Knob and tube tie-in

[danickstr]

I couldn't find a supplier int he greater Seattle area today to sell me the proper knob and tube fittings to bring it into a box. Makes me think that no one is actually doing it to code, or selling complete tear-outs. Are they just burying the connections where the inspector can't see them?

Anyhow I wondered what most folks use to make it up, since I can't find anything.

 

[ultramegabob]

I wouldnt touch knob and tube except to remove it, just run a new circuit from the panel if you have to add somthing....

 

[480sparky]

What 'fittings' are you looking for?

 

[brother]

I couldn't find a supplier int he greater Seattle area today to sell me the proper knob and tube fittings to bring it into a box. Makes me think that no one is actually doing it to code, or selling complete tear-outs. Are they just burying the connections where the inspector can't see them?

Anyhow I wondered what most folks use to make it up, since I can't find anything.

just what type of 'connectors' are those. I will admit that is 'very rare' that I see people in my area even fool with knob and tube.

 

[danickstr]

If it was code in the past then they have to give us a way to incorporate it. There is not much wrong with good knob and tube, IMO, other than it has no ground. Its not like the casing will magically vanish and one wire will jump across the joist bay and ignite. It cuts harder with my snips than the stuff I am using now. The customer does not want to tear out a bunch of the ceiling in another room just to replace a run that goes through that area, and I really don't see why they should.

 

[480sparky]

What fittings are you looking for? I'm unaware of any special fittings for K&T, other than loom.

 

[480sparky]

From the 1959 NEC:

370.7(b) Metal Boxes and Fittings. Where metal outlet boxes or fittings are installed with open wiring or concealed knob-and-tube work, conductors shall enter through insulating bushings or, in dry places, through flexible tubing extending from the last insulating support and firmly secured to the box or fitting.

370.7(c) Non-Metallic Boxes. Where non-metallic boxes are used with open wiring or concealed knob-and-tube work, the conductors shall enter through individual holes. Where flexible tubing is used to encase the conductor, the tubing shall extend from the last insulating support and may be run into the box or terminate at the wall of the box. If non-metallic sheathed cable is used, the cable assembly shall enter the box through a knockout opening. Clamping of individual conductors or cables to the box is not required where supported within 8 inches of the box.

 

[danickstr]

I didn't notice that was from 1959 right away. Wondered how I had missed it all these years, but it would be 4 years til I was even born

I am not going to stress about it. I will put loom around the wires and gently clamp it and make up the box. See how it goes. I know I have seen some kit for it but I can't find it on the web.

This particular K & T have never been exposed since install and apparently has not ever been overheated by an oversized fuse, so it still has almost all of its waxiness and suppleness. Otherwise I would not advocate leaving it.

 

[480sparky]

..........I am not going to stress about it. I will put loom around the wires and gently clamp it and make up the box. See how it goes. I know I have seen some kit for it but I can't find it on the web........

If it's a metal box, run them in through the same connector.

I didn't notice that was from 1959 right away...........

Then look in your '08 for 314.17 (B) and (C). Look familiar?

 

[danickstr]

I guess it does still allow for good ole' K & T. Thanks! I must be thinking of the old splice kit that is not legal anymore.

 

[480sparky]

I guess it does still allow for good ole' K & T. Thanks! I must be thinking of the old splice kit that is not legal anymore.

You mean the old 'tie it in anywhere and wrap it with tape' splice?

 

[danickstr]

lol. There was some sort of underground looking splice kit that was legal at one point, but I think it is not allowed anymore. I think there is a thread on it here or some other forum.

The K & T used to have in run t-splices of course, but due to idiot homeowners making bad ones, we now have to use stupid boxes.

 

[al hildenbrand]

Look at 2008 NEC 300.16(A)

300.16 Raceway or Cable to Open or Concealed Wiring.

(A) Box, Conduit Body, or Fitting. A box, conduit body, or terminal fitting having a separately bushed hole for each conductor shall be used wherever a change is made from conduit, electrical metallic tubing, electrical nonmetallic tubing, nonmetallic-sheathed cable, Type AC cable, Type MC cable, or mineral-insulated, metal-sheathed cable and surface raceway wiring to open wiring or to concealed knob-and-tube wiring. A fitting used for this purpose shall contain no taps or splices and shall not be used at luminaire outlets. A conduit body used for this purpose shall contain no taps or splices, unless it complies with 314.16(C)(2).

As well as 2008 NEC 394.56

394.56 Splices and Taps.
Splices shall be soldered unless approved splicing devices are used. In-line or strain splices shall not be used.

And then look at 110.14, which I won't insert here.

There used to be a fitting that I've known as a birdseye that would go on the end of NM cable, allowing the sheath to end, and allowing the inner conductors to emerge into free air through two bushed holes. One then splices the NM conductors to the K&T at the knobs, using a bit of loom from the fitting to the knobs.

 

[danickstr]

So if it is twisted together, soldered and taped up like a split bolt (110.14), it does not require a box? The GC would love that, since he hates blank SG boxes. I have many hundreds of hours of soldering experience from low voltage work making custom cables. The trick is to never rely on flux core solder. It runs away just when you need it. Just slather on the flux and use solid solder.

 

[al hildenbrand]

So if it is twisted together, soldered and taped up like a split bolt (110.14), it does not require a box?

I like to sokder mine, as well. The splices are K&T splices. They're done without boxes. The key is the "or", the fifth word in 300.16(A).

 

[ohm]

Two seperately bushed holes? Aren't they afraid of overheating the metal box?

My first exposure to electricity was w/ K&T. Wonder if I can still do a Western Union tap...now where did I put my 300W iron?

 

[al hildenbrand]

Two seperately bushed holes? Aren't they afraid of overheating the metal box?

There's no box. This is a fitting. Think of it as a little weatherhead with a romex clamp in its base. The holes are in a non ferrous surface so there can be no heating issue.

 

[ohm]

There's no box. This is a fitting. Think of it as a little weatherhead with a romex clamp in its base. The holes are in a non ferrous surface so there can be no heating issue.

Thanks Al I vaguely remember that. I was just kidding about the heating, I think it's way overrated.

Especially, everytime I use my Lincoln welder. The leads come out two seperate holes in sheet metal and never get above ambient even at 225A AC.

 

[gndrod]

K&T

K&T

I couldn't find a supplier int he greater Seattle area today to sell me the proper knob and tube fittings to bring it into a box. Makes me think that no one is actually doing it to code, or selling complete tear-outs. Are they just burying the connections where the inspector can't see them?

Anyhow I wondered what most folks use to make it up, since I can't find anything.

McClendon's or Habitat Second Hand Recycle Store in SouthPark.

Check with the AHJ on K&T splices. Some locals no longer allow tinned splices in remods.

 

[e57]

I deal with K&T a lot - and still solder, etc. A little skill can go a long way to save surfaces that no carpenter could reproduce today in older buildings. (without considerable expense)