Knob and Tube Insulation

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#1

Originally Posted By: dfrend
This post was automatically imported from our archived forum.


Was doing some consulting work for a contractor friend the other day. The house had what we thought was knob and tube. The electrician out there said it does appear to be knob and tube, but they used stranded fixture wire and not the solid cable used for knob and tube. I have never come accross knob and tube before.


The electrical system was determined to be a mess. There was bx tied into the knob and tube. Knob and tube wiring went down the walls to outlets which appeared to be wired with more modern means but the knoba nd tube was live. And the electrician was unable to find where the source of the power to the knob and tube came from. There was bx and romex coming from the panel installed in 1983. But somewhere between the cellar and attic it became knob and tube.

Anyhow, the question is: can attic insulation be added somehow with the knob and tube wiring? If so, what is acceptable?

--
Daniel R Frend
www.nachifoundation.org
The Home Inspector Store
www.homeinspectorstore.com

#2

Originally Posted By: mcraig
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I do a lot of turn of the Century homes and have seen a lot of Knob and Tube wireing. I would need to answer several questions before makeing any desision on a plan for installing insulation 1) the Year of the House? also in most homes I see 1910 threw 1930 the wire insulation may be brittle and moving it to install insulation could crack it and make it a possable fire hazerd, next you said there is wire installed that dosn’t look like knob and tube this could be a spliced in new service addition this needs to be traced back to the splice to make sure the splice is correct in the original knob and tube wireing you would find that a splice would have been solderd then in the early nineteen hundreds it would have been wraped in black cloath type tape if you find a modern type connection like a colored wire lug I would stop and recomend a rewire of the house for safety reasons if knob and tube wireing has been modified there is to high of a chance for fire, also the main panel on knob and tube is 99% of the time 60 to 100 amps not grounded. if modern appliances are to be used this can have bad safety risks to it. Next what type of insulation is going to be used? I always tell people to check on Blown in so that you dont


disturb the wireing if at all posable. I have actualy inspected homes here that are over 80yrs old with working knob and tube wireing (it was undisturbed and in a dry attic in AZ.) you can live with knob and tube wireing if you are aware of simple rules like turn off everything on a circuit when you plug in a vacuum cleaner or you will blow a fuse. icon_lol.gif also this type of wireing is not good for your modern appliances, TV’s, computers, dishwashers, A/C etc… icon_lol.gif icon_lol.gif


Enjoy the time you have with this I love old homes they are a learning expierence like no other take a lot of pictures and enjoy. icon_lol.gif icon_lol.gif icon_lol.gif

#3

Originally Posted By: rmoore
This post was automatically imported from our archived forum.


dfrend wrote:

Anyhow, the question is: can attic insulation be added somehow with the knob and tube wiring? If so, what is acceptable?

Here in Washington State it's not automatically disallowed, but read the following.
Quote:
WAC 296-46A-324 Knob-and-tube wiring. Article 324 NEC does not prohibit the installation of loose or rolled thermal insulating material in spaces containing existing knob-and-tube wiring provided that all the following conditions are met:

(1) The wiring must be surveyed by an appropriately licensed electrical contractor who must certify that the wiring is in good condition with no evidence of improper overcurrent protection, conductor insulation failure or deterioration, and with no improper connections or splices. All repairs, alterations, or extensions to the electrical system must be inspected by an electrical inspector as defined in chapter 19.28 RCW.

(2) The insulation must meet Class I specifications as identified in the Uniform Building Code, with a flame spread factor of twenty-five or less as tested using ASTM E84-81a. Foam insulation may not be used with knob-and-tube wiring.

(3) All knob-and-tube circuits must have overcurrent protection in compliance with the 60 degree C column of Table 310-16 of the NEC. Overcurrent protection must be either circuit breakers or Type S fuses.

I don't know how many electricians (or their insurance companies) would be willing to "certify" old K&T, but I imagine it's a very, very small number.

--
Richard Moore
Rest Assured Inspection Services
Seattle, WA
www.rainspect.com
#4

Originally Posted By: gbeaumont
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Hi to all,


Dan I have to agree with Richards answer, I myself teach that insulation over K&T is both undesirable and potenialy dangerous for the following reasons.

1. K&T was designed to operate in "free air"
2. Installing insulation can easily further damage old wiring
3. Burying K&T in insulation can lead to further accidental damage to the wires (getting stood on etc)
4. in your particular case where energized K&T is present and connected to other wire forms in unseen locations I would recommend without doubt that the systems should be replaced.

Regards

Gerry

--
Gerry Beaumont
NACHI Education Committee
e-mail : education@nachi.org
NACHI phone 484-429-5466

Inspection Depot Education
gbeaumont@inspectiondepot.com

"Education is a journey, not a destination"

#5

Originally Posted By: jpeck
This post was automatically imported from our archived forum.


From the 2002 NEC.


ARTICLE 394 Concealed Knob-and-Tube Wiring
- I. General
- - 394.1 Scope.
- - - This article covers the use, installation, and construction specifications of concealed knob-and-tube wiring.
- - 394.2. Definition.
- - - Concealed Knob-and-Tube Wiring. A wiring method using knobs, tubes, and flexible nonmetallic tubing for the protection and support of single insulated conductors.
- II. Installation
- - 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 in 394.23 only as follows:
- - - - (1) For extensions of existing installations
- - - - (2) Elsewhere by special permission
- - 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

--
Jerry Peck
South Florida

#6

Originally Posted By: rmoore
This post was automatically imported from our archived forum.


It’s now WAC 296-46B-394…they changed the numbers but the wording remains exactly the same.


Jerry... Yep...394.12(5) sure does read like it's prohibited. I have no idea how our local guys managed to come up with their translation...but that's the current "law" around here as far as I can find out. The "certification" requirement pretty much prohibits it anyway.

--
Richard Moore
Rest Assured Inspection Services
Seattle, WA
www.rainspect.com

#7

Originally Posted By: dfrend
This post was automatically imported from our archived forum.


Thanks for the help. The electrician is recommending all new wiring since the wire used is not the right wire anyhow.

–
Daniel R Frend


www.nachifoundation.org


The Home Inspector Store


www.homeinspectorstore.com

#8

Originally Posted By: mcraig
This post was automatically imported from our archived forum.


This is another example of how things are different in different parts of the Country. You are all right if you read my post I said if there was any sign that the Knob and Tube wiring had been messed with to rewire the home. Next off in Arizona we did not have Historic districts set up until recently to make sure that older homes were cared for properly. So I see things that you won?t see in Boston etc? Most old homes fall in two categories out here 1) the attic has never been entered in over 50 years so it is intact the k&b has not been disturbed in any way or shape these homes are rare and beautiful to see. Next off is what I see the most where Harry Homeowner did his own upgrades with his brother the handyman (unlicensed). So here is what I was trying to explain on this post. We didn?t have home inspectors certified until only three years ago and people out here have always done there own thing even on home additions there are many homes that didn?t have permits on them and there are areas out here that if you did the addition over X-number years ago that it will be accepted weather it had a permit or not. These old homes here had many years of people playing with them they were not protected by historic societies.


So I tell someone that is going to insulate one of these homes with k&b wiring to think about blown in insulation because they will have to get a contractor to do this they cant go to Home Depot with there brother and get roles of insulation and cover everything up. Most contractors will tell them not to insulate at all but if they are set on it they will only blow in 2 inches of insulation and leave the k&b wiring exposed. The only time Harry home owner gets in his attic out here is to install ceiling fans or pull his cable (TV) to an inside wall. Or in time they will have to repipe water and gas. I agree with you all but things are different out here and have to be handled differently I just answered this so people could see that there are other ways of things being done