Knob and Tube wiring

6

618electrician

Member
Location
St. Louis
Occupation
Maintenance electrician
by the nec 2020 is nob and tube legal in your house if not covered with insulation. /// ////////////////////////////////////////////////////////////////////////////
 
The NEC is not the only 'approval' you need.
Local building codes may address the issue of adding insu.ation over and around know and tube wiring.
And don't forget insurance companies that get to make up their own approval/disapproval judgements.
 
In most jurisdictions I have worked in, K&T is only allowed to remain if already installed and not covered by insulation, but cannot be added on to. You must run any new circuits in parallel and if the owner wants to insulate, it must all be replaced with modern wiring methods and materials.

But as mentioned, MANY insurance companies are now calling the shots, code or no code, by saying that they will no longer underwrite a home with K&T wiring. In 1998 I sold my house in Seattle that was built in 1910 and was all K&T when I bought it. I completely rewired it, but I just left a lot of the old K&T as abandoned in place (because I was too fat to get to it to rip it out). I got a call a couple of years ago from the guy I sold the house to, because he changed insurance and the new company came to inspect it due to the age, saw the K&T and told him they wouldn’t underwrite the house until it was removed. I had permits on file for my work, and the AHJ was fine with my leaving the old stuff as abandoned in place, but that was not in the permit records. I had to give them an affidavit stating that none of the K&T was in use or connected. They accepted that (along with the permit and inspection reports on file).
 
K&T was a big one about 10 years ago, frankly I see alot of it and if its untouuched I dont see any issue personally. and when did they quit using it 1930? only so may existing homes can have it,
aluminum wiring on the other hand is much more of a snag it is still common for 30 - 50 amp circuits many policies exclude it with a waiver.
I actually had a friend call he thought he had aluminum wiring, what he saw was tinned copper, when I looked over his attic I told him no that's not aluminum garbage you have good quality knob and tube it will last forever! (Just take that penny out from behind the 30A fuse and use a 15A fuse LOL)
 
WD40 said:
K&T was a big one about 10 years ago, frankly I see alot of it and if its untouuched I dont see any issue personally. and when did they quit using it 1930? only so may existing homes can have it,
aluminum wiring on the other hand is much more of a snag it is still common for 30 - 50 amp circuits many policies exclude it with a waiver.
I actually had a friend call he thought he had aluminum wiring, what he saw was tinned copper, when I looked over his attic I told him no that's not aluminum garbage you have good quality knob and tube it will last forever! (Just take that penny out from behind the 30A fuse and use a 15A fuse LOL)
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Most of the issue with the old aluminum was related to the excessive cold flow and temperature related expansion and contraction of the alloy used in the past. All building wire made since the mid 70s uses the 8800 series alloys, and perform much better.
I did a project as an apprentice in the mid 70s, using 10 and 12 new alloy aluminum single conductors in EMT along with CO/ALR. I moved on the service truck shortly after that, and we had no more problems with the aluminum project than with copper projects installed in the same time frame.
 
ptonsparky said:
Knob and Tube would be grandfathered in. If it was legal when installed, it would be legal now. Modifications to it may bring up some issues and local codes along with insurance coverage may add pressure to update. YMMV.
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Have you seen any that wasn't modified, spliced or added to, or covered in insulation post when it was commonly used? I haven't.
 
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