K & T Question

[A/A Fuel GTX]

I have a house built in 1927 that was written up for K & T encapsulated with insulation in the attic. Does anyone know when this became a violation or was it a violation from day 1?

 

[infinity]

I looked at the 1965 NEC and could not find anything about insulation but it does mention that it is permitted only in "hollow spaces". Doesn't sound like an insulated space is a hollow space. The 1987 added the insulation limitation. In the 2020 NEC is clearly spelled out as prohibited.

2020: 394.12 Uses Not Permitted. Concealed knob-and-tube wiring shall not be used in the following:
(5)Hollow spaces of walls, ceilings, and attics where such spaces are insulated by loose, rolled, or foamed-in-place insulating material that envelops the conductors

 

[A/A Fuel GTX]

Thanks Infinity. If this attic was insulated in the 40's or 50's or prior, would this be considered acceptable? My only other option would be to have all the blown in insulation removed, remove the K & T and reinsulate.

 

[infinity]

Thanks Infinity. If this attic was insulated in the 40's or 50's or prior, would this be considered acceptable? My only other option would be to have all the blown in insulation removed, remove the K & T and reinsulate.

Although the word insulated was added to the code section I believe that it was only done to add clarity. You cannot have a hollow space that is full of insulation.

 

[tom baker]

My neighbor did a major remodel on house with blown in insulation. He sucked the insulation out and blew into a giant bag in his driveway, like a beached whale. Remodeled and blew back into attic

 

[A/A Fuel GTX]

Although the word insulated was added to the code section I believe that it was only done to add clarity. You cannot have a hollow space that is full of insulation.

Agreed but if the code didn't address it prior to the insulation being added and the code is not retroactive, would it be an issue?

 

[infinity]

Agreed but if the code didn't address it prior to the insulation being added and the code is not retroactive, would it be an issue?

It's an issue because it was only permitted in "hollow spaces". Filled with insulation is not hollow.

 

[don_resqcapt19]

I don't see any real world issue with the K&T being in the insulation. The wire separation with that wiring system would result in less heat build up than where NM is in insulation. A single NM cable in insulation does not even require any ampacity adjustment.
However the code sees it as a hazard.

 

[A/A Fuel GTX]

It's hard to tell an elderly couple without a lot of money that the house they've lived in for 60 years needs the insulation sucked out of their attic, the K & T has to be removed and replaced and then the insulation has to be reinstalled. Back to my original post, what code cycle was this cited as an issue?

 

[infinity]

Back to my original post, what code cycle was this cited as an issue?

Post #2.

 

[electrofelon]

I have a house built in 1927 that was written up for K & T encapsulated with insulation in the attic. Does anyone know when this became a violation or was it a violation from day 1?

Just curious, written up by who?

 

[don_resqcapt19]

The substantiation for the 1987 change said:

Weatherization of the hollow spaces by blown-in insulation or roll insulation prevents the dissipation of heat into the Free air space; resulting in higher (dangerous) conductor heat buildup, conductor insulation breakdown resulting in a probable or possible fire situation.

There was one dissenting vote and his statement said:

The substantiation to support this proposal does not contain the necessary factual data to support this restriction on concealed knob and tube wiring. There is a large number of installations of concealed knob and tube wiring. I have neither heard of any problems with this wiring method nor have I seen any studies on actual in service installations that will support this restriction on concealed knob and tube wiring.

I agree with the dissenting comment.

 

[electrofelon]

The substantiation for the 1987 change said:

There was one dissenting vote and his statement said:

I agree with the dissenting comment.

Me too. It's baffling how that passed with no data and solely someone's opinion.

 

[infinity]

Me too. It's baffling how that passed with no data and solely someone's opinion.

Not surprising to me. That seems to be an unfortunate trend with some of the CMP's.

 

[don_resqcapt19]

There were three comments that asked CMP to reject what they did in the first draft. Those comments were all rejected, but in rejecting one of the comments the panel said they do not intend this to be a retroactive rule.

7- 16 - (324-4): Reject
SUBMITTER: Larry Seekon, Minneapolis Electrical Inspections Department
COMMENT ON PROPOSAL NO.: 7-22
RECOMMENDATION: Reject the proposed revision.
"or in the hollow spaces of walls, ceilings and attics when such spaces as insulated by loose or rolled insulation material."
SUBSTANTIATION: No factual substantiation of dangerous overheating has been submitted to justify prohibiting loose or rolled insulation material in contact with concealed knob and tube wiring. I am not aware of fires due ONLY to insulation touching knob and tube wiring. However fires do occur because of overfusing and improper splicing or tapping of these circuits. These hazardous conditions are already Code violations.
In the colder regions of the United States there are many thousands of homes now existing with loose or rolled insulation in contact with concealed knob and tube wiring. Most current building codes require the insulation to be fire retardant.
To comply with such a restriction would result in a substantial increase in the cost of rewiring existing homes. New wiring would have to be fished in or surface raceway would have to be installed to replace existing knob and" tube wiring. Both of these methods are very labor extensive and would substantially increase the cost of rewiring. Many people also object to the installation of surface raceway in the nicely decorated homes. In many circumstances, it would be very difficult if not impossible without damaging the walls or ceilings, for an electrical inspector to determine if insulation
material had been installed.
I am very apprehensive of what a judge would think about an inspector issuing an elderly widow on Social Security an order to eliminate all concealed knob and tube wiring in contact with loose or rolled insulation, especially when the home was reinsulated ten years ago
and there have been no electrical problems.
I foresee many enforcement problems if the proposed revision is accepted.
PANEL ACTION: Reject.
PANEL COMMENT: The Panel wants to reaffirm its previous action and to inform the submitter that it is not the intent to make this change retroactive.
VOTE ON PANEL ACTION:
AFFIRMATIVE: 10
NEGATIVE: Roberts.
EXPLANATION OF VOTE:
ROBERTS: The Panel Action to reject this comment will require that concealed knob and tube wiring installations in older homes be replaced i f , in the process of insulating the home, the wiring becomes embedded in insulation. The Panel has no substantiating evidence to reject this comment. The substantiation stated in Comment 7-16 is correct. Concealed knob and tube wiring systems in thousands of residences are now embedded in insulation and no overheating problems have been reported

It also appears that the Correlating Committee agreed with the negative comment in the proposal stage.

7- 17 - (324-4): Accept
SUBMITTER: NEC Correlating Committee
COMMENT ON PROPOSAL NO.: 7-22
RECOMMENDATION: Give further consideration to the comments expressed in the voting.
SUBSTANTIATION: NEC Correlating Committee action.
PANEL ACTION: Accept.
The Panel reconsidered and reconfirms its previous action. See Panel Comment 7-16.
VOTE ON PANEL ACTION:
AFFIRMATIVE: 10
NEGATIVE: Roberts.
EXPLANATION OF VOTE;
ROBERTS: Same as Comment 7-16.

 

[infinity]

Those comments were all rejected, but in rejecting one of the comments the panel said they do not intend this to be a retroactive rule.

Not being retroactive did not end up in the final version that appears in the 1987 NEC.

This is another example of where the CMP that approved this is clueless.

 

[A/A Fuel GTX]

Just curious, written up by who?

It was mentioned in a home inspection report as the house has been sold.

 

[A/A Fuel GTX]

I really appreciate all the feedback. So, as a licensed electrician who has had this ball placed in my court, if the insulation was installed prior to 1987, there is no liability on me if I document the insulation was in place prior to the NEC ruling?

 

[don_resqcapt19]

Not being retroactive did not end up in the final version that appears in the 1987 NEC.

This is another example of where the CMP that approved this is clueless.

It was never in the code text, just the panel statement.

 

[ptonsparky]

My brother worked for an agency that had enough fires after blowing in insulation around K&T, that they would not do it. Yes, most likely it was in poor repair. Does not matter. It happened.