Cloth covered wire

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G

G & G Electric

Member
In my experience with cloth covered wire, the cloth will deteriorate in water. The cloth will start to unravel and become almost powdery after many years. It doesn't have to be direct contact with water, either. Areas with high humidity, such as bathrooms, really give that old wire a beating. And the insulation between the cloth and the wire is usually some sort of plastic material that gets super brittle with time. I've seen such insulation crack and fall off in sections when that old wire is bent in a tight radius.
 
ceb58

ceb58

Senior Member
Location
Raeford, NC
The wire will also get very brittle in boxes that lighting fixtures are attached to. The heat over the years will cause it to dry and break.
 
R

Riograndeelectric

Senior Member
Location
Lakewood Colorado
I do not believe that that type of insulation is rated for water as thhn/thwn is.
I have worked on many of the old houses here and deal with the cloth wire quite a lot. The insulation become very brittle from age and the heat of the lighting fixtures installed on the wire.

I have in the past used heat shrink tubing when repair cracked insulation in boxes.

I had a house a rewired several years ago because a water pipe froze up and burst and flooded the basement and the kitchen. Water break was not discovered for 3 days due to house being vacant. The electrical inspector made me rewire every thing that got wet. This was the old metal type of BX cable.
 
Greg Swartz

Greg Swartz

Senior Member
Location
Colorado Springs, Colorado
Riograndeelectric said:
I do not believe that that type of insulation is rated for water as thhn/thwn is.
I have worked on many of the old houses here and deal with the cloth wire quite a lot. The insulation become very brittle from age and the heat of the lighting fixtures installed on the wire.

I have in the past used heat shrink tubing when repair cracked insulation in boxes.

I had a house a rewired several years ago because a water pipe froze up and burst and flooded the basement and the kitchen. Water break was not discovered for 3 days due to house being vacant. The electrical inspector made me rewire every thing that got wet. This was the old metal type of BX cable.
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Funny you mention that. I am writing a letter for a disaster restoration company, letting them know that in my "expert" opinion, the wiring needs to be replaced.

Story: Dec 24th, we get a phone call from our disaster restoration company. A boiler had a pipe burst, and water from the boiler was leaking into the main electrical panel.
Except this panel is from the 40s or 50s, and has completely exposed buss, and huge 400A fuses. It also has cloth covered wiring.

What I am concerned about is the cloth wiring that came in contact with the water, and how it will need to be replaced.

However, I KNOW that as soon as I touch it, everything will need to be brought up to code.

There is some flaring of the cloth, but not much.

Am I correct in saying that the covering is cloth, and that it has already deteriorated, and will continue to do so, which presents a potential fire hazard?
 
cadpoint

cadpoint

Senior Member
Location
Durham, NC
Which hat are your wearing when you reply to them ?
You won't get the job they will just shop your work and price if you give them one.

What would be interesting to see is what is the chemical composition
the many different era's of Copper used through the years 1900's, 1930-40, 50-60's, 70'-80's and modern day stuff.

If not testing the metal itself testing the insulation that's around it!
 
quogueelectric

quogueelectric

Senior Member
Location
new york
I just had ti fix a 2 gang sw with just this wire in it.
The funny thing was the electrician 60 yrs ago skinned 1/2" of the wire and twisted the feed thru like a hellicopter No wirenuts solder or tape, left insulation for annother 2 inches then terminated in the 2 screws of the 2 receptacles closest to the middle of the box.
I was able to cut back to the helicopter splice and splice new thhn to refeed the new switches without marrying myself to the cables. There was NO slack.
I didnt ground the switches so shoot me.
Got the decoras in switch plate on and ran.
Oh btw the helicopter splice was failing to lights downstream of this nightmare.
Had to turn on kitchen to get bathroom lights to work.
 
quogueelectric

quogueelectric

Senior Member
Location
new york
Greg Swartz said:
That is called a western union... learned that with Uncle Sam's Misguided Children.
It's even official. (I know: You're saying it's officially wrong!)
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It cant be legal without solder and tape in a metal box can it?? Anyway it failed as a feed thru. I always pictured western unions to extend a wire like couple it to annother wire not like a helicopter bump and run but I never thought about it that deep.
 
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L

Lcdrwalker

Senior Member
Location
Columbus, Ohio
Most of the wire that I have run into with a cloth jacket is covering rubber insulation, as everyone has pointed out, gets extremely brittle over time. I believe the best test would be a 500V megger.
 
G

G & G Electric

Member
Greg Swartz said:
Am I correct in saying that the covering is cloth, and that it has already deteriorated, and will continue to do so, which presents a potential fire hazard?
Click to expand...

I believe you are correct. I would convince (rightfully and legally) the owner the place is in dire need of a total re-wire. Tell them when you are done, there shouldn't be any problems for another 40 or 50 years. And remind them that they aren't just paying for a new install - they are increasing the value of the property. Throw in a one year warranty on labor, and walk away like a hero.
 
al hildenbrand

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Greg Swartz said:
Am I correct in saying that the covering is cloth, and that it has already deteriorated, and will continue to do so, which presents a potential fire hazard?
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Greg,

I think that, without being able to quote the conductor manufacturer specs for the actual conductors in consideration, that it will be hard to draw that general conclusion. Looking at my 1947 American Electricians Handbook, I see the rubber insulation covering called a "fibrous braid". They list eleven different materials that could be used as the fibrous braid. the most common is cotton, but there also was hemp, silk, asbestos, paper, jute, glass, etc. The braid is then thoroughly saturated and the outer surface is finished "in order to provide protection against moisture, flame, weathering, or oil, etc. The common materials employed for saturating the braids are" asphalt, paint and/or varnish. The Handbook makes the point that the rubber insualtion covering was not standardized and varied from manufacturer to manufacturer, within a given conductor designation.
 
growler

growler

Senior Member
Location
Atlanta,GA
al hildenbrand said:
They list eleven different materials that could be used as the fibrous braid, but there also was hemp
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Those really were the good old daze. :smile: I have alway wondered why so many people wanted to do electrical work and now I know.

Don't bogart that splice my friend, pass it over to me. :D

By the way I do know that this is commercial hemp and not the good stuff. My dad said that when he was young there were big fields growing everywhere.
 
al hildenbrand

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Jaime Brockett and the Legend of the U.S.S. Titanic comes immediately to mind.:D
 
electricalperson

electricalperson

Senior Member
Location
massachusetts
Lcdrwalker said:
Most of the wire that I have run into with a cloth jacket is covering rubber insulation, as everyone has pointed out, gets extremely brittle over time. I believe the best test would be a 500V megger.
Click to expand...

i had experience with cloth wire. a good way to test if the insulation is bad is by bending the wire 90 degrees onto itself. if it cracks the wire is at the end of its life. if it didnt crack it might have a few years left. usually the wire is crappy inside of those crammed ceiling pans. you can usually strip back and find good wire. best way to work with the cloth wire is just to replace it all and install romex.

water will destroy cloth covered wire in no time. if a piece of BX has water on it, it will megger bad always. megger at 1000v anything less than 100 megaohms is bad and must be replaced. 500 megaohms is ideal
 
Greg Swartz

Greg Swartz

Senior Member
Location
Colorado Springs, Colorado
Thank you everyone

Thank you everyone

Well,
I delivered the letter to the disaster restoration company today. We are their only electrical contractor, so, if they get the job, we get the job.

I wrote the letter in such a way to imply that the wire covering would constitute a fire hazard, should the cloth disintegrate and the wires touch each other.
If the insurance company bites, we will have to at least replace the wire. If that happens, the regional building department will make us bring everything up to code...

On the side, the homeowner (8000 sq ft house, 2000 sq ft carriage house) has us lined up to perform a few small jobs...

So, life is good.
 
jrannis

jrannis

Senior Member
Location
Fort Lauderdale/ Miami
I hear people call it cloth covered all of the time. Its a rubber insulating material with a varnished cotton or whatever jacket over the rubber.
I have noticed that where the rubber insulation is exposed to air, its gets brittle. The rest of it usually looks and acts like its factory new.
I was just in a house the was origionally knob and tube, then updated with this wiring method.
Too bad people were in ahead of me and over handled the wire to the point that it was skinned all the way down to the connector.
Now somebody has to crawl around in the attic and replace everything. And of course, nobody has any money these days. Not gonna be a money maker!
 
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