K & T Question

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kwired said:
I would never sign anything stating there is none in use - unless I did run all new circuits in the place and know nothing old was reconnected.
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Yeah, well, as an electrician I'd assume you'd know for sure whether or not there was anything K&T connected.
 
A/A Fuel GTX said:
Does anyone know when it became a violation to cover knob and tube in attics with insulation?
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1987: NEC- 324.4: "Concealed knob and tube wiring shall not be used in the hollow spaces of walls, ceilings, or attics when such spaces are insulated by loose or rolled insulating material."
 
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jaylectricity said:
I think the main trouble with K&T is when it's installed in a home that still has a fuse panel and that fuse panel has the ability to house 30amp fuses AND the neutrals are all shared so the full load of two circuits may be carried on one neutral for a time.
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I have never seen a neutral shared with more than one circuit on any of the K&T that I have worked on. As far as the size of the fuse being increased, that applies to any wiring method.

Also if there is no insulation the K&T is a "free air" installation and the 60°C ampacity of #14 copper is 25 amps in free air, the 75°C ampacity is 30 amps, so even with a 30 amp fuse, there is not a serious hazard as long as the K&T is not in insulation.
 
LEO2854 said:
With 300 watt lamps....:p
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And duplex lamp adapters.

jaylectricity said:
Yeah, well, as an electrician I'd assume you'd know for sure whether or not there was anything K&T connected.
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Until you have verified what is concealed you don't have a clue. If owner wished to remove all wall and ceiling coverings so it is easy to verify I will not state it is K & T free, even with quite a bit of newer wiring present - they often do tap at least a portion of an old circuit onto a newer circuit.
 
kwired said:
And duplex lamp adapters.

Until you have verified what is concealed you don't have a clue. If owner wished to remove all wall and ceiling coverings so it is easy to verify I will not state it is K & T free, even with quite a bit of newer wiring present - they often do tap at least a portion of an old circuit onto a newer circuit.
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We had to do a k&t check one time and it appeared that the house had been rewired. All the home runs come from the panel (sylvania) were #12 nm (pre 2001 white cerro wire) and every device was also fairly recent and had the newer cable terminated to it.

But we found one lone exception: I happened to notice the faint outline of a faceplate buried under wallpaper in a hallway that shared a wall w/ the kitchen. I sliced the paper around the edges and discovered a duplex double t that was still very much alive and connected to cloth shielded rw.

We got the the rec/ black steel box out and using the dorcy/small mirror combo, we spotted the splice. The "access" to the splice was a hole that had also been papered over and located in the rear of the upper kitchen cabinets on the walls opposite side.
 
ptonsparky said:
The 2 Button switch that still works!
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I believe you can still get them , and The Brass Plates .


All K&T should be removed for lack of Equipment Ground . I have always told people to plan on its removal in other parts of the dwelling when doing a rewire of a Kitchen or room .



Don
 
don_resqcapt19 said:
I have never seen a neutral shared with more than one circuit on any of the K&T that I have worked on. As far as the size of the fuse being increased, that applies to any wiring method.

Also if there is no insulation the K&T is a "free air" installation and the 60°C ampacity of #14 copper is 25 amps in free air, the 75°C ampacity is 30 amps, so even with a 30 amp fuse, there is not a serious hazard as long as the K&T is not in insulation.
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Really no issue with a 30 amp fuse. What planet are you on. K&T us not a free air wiring system.
I had a friend with a apartment bldg with N&T, almost burned to the ground. The renter placed 30 amp fuses in the Edison base holders. cooked the wiring and started a fire one winter. Had a heater plugged in a 14 gauge wire.
 
Sierrasparky said:
Really no issue with a 30 amp fuse. What planet are you on. K&T us not a free air wiring system.
I had a friend with a apartment bldg with N&T, almost burned to the ground. The renter placed 30 amp fuses in the Edison base holders. cooked the wiring and started a fire one winter. Had a heater plugged in a 14 gauge wire.
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If the 14 AWG conductor is not in contact with other materials besides the porcelain knobs and tubes - what is going to start a fire? You could load it until the insulation is burned off which wold likely take well over 30 amps to do and it will still be left hanging there on the porcelain knobs and tubes, it needs to have something combustible in close enough proximity to start a fire.
 
user 100 said:
1987: NEC- 324.4: "Concealed knob and tube wiring shall not be used in the hollow spaces of walls, ceilings, or attics when such spaces are insulated by loose or rolled insulating material."
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Thanks, so prior to 1987, it would have been legal to blow insulation over K & T? I'm sure in this case, it was done pre 1987 so therefore, it would be acceptable as is.
 
kwired said:
If the 14 AWG conductor is not in contact with other materials besides the porcelain knobs and tubes - what is going to start a fire? You could load it until the insulation is burned off which wold likely take well over 30 amps to do and it will still be left hanging there on the porcelain knobs and tubes, it needs to have something combustible in close enough proximity to start a fire.
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I've seen the cloth catch fire

I used to say " those K&t homes have great radiant heat in the walls".
 
A/A Fuel GTX said:
Thanks, so prior to 1987, it would have been legal to blow insulation over K & T? I'm sure in this case, it was done pre 1987 so therefore, it would be acceptable as is.
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Don't know how to interpret what was mentioned there. Could be he just happened to find that section in 1987 NEC or it could be new text for that year.
 
A/A Fuel GTX said:
Thanks, so prior to 1987, it would have been legal to blow insulation over K & T?
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Affirmative-the 1987 nec was the first to address this issue so any insul done prior would have been allowed per the nec and another footnote: it was the 1990 code cycle that prohibited spray foam over k & t.
 
kwired said:
Thanks, that is what I wanted verification of.

This does complicate things though. Technically insulation installed enveloping k &T wiring before 1987 is code compliant.
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It seems it would make things more questionable during a K & T check because barring personal knowledge from the h.o., how would one be certain ​when the attic was insulated with the cellulose?
 
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user 100 said:
It seems it would make things more questionable during a K & T check because barring personal knowledge from the h.o., how would one be certain ​when the attic was insulated with the cellulose?
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Well in say 1992 it may have been more clear how new that insulation may have been, but certainly not as easy to determine today.
 
So without an invoice from the insulator, I guess the HO's word is adequate. Seems impossible to enforce and require any action for removal on existing situations. Maybe I should work on an insulation analyzer to determine the age of existing insulation.
 
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