Knob &Tube Wiring Dense Pack Insulation
Kimball_house
| Posted in Energy, Heating & Insulation on
I’ve decided to add dense pack cellulose to exterior walls in this 1905 two story NJ Victorian. The most credible installer told me that the remaining active knob and tube wiring is not a problem and they routinely add dense pack cellulose in such situations, having done hundreds of similar houses without a problem. Websites clearly recommend replacing K&T wiring. Thanks for advice. In the case you recommend replacement, are there efficient strategies to identifying runs and replacing? Interior walls are lath and plaster. Exterior is shake with asbestos shingles added decades ago.
Replies
All I know is that our local electrical inspector told us that codes did not allow dense packing cellulose in walls with existing knob and tube wiring. Your insulator might have done 100's of houses without a problem, but from a code point of view, if one in a thousand burns, and someone dies, that's too many.
My understanding is K&T needs to breathe. Why not skip the wall cavities with the K&T in them?
Family.....They're always there when they need you.
no DP with knob & tube
but K&T is bad news anywaysget it rewired .... snake new wiring and have the K&T removed from the panelbeware of funny circuits with it alsoMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
I was going to suggest the rewire too but I wasnt sure how far he wanted to go here.
I agree. I've taken it out of all my rentals, not worth the worry.
It was a neat system though, run one set of wires the length of the house then simply tap in wherever you need to.
Family.....They're always there when they need you.
Ditch the knob and tube.
Jeff
I always thought K&T didn't meet current codes. I ran into a house inspector once. He said K&T is just fine, meets current codes; it's a good technology (it keeps the wires separate). Having said that, our conversation had nothing to do with 1) insulation and 2) the practical aspects of K&T (installing or dealing w/ it later).
I'd check w/ the BO if you have any issues. Remember, the contractor is technically on the hook, so he should know what the code allows him to do. While installing insulation may be considered a somewhat benign contracting activity, there are issues that may be significant, so he really should know if this is a code issue. If anything happens to your house, it would be his liability. That doesn't help if it is 15 yrs from now and he's long gone.
Check w/ the BO to be sure, though. Test the contractor's reaction to see if he is still worth his salt.
Logically, I'd think it's a non issue. It's not that much different from other wire; but I ain't no 'lektrishon, so I wouldn't know. Maybe these comments will attract other comments ...
>>I always thought K&T didn't meet current codes. I ran into a house inspector once. He said K&T is just fine, meets current codes;He was technically right until the last code revision.
"Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."
Howard Thurman
"He was technically right until the last code revision."Have you seen the 2008?At least through the K&T was one of the allowed wiring methods and not just grandfathered in, but can be extended.But from monitoring forums there are lots of local variations in what is "accepted". In a number of areas insurance companies specifically ask about K&T and won't insurance a new purchase if it is not replaced.But people in one state (IIRC it was either Oregon or Washington) state inspectors allow it to be covered with insulation if an electrician certifies that the wire insulation is in good shape. I suspect that this is only for attics where the wiring is visible before hand..
William the Geezer, the sequel to Billy the Kid - Shoe
Well allrighty. Although I suspect it does still meet current codes ... in the sense that if it is allready there, you don't have to tear it out. You just can't install it ... which w/ the products currently available, there is no reason why you would want to. I don't know of any house inspection (e.g. for renovation and/or financing) that would red flag K&T ... but admitedly, I'm not very close to that kind of activity. I suspect it is much like many code issues ... it is grandfathered in as being acceptable. Few codes require you to go retrofit to bring something up to current standards/codes.
Why is it not allowed when, as I said, that it is specificaly listed in the code as an acceptable method.From the 2005 NEC."394.10 Uses Permitted
Concealed knob-and-tube wiring shall be permitted to be installed in the hollow spaces of
walls and ceilings or in unfinished attics and roof spaces as provided by 394.23 only as
follows:
(1) For extensions of existing installations
(2) Elsewhere by special permission"Then that section goes on to detail the requires for installing it.And it is mentioned in many other sections such as what kind of boxes can be used..
William the Geezer, the sequel to Billy the Kid - Shoe
>>I've decided to add dense pack cellulose to exterior walls in this 1905 two story NJ Victorian. The most credible installer told me that the remaining active knob and tube wiring is not a problem and they routinely add dense pack cellulose in such situations, having done hundreds of similar houses without a problem.
He is absolutely wrong. First, the installation/blowing itself could damage the K&T. Second, the amperage rating of K&T is based on being in open air. Put insulation around it and there is a definite hazard.
I suggest asking a fire marshal or fire investigator whether doing so is safe. (You might also ask the insulation installer how many fire sites he has investigated.)
As an HI, I have asked a number of electricians, a couple of insulators and a number of fire fighters and investigators over the years that very question.
Electricians: probably 10: against.
Insulation guys: "No problems"
Fire folks: 100% against.
(You might gently suggest to the installer that he make sure his insurance carrier does not learn of his practices....)
BTW, there are number of joisey folks here - where you from?
"Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."
Howard Thurman
Insulation guys: "No problems"
Well here is one against. I used to insulate 100's of houses with DP. I never put any on knob and tube wiring. I was told that the boric acid would eventually eat away any insulation on the wires. I have to believe that because I have seen it eaten away when it was touching roach poison. Even in this backwards place for codes in Texas I dont know of any insulators who will admit to doing it.
That guy has got to be a hack and needs to be out of business or at least go get some school on the subject.Due to the recent state of the economy, the light at the end of the tunnel has been turned off