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K&T under cellulose insulation


mridgeelk
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I found this today in an attic. It was active. The owner said the cellulose has been there over 25 years without any problem. I explained to my client the safety hazards of this situation, how some insurance companies view this setup and to have it reviewed and evaluated by a licensed electrician. The owner said that the house was inspected by his insurance company about three years ago and did not mention anything about the wiring.

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Well, it isn't right, but I see it all the time, I grew up w/it, and honestly, the likelihood of anything going wrong is just about zilch.

That said, I always tell folks to get rid of it. I explain it along the lines of "do you really want to wait until it's a problem? Because it will be a very big problem."

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I had a home that was "completely" remodeled that had K&T just this week. It too was covered with insulation. The prospective buyer called his insurance company at my recommendation and they (State Farm) said they no longer cover homes with K&T. End of story and sale!

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It's not a "serious code violation" here,

This is one of those western states that Bill referred to that allows it to be covered with blown-in cellulose. In fact, down by the airport, where they have soundproofed literally tens of thousands of homes by adding new triple-glazed windows, storm doors, pumped cells into the walls and attics, and built sound baffles under/around the attic vents, the city had a program of having Seattle City Light go out, inspect the K & T, and then post a certificate that says it was approved for burial in cells.

Blown-in cells is permeated with borate so it won't burn. I've actually found bad K & T connections buried in the cellulose where the connections have been arcing and overheating - probably for years. The cells all around the splice was scorched black, and the material around the wiring was warm - almost hot - to the touch, but the borate-permeated cells surrounding the wiring had prevented any sparks from flying around and igniting any of that old tinder-dry wood in the attic, so all that the bad splices were able to do was scorch the insulation, which had literally snuffed out any fire.

The whole idea of not covering it is so that it will cool more efficiently is fine, except I sometimes wonder how much of that was originally based on science instead of supposition. I routinely uncover and touch the insulation on one or more K & T conductors in cells-filled attics to see how hot they are, and it's pretty clear that they don't get hot in the winter months - unless they're overloaded or poorly splices anyway - and even in the summer months they only get mildly warmer. However, it rarely bumps out of the 70's here in the summer and when it does the temps will usually peak around 90 to 93 degrees. Under those circumstances, it might get about 115 to 130 in an attic in the summer and the wiring buried in that insulation is usually fine - not hot at all compared to the rest of the attic.

I'm not saying that the cells covering the wiring is a good thing, 'cuz it isn't, but circumstances are different in different places. In other states, where the summer temps are routinely in the high nineties, I suppose attic temps could get so high that the combined heat from solar gain, the heat from an accumulated load, and the inability of the wiring to cool because insulation is packed around it can all combine to make it overheat, and that could ignite the insulation. However, where it's buried in borate-treated cells, I don't think it will do much more than scorch the insulation - it's the other stuff; very dry framing and paper facings on other types of insulation that one has to worry about.

I'm not an electrical engineer but some electrical engineer somewhere has decreed that covering K & T is a bad thing. OK, I accept that, except that convincing someone that K & T buried in cells is a bad thing (here) is difficult when it's the utility provider that inspects this stuff here and has posted inspection certificates everywhere that says the wiring is perfectly alright to bury. Here, I have more success just explaining that the stuff is an obsolete system that's usually rife with improperly-made splices outside of junction boxes that can't be seen because they're buried in the cells. Even that used to elicit a lot of push-back from 'zoids until some insurance companies began either refusing to insure a home that has it or charged higher premiums. Once word got out about that, the attitude of the 'zoids changed markedly.

This is not a one-size-fits-all business. A good inspector has to know peculiarities of his own region as well as others in order to be able to properly educate clients about their prospective new homes.

ONE TEAM - ONE FIGHT!!!

Mike

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Originally posted by hausdok

It's not a "serious code violation" here,

I don't know where "here" is, but I hope you are not under the NEC, because if you are, unless you have a SPECIFIC amendment, it IS quite illegal.

ARTICLE 394 Concealed Knob-and-Tube Wiring

394.12 Uses Not Permitted

Concealed knob-and-tube wiring shall not be used in the following:

(1) Commercial garages

(2) Theaters and similar locations

(3) Motion picture studios

(4) Hazardous (classified) locations

(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

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Originally posted by Speedy Petey

Originally posted by hausdok

It's not a "serious code violation" here,

I don't know where "here" is, but I hope you are not under the NEC, because if you are, unless you have a SPECIFIC amendment, it IS quite illegal.

ARTICLE 394 Concealed Knob-and-Tube Wiring

394.12 Uses Not Permitted

Concealed knob-and-tube wiring shall not be used in the following:

(1) Commercial garages

(2) Theaters and similar locations

(3) Motion picture studios

(4) Hazardous (classified) locations

(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

Not illegal just not permitted by the code.

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Originally posted by Speedy Petey

Originally posted by hausdok

It's not a "serious code violation" here,

I don't know where "here" is, but I hope you are not under the NEC, because if you are, unless you have a SPECIFIC amendment, it IS quite illegal.

ARTICLE 394 Concealed Knob-and-Tube Wiring

394.12 Uses Not Permitted

Concealed knob-and-tube wiring shall not be used in the following:

(1) Commercial garages

(2) Theaters and similar locations

(3) Motion picture studios

(4) Hazardous (classified) locations

(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

I'm in Washington State; it says so right next to my user name.

You're wrong; the NEC is not a law until it's proclaimed a law by a governing power that has jurisdiction. As you must be aware, neither the NEC, or any other code, is ever adopted in-toto and untouched by legislators. In our case, there is an FPN at the bottom of the section you cite that says: See WAC (Washington Annotated Codes) 296-46B 394 001, knob-and-tube wiring, for insulation voids in spaces containing existing knob-and-tube wiring. If you look at the City of Seattle Electrical Code, which is the NEC, you'll find whole sections lined out that refer to WACs.

As Bill and I have already pointed out, some western states permit it 'by law' so it is not illegal. Here's your reference: http://apps.leg.wa.gov/WAC/default.aspx ... 96-46B-394

We all of us have to be careful not to be so quick to declare a code fact when we don't know the rules that were adopted in the area that we're criticizing.

ONE TEAM - ONE FIGHT!!!

Mike

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Mike,

Deferring to a licensed electrician in NY will only get you someone with a municipal license.

As I have stated in the past, NYS does not license contractors, not electricians, not plumbers, not builders.

Most municipalities do not license contractors, some do. Of the ones that do, some are meaningful, most are not.

Kinda like state licensing of home inspectors.

Tom Corrigan

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You're wrong; the NEC is not a law until it's proclaimed a law by a governing power that has jurisdiction. As you must be aware, neither the NEC, or any other code, is ever adopted in-toto and untouched by legislators. ..........

We all of us have to be careful not to be so quick to declare a code fact when we don't know the rules that were adopted in the area that we're criticizing.

Actually Mike I am not wrong.

I NEVER stated this was for everyone. In fact, the first paragraph in that post said exactly what you just did:

Originally posted by Speedy Petey

I don't know where "here" is, but I hope you are not under the NEC, because if you are, unless you have a SPECIFIC amendment, it IS quite illegal.

I specifically state, "IF you are under the NEC without amendments..."

Obviously, you do not fit this description.

I for one am VERY surprised that your state would turn that code 180 deg around and allow this, but then again, I am in NY. We have our own problems.

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Originally posted by Speedy Petey

I for one am VERY surprised that your state would turn that code 180 deg around and allow this, but then again, I am in NY. We have our own problems.
Yeah, I know a little about New York; my father lives in Dutchess County and built houses there for more than half a century. It could be worse; we could be working in Chicago where everything is in conduit and they don't know what NM looks like.

OT - OF!!!

M.

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  • 2 weeks later...
Originally posted by hausdok

It's not a "serious code violation" here,

This is one of those western states that Bill referred to that allows it to be covered with blown-in cellulose. In fact, down by the airport, where they have soundproofed literally tens of thousands of homes by adding new triple-glazed windows, storm doors, pumped cells into the walls and attics, and built sound baffles under/around the attic vents, the city had a program of having Seattle City Light go out, inspect the K & T, and then post a certificate that says it was approved for burial in cells.

Blown-in cells is permeated with borate so it won't burn. I've actually found bad K & T connections buried in the cellulose where the connections have been arcing and overheating - probably for years. The cells all around the splice was scorched black, and the material around the wiring was warm - almost hot - to the touch, but the borate-permeated cells surrounding the wiring had prevented any sparks from flying around and igniting any of that old tinder-dry wood in the attic, so all that the bad splices were able to do was scorch the insulation, which had literally snuffed out any fire.

The whole idea of not covering it is so that it will cool more efficiently is fine, except I sometimes wonder how much of that was originally based on science instead of supposition. I routinely uncover and touch the insulation on one or more K & T conductors in cells-filled attics to see how hot they are, and it's pretty clear that they don't get hot in the winter months - unless they're overloaded or poorly splices anyway - and even in the summer months they only get mildly warmer. However, it rarely bumps out of the 70's here in the summer and when it does the temps will usually peak around 90 to 93 degrees. Under those circumstances, it might get about 115 to 130 in an attic in the summer and the wiring buried in that insulation is usually fine - not hot at all compared to the rest of the attic.

I'm not saying that the cells covering the wiring is a good thing, 'cuz it isn't, but circumstances are different in different places. In other states, where the summer temps are routinely in the high nineties, I suppose attic temps could get so high that the combined heat from solar gain, the heat from an accumulated load, and the inability of the wiring to cool because insulation is packed around it can all combine to make it overheat, and that could ignite the insulation. However, where it's buried in borate-treated cells, I don't think it will do much more than scorch the insulation - it's the other stuff; very dry framing and paper facings on other types of insulation that one has to worry about.

I'm not an electrical engineer but some electrical engineer somewhere has decreed that covering K & T is a bad thing. OK, I accept that, except that convincing someone that K & T buried in cells is a bad thing (here) is difficult when it's the utility provider that inspects this stuff here and has posted inspection certificates everywhere that says the wiring is perfectly alright to bury. Here, I have more success just explaining that the stuff is an obsolete system that's usually rife with improperly-made splices outside of junction boxes that can't be seen because they're buried in the cells. Even that used to elicit a lot of push-back from 'zoids until some insurance companies began either refusing to insure a home that has it or charged higher premiums. Once word got out about that, the attitude of the 'zoids changed markedly.

This is not a one-size-fits-all business. A good inspector has to know peculiarities of his own region as well as others in order to be able to properly educate clients about their prospective new homes.

ONE TEAM - ONE FIGHT!!!

Mike

I am an electrical engineer and K&T wiring is meant to be air cooled. As we all know, putting insulation around it can raise its temp and possibly allow a fire.

I know State Farm doesn't allow any active K&T, but that is the only one I've heard that definitely doesn't allow it.

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