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What is Knob-and-Tube Wiring and Is It Safe?

Knob-and-tube wiring is an outdated electrical system that can still be found in many homes today. But is it safe, and should you replace it? We're sharing how to manage, buy, and sell a house with old-school wiring.

Knob-and-tube wiring is an outdated electrical system that can still be found in many homes today. But is it safe, and should you replace it? We're sharing how to manage, buy, and sell a house with old-school wiring.

The process for buying or selling a home with knob-and-tube wiring can be more complicated than the buyer or seller is prepared for. Knob and tube wiring is a type of outdated electrical system that is still found in homes today, mostly those built between the 1880s to 1940s. It’s in so many homes today, but is it safe and should buyers avoid purchases because of it?

The Basics of Knob and Tube Wiring

Knob and tube wiring is essentially an electrical system of copper wire covered by black tubes and white ceramic knobs that winds through a house in the walls, attics, and crawl spaces. The main difference that makes knob-and-tube wiring so different from today’s electrical wiring, is that knob-and-tube wiring has no ground wire.

Because there is no ground wire, the chances of a fire starting from overloaded circuits is much higher and there’s no protection for it when this type of fault occurs. Wire insulation from this time was also made from materials that degrade over the years, adding an extra layer of headache and danger.

Where You’ll Find Knob-and-Tube Wiring

Many homes built since this time have updated some of their wiring, but knob-and-tube wiring is still present in harder to access areas of the home. This means homeowners may not even know it’s there, especially if camouflaged by the appearance of the updated wiring.

If installed correctly, knob-and-tube wiring can be safe. The tricky part is that most construction companies, maintenance teams, and home builders no longer work with knob-and-tube wiring.

Buying or Selling a Home with Knob-and-Tube Wiring

While knob-and-tube wiring can present some challenges, not all home buyers should immediately write off purchasing a home with this type of electrical system. Getting a professional home inspection before making an offer will ensure buyers walk into the situation with a clear expectation of the quality and type of wiring.

Concessions for repairs may also be negotiated during the inspection on a home with poor electrical structure. Sellers should consider offering buyer concessions as they are less time consuming and easier than having to make the repairs themselves for the buyer. Buyers and sellers can also consider being willing to request or accept a lower offer, rather than have to make concessions for repairs.

For those buying or selling a home with knob-and-tube wiring, it may be smart to work withan experienced agent who can successfully navigate the process and all the negotiations.

Insuring a Home with Knob-and-Tube Wiring

The next phone call made before signing on the dotted line when buying a home with knob-and-tube wiring should be to a home insurer. There is a high chance that home buyers could run into an insurance company that refuses to insure or renew a policy for homes built with knob-and-tube.

If an insurance company does decide to cover a knob-and-tube home, it’s sure to be much more expensive. Consider negotiating this into the price when making an offer or buying. If you’re unsure how to navigate insuring a home with outdated wiring, consider asking a real estate agent for advice.

Hiring a Professional

There is no home inspection code mandating that all knob-and-tube wiring be removed, but any expert would tell a home buyer to do so. The cost of replacing knob-and-tube wiring is dependent on the square footage of the home, and can range anywhere from $8,000 to projects closer to $20,000.

Experts say buyers and sellers should never look to shave costs by replacing the wiring themselves. An unsafe DIY knob-and-tube wiring project is far more dangerous than knob-and-tube wiring alone. It could be more costly down the road, especially if a home inspection reveals a poorly done DIY job, leaving sellers paying to redo their original fix or pay out repairs in concessions.

Sellers looking to be smart with their budgets should consider redoing the wiring during larger remodeling projects when walls are already exposed to cut costs.

When buying or selling a home with knob-and-tube wiring, be sure to consider all costs associated with this from replacement to steeper insurance policies when negotiating price. All of the dollars can add up, and working with a Partner Agent who knows their way around all kinds of homes and understands home improvements, including electrical, can save your bottom line big time in the end.


Reuven Shechter

Reuven Shechter is the Outreach Coordinator at Clever Real Estate, the free online service that connects you with top real estate agents to help save on commission. He spreads the word about Clever, disseminating studies to journalists and developing relationships with media outlets. Reuven is passionate about investing in real estate and creating lasting success for families. His writing has been featured in Max Real Estate Exposure, Leverage Marketing, and more.

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