More Knob & Tube

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bjp_ne_elec

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I just did a search and couldn't find something specific I'm looking for direction on.

This old house that I took the previous pic of that "brass" cap. There is an old fuse block - the ones that had the fuse in line with both the hot and the neutral. There was a Romex just run to it from the new style panel (looks like they may have been added 4-5 year ago) - but whoever did the work just simply spliced in to the existing K&T in open air just putting wire nuts on what would be the line side of the fuses. I'm not sure why they just didn't run the Romex's hot and neutral to the line side of the fuse blocks - but I'm not even sure that's legal. Is it?

Even if it's not legal, it would be safer than having two open air splices with no JB.

Now my next question. If you had K&T that was running out to parts of the house, is it legal to feed the existing K&T with a new Romex. I'm asking this question, as I had no experience even going through my apprenticeship with K&T. As I said in the previous post, the house I grew up in had it, and my father re-wired it - but I was "knee high to a grasshopper" when he was doing this. So, could one the proper size Romex to a non-metallic box and then feed some existing K&T that was still existing in an older house?

I did find posts that covered capping off some ends of K&T, where some part of the circuit was eliminated. This covered removing "downstream" wiring. But my question is dealing with the other end.

Thanks
 
bjp_ne_elec said:
Now my next question. If you had K&T that was running out to parts of the house, is it legal to feed the existing K&T with a new Romex.
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Now you need to go to the truck and read art. 394. And yes you can feed the K & T with romex.

Edit to add last sentence
 
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OK - Dennis made me go to the truck. Read it, and I'm still not sure what the answer to my question is.

What's surprising is, that if my interpretation of 394.10(1) is correct, you can still use K&T to extend existing locations. Now, I know I wouldn't even think of doing that.

I don't see in 394 where it deals with tying in existing K&T, or did I totally miss something ( I do have ADD - so it's possible)?
 
So Dennis, as far as the splice point, would it be permissible to do this in a non-metallic JB? This is working off your feedback that you can feed existing wK&T with Romex.
 
Yes you could extend K&T.

The transition between K&T and NM is covered in 300.16(A)

I suggest you search for posts by member e57 , he has a K&T pamphlet posted around here somewhere. He deals with a lot of it and is a stickler for doing things right. :cool:
 
OK - now after reading 300.16, are those holes that you punch out of an NM box acceptable - running each conductor (hot and neutral) through a separate one? They aren't officially "bushed". I think I did find one of his posts that dealt with how to splice K&T - pretty informative - but I didn't come across something that specifically dealt with the transition from Romex (or any other wiring method for that matter) and K&T.
 
bjp_ne_elec said:
OK - now after reading 300.16, are those holes that you punch out of an NM box acceptable - running each conductor (hot and neutral) through a separate one?
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Look for K&T to be stamped inside the box, many time it is there and that means you may use it with K&T.

The few times I have had to work with K&T I use a 4" square box with plastic bushings for each K&T.
 
If I had to work it, I'd prefer using something NM, as then there's much lower risk of shorting. Concern is breakdown of the insulation.

I usually use those light brown Allied Molded boxes, so I'll have to see if they're listed for K&T.
 
bjp_ne_elec said:
If I had to work it, I'd prefer using something NM, as then there's much lower risk of shorting. Concern is breakdown of the insulation.
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Properly installed and maintained K&T is is very safe.

Typically the problems are where the unqualified modify it.
 
iwire said:
Look for K&T to be stamped inside the box, many time it is there and that means you may use it with K&T.

The few times I have had to work with K&T I use a 4" square box with plastic bushings for each K&T.
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Never seen a box stamped K & T. I've seen many stamped T & N, however.
 
i really appreciate some of the craftsmanship i see in knob and tube. i take time to look at it every time i rip it out. its pretty interesting seeing how electricians of the past done things. using a bit brace to drill all those holes must of been a good time
 
electricalperson said:
using a bit brace to drill all those holes must of been a good time
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That's why old electricians have forearms like Popeye.

popeye-yam-spin.gif=
 
What's the proper way to cap the end of a run of K&T?

What's the proper way to cap the end of a run of K&T?

Seem to be running in to a rash of homes with K&T. Got a call, and the customer is looking to address some things that the insurance inspector wrote up. Get in to the basement and wonder why the insurance company would even insure the house with K&T, as I'm hearing most won't when a new owner takes over.

Well, he sighted in multiple spots where someone (not sure an EC would do this, unless he's a real hack) just cut the wire just beyond the ceramic insulators - obviously abandoning what was ever down line. The issue is that the copper is exposed where wire was cut - no tape, no wirenut, nadah.

What is the proper way to terminate this situation? Wire nut, rubber tape with Scotch 33+ over it, or heat shrink. Or does it have to terminate in a box? I've never used a wirenut that wasn't in a box, but is it legal to put a wirenut on the end of a K&B? If it was, I wouldn't be totally comfortabel unless I reinforced it with Scotch 33+ - as I'd be concerned that on an individaul wire - it could be knocked off.

Or (if it's long enough) can it be folded over and then wrapped with a sufficient amount of Scotch 33+.

Thanks
 
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