K & T still in use- Hey Guru's !!!

These pics are from todays inspection. House built in 1921. Several additions and remodels later, the Knob and Tube is still in use in the attic. Not sure who did thier electrical work but someone should smack the sh*t out of him! There are open boxes, splices, wire running wild everywhere.

I do have a question though. I seem to recall that live K&T should NOT be buried with insulation. Is this a true statement? Thanks for your help fellas, Rick






Correct K&T is designed to operate in free air



Thanks Gerry !

Yup, what Gerry said.
And if anyone extended that K&T they definitely should be smacked.

Remember write hard talk soft miss nothing .
I write on every one of my reports to please check with your insurance company re Home insurance.
If they ask I remind them that many companies no longer will give insurance in our area for Knob and tube and also Fuse panels.

… Cookie

Thanks Speedy, hell they extended it, spliced into it all over the place up there.

Good advice Roy, thanks !

I inspected a home recently, that had been beautifully remodeled, new paint, wallboard, fixtures, flooring, etc. I got into the attic, and saw a large amount of the very same electrical defects in the attic. Horrible. It was not a question of “if” the house would burn, but when! “Flip this house” my ***!

Unfortunately this is a VERY common mentality Mike. This is the same mentality of electricians who do sloppy rough-ins.
Out of sight, out of mind.

Off topic but may be an item:

Most of the insulation in the background appears to be vermiculite. In my area, 90%+ of vermiculite here contains 1-5% asbestos. It came from the Libby, Montana mine.

Some people do not want to purchase a home with a potential environmental concern at a future re-sale and have walked from houses with this brand of vermiculite or it was removed as part of sale conditions($3,500 - $5,000+). Recently I had an electrician/trade school instructor with training about asbestos simply show no concern and buy the house.

Reality is, most old government buildings including most schools have asbestos or vermiculite in them. It is not a panic situation. Do not entertain your guests in the attic! As long as it is undisturbed it should not be a concern. Big trucks drive by my house all the time. As long as I do not walk in front of them, it is not a concern.
Just advise the purchaser of the situation but explain this area is separate from living quarters. If someone has to work up there they need to be advised to wear protective gear. (If it is a man, he will not listen anyway.)
When I was a mason in the early eighties, I probably poured a billion bags of this stuff in many walls in Alberta. I am not dead yet… or am I ?

BAck to electrical… my house was listed as “UPGRADED WIRING” When I looked at it, it looked just like the first picture. Any new wires that had been added had every ground cut. They added a 220 subpanel 2feet above the bathtub and ran a BX cable out to the water heater. And cut the ground off… can you say… bzzzzzzzzzzt! Here is a photo of one good connection.


I’m not an alarmist on this stuff! Was just giving the range of reactions that you will get when you mention asbestos here. I got booted from Mike Holme’ forum for challenging the top poster’s and moderator’s claim that “One fiber can kill you” Alarmist or what?

Here’s my website page where, in the second section, I challenge a local engineering/testing/remediation company’s attempt to make big $$$$$ on mould, some very minor, in attics. They claim to kill the mould and then apply “AEGIS”, a very good “physically resistant to mould/bacteria” compound to the sheathing- cost $4-5 per sq ft!..so a small bungalow costs $5-6,000!!!

The current consensus that K&T should not buried in insulation comes mainly from two theories;

  1. It can not dissipate its own heat
  2. deteriorated wire insulation and connections outside of electrical boxes pose unseen hazards to those who might be working in the space.

Lets look at the first one. “It can not dissipate its own heat.”

More accurately, It was not designed to operate burred in insulation. While this may seem like semantics, it is important to distinguish between the two statements. The difference is the original design and intent of use.

The statement “designed to operate in free air” suggests that it was purposely designed that way. The designers gave thought about it being buried but in the end developed a product that that either they, or though testing, decided it should not be buried. This is unlikely since insulation was not used very much back then. At least by today’s standards.

The statement “not designed to be buried in insulation” means just that. It was not considered in this application. It may work just fine who knows. My wife’s cooking was not designed to fill the kitchen garbage can but it works just fine in doing it :frowning:

The load on the circuit may have changed over the years as people tapped into it for more power how ever if the over current protection device is sized accordingly there should not be any heat dissipation problems. After all, if we can bury a Romex cable (with two conductors running side by side) in insulation, why would that cause less heat than the same gauge of single K&T wire. It won’t. In fact in theory it should be more because of the bundling of the two wires into a single cable. The difference comes in the wire insulation. The wire insulation used in Romex has been tested and marked that it will withstand a certain temperature. What is the temperature that the rubber wire insulation used on K&T will withstand? Is it still the same after decades of use? Unknown.

It is for this reason that I prefer to use the statement “not designed to be buried in insulation”. This, in conjunction with not being able to fully see an aging wire system for inspection on a regular basis are good enough reasons in my opinion to just replace it.

Ontario Hydro has never condemned it, providing its in good shape. To say that all K&T has to be replaced is a misnomer unless its in poor shape, or renovations are planned anyway. The demand by insurers is not back up by any code or authority.

I tell people that knob and tube is is “acceptable if done right”… but that when there is a significant quantity of K&T present, I almost never see it done right, and in any case visible K&T is often seen extending into into areas where it cannot be visually inspected, so I can’t tell if it’s done right.

BTW, some AHJs specifically allow the installation of loose-fill insulation over knob and tube:


K&T and insurance:


K&T and the NEC: