Originally Posted By: cbuell This post was automatically imported from our archived forum.
May/June 1996
LETTERS
Knob and Tube Not a Fire Hazard
In "Retrofits We'd Rather Forget" (Jan/Feb '96), you made reference to insulating over knob-and-tube wiring as being a fire hazard. This statement is incorrect.
Legislation was enacted in Washington state to allow insulating over knob-and-tube wiring per Bonneville Power Administration (BPA) specifications. This resulted because there were no documented cases of a fire being caused by knob-and-tube wiring, whether insulation covered it or not. Because the two conductors of knob-and-tube wiring circuits are spaced some distance apart, it is nearly impossible to short out. Even when covered with flammable materials such as wood shavings, the only way you could get a short was if the insulating materials were wet ... then they won't burn, so you couldn't start a fire anyway.
Overheating the wire would be the only method of ignition for knob-and-tube. Nonmetallic sheathed cable (NMC) such as Romex, on the other hand, can short as well as be overheated, increasing the potential for fire. NMC has started fires, and we insulate over it.
As an extra safety measure, it is a good idea to use Type S fuses or breakers sized properly for the wire size, the same as you would for NMC. An inspection by the Washington State Electrical Inspector and the installation of proper fusing (or breakers) is a requirement when insulating over knob and tube wiring in Washington and where allowed in other northwest states that follow BPA specifications.
Dale Hellewell
Energy Conservation Specialist
Grant County PUD
Moses Lake, WA
Editor's reply: It's true that insulating over knob-and-tube wiring does not generally create a fire hazard and that the nonmetallic sheathed cable electricians currently use could cause fires. (Knob-and-tube was the most common form of home wiring until about the mid-1940s. See "Knob-and-Tube Wiring Hang-ups," HE May/June '91, p. 7.)
Weatherization program policies concerning insulation in attics with knob-and-tube wiring vary, depending partly on electrical codes. Since 1987, the National Electrical Code has prohibited insulating walls, ceilings, and attics that contain knob-and-tube wiring, but several states have adapted their codes to allow insulation after a wiring inspecton. In the situation discussed in the article, the wiring was not inspected before insulating with cellulose.
Knob-and-tube wiring can be a fire hazard if the original fuses have been replaced with oversized fuses to handle larger electrical loads (an all-too-common practice). Type S fuses prevent homeowners from installing the oversized fuses, as long as the Type S fuses are not oversized. It's also good to check for bad connections or "hot spots," as described in "Assessing the Integrity of Electrical Wiring" (HE Sept/Oct '95, p. 5). Once the wiring has been inspected and proper fuse sizing assured, it should be at least as safe after insulating as before. However, some weatherization programs require a sign to be posted to warn attic-goers of the danger of electrocution from concealed wires.
-- It is easier to change direction than it is to forget where one has been.
Originally Posted By: Mike Parks This post was automatically imported from our archived forum.
Charles
It is up to you who has more credibility.
"Bonneville Power Administration (BPA) specifications."
OR
The NFPA.
I am using my new 1971 NEC (thank you Joe).
324-7(b) Conductors passing through wood cross members in plastered partitions (editors note: I would apply this to drywall) shall be protected by an additional noncombustible, nonabsorptive insulating tube extending at least 3 inches above the member.
Why do you think that the NEC, IMHO, the most credible organization regarding electrical and fire safety would state this?
Who in a court of law would you what on your side?
PS If your area has codified the NEC it is the law.
Originally Posted By: dbozek This post was automatically imported from our archived forum.
New 1971 NEC Mike…me thinks you are like 31 years behind times. Tis not good to use old code books Mike, for the codes in certain areas change every 3 years.
– You cannot help men permanently by doing for them what they should and could do for themselves. Abraham Lincoln
Originally Posted By: jpeck This post was automatically imported from our archived forum.
Dennis,
Mike is referring to his 'new' 1971 NEC he got from Joe T.
Like my 'new' 1935 (among others) I got from Joe T. I have got most of the ones from 1935 to 2002, with many handbooks to go with them. Missing a couple of 1940 years, but would like to fill in my collection backwards to the beginning (I have a replica of the 1897, then I jump to 1935, would like to acquire the in between years).
Ask a question about an older house and the "NEW" 2002 NEC is not necessarily applicable.
Originally Posted By: roconnor This post was automatically imported from our archived forum.
roconnor wrote:
"... look at 2002 NEC 394.12.5 (formerly 324-4) which does not permit K&T wiring to be in insulated spaces. There is a reason that is in the model codes (see the commentary in the NEC Handbook), and has been there for a while ... it's considered to be a fire hazard by NFPA.
Using the current NEC as a guide, I would flag any K&T wiring in insulated spaces as a safety/fire hazard.
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: dbozek This post was automatically imported from our archived forum.
Ok Jerry I see your point about the code books and for the most part probably a good idea to find out how things were done “codewise” in them days. But those were those days…and today is today…umm does that make sense
I reckon if there is a grandfather law then it would be good to check to see if the grandfather situation was done correct to the old codes, but then if a HI is not supposed to quote codes....what would it matter? Why wouldn't it just be better to recommend the sparky? I'm soooo confused with this stuff anymore.....not supposed to quote codes but then go deep in detail about them.....
So lets say you run across some k&t that looks really good and you check the 1935 code book and find out....ohoh....a code violation.....then what? Do ya say.....according to the 1935 code book when this house was built....this stuff is improper.......or do ya just go........recommend further evaluation from a sparky dude? Chances are the sparky doesn't have a 1935 code book....I know I don't. So if I am the sparky...I'm going to relate the situation to the 2002 code. Besides I don't think my van has any room left to carry 40 volumes of code books 
-- You cannot help men permanently by doing for them what they should and could do for themselves. Abraham Lincoln
Originally Posted By: jpeck This post was automatically imported from our archived forum.
Dennis,
You are getting there, getting closer, 
NO ONE, not even an electrician, should ASSUME that anything is, or should be, 'grandfathered' in.
We now know (from past experience) that most (at least much) of todays work does not meet code (not in every single way), thus, why should we automatically assume that an old installation met code back then?
With K&T, having so many problems and so many more potential problems, just either needs to be replaced (safest), or have the entire system thoroughly electrically and visibly checked by an electrician (rather difficult to do).
Dennis, recommend a sparky who will be applying the 2002 code to 1920 wiring? Why on earth would we do that? Either bring the wiring up to 2002 or use the right book for it. Hey,wait a minute, isn't that where I started? Replace the K&T? Yeah, I think it was.
Originally Posted By: roconnor This post was automatically imported from our archived forum.
dbozek wrote:
I'm soooo confused with this stuff anymore.....not supposed to quote codes but then go deep in detail about them.....
It's actually pretty simple. An HI is not performing a code evaluation or flagging code violations. That is left up to licensed design professionals and code enforcement officials. An HI is performing a "visual" observation to determine the overall condition of a dwelling, and to flag any potential deterioration, defects, or hazards.
Current model codes like the IRC and NEC are used by HI's as a guide to help identify defects and safety hazards. So an HI needs at least a working knowledge of those model codes (particularly the IRC), and I highly recommend a more in depth understanding ... thus the detailed discussions about model code provisions.
Take a house that has bathrooms without GFCI protected outlets. If I am wearing my HI hat I dont care what code it was built under, that is a safety hazard in my book and should be upgraded.
Likewise, I don't care what code K&T is installed under ... K&T wiring in insulated spaces is a fire hazard according to NFPA and current model codes, so it will get flagged as a safety hazard every time (but not a code violation).
Do ya follow?
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
