1940s house with old clothed insulated wires

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Old 04-11-20, 09:30 AM
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1940s house with old clothed insulated wires

I found some cloth romex inside my 1940s house. I have no idea how much of it is there, and I am in the process of slowly opening up every junction box and fixing the wiring as I go.

The property had an addition in 1992, and a kitchen remodel in 2008. So at least half of the wiring is newer. When I removed the electrical panel cover and looked at the wiring inside, I do not see any clothed romex there, so at some point there had some rewiring and yet so far (I am about 60% through) I found parts of 3 circuits that had this old wiring.

This is a piece of that stuff.


I will need to replace/abandon/rewire these somehow. The bad news is one of those circuits is on many receptacles on the inside of an exterior wall so it will be a real pain.

I am looking for a temporary solution to keep those receptacles in service until I can change them all out.

The bad news is once I opened these boxes, if I manipulate these old wiring by pulling, tucking the cloth crumbles. There is also no ground conductor.

The wire contains two layers. There are two conductors. Each conductor is wrapped in cloth. I believe at one point it was a white cloth and a dark cloth, but by now there look about the same. Then there is another layer of cloth over both which seems to be coated in some sort of tar?

If I undo the clamps in the back of the metal box, I was able to tease out another 2-3 inches of the wiring into the box, and that wiring seems to be in much shape then the portion inside the box.

So now I have this wire inside the box, with the last 4 inches of it as bare copper because the old insulation has disintegrated. How can I repair it in the mean time?

I am thinking of using some skinny heat shrink tubingnover the bare copper up to where I found intact insulation. Then a larger tubing over the existing insulation, while overlapping the two.

Are the heat shrink tubing in hardware stores adequate for this task if it's rated to 125C? I have used heat shrink tubing before to repair a nick over insulated conductor, but I have never use heat shrink tubing over several inches of bare copper conductors. Can it be used in this manner until I rewire which I can't do now with this COVID-19 thing hanging over our heads.

Would tape be better? Would liquid tape be better? What are marine grade heat shrink tubings? Is it a better product then regular HS tubings?
 
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Old 04-11-20, 09:39 AM
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Marine grade HS has hot melt glue inside to water seal.
You can get HS in white
and many other colors.
High flexibility HS also exists. Usually only black neoprene though. You you may find double wall stiff to work with inside boxes.

NO to tape. Also strongly suggest a HS gun with the curved, HS attachment.
 
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Old 04-11-20, 10:31 AM
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Thank you.

I will get one of those deflectors to attach to my heat gun.

The high flexibility HS, are they thinner or a different material allowing the flexibility?

Also I noticed some HS tubings are 2:1, 3:1, 4:1, I assume the lower shrinkage like 2:1 is of better material?
 

Last edited by MiamiCuse; 04-11-20 at 11:40 AM.
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Old 04-11-20, 12:14 PM
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That is a tough job. Even if you get back to better insulation..... it still cracks.
2 or 3 to 1 shrink is all you need.

This is a problem we run into all the time. Ultimately it comes down to replacing the old wiring.
 
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Old 04-11-20, 03:57 PM
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The hi flex stuff wonít cause such a hard spot at the edge, causing even more cloth cracks. Itís much harder to find and itís black neoprene based. Made for wiring harness in vehicles.
 
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Old 04-13-20, 10:43 AM
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That is a tough job. Even if you get back to better insulation..... it still cracks.
2 or 3 to 1 shrink is all you need.

This is a problem we run into all the time. Ultimately it comes down to replacing the old wiring.
Thanks!

Yes it is difficult. I do plan to rewire, depending on how bad the wiring is outside of the box (in wall cavity, under the crawlspace etc...) I was able to pull some of the slack into the box by loosening the clamps on the back of the box, and pulling a little very carefully. From what I can see, the overall clothed sheathing is not too bad. It seems to be covered in some tar like substance. But when I cut back the sheathing to expose the individually cloth insulated conductors inside, those clothed insulation seems more brittle LOL.

I don't know which is worse, trying to save/prolong this brittle crumbling clothed wiring, or trying to save old cracking partially de-laminating plastered ceiling, by driving more plaster washers into the ceiling lath and creating more cracks in the process.
 
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Old 04-13-20, 10:47 AM
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The hi flex stuff wonít cause such a hard spot at the edge, causing even more cloth cracks. Itís much harder to find and itís black neoprene based. Made for wiring harness in vehicles.
Thanks!

Well I guess good news is I bought some of each.

I bought some regular HS tubing, some polyolefine ones, some marine grade ones, some dual wall ones, all in small quantities to try them out.

I also found some in neoprene I might order, but the neoprene I found they do not show specifications as far as maximum temperature and whether it's rated for line voltage.
 
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Old 04-14-20, 07:20 AM
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Old 04-17-20, 09:58 AM
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I was able to remove two pieces of this wiring completely between two wall receptacle boxes about 4' apart horizontally. I know the part of the wiring inside the box is bad, brittle, crumbling, from all the twisting, folding, pulling and pushing over the years, but I wanted to have a look at the part of the wiring outside of the box to see if they are in the same bad shape or if they may still have some life left. In other words, if the wires outside of the boxes are as bad, then there is no fixing anything except to replace all, but if they are in much better shape then my option of either loosening the clamps inside the box to pull in more slack or to use heat shrink tubing on the crumbled ends may work to buy me some time.

Here are some pictures of this piece of wire. I already cut off the crumbled portion inside the box. The outside black colored sheathing seems to be OK, It survived the hard pull through the stud holes, but if I were bend it back and forth at a 90 degrees like 5 to 6 times it will break the sheathing.





I used a razor blade to cut open the sheathing, inside are two conductors wrapped in paper. This paper coiled around on the outside and it's brittle.



If I then tear the paper away I then see the cloth insulation. That seems to be in pretty good shape actually.



If I cut away the cloth insulation, there is some black brittle plastic coating on the conductor but they broke off easy too.



Thoughts? Do I have time to plan out the rewire in phases or is this a "the house would be on fire tomorrow" situation?

By the way, I have been reading up on this clothed wiring on the net and there is a bunch of warning about abestoes, that if I touched this I would release abestoes into the air and get lung cancer. I have already touched about a dozen boxes, where is the abestoes? Is it part of the outer sheath or the inner cloth? Is it the black tiny dust particles that came off when I exposed the various layers? Is it a significant risk?


 

Last edited by MiamiCuse; 04-17-20 at 10:17 AM.
  #10  
Old 04-17-20, 12:14 PM
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Prior to 1980..... there could have been asbestos used in the cloth covering.
I don't see much of a problem handling the wire. It's the dust that is harmful.
It probably wouldn't hurt to wear a mask when working with it.

As far as cloth covered wiring..... I have not seen it as the direct cause of fires.
Usually as long as it's not disturbed it's integrity is ok.
That's not to say it's completely safe. I recommend to customers to have it replaced as soon as possible.
 
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Old 04-17-20, 04:20 PM
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You are seeing the rubber insulation breaking off, not plastic. You have tinned copper conductors.
 
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Old 04-17-20, 04:26 PM
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There is an overall cloth covering.
Then each wire has a cloth covering over rubber insulation.
The cloth covering has the white and black coloring. The rubber inside is only black.
 
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Old 04-17-20, 07:36 PM
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OK then where is the asbestos? Is it on the black outer sheath? On the inside cloth covering? Or on the innermost rubber insulation?
 
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Old 04-17-20, 07:52 PM
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I have another question, this wiring has two conductors, no ground conductor.

However, if it comes into a junction box where a 12-2 NMB wire from another circuit is present, can I use that ground conductor?

In other words, is it OK for a receptacle wired to say circuit 10 with no ground, to connect a bare copper conductor from that receptacle to the ground conductor of a 12-2 romex wire from circuit 14 that's powering a microwave oven on the other side of the wall?
 
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Old 04-17-20, 10:47 PM
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If there were asbestos it would be in the cloth covering.
Either the overall outer jacket or the individual jackets.
 
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Old 04-18-20, 05:46 AM
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If those are tin plated copper conductors, I am surprised the tin has not turned dark. Have u scraped enough to see bright copper?
i suppose it is likely those could be solder (tin/lead) coated.
 
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Old 04-18-20, 10:10 AM
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If those are tin plated copper conductors, I am surprised the tin has not turned dark. Have u scraped enough to see bright copper?
i suppose it is likely those could be solder (tin/lead) coated.
I have not done any scrapping on the metal. The original semi-exposed crumbled conductors have been cut out already so what you are seeing are newly exposed after I cut away the black sheathing, the paper wrap and cloth on each conductor. The black rubber inner insulation just kind of turned to dust on it's own.
 
 

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