Knob and Tube Wiring

I just purchased an old Victorian ,sort of, farm house with knob and Tube wiring. A lot of it is in pretty bad shape with broken knobs and tubes and
light switches. What I want to do is refurbish the old wiring to power lights and ceiling fans. Plenty of old insulators came with the house. Rest of the house would be modern. Is this legal?
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Jimmie wrote:

Whether it is legal or not is not the first question to ask. Do you want to pay a whole lot more, and spend more time to refurbish K & T to end up with wiring that is unsafe by todays standards?
It is a whole lot better, cheaper and faster to install a circuit with modern wiring than to install a circuit with K & T. Your old K & T system has no ground, and the existing wires have brittle insulation. "Refurbishing" a K & T circuit has to include getting rid of the brittle wiring along with cracked/broken tubes, switches etc.
Unless you have a compelling reason and a bankroll to match, go with new wiring, as has been suggested in this thread.
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and
Rest
Cost is not an issue since I will be doing the work myself and I have bushel baskets of parts. Ground wires can be added out of site and I plan to use the exixting light fixtures and ceiling fans that were made for K&T wiring. It I am not worried about the saftey aspect of it. Electricity was put in this house in the thirties. The K&T iis really the least of my worries. The more modern wiring 50s era is really shot. This definitely has to all be stripped out and totally replaced. The K&T would actually be in pretty good shape except for vandalism that has taken place. Only K&T that I plan on uing is for the lights and ceilng fans. This is all surface mounted on the walls and ceiling where it is visible.Rest of wiring will use modern techniques
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| shape except for vandalism that has taken place. Only K&T that I plan on | uing is for the lights and ceilng fans. This is all surface mounted on the | walls and ceiling where it is visible.Rest of wiring will use modern | techniques
Do what I would do ... leave the K&T unenergized ... present only for looks.
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Tube
bushel
wiring.
The
good
Talked with the building inspectors and they said what I wanted to do with the K&T was OK since the wiring was grandfathered in. I can make repairs to the existing wiring but could not add any more, not that I want to. I thnk they are being very easy on me since it will all be stripped out during restoration of the house
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Applogies for showing my total ignorance here, but can someone please explain what Knob & tube wiring is, as I have never come across the term before. Many thanks. Len.

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term
"Knob and tube" wiring is an obsolete method of running wiring. Individual insulated conductors are used, supported off wall and ceiling surfaces by porcelain "knob" insulators, and where it must pierce a wall or floor joist, the wires are run individually through porcelain tubes. It's very labour-intensive to install correctly and modern buildings are invariably wired with cable - but you'll still see knob and tube in buildings wired before, oh, say, WWII. The rules for knob-and-tube wiring were dropped from the Canadian electrical code a few editions ago and I imagine also from the US NEC about the same era.
Bill
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Many thanks Bill. I must admit that I have never encountered anything like this before, and as you say, very labour intensive to install. Thanks again. Very best regards. Len.

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GKN wrote:

There's also the fact that it is exposed that leads to trouble. I saw a house where the lady hung her wet laundry on metal hangers to dry. She hung the hangers from the exposed K&T wiring in the basement. Not a pretty picture.

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ceiling
wall
tubes.
are
ago
I was mistaken.
It turns out that "open wiring" is still permitted in the Canadian electrical code - they don't call it "knob and tube" but the section mentions supporting wires on porcelain insulators and protecting wires with non-conductive tubing. The section doesn't seem to allow concealed wiring. But it sounds like if you were really bloody-minded you could install something that looks very much like "knob and tube" even today.
Bill
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Rest
Are you talking exposed? If it is inside the wall I would be using modern wiring.
Better check with you local folks first. I would have issues with 120 volt exposed wiring. All it would take is one drunk and you could be going to an funeral. God forbid some child got into it. Just my opinion
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One does not usually "refurbish" knob and tube wiring. For example, replacing broken tubes would require cutting wires and then reconnecting them; not good! If you have an occasional knob that has problems, they could be replaced or tapped with a hammer to seat the nail. (You can have some of the knobs and tubes residing in boxes in my basement -- if you pay the postage and handling. It is much better to replace at least some of the wiring with modern romex (if your local code allows it), AND to install junction boxes where lights/fans will be. The old knob and tube wiring did not use junction boxes for lighting fixtures, and the wiring in those places will usually be brittle and therefore more dangerous. Switch boxes were often heavy cast iron, with no wire clamps and not much room in them, so replacing them is usually a good thing, too. On the other hand, this kind of work does not need to be done all at once -- unless you have a really dangerous situation. Start with an appropriate entrance box, and do a few circuits and additions at a time, perhaps tied in with other work that requires access into wall spaces, e.g., insulation or plumbing. These are opinions based on the approach taken with our house, where we still have just a few knob and tube runs for just a few ceiling lights. Boxes and pigtail leads have been added at all those light positions, however. --Phil
Jimmie wrote:

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mailto: snipped-for-privacy@cc.ysu.edu Youngstown State University
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| I just purchased an old Victorian ,sort of, farm house with knob and Tube | wiring. A lot of it is in pretty bad shape with broken knobs and tubes and | light switches. What I want to do is refurbish the old wiring to power | lights and ceiling fans. Plenty of old insulators came with the house. Rest | of the house would be modern. Is this legal?
I've considered doing this myself. But what I would do is run power only through new modern hidden wiring, up to code and then some (e.g. #10 for 20 amp circuits). I would then refurbish the K&T so it looked new at the era the house would have had it first installed. New wiring with new insulation of the proper type, or none as appropriate for how it was done originally. But ... the K&T would not carry any power. It would be there primarily for looks. In some cases it could carry low voltage signalling such as the open K&T terminating at an old style twist switch. The 1 volt 1 milliamp circuit would be amplified by a transistor circuit run from an isolated 6 volt supply (maybe even battery powered), driving a contactor to turn on the power in the hidden wiring that is safe.
I'd bet the inspector would initially freak out when he first walks in :-)
Of course, in reality he'd be checking the rough-in first, so all the real wiring would be visible then.
Now to figure out how to get the stairway to rise up and have a dragon spit out fire from underneath.
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snipped-for-privacy@ipal.net wrote:

You would be *lowering* the safety/reliability of the circuits and adding unnecessary labor and expense. The #10 wire won't fit standard receptacles and snap switches. You'll need bigger boxes to avoid overfill and in any event, using up additional volume in the boxes with splices that you would not need if you used #12.
There can be individual circumstances where using #10 on a 20 amp circuit is needed - but consider the paragraph above before doing it as a general practice.
<snip>
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On Thu, 21 Oct 2004 03:29:14 GMT snipped-for-privacy@bellatlantic.net wrote: | snipped-for-privacy@ipal.net wrote: |
|> |>| I just purchased an old Victorian ,sort of, farm house with knob and Tube |>| wiring. A lot of it is in pretty bad shape with broken knobs and tubes and |>| light switches. What I want to do is refurbish the old wiring to power |>| lights and ceiling fans. Plenty of old insulators came with the house. Rest |>| of the house would be modern. Is this legal? |> |>I've considered doing this myself. But what I would do is run power only |>through new modern hidden wiring, up to code and then some (e.g. #10 for |>20 amp circuits). |> | | You would be *lowering* the safety/reliability of the circuits and | adding unnecessary labor and expense. The #10 wire won't fit | standard receptacles and snap switches. You'll need bigger boxes | to avoid overfill and in any event, using up additional volume in | the boxes with splices that you would not need if you used #12.
#10 has fit _every_ receptacle and switch I have wired it to, which is several. I didn't need any new splices. I don't do "shared neutral", so those issues don't apply. Only place I've ever needed a splice was on a switch loop or ground.
| There can be individual circumstances where using #10 on a | 20 amp circuit is needed - but consider the paragraph above | before doing it as a general practice.
I've done it before and never had a problem. Good receptacles accept it just fine. Electrical installations are not where I go cheap. And I sure as hell neve use the push-in holes (well, I tried one once to see how it behaved, back in the early 1970's, but I never installed it).
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why?
Plenty of old insulators came with the house. Rest

according to "this old house" it might be safe. see http://www.oldhouseweb.com/stories/Detailed/10327.shtml
just my opinion but i would not feel save living there.
there is a strip of paper like material that runs inside modern house wiring. it is chemically impregnated to prevent rodents and insects from chomping on the wiring.
here is the safety form for the city of Berkley, Ca http://www.ci.berkeley.ca.us/energy/forms/K&T%20Form.pdf
do a websearch on "knob and tube". there seems to be insurance issues in a lot of places.
i have seen a result of an old wall lamp miswired to a 2 wire circuit in an old house. it had a hot base. fortunately my friend lived.
do yourself a favor. modernize.
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Since you plan to do some rework anyway it would be in your own best interests to do it right. Rip out the dangerous K+T wiring and replace it with modern, more safer stuff.

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Rest
In general concealed Knob and tube wiring is permitted for extensions to existing installations by the 2002 NEC. I think the 2005 NEC has removed this but we will have to wait and see when the 2005 NEC comes out. NEW Exposed knob and tube wiring is not permitted for dwelling units and is not permitted concealed in any installation by Article 398.
Article 394 covers concealed knob and tube wiring. Article 398 covers new installations and exposed knob and tube wiring. Here are some excerpts.
"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"
"394.23 In Accessible Attics. Conductors in unfinished attics and roof spaces shall comply with 394.23(A) or (B). FPN: See 310.10 for temperature limitation of conductors. (A) Accessible by Stairway or Permanent Ladder. Conductors shall be installed along the side of or through bored holes in floor joists, studs, or rafters. Where run through bored holes, conductors in the joists and in studs or rafters to a height of not less than 2.1 m (7 ft) above the floor or floor joists shall be protected by substantial running boards extending not less than 25 mm (1 in.) on each side of the conductors. Running boards shall be securely fastened in place. Running boards and guard strips shall not be required where conductors are installed along the sides of joists, studs, or rafters. (B) Not Accessible by Stairway or Permanent Ladder. Conductors shall be installed along the sides of or through bored holes in floor joists, studs, or rafters. Exception: In buildings completed before the wiring is installed, attic and roof spaces that are not accessible by stairway or permanent ladder and have headroom at all points less than 900 mm (3 ft), the wiring shall be permitted to be installed on the edges of rafters or joists facing the attic or roof space."
"ARTICLE 398 Open Wiring on Insulators I. General 398.1 Scope. This article covers the use, installation, and construction specifications of open wiring on insulators. 398.2 Definition. Open Wiring on Insulators. An exposed wiring method using cleats, knobs, tubes, and flexible tubing for the protection and support of single insulated conductors run in or on buildings. II. Installation 398.10 Uses Permitted. Open wiring on insulators shall be permitted only for industrial or agricultural establishments on systems of 600 volts, nominal, or less, as follows: (1) Indoors or outdoors (2) In wet or dry locations (3) Where subject to corrosive vapors (4) For services 398.12 Uses Not Permitted. Open wiring on insulators shall not be installed where concealed by the building structure."
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