Remove A Single Knob & Tube Fixture

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  #1  
Old 09-29-15, 12:21 AM
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Remove A Single Knob & Tube Fixture

I need to remove an overhead light that's running into a finished attic room I need to insulate the ceiling of.

It runs from K&T under the attic floor boards then is tied into BX where it runs to a junction box, then splits to a switch and to a light.

Can I just cut this where it's spliced with the BX and secure the wires with wire nuts? If not, how should this be done?
 
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  #2  
Old 09-29-15, 05:58 AM
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Yes.

The secured ends must remain curled up inside the respective outlet box(es).

Then, in the future (which could be just minutes away), after you identify all of the ends including T-subbranches of that knob and tube section as being unhooked and secured with wire nuts, you can cut away the now orphaned section either completely or piecemeal leaving portions buried in the wall.
 
  #3  
Old 09-29-15, 09:14 AM
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I used to do a lot of work on old Knob and Tube wired houses. In a lot of the homes, the wiring still looked good, and in others, you could tell where "hacks" had been at work.

When it was properly installed, Knob and Tube wiring was a very safe and effective wiring system. It is the "wire men" who have cut and left "hanging splices", changed out fuse panels for breaker panels and overloaded the wires that have made it less safe.

When these old homes were built, there were no Microwave Ovens, Dishwashers, very few hot water heaters, no such thing as Central Heat and Air, and even more could be applied to the list. Expecting old 14ga. K&T wiring to handle all of that added load is a sure recipe for a fire....especially if a breaker panel has been replaced and larger breakers installed to stop that "nuisance" tripping.

If I was remodeling a house with K&T wiring, I would run new individual circuits from a new (and properly installed) main breaker panel to each of the high load appliances and certain branch circuits, such as the Heat and Air Unit, the Kitchen Range, Hot Water Heater, the kitchen counter receptacles, the bathroom receptacles and heater if equipped, the dining room receptacles, and any other heavily loaded circuits.

Most of these old homes have a interior wall finish of Plaster and Lath. This is lath boards with a covering of steel screen that has been permeated and covered with concrete mortar. After 60-70 years, this stuff can be almost impossible to cut in to. If the plaster hasn't been disturbed, it's a very good bet that the K&T wiring hasn't either. If you're planning on replacing all of the wiring on a home of this type, make sure it has both a attic and a basement before you bid the job.


The K&T wiring, if it hasn't been "butchered" will still work perfectly well for general use receptacles and lighting circuits.......If it has the properly sized over current device.
I always approached it from the perspective of installing new circuits and wiring for heavily load circuits, tracing out all of the K&T circuits and removing the ones that are no longer in service, inspection of the remaining K&T to make sure it hasn't been "repaired" and basically doing selective surgery on any circuit that required it.

I wouldn't leave a job with K&T wiring until I was positive that I understood all of the circuits and that each were serviceable and properly protected. Working on Knob and Tube is pretty intense if you don't understand how it's wired......and the only way to learn is by experience, preferably working with someone with experience in this old style of wiring.

Just my Opinion and some of my personal experiences.
 
  #4  
Old 09-29-15, 10:55 AM
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Thank you and Allan. But the issue is that the BX is running across the exposed side of a ceiling I am going to blow insulation into, so I don't think the BX or the fixture should be left there.

How can I cut them back correctly to at least the junction box or to the attic floor?
 
  #5  
Old 09-29-15, 11:06 AM
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the issue is that the BX is running across the exposed side of a ceiling I am going to blow insulation into, so I don't think the BX or the fixture should be left there
What would the issue be. Yes, K&T can't be in insulation but BX can. Pictures would help us understand. http://www.doityourself.com/forum/li...rt-images.html
 
  #6  
Old 09-29-15, 01:01 PM
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OK. Here's the junction of the K&T to the BX.

[ATTACH=CONFIG]56691[/ATTACH]

This becomes one BX that goes to this box.

[ATTACH=CONFIG]56688[/ATTACH]

Here it goes to the switch but over the top goes to a fixture and then to the other side of the room, down the wall, to an outlet.

[ATTACH=CONFIG]56692[/ATTACH]

This last picture is what's going to be covered by many inches of blown in insulation. I think that's a bad idea.

Can I do this over BX or can I cut it out. If I can cut it out, how do I do so to make it safe?
 
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  #7  
Old 09-29-15, 02:53 PM
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There needs to be a box where the K&T meet. The box must remain accessible. You can't cover the K&T with insulation. Where is the other end of the K&T at that connection.

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Where is this in relation to the splice in the above picture?

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  #8  
Old 09-29-15, 03:59 PM
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I had nothing to do with any of this wiring fiasco!

Where the K&T meets is in the attic floor, at the base of the wall atop which is the second picture junction box.

I'd like to disconnect it right at the first picture, if possible.

The other end of the K&T connection is in another junction box near the stack where it's tied into romex coming from the basement panel. At least I think that's it. All of the original K&T are connected to this basement run in the attic. I haven't traced it all successfully yet.
 
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Old 09-29-15, 04:19 PM
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Just my Opinion and some of my personal experiences.
Great perspective Ace!
 
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Old 09-29-15, 04:43 PM
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I'd like to disconnect it right at the first picture, if possible.

The other end of the K&T connection is in another junction box near the stack where it's tied into romex coming from the basement panel.
Disconnect it on both ends. If needed replace with NM-b.
it's tied into romex
If that NM-b has a ground you can connect the new NM-b to it. If not you will need to run from the panel.
 
  #11  
Old 09-30-15, 10:57 AM
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What if, for the sake of preserving the light fixture, I just remove the fixture from overhead and move the BX and fixture to a sidewall? Then there'd only be the one BX cable running across the ceiling that feeds the outlet on the far side.

I suppose I still don't know if I can insulate over BX!
 
  #12  
Old 09-30-15, 11:12 AM
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Yes, you can insulate over BX. It is only K&T that can't be in insulation.
I just remove the fixture from overhead and move the BX and fixture to a sidewall?
No problem with the fixture where it is so long as there is no K&T. Both the box and the BX can be buried in insulation.
 
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Old 09-30-15, 11:21 AM
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OK, well that helps a lot. And, just to be clear, what I show in the pictures is BX/armored cabled, yes?
 
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Old 09-30-15, 11:27 AM
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what I show in the pictures is BX/armored cabled, yes?
Yes but probably old style which means it doesn't provide and adequate ground. Newer armored cable has a bonding strip to provide ground the older BX doesn't therefore can't be extended but is fine as is because it is grandfathered. Since you have easy access before the insulation though why not just replace everything with new cable?
 
  #15  
Old 09-30-15, 11:41 AM
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Replacing everything with a new cable is what I was thinking. But it'd have to be tied in to the K&T. I am not certain where that K&T begins and don't want to get into the possible mess of it until I am going to redo the entire wiring scheme.

So, can I just tie in 12-2 to this K&T where the BX now ties in?

Or, I already ran 2 new 20 amp circuits to the room for use with tools. 4 duplex outlets per 20 amp circuit. Can I just wire a switched fixture off one of these outlets?
 
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Old 09-30-15, 11:58 AM
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But it'd have to be tied in to the K&T.
It can not be tied into the K&T. The whole purpose of a new circuit is to eliminate the K&T and provide a code compliant grounded circuit.
 
  #17  
Old 10-03-15, 12:57 AM
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OK, so back to the original question. How can I sever the K&T from the BX and secure the K&T without disconnecting the entire circuit (because I have no idea where it begins)?

THEN, can I wire a light fixture from one of my 20 amp circuit outlets?
 
  #18  
Old 10-03-15, 01:26 AM
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K&T without disconnecting the entire circuit (because I have no idea where it begins)?
Trace it back as far as you can and cut it at that point. Place it in a junction box and cap the wires. There can be no K&T wire covered by insulation so if is you need to lift the insulation and remove the K&T.
THEN, can I wire a light fixture from one of my 20 amp circuit outlets?
Only if they have a reliable ground. Old style BX or K&T no.
 
  #19  
Old 10-03-15, 12:17 PM
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Awesome, thanks. The fixture will be wired to a new circuit run with romex.

There are 3 duplex receptacles per each of 2 20 amp circuits. OK to run switch and fixture off the first of either of these receptacles?
 
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Old 10-03-15, 12:59 PM
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OK to run switch and fixture off the first of either of these receptacles?
Yes, if it is not a restricted circuit such as bathroom, kitchen, or dining room.
 
  #21  
Old 10-04-15, 03:54 PM
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Ray2047 "Only if they have a reliable ground. Old style BX or K&T no".
Amen to that. It's possible for that old style BX to heat up and get red like a heater element if it is used as a equipment ground. The resistance is high on that metal sheath.
 
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