Terminating Knob and Tube

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DSamson

DSamson

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San Francisco, CA
I'm doing a kitchen remodel. The old kitchen was served by knob and tube (K&T). We are abandoning all of it. We can't remove all of it because some of it is still serving other loads in rooms adjacent to the kitchen. My question is what is the proper method of terminating abandoned, but still hot, K&T.

I was taught, (METHOD A) leave a length of about 8 inches past the last knob, tape the cut end of the conductor, wrap the conductor tightly around the knob, cover the whole mess with several layers of Super 33+.

An inspector is asking me to, (METHOD B) leave a 12 inch length past the last knob, double the conductor back over itself and tape the cut end of the conductor to itself back near the knob.

I think METHOD B has several shortcomings: 1) It is not very secure, you've got a doubled over length of about 6 inches dangling in mid air. 2) You're bending crispy, crumbly, old insulation at a pretty severe angle. So you get this piece with compromised insulation left floating around.

Does anyone know the correct method for terminating abandoned knob & tube? (Oh, it is not possible to bring it into a junction box, so let's eliminate that answer.) Any photos would be greatly appreciated.

Thanks,

David
 
When I have terminated K&T I always use the first method you described. Cut the wire, wrap it twice around the knob tightly , then wrap it about 4 times around the lead that original lead, tape the cut end. I have done this many times in San Fransisco and none of the inspectors have had a problem with it , but SF inspectors are some of the biggest offenders for ''do it my way''. You may want to ask him what the code is on requiring it to be his way ? :rolleyes:
 
How about a couple of shrink tubes leave them a little longer than the conductor an shrink them
 
David,

I use Method A as well, with the exception for fished K&T.

As for the inspector's Method B, ask the inspector how the loose, doubled over end satisfies 394.30(A)?
394.30 Securing and Supporting

(A) Supporting Conductors shall be rigidly supported on noncombustible, nonabsorbent insulating materials and shall not contact any other objects.
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SiddMartin said:
cut it, tape it, put it in a box and blank it.
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No need for a box or a blank. Only splices and such need access. You can abandon (dead end) in place and bury permanently in the wall, ceiling, or floor. There is no requirement that you need access to that dead end. Myself, I just cut it a couple inches past a knob, strip it maybe 3/8", and twist a wire nut on the end. No wasted tape or anything of the sort.
 
mdshunk said:
Myself, I just cut it a couple inches past a knob, strip it maybe 3/8", and twist a wire nut on the end. No wasted tape or anything of the sort.
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I just cut it and tape it, no wasted wirenut....:D
 
mdshunk said:
No need for a box or a blank. Only splices and such need access. You can abandon (dead end) in place and bury permanently in the wall, ceiling, or floor. There is no requirement that you need access to that dead end. Myself, I just cut it a couple inches past a knob, strip it maybe 3/8", and twist a wire nut on the end. No wasted tape or anything of the sort.
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thought it was hot, u bury hot taped wire?
 
SiddMartin said:
thought it was hot, u bury hot taped wire?
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Yes. What's the difference? The knob and tube is already burried. Most of us just cut and tape. There really is no change to the existing installtion. The insulation is either good or its not, in which case it might be best to remove it. Knob and tube has to stop somewhere. That's how I see it terminated from the original install, from way back when.
 
K8MHZ said:
If it's abandoned, why would it still be hot?
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The opening post explains it . . .
DSamson said:
I'm doing a kitchen remodel. The old kitchen was served by knob and tube (K&T). We are abandoning all of it. We can't remove all of it because some of it is still serving other loads in rooms adjacent to the kitchen.
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I read this to say that in the kitchen, the K&T exposed by demolition is all being removed except for the trunk run that supplies undisturbed load in areas outside of the scope of the work.

I also read the description of the "Methods" to be describing a K&T spur, or spurs, off the trunk that can't be removed all the way to the trunk conductors without additional demolition, and therefore must be abandoned in place, still energized by the K&T trunk conductors.
 
Hello All,

Original Poster here.

al hildenbrand said:
The opening post explains it . . .
I read this to say that in the kitchen, the K&T exposed by demolition is all being removed except for the trunk run that supplies undisturbed load in areas outside of the scope of the work.

I also read the description of the "Methods" to be describing a K&T spur, or spurs, off the trunk that can't be removed all the way to the trunk conductors without additional demolition, and therefore must be abandoned in place, still energized by the K&T trunk conductors.
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Al, thanks for providing the correct vocabulary. Yes, you deciphered the situation exactly.

acrwc10 said:
When I have terminated K&T I always use the first method you described. Cut the wire, wrap it twice around the knob tightly , then wrap it about 4 times around the lead that original lead, tape the cut end.
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acrwc10, It sounds like the method you're describing is not exactly my "METHOD A." Using Al's vocabulary (above) let's call the end of the spur closest to the trunk the "upstream" end, and the end past the knob in question the "downstream" end. It sounds like you take the downstream end, leave it long past the knob, wrap that long end twice around the knob and then twist the remainder of the downstream end around the upstream end, and tape the cut end of the wire there. Is that basically what you're describing?

Thanks to all for your advice.
 
SiddMartin said:
thought it was hot, u bury hot taped wire?
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That is the most common method of abandoning wires in a powerhouse I worked in almost all tape hardly any wirenuts. 33 of course. edit to say most of this stuff was in some sort of enclosure or cable tray.
 
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DSamson said:
Hello All,

Original Poster here.



Al, thanks for providing the correct vocabulary. Yes, you deciphered the situation exactly.



acrwc10, It sounds like the method you're describing is not exactly my "METHOD A." Using Al's vocabulary (above) let's call the end of the spur closest to the trunk the "upstream" end, and the end past the knob in question the "downstream" end. It sounds like you take the downstream end, leave it long past the knob, wrap that long end twice around the knob and then twist the remainder of the downstream end around the upstream end, and tape the cut end of the wire there. Is that basically what you're describing?

Thanks to all for your advice.
Click to expand...

Sorry for the delay, Yes that is the way I terminate the K&T and it has never been a problem for the inspectors.
 
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