ECN Forum Forums General Topics of the Trade General Discussion Area Knob and Tube?

I've filled dumpsters with K&T in my carear.

I suppose at one time it was a premium install, after all much of the world continues to operate on this fairly outdated wiring method

If in fact it was left alone it is usually not the worse for wear, it's when the years of retrofit, tag-on, and similar intervention starts that bad things happen.

20 years ago, a home inspector in his 70's whom had previously been an EC installing K&T told me 'you young bucks are'nt going to top this method'

maybe he had a point? we've been trying to one-up the mighty fuse ever since also.....

1999 NEC
Art. 320 - Open Wiring on Insulators (read knob & tube)

320-3 - Uses Permitted
'Open wiring on insulators shall be permitted on systems of 600v or less only for industrial or agricultural establishments,indoors or outdoors, in wet or dry locations, where subject to corrosive vapors, and for services.

320-5(a)
Conductors shall be of a type specified by Art. 310

ever seen a K&T meter setup?

they're a riot........can't quite find one on the net tonight......
(hint hint....)




somewhat debatable method eh?
from this site

knob....tube!

not enough cobwebs to keep me happy here....

if your good, these go flying with one whack of the hammer...

[This message has been edited by sparky (edited 05-11-2003).]

[This message has been edited by sparky (edited 05-11-2003).]

sparky,
Thanks for the cool pics, mate!!.
This system, seems to me like the most simple of wiring techniques.
Although, you would think that the wires must have been pretty cheap, who these days would run a whole heap of single cores around a building, to effect the same thing as a 3 core or similar?.

Small aside — In sparky’s last picture, porcelain knobs were usually furnished with a ~12-penny nail and with some—a washer of cut leather.

Nowadays, I imagine the high-brow construction junk shops—er, “vintage building restoration and antiquities” firms are probably selling salvaged knobs and tubes at 50 times their original price.

As far as “cutting-in” to existing K&T from modern nonmetallic cable, I have successfully {passed inspection by} using a 3¼-inch metal octagon box, with a clean ~6-inch length of romex jacket as “loom” for single conductors exiting the box. In these cases, just dogged off the bare ground with a standard 10-32 green/hex machine screw, for luckily there was no need to extend an equipment-ground conductor.

If you want knobs and tubes come to Oak Park, IL and you can get about a million of them. Many of the homes are pre and early 1900 and many still loaded with k&t. I have fun all the time trying to get the electrician to tie in the existing k&t properly on partial remodels.

I even saw a non-compliant installation of k&t that looked ok except for the fact that no knobs or tubes were used. Just wire run thru holes in the joists.

Yes even in the early 1900's there were the handy man specials!!

When I worked at the Great Lakes Naval Training Center Fire Department, we remodeled the day room in one of the "out" houses - two bay frame fire houses that had been built as "temporary" structures during WWII, and were still occupied 55 years later...

Chock full O' K&T. Replaced it all w/EMT, but it was still in pretty good shape.

Since someone reopened this thread, Article 324 in the 99 code allows K&T ONLY for extensions of existing, or by special permission.

It is not a grounded system, which is it's worst feature electrically speaking.

Trumpy, think open air, cause that's what this was, it would take lots and not harm anything. Anywhere it touched wood it was insulated with porcelain (if done properly). It was also often done with hard drawn copper, which made it even tougher, and danged hard to cut.

Thanks George,
Knob and Tube just seemed like a really strange way of wiring a house.
But, I suppose they just used what was available back then!.

In Austria (and probably elsewhere in Europe) the earliest way of electrical wiring were twisted cloth wires like old lamp cord on porcelaine insulators, always surface mount, with beautiful porcelaine and brass rotary switches and receptacles mounted on wooden pattresses. In rural areas this wiring method was used well into the 1920ies if not longer. 2 or 3 years ago I saw a house where all that wiring was still in service. There weren't any junction boxes, just open taped splices on the wall. Max. 2 receptacles in each room. In this house I also saw a really weird thing, a piggyback plug. It was an angle plug that plugged into the receptacle and the a second plug went into the back of the plug. I don't think combining more of these would be a good idea...