1950 with a knob and tube wiring system. And, most of the homes with the old system were renovated to remove it because the insulation, made of either porcelain or rubber, eventually wore away, leaving the wiring dangerously exposed.

Dangers of old wiring

Knob and tube wiring is not, inherently, a danger. But, modern electrical practices are, by far, much safer. Given the advanced age of the system, the insulation tubes just deteriorate over time. And with enough deterioration, the wires can become exposed, posing a significant risk of fire to the home or building. There are five primary risks when the home uses knob and tube wiring.

  1. Brittle insulation. Naturally, over many decades, the porcelain tubes that insulate the copper wiring lose strength over time and become brittle. Once it’s brittle, it cracks and flakes, leaving the wires exposed. If they’re close enough to wood or other flammable, they can ignite.
  2. Damage. When there is damage to the system it can cause serious safety concerns. Whether it’s age, modifications made or any other situation that has damaged the porcelain tubes, the result is frayed and exposed wiring that can easily cause harmful shock when touched or ignite nearby flammables.
  3. Modifications. Most of the problems that homeowners experience with their knob and tube electrical stem from improper DIY modifications made to the wiring. Given how old and obsolete the system is, finding replacement components and parts can be difficult. Consequently, some homeowners take things into their own hands and improvise potentially dangerous fixes. For example, splicing old tube wiring into new can create a potentially risky result.
  4. Excess use. At the height of knob and tube wiring use, compared to today, there really weren’t that many electrical components to support. At most, there were lights, the telephone, and maybe a radio to power. The system wasn’t designed to handle the electrical demands of 21st-century life! Everything we do – television, refrigerators and freezers, device chargers, game consoles, washers, dryers, and all the other appliances pose a significant risk to such an archaic system’s ability to function. When the knob and tube system is tapped out in the amount of power running it can handle, it will overheat and combust, creating a serious risk of fire to your house.
  5. Insulation that covers the wiring. Household insulation is made from highly combustible fibreglass material. If it is inadvertently installed over the copper wires of a knob and tube system, it essentially turns your attic or basement into a huge tinderbox! Electricity produces heat and it needs a lot of space in which to disperse it and prevent it from becoming a hazard. Insulation impedes the process of heat elimination and can create a very dangerous situation.

Consider, too, if your old wiring system is close to the water system of your home. Water and exposed wiring and water is a volatile combination!

Should you purchase a home with old wiring?

Can you say, deal-breaker? it’s common for homes with old-style wiring to be a difficult sell. Prospective buyers understand the complications – time and cost – associated with an old electrical system. Outdated wiring means increased fire risk.

But, you shouldn’t simply dismiss a desirable home that has old wiring outright. Before you decide, get the wiring inspected and assessed by an electrician. There are vintage homes that still have the old wiring, but it’s not in use. If the old wiring is still in use, you might have to replace it.

NOTE: Many insurance companies will require you to replace it within 60 days or they won’t insure the home.

Before you purchase an older home, get all the information you need! Contact a qualified electrician for an assessment of the electrical system and what might be involved to fix it.

Questions about your home insurance or purchasing home insurance for a vintage home? GET IN TOUCH with an HG Insurance representative to get the answers you need!