Knob and Tube in the way

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  #1  
Old 11-11-12, 11:39 AM
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Knob and Tube in the way

I am take a portion of this wall down and have a neutral knob and tube running through it. Can i simply cut it and put each end in a junction box and run a new length of wire so I can put the wire in the wall ? Both new junction boxes would be accessible. This neutral basically feeds 3 bedrooms and a bathroom on the second floor one light and one plug so rewiring it all would be difficult.


Thanks in advance
 
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Old 11-11-12, 12:26 PM
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By code K&T should not be altered. Best practice you need to replace the existing circuit starting from the breaker box with NM-b (or equivalent).
 
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Old 11-11-12, 12:39 PM
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I have to come up with some solution here, re wiring the second floor is not practical dollars and sense wise at the moment.
 
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Old 11-11-12, 02:48 PM
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Can i simply cut it and put each end in a junction box and run a new length of wire so I can put the wire in the wall?
No, that would be contrary to code because it is dangerous. For openers, knob-and-tube wiring was developed and installed before modern junction boxes, cables and cable clamps were developed. Successfully inserting a piece of that K&T wire into a J-box is an obscure skill that I won't explain here because it is still, technically, a violation of the code. That, plus the fact that both hot and neutral are required to share a raceway (cable sheath) by modern code are just two of the reasons your proposed solution is not allowable.

Does that mean that your only alternative is to rewire everything that is now wired with K&T? Maybe, but there might be one way to do it. If you can replace the entire pull that this wire is part of, and if the K&T wiring on each end is already in a box or other housing where splicing is allowable, then you might be able to replace just that run. Where does this particular stretch of K&T begin and end?

One more point. You say
re wiring the second floor is not practical dollars and sense wise at the moment.
I hear you, but what's more important - saving a few dollars or preventing a fire that could destroy your house and possibly kill you and your family? We often say here that electricity is an equal opportunity killer. That's just as true of the fires that it can ignite.
 
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Old 11-11-12, 04:04 PM
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I can physically trace this wire back to the panel, as soon as it goes trough the follow the hot wire is in the same joist cavity back to the panel, however there is some splices into it along the way back to the panel. Also as soon as the wire exits the double plate it goes in 2 different directions. What is involved in rewiring a house to replace knob and tube ?

Thanks again for the replies
 
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Old 11-11-12, 04:27 PM
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If the attic is open, it will not be a difficult task to fish new 12-2 cables in place of the K&T. Disconnect all of the K&T at once. It'll save a big headache.
 
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Old 11-11-12, 04:46 PM
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If the attic is open, it will not be a difficult task to fish new 12-2 cables in place of the K&T. Disconnect all of the K&T at once.
I think this is on the first floor of a two-story house, Justin, and the K&T run is supplying loads on the second floor.
 
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Old 11-11-12, 04:46 PM
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Attic has a good 12" of blown in insulation in the attic, so that would probably have to me removed first, since I will go ahead and assume its the OLD KIND
 
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Old 11-11-12, 05:16 PM
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I can physically trace this wire back to the panel, as soon as it goes trough the follow the hot wire is in the same joist cavity back to the panel, however there is some splices into it along the way back to the panel. Also as soon as the wire exits the double plate it goes in 2 different directions. What is involved in rewiring a house to replace knob and tube ?
New lengths of modern cable are pulled in to replace the K&T. The type of cable you need to use is determined by the authority having jurisdiction (the AHJ) over electrical work where you live. The size of the wiring is #14 for 15 amp circuits and #12 for 20 amp circuits. Dedicated circuits for heavier loads such as a water heater, an electric range or an A/C condenser will require larger wire and higher-rated protection, but there will only be a few of those. (Tip: If you fill in the location information in your profile, that will help give us a lead on your regulatory environment.)

Any K&T wiring that is completely disconnected from power can be cut back to end inside a finished space, such as a wall, and abandoned in place. However, the splices you mentioned cannot be made safe, assuming they are the standard soldered-and-taped splices that were usually done with K&T. You appear to be saying that the K&T extends to the panel. If so, that is where you will need to start replacing it. On the load end, once you've disconnect a K&T circuit from power, you can probably leave most of the wire in place, and just cut and cap it to stay in the wall or ceiling, as I said above.

What kind of panel do you have? If it's as old as the wiring, and has screw-in or push-in fuses instead of circuit breakers, it probably needs to be replaced and/or upgraded as well. How large is your electrical service? If the main circuit breaker in your panel rated at 60A, 100A or 200A?

All of the work I've described can be done by a homeowner, except for replacing the panel - and you can do a lot to reduce your out-of-pocket cost for that. You should obtain a permit before starting. That way, we will all know you're covered and you'll be able to ask the inspectors questions, in addition to us. Yes, we can help guide you through the work. This is the best time to do it, too, while you've got some walls open and before you close them. Getting the new cables to the second floor, for example, is a perfect task for this point in your renovation.

One more point: You can do this work in stages, as time, money and energy are available.
 
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Old 11-11-12, 05:26 PM
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Attic has a good 12" of blown in insulation in the attic, so that would probably have to me removed first, since I will go ahead and assume its the OLD KIND
Mark, if you have K&T wiring covered by blown-in insulation, that is a significant code violation because is creates a clear and present hazard.

The functional premise of K&T wiring is that the primary insulator is dry air. That's why you see it hung on knobs on the two opposite sides of a stud bay, or pulled through tubes that are installed 12" or so apart where it is traversing joists. Insulation can, and does, get wet sometimes. All K&T wiring should be removed - replaced - before insulation is installed where it is run.

Yes, I would start rewiring first in the attic, dropping home runs down to the panel as needed.
 
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Old 11-12-12, 01:40 PM
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Just to reiterate what Nash said, K&T wiring is a bit of a hazard in itself. Junctions have a tendency to overheat and any movement of the wires often results in the insulation flaking off or the wires shorting against any metal box. Couple that with being buried in insulation and not allowing any cooling, I would be worried about a potential fire risk.

Also, your reference to the "old kind" makes me think that you're already thinking it may contain asbestos. If so, stay away from it until you either have it tested or removed.

Old houses are great, but they can be money pits... start saving up for those bigger projects.
 
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Old 11-12-12, 04:16 PM
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Also, your reference to the "old kind" makes me think that you're already thinking it may contain asbestos. If so, stay away from it until you either have it tested or removed.
The attic insulation or the insulation on the wires?

I thought the OP was referring to the wiring, as in old kind = K&T. Just guessing, though.
 
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Old 11-12-12, 04:30 PM
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I went though this same thing years ago. My 1892 3 story Victorian full of K&T was a gem. It got to the point where I couldn't get homeowners insurance for it anymore. Only 1 outfit would insure it with K & T and it was about 3 grand a year.
 
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Old 11-12-12, 06:34 PM
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Yes I meant the insulation, I dont know for sure but could be the Vermiculite type, have to send a sample away
 
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Old 11-12-12, 06:39 PM
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Doesn't matter. Asbestos isn't all that harmful except in the eyes of the lawyers and abatement companies that make a living off it. Whatever the insulation is it is dangerous and it should never have been installed because of the K&T. Now there is a fire hazard because of it.
 
  #16  
Old 11-14-12, 06:15 PM
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So looks as if I`m in to a full re wire which is definitely do able and seems to be my best option for obvious reasons. One idea I now have is since I will be re wiring everything back to the main panel, and the panel is full, and to make things easier, and since I was adding a sub panel anyways. Can I add a 100 amp sub panel and basically transfer everything over to this new sub panel one circuit at a time as time and money permits.
 
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Old 11-15-12, 09:20 AM
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Can I add a 100 amp sub panel and basically transfer everything over to this new sub panel one circuit at a time as time and money permits.
Probably. It depends, in part, on your existing service.

If you post some pictures of your existing panel, including one from far enough away to show the panel and the cables or wires coming into it, plus a couple showing the open panel and the label inside the door, that should help us give you more specific advice on doing that.
 
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Old 11-15-12, 04:28 PM
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Have 100 amp service here are some pics
 
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Old 11-15-12, 07:55 PM
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Wow that's a mess. You can indeed add a 100A subpanel. That panel takes Cutler-Hammer BR style breakers. I'd buy a good copper buss panel if I was you.
 
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Old 11-16-12, 11:56 AM
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Have 100 amp service here are some pics
That looks like an old split-bus panel. It is, as Justin said, a bit of a mess. The two wires fed in where the cover should be are particularly interesting.

My suggestion is that you buy a new main distribution panel and mount it next to this one. I would make it a 200A panel unless you have done a load calculation, including everything you have now and everything you intend to add, and determined that 100A is plenty for all current and future loads. You can buy that new 200A panel with a few breakers already in it at your local big box store for less than $100.

I would feed it with 3 #6 wires and a #8 ground from a 2-pole 100A breaker in the existing panel. I would add or upgrade the Grounding Electrode Conductor (the ground) system and connect that to a separate bonded bus bar in the new panel. I would isolate the neutral bar that comes with the panel.

This will give you a modern panel, wired and configured as a subpanel, that you can move or add circuits to as you work. When you're done, and you have everything in that panel, feed it from the meter and demo the panel you have now. At that point, you can make the neutral/ground service entrance bond in the new panel.

Check with the authority that issues you the permit for this work and with the licensed contractor you will pay to make the change-over to determine the best location for your new subpanel/panel.
 
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