On another forum I've spotted this guy looking to do some 'improvements' to a rental cottage with a solar, and hydro LV system in K&T - I was wondering if any of those across the pond might now of the legalities (Code or otherwise) of that.

Ref: Other Forum

I'm having trouble linking to the thread.

Which forum area/thread title is it?

Paul the thread was removed.

It was getting into a debate about the posters qualifications.

All the person really asked was where to buy knobs & tubes, he was given a link for that.

Bob, Paul, Mark.
I have never seen Knob and Tube used in the UK, and never even knew it existed till I joined ECN. The proposal was to use pv, invert to 230vac, then to 'wire up' a cottage, owned by a UK Charitable Trust, with public access [ ie. not his private dwelling ], with a silly olde-worlde, mock-tudor wire and K&T antiquified 'look' scheme; this by an amateur with no idea of the dangers involved, nor the risk to innocent parties. A person who was also unwilling to accept the advice, doubts and concerns of a certain highly-skilled San Francisco electrician. In this case those at risk are not he [ of whom I don't give a hoot; if he wants to kill himself, that's his right ], but young persons on educational courses.

I have taken the liberty of writing to Mr Simon Roberts at the Pilton Community College, Limecombe Trust, Barnstaple, Devon EX31 1RB, U.K. voicing my concerns.

Alan

As a ps.
Denise worked for a similar educational trust as the lab tech. They were beset by eccentic, [ to be kind], part-time unpaid volunteeers with similar er.. conceptual artistic ideas; usually harmless, like building a full-size Saxon house out of cow-dung and twigs or filling the woods with hundreds of luminous plastic butterflies on sticks. Quite funny sometimes, with me desperate not to collapse in fits of laughter and hurt their feelings! But hey, it's a free country!

This certainly poses some interesting points. I'm assuming that the "Olde Worlde" look he's striving to achieve is for a traditional British cottage, in which case K&T would be totally out of character anyway.

Bearing in mind that electricity in houses has only been around for a little over a century, if the object is to make the place resemble something from much earlier times, I would have thought a wiring scheme which is as inconspicuous as possible would be more the mark. That's certainly what a lot of people in the old places want -- And it isn't always easy with solid stone walls and beams which are covered only on the top (so that the underside of the second floor's floorboards are also the first floor's ceiling).

I'm going to play devil's advocate now though, and say that if the K&T wiring were to be installed properly, would it be a problem? In my opinion, it would certainly not be prohibited here in the legal sense.

In a residential building, whether owner-occupied or rental, compliance with BS7671 (IEE Wiring Regs.) is still not mandatory (at least not in England; it's a little different in Scotland).

The only legal requirement is the much talked-about Building Regs. Part P, which simply states in rather vague terms that the wiring much be installed in such a manner as to be safe, etc.

The American NEC still recognizes K&T as a accepted wiring method in certain circumstances (article 394). If a major electrical code such as the NEC still allows K&T to be used, then I think it would be hard to argue that the method is unsafe.

In Germany K&T was outlawed in 1910!

Usually it looked like this:

I know a few houses in Austria that still have original wiring like that live @230V.

I love the way that stuff looks!

Very old stuff (only seen that once or twice, still live) looked like this:

It sounds rather pointless and it would be totally historically inaccurate, as paul said, for a rural home.

VERY few homes in rural areas had electricity in the days of knob and tube. If you wanted authentic, you'd be looking more at 1930s-50s fittings.

I was in a french house built in the 1500s which used a panel of contactors and low voltage cables to avoid heavy wiring for switches on the walls. All they needed was 12V speaker cable type stuff which could be easily and safely grouted into the stone work.

Sockets were all done in colours that complemented the stonework and hidden as best as possible.

K+T would just look ridiculous in a british cottage.

Did the UK ever use K+T ? If so it would have been in older urban areas only i suspect...

I have K&T fittings here sent to me by ThinkGood ages ago.
Judging by the wire and the insulators, 230V is way out of the question.
No way are they within IEC touch voltage limits.
They don't even comply with basic insulation requirements (ie: Double Insulation).

{Just as a note, thanks a heap ThinkGood if you are watching mate!. }

Well, don't forget regulations were much less strict way back when such stuff might have been used.

Definitely, rural houses are far more likely to have 30s-50s wiring. We've got remnants of the original 1949 wiring in our place. The entire village didn't get electricity until 1949!

I've never heard of it being used here, at least not in general domestic wiring. I suppose something similar might have been employed in the very early days.

We did have a wiring method in the early part of the 20th century which consisted of a kind of wooden trim strip which had grooves along its length into which individual rubber/cloth covered conductors could be laid. A wooden cover then went over the the top of the whole lot so that it could be painted into the room's decor.

Paul,

I've seen the remenants of such a system .. looks a little bit like skirting boards (base boards) or heavy picture rail

If it's a public building, he's got to comply with current IEE regs I would assume.

I often find understated modern fittings can look far better in a very old structure anyway. They're less clunky looking.

[This message has been edited by djk (edited 11-29-2006).]

[This message has been edited by djk (edited 11-29-2006).]

K&T is allowed only for extensions of existing installations, and elsewhere by special permission. In practice, I don't know many AHJs who would look favorably on this. Here in Texas, where I have seen K&T, it's usually limited to the attic, as there was one pull-chain fixture per room and no wall receptacles. Then you will see where receptacles were added in the 50s and wall switches in the 60s, and it's obvious by the type of romex used. It's just stripped back far enough for the romex conductors to reach the distance between K&T conductors. No, that's not the way the NEC says to do that transition, but that's how it's always done, and it will usually have been done fifty years ago.

K&T stopped being used quite a few years before the NEC adopted this restriction, because it is considerably more labor intensive to install than romex.

I read someplace that K&T is still allowed in flood-prone areas, since it dries out faster than other wiring methods.

Next time I'm in Fredericksburg, I'll take pictures of the only modern K&T installation I've ever seen. It's in a former feed store turned brewpub. It uses #8 THHN, and obviously aims for that antique look. The reason #8 is used becomes evident with a close look at the bulbs: 12V. They are fed from 12V isolation transformers. Apparently, that's what it took to get the AHJ to approve the job.

I was wondering just what sort of circumstances would be considered for that special permission to be granted.

Whether by special permission or an extension to an existing circuit though, am I correctly interpreting 394.10 to mean that the conductors may not be exposed to view, other than in an attic or unfinished basement?

In other words, just running K&T wiring along the ceiling or wall of a living room (which is what the original point seems to be suggesting) so that it's clearly on view would not be acceptable?

If it is concealed, it is K&T and subject to Article 394. If it is exposed, it is "open wiring on insulators" and subject to Article 398. Other than that, I'm not sure what differences there are. I do know I have old books showing exposed K&T or open wiring on ceilings of commercial buildings, suggesting that was the right way to do it. I'd say it was rarely left exposed in residences (other than in basements and attics), because it's ugly and catches dust.

Good point. 398.10 seems to rule out use in residential wiring.

The rules here appear to totally rule it out in any residential or business environment.
Double insultation requirements on all cables etc.

Industrially, you would be required to have all sorts of very serious enclosures around any live exposed conductor e.g. bus bars and I'm sure that K&T would be the same.

You see exposed conductors though on those 12V (SELV) halogen lamp fittings i.e. the ones that are pegged onto wires across the ceiling etc
Decorative type things.

[This message has been edited by djk (edited 12-02-2006).]

I'm not that sure it would be illegal here... the typical wire used back then had a double insulation of rubber and cloth, placing it into the same boat as cloth covered iron cords and similar stuff. The typical twisted cord I pictured above is still sold by some companies, the only thing I'm not sure is whether it would be allowed for permanent fixed wiring.