Knob and tube wiring

In early 2018, I purchased a house "as is". It was a house sold through an estate and it had been lived in by three generations of one family. Both the good and the bad news was that it had not been updated. My biggest concern was that it had knob and tube wiring. Everywhere.  Knob and tube wiring made me nervous and my number one priority after the purchase was to replace all the K&T (short for Knob and Tube).

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This is the wiring that always seems to be a big issue in many HGTV shows (Property Brothers, Love it or List it etc.). In these HGTV shows, they always seemed surprised to find knob and tube wiring, but I sure wasn't. The sellers, including the real estate agent, were very upfront about some of the issues of the house. And then there was the 64-page inspection report ...

Knob and tube switches and fixtures.

All the light switches looked like this. I loved the look of these push-button switches. But my electrician said I couldn't keep these. Fortunately, I found modern, safe reproductions!

Here is an example of the reproductions I had installed.

I was in love with my dining room chandelier light.  Many of my light fixtures were original, fit the style and age of the house and I loved them!  The fixtures did need to be rewired but that was much cheaper than buying new ones.

Some sketchy DIYs

One of the main reasons I was afraid of the knob and tube electrical system was because there were DIY's like the one below, which was behind the fridge.  I'm assuming they were DIY projects!    I'm sure an electrician wouldn't use a power bar to plug in electrical appliances.  How safe were the installation of the newer modern wiring and any recent repairs.  Seeing this concerned me that unsafe splices might be hidden from view.  I did not know if there were any unsafe modifications behind the walls.

It sure looked a lot better once my electrical contractor installed a proper electrical outlet!   I felt a little more assured that this was done to the national electrical code.

I guess you can see why replacing all the electrical was a huge priority for me!

(FYI, I do share the cost and some cost-saving ideas of rewiring your home further down).

Why replacement of the knob and tube wiring system was a priority.

There were safety issues, insurance issues, and peace of mind assurances I needed.

Safety Issues

Lack of Grounding

Did you know knob and tube wiring doesn't have a ground wire?  So, all those appliances etc., are not grounded when they are plugged in.  Just because you can plug in a plug with three prongs doesn't always mean that outlet is grounded - it just looks like it is.  Seeing the three-prong outlets that weren't grounded made me not trust what was there.  The technical term is there is an absence of an electrical grounding conductor.

Live wires touching flammable materials

There was some visible damage caused by rodents in my attic.  The live, exposed wires were touching the flammable insulation.  I would never have been able to sleep knowing my house had wiring that in certain areas was a fire hazard.

Loose insulation covering knob and tube wiring in attic.

Safely installed K&T has the wires suspended in open spaces so that the wires can be kept cool. Insulation covering the wires does the opposite and allows the wires to get hot. This could be a potential fire hazard.

A licensed electrician should do a full inspection. But he/she wouldn't be able to see what was in the walls.

My home inspector told me my knob and tube were properly installed and most of it was safe.  But, I needed to get a licensed electrician to do a thorough electrical inspection of all of it (some was in the ceiling and some in the walls!). In my mind it would be a partial inspection because they wouldn't be able to see everything.

Original k&t systems were not made for modern demands of electrical systems.

When I purchased my home, I was happy to note it didn't have fuses in the electrical panel.  However, even though there were circuit breakers, it was felt that with modern use, the panel should be upgraded.

When my system was installed in the early 1920's, things like washers, dryers, sound systems, and computer systems didn't exist.

So many GFCI's!

There were a number of ground fault circuit interrupter (GFCI) electrical receptacles in my house.  Those are the outlets that can individually be tripped and have a little reset button on each outlet. The number of those in my home made me uncomfortable.  Especially when some of them made buzzing sounds or did not reset.

The electrical receptacles (outlets) in the bathrooms and kitchen were not grounded.

If I had chosen to keep the existing knob and tube wiring, they all would have had to be changed to GFCI receptacles. Even with GFCI's, there still wouldn't have been a ground, but the individual outlet could trip.

The k&t was almost 100 years old!

There was the potential that some of the wiring could stretch or sag within walls or ceilings. If this was the case, the wires might not be suspended to allow the heat to dissipate.

Also, the wires were insulated with a rubber-coated cotton cloth tube in areas. This rubber could become brittle, fray or damaged purely from age! This covering is called loom. It's the black tube-type covering shown in this picture (closer to the switch).

Signs of bad unprofessional electrical DIY's

This should be of concern for any electrical system! Another hint that there are issues is extension cords being used extensively.

Insurance Coverage and Potential Issues

I was surprised my homeowner's insurance company didn't have an issue with the wiring.  I was told that although my home insurance didn't have an issue at that point, there was a potential insurance issue later.

In some areas, home insurance companies will either not insure the house with knob and tube electrical wiring or they will charge a premium.

What knob and tube systems/components look like

But, back to the knob and tube. This is what they look like.  The knob is on the left and then there are three protective porcelain tubes.  At the bottom is the rubberized flexible cloth tube called a loom (that I mentioned above).

The porcelain knobs were nailed into the wood so that they could hold the wires away from the wood. This was so the wire would be exposed to air so it wouldn't get hot and start a fire. The knobs made sure the wires were kept safely in the hollow spaces of walls and did not touch anything flammable.

How to know if you have knob and tube wiring?

Professionals such as a licensed electrician or home inspector can easily tell you.

If you are trying to figure it out yourself, the easiest way is go into the basement and look at the joists.  Do you see the knobs and ceramic tubes like the pictures above and below?  That's a good indication.

In the picture below, take a look below the knob, and you will see how the tube is used.   The copper electrical wire is threaded through the 2 x 4 and the tube insulates the wood from making contact with the wire.

I had my electricians pull out all the old k&t wiring even though it was disconnected.  I didn't want anyone buying the house (years and years from now) seeing it and thinking there was still live knob and tube.  Sadly, I can't find the box where I had all the knobs and tubes stored!

Rewiring the house was my number one priority when I purchased this house.  I even ended up firing my first electrician because he didn't seem to feel it was as important as I did.

I have a walk-up attic.  One day, when I win the lottery, this is going to be a really fun hang-out room.  But not now.

There was a rough wooden floor in the attic but it was removed so that the electricians could replace the wiring in the second story.  I had the choice of taking down the second story ceiling or the attic floor.  So the floor went.   That's when we discovered that the insulation was not good and the wiring was touching it.

The wiring had also been nibbled on by, I believe, some mice.  So there was exposed wire touching the flammable insulation.  So yes, I was glad I decided to rewire the whole house.  It gave me peace of mind knowing I made the right decision to replace everything especially once I saw what I could have potentially have left in the ceilings.

One of the most exciting things I did was remove a kitchen wall when I did a total kitchen gut and renovation.  If you want to see those details, take a look at my post called, My Kitchen Renovation, I bought a house without a kitchen!

The kitchen had flooded two weeks before someone else was supposed to buy it.  They backed out of the closing and I was able to buy it.

The dining room looked like this!  Everything from the kitchen, laundry room, and a powder room was in the dining room because of the flood in the kitchen.

See the wall on the left side of the picture below?  That's the wall we took out.

Here's the wall, down to the studs and the original electrical and plumbing.  Three generations of women in one family stared at a wall when they did the dishes.  I had the kitchen sink moved to under the kitchen window.  It wasn't cheap to do, but that's where it was supposed to be!

And when the rest of the wall was taken down, the original electrical wires were the last thing removed.

This was a major remodel.  Do you see the new header in the picture above?  I know way more about the internal structure of my home than most people ever would!  Plus I have pictures!

The picture below is my favorite picture of the remodel.  It's a closeup of the light switches for the kitchen and dining room. Where the wall no longer existed.  And they were still functioning at the time!

Fortunately for me, I was able to buy new, safe reproductions of the push button switches and the inner workings of these lights.  My electrician insisted I replace the old switches because he didn't feel the old ones were safe.  But the new ones that were installed on the main floor look the same!  It was a splurge that I was glad I made.

Replacing the electrical in a house is a ton of work.  I also added a few outlets and they had to cut out big holes in the walls so they could figure out what was behind the lathe and plaster so they could put the outlets in the appropriate places.

I sure had a high drywalling bill as part of this project!

I'm so thankful that I had a great drywalling crew.  They did an amazing job patching up these holes.  You would never know there were holes like this all over my house.  Like over 40 of them!

It was a huge expense rewiring the house but it was the right time to do it.

I also had to gut the one full bathroom in the house and then added one right behind it.  That wall was taken down to allow the electricians and plumbers to do what they needed to do.  Here was the wall after the hall bathroom was removed.

Then the picture below was with the new plumbing and new electrical.  For two bathrooms instead of just the one original.   I do have a post on renovating my hall bathroom if you are interested in reading it.  If you like bathroom remodeling details, take a look at that post.

I found the new style of pipes amusing.  You don't need to be a genius to figure out the red pipes are for hot water and the blue for cold.  And of course, all that new electrical wiring!

Back to the kitchen!  The electricians installed a ton of wiring.

And I was able to install beautiful fixtures like this!

And this.

Push Button Light Switch

The original light switches were replaced with reproductive outlets like the one shown below.  Because people have been asking, here is a link to the vintage reproduction switch and for the vintage switch plate covers.

Is K&T wiring aluminum?

No. It is copper wire. Aluminum wiring was used more during the 1960's & '70's. However, aluminum and copper should still not be spliced together.

Knob and tube rewiring cost

It costs a lot!

This is the question I have received from so many of my readers.  I have decided to share this information with you.

The cost to replace the wiring, including a new upgraded panel was just over $20,000.  That was in 2018, and my house is a two story, approximately 2,300 square foot home.  Sorry, can't give an exact number but the electrical was part of a huge renovation that included a new kitchen, updating two bathrooms and adding a third bathroom.

I'm giving you numbers I pulled out of the quote and that I would tell a friend who is looking to do this.

There are other costs involved. The $20,000 did NOT include the repair of the drywall.

What my electrical bill to replace k&t did not include.

Rewiring the existing light fixtures.  Yes, if they are original, this needs to be done.  I found a great shop that was cheaper than my electricians doing this.

Additional outlets, locations of additional light fixtures, ceiling fans etc.

Patching the drywall.  Areas, where they could not fish new wiring through walls, had to be cut and repaired.  Can't give you a price on how much the drywall cost for the rewiring because I moved walls etc. and it was one big bill.

How to save money rewiring your home.

The main way to save money would be to do the rewiring in stages.  That is if your licensed electrical contractor says your wiring is safe and your insurance company is ok with that.

Rewire areas you are renovating

My kitchen and bathrooms were taken down to the studs.  The electricians loved working on clean and accessible areas of just wood framing.  Below is the wall between a bathroom update and the other side where I added another bathroom.

Rewire safety priority areas first

Discuss this with your home inspector and electrical contractor. Their priorities would be any areas where there are safety issues. In my home that would have been the attic with exposed wiring, and areas where water is used like the kitchen and bathrooms. Also, areas with high electrical usage would be a priority.

Add in hardwired safety features

Although it didn't reduce my bill, the cost of hardwiring my (up to code) smoke detectors was much less than if that was an isolated project.

Careful placement of new outlets and fixtures

I had some significant drywall repairs because of the locations of new outlets. After living in my home for a while, other easier to get to locations would have sufficed (and the drywall repairs would have been fewer and cost less). If I did this again, I'd work closer with the electricians to place the outlets.

Would I do this again?

Yes, yes and yes! For the right house. But, I wouldn't be so afraid of this style of wiring. I also would have appreciated more how most of my wiring was well done and safe. Because of that, I would have saved some significant money!

***Please note that I am not an electrician and I used a licensed electrician to do all the electrical work in my home.   I'm just an interested homeowner, with a very detailed inspection report who likes to share information on my blog.***

Other renovations on my 100-year-old house.

My kitchen remodel.  I bought a house without a kitchen.

My 5 x 8 bathroom remodel - it was a total gut!

Vintage Picture Rails - How they are used.

Vintage crystal doorknobs, mortise locks & skeleton keys.

Adding moisture to dry winter air
The air in my house is so dry my skin feels like it's cracking. And, I can hear the wood cracking from the dryness!