Knob & Tube Q. for the Electrical Gurus?

[Peter Doane]

Some say its fine, other say its a fire hazard. Installing floor insulation around K&T, is it really a fire hazard? Or is it just the fact that its not readily accessible (viewable) to see potential issues like frayed insulation, improper connections etc. What says you?

[Brian E. Kelly]

http://www.oldhouseweb.com/stories/Detailed/10327.shtml

The greatest problem with such wiring is its insulation, which turns dry and brittle with age and often falls off on contact, leaving the wire exposed. Insulation that can be seen to have failed also will likely have failed where wiring is concealed. If any failed insulation is observed, the knob and tube wiring should be replaced.

So how can the insulation be evaluated if it is covered with insulation?

With special thanks to Abott & Costello, "who's on first?"

[Roy D. Cooke, Sr]

I tell people most insurance companies will not give youcoverage and if you can get coverage you might have to pay a premium.
I recommend upgrading to a modern service,

[Jeffrey R. Jonas]

NEC 324-4...Concealed Knob-and-Tube Wiring...Uses Not Permitted......"or in the hollow spaces of walls, ceilings, and attics where such spaces are insulated by loose, rolled, or foamed-in-place insulating material that envelopes the conductors".

[Peter Doane]

Originally Posted by jjonas

NEC 324-4...Concealed Knob-and-Tube Wiring...Uses Not Permitted......"or in the hollow spaces of walls, ceilings, and attics where such spaces are insulated by loose, rolled, or foamed-in-place insulating material that envelopes the conductors".

Jeff broke out the NEC!

[Jeffrey R. Jonas]

Originally Posted by pdoane

Jeff broke out the NEC!

Yea...well...brain dead tonight...easier to look it up than think about it

Jeff

[Peter Doane]

What I found at the " Weatherization Assistance Program Technical Assistance Centers" Web site here: http://www.waptac.org/sp.asp?id=6914

Electrical Issues - The two primary energy-related health and safety electrical concerns are insulating homes that contain knob-and-tube wiring and identifying overloaded electrical circuits. Older electric wiring, primarily knob-and-tube wiring, located in a wall cavity or exposed on an attic floor was intended by code to have free air movement for that would cool the wire when it is carrying an electric current. Laboratory tests have shown that retrofitting thermal insulation around electric wiring can cause it to overheat, resulting in a fire hazard. The October 21, 1988, Weatherization policy guidance on knob-and-tube remains in effect. The policy places responsibility on the states to ensure that insulation around knob-and-tube wiring conforms with applicable codes in jurisdictions where the work is being performed.
In 1987, Section 324 (article 324-4) of the National Electrical Code (NEC) was revised to prohibit the use of concealed knob-and-tube wiring in the hollow spaces of walls, ceilings and attics when such spaces are insulated by loose or rolled insulating material. Since 1987, NEC added a prohibition against foamed in-place insulation as well. While the NEC is a national code, it is not administered and enforced nationally. Building codes are administered on the state, county, or local level but are usually based on one of the national model codes (e.g., BOCA, CABO, UBC), which reference the NEC for electrical requirements. State or local jurisdictions can amend the model code they have adopted to meet specific local concerns. For example, Washington, Oregon, and two local jurisdictions in Ohio amended NEC 324-4 to allow loose or rolled thermal insulation in spaces containing knob-and-tube wiring providing specific conditions are met. (For more on DOE s Knob-and-Tube guidance, see Attachments 2 and 3.)
Serious electrical hazards exist when gross overloads are present. Should auditors and crews find such existing problems, they should notify the owner. Weatherization measures that involve the installation of new equipment such as air conditioners, heat pumps, or electric water heaters can exacerbate previously marginal overload problems to hazardous levels. The problem should also be noted in the client file. To the extent that these problems prevent adequate weatherization, the agency should consider repairing them on a case-by-case basis.

Attachment 2 here: http://www.waptac.org/si.asp?id=556
Attachment 3 here: http://www.waptac.org/sp.asp?id=7190

[tdietrich1]

I love when I meet people who shout, "All Old Knob and Tube must be exterminated". I ask why, and get a diatribe about reliability, danger, etc.... I usually just point at a utility pole and leave them wondering.

Truth being, if any home improvements are being made, then rather than install stuff around the old wiring(which will get beaten up), best to think about changing it out.

tom

[Brian E. Kelly]

Originally Posted by pdoane

What I found at the " Weatherization Assistance Program Technical Assistance Centers" Web site here: http://www.waptac.org/sp.asp?id=6914

Electrical Issues - The two primary energy-related health and safety electrical concerns are insulating homes that contain knob-and-tube wiring and identifying overloaded electrical circuits. Older electric wiring, primarily knob-and-tube wiring, located in a wall cavity or exposed on an attic floor was intended by code to have free air movement for that would cool the wire when it is carrying an electric current. Laboratory tests have shown that retrofitting thermal insulation around electric wiring can cause it to overheat, resulting in a fire hazard. The October 21, 1988, Weatherization policy guidance on knob-and-tube remains in effect. The policy places responsibility on the states to ensure that insulation around knob-and-tube wiring conforms with applicable codes in jurisdictions where the work is being performed.
In 1987, Section 324 (article 324-4) of the National Electrical Code (NEC) was revised to prohibit the use of concealed knob-and-tube wiring in the hollow spaces of walls, ceilings and attics when such spaces are insulated by loose or rolled insulating material. Since 1987, NEC added a prohibition against foamed in-place insulation as well. While the NEC is a national code, it is not administered and enforced nationally. Building codes are administered on the state, county, or local level but are usually based on one of the national model codes (e.g., BOCA, CABO, UBC), which reference the NEC for electrical requirements. State or local jurisdictions can amend the model code they have adopted to meet specific local concerns. For example, Washington, Oregon, and two local jurisdictions in Ohio amended NEC 324-4 to allow loose or rolled thermal insulation in spaces containing knob-and-tube wiring providing specific conditions are met. (For more on DOE s Knob-and-Tube guidance, see Attachments 2 and 3.)
Serious electrical hazards exist when gross overloads are present. Should auditors and crews find such existing problems, they should notify the owner. Weatherization measures that involve the installation of new equipment such as air conditioners, heat pumps, or electric water heaters can exacerbate previously marginal overload problems to hazardous levels. The problem should also be noted in the client file. To the extent that these problems prevent adequate weatherization, the agency should consider repairing them on a case-by-case basis.

Attachment 2 here: http://www.waptac.org/si.asp?id=556
Attachment 3 here: http://www.waptac.org/sp.asp?id=7190

Look Peter if you are going to answer your own questions...............................

[Peter Doane]

Originally Posted by bkelly2

Look Peter if you are going to answer your own questions...............................

HA!!!!!!! Got me there Brian,.... well I wasnt getting answers quick enough so I was googling info.

You're lucky I recently gave you a greenie, 'cause I was tempted to give you a red square mister but it wouldnt let me.

[Paul W. Abernathy]

Ok..I dont have time to read all the replies to this but I will say this.....when dealing with K & T and placing it within insulation is only part of the problem. The stem of the problem is in old K & T wiring homes the lack of plugs and resources for modern equipment create an overload on the wiring and chances are it has poor OCPD protecting the wiring which results in the conductors heating up and with no way to dissipate the heat as it was intended the conductors heat up, the insulation which is crappy at best cracks away and exposes live conductors......

So in result you have poorly covered conductors exposed which is a hazard to someone crawling around and reaching two possibly potential areas ( you just never know ) and heat from the overloaded improperly protected circuits ( overfused ) can create fire issues and so on.

I like the example where someone says...but Paul it has worked fine for 40 years. Well fires dont burn homes down UNTIL they burn the home down...poor analysis by someone who might raise that point.

But thats just me......others may disagree..

[wforsyth]

Like Roy said, most insurance will not insure, or they raise the premium so high it's prohibitive. My insurance guy when I said I had just shook his head and said no you don't right? No K&T right? and I just started shaking my head cuz back then I didn't know jack and said whatever. And i got my homeowner's insurance which I wouldn't have otherwise and couldn't have purchased my home.

[Paul W. Abernathy]

Wendy,
While insurance people may have certain issues with things, it is not my position to play Insurance agent.

I can only state the facts about K & T as I know them, what I do know is insurance agents also do not like fuses on apartments when to be quite frank it is probably safer considering the wiring that is actually IN the apartments and no real upgrade needs by the tenants.

However I have seen the insurance companies make a landlord upgrade the panel to a circuit breaker only to allow older 1968-1972 aluminum wire within the walls....and did not even demand GFCI's or anything on the existing circuits and they were fine with that....so different strokes for different insurance folks.

[wforsyth]

I wasn't suggesting that at all Paul. It was all just anecdotal.
I was also trying to post something diplomatic about something that Roy had posted.
I think you should LOL or something.

[Paul W. Abernathy]

lolololol........was only adding my comentary Mrs. Forsyth...nothing more.