Rewiring homes with cloth covered wire

J

jeffelectric1992

Member
Location
Chicago IL
Occupation
Supervising Electrician
I have been rewiring homes in the Chicagoland area for the last ten years. While I have rewired a few homes in that time that had
Knob & Tube installed the vast majority have been a combination of individual cloth covered conductors installed in rigid black conduit
or cloth covered conductors in BX cable. As these conductors age they become brittle and the cloth and rubber insulation deteriorates
leading to failure. We have developed many techniques to minimize the damage we do to our clients homes. I would love to hear from
other electricians who specialize in this type of service and to share tips and techniques that we have developed to make this kind of work
safe, rewarding and worthwhile for our clients.
 
A lot of what I come across is this same wiring types and issues but most times it is after the HO has already painted the house and now the receptacles and switches don't look good with the new painted walls and you get: "Do you really need to open the wall to wire?", comment from the HO. "We only wanted new receptacles and switches. And while you're at it can you move the light?"
 
I was confident that older parts of the country would have similar issues with old buildings and their wiring. Overcoming the Homeowners reluctance to deal with the potential for damage to their walls and ceilings is indeed one of the greatest hurdles when selling this kind of job, but it isn't insurmountable.
One thing we wont do however is replace devices and fixtures when this type of wiring is present unless it is in unusually good condition. The liability of working on old cloth wiring is just to high.
 
I've dealt with cloth wiring quite a bit. Depending on the style of the house, there have been some easy and some extremely challenging.

Easiest is a single story house, where receptacles can be rewired from the basement while lights and switches get rewired from the attic. If it's NM cable I always try to cut out the boxes and install new, larger ones.

Sometimes finding or making access is a daunting task.

Adding a floor receptacle can be helpful at times. Or running cables in the corner angle at the ceiling, then covering with crown molding. Sometimes a closet (or two) can be severely damaged, then covered with cedar panels.

I had to rewire a bunch of stuff in a 1920s house once, which had cork boards on the wall in almost every room. I had to do some damage, and the homeowner asked what could be done to fix it. Um, cover it with cork board?

Being an expert fisherman and having some general construction/repair knowledge will take you a long way. How to get past cast iron stacks, how doorways and windows were framed, cutting plaster and lath, etc
 
Are you sure the cloth/rubber is really what you've got?

In San Francisco's East Bay most of that K&T is run through ceramic tubes & knobs, reaching metal only at the junction boxes. The cloth stuff mostly covers over plastic insulation, and in later decades really good plastic insulation, which in many homes is just fine.

Have you been working from live failures, or live worry about future failure?
 
I work extensively with wire that is rubber insulated with a overwrap of woven waxed or lacquered cloth in various colors though.ty most is so old that the original color cannot be distinguished
 
When in armor we refer to it as BX, two to three rubber insulated conductors each covered with a lacquered woven cloth wrap then overwrapped with a woven cloth protective wrap over all the conductors.
I have also noticed that the best rewire electricians i have trained or worked with are those that have a good understanding of how these buildings were constructed.
Many structures old enough to have these early wiring materials are balloon framed or will have solid two to three layer masonry exterior walls with let-in floor and ceiling joists with just furring strips applied to attach plaster lathe to. It is often possible to push fish rods between the masonry and the lathe and pull new AC cable.
 
I my area there are two types of rewire contractors: patch and no-patch.
I think the patch guys have a leg up.

My area the best way to keep costs down is to replace fewer outlets. This area won't make you add outlets every 12 feet in a 1890s building, most of the time. A historic destination can further allow right sizing the electrical work to the character of the home. Using air sealed boxes on outside walls is important, as the interior of those walls are so drafty (in part from balloon framing). Attics are your friend, finished basements not so much. But getting a good GC can help: if you have to sprinklers or foundation work, then the electrical becomes a gimmie.
 
We have to be careful were I work. If we replace or modify fifty percent or more of a dwelling units electrical system then we must bring it up to current code standards for residential outlet placement and switching requirements for hallways stairwells and closets.
 
A number of years ago I was listening to talk radio, and the news came on. There was a building in Jefferson City, Missouri that had a second story dance hall floor fall in, and I think there were several people hurt. Don't remember that part by now. But they said investigators were going to start looking at the cause.

I've worked on quite a few buildings like that from the same era, mostly fourplexes, but also a couple of 14 unit apartment buildings. I had a hunch immediately.

The building was something like 1920s, and I knew it would have had the floor joists set into pockets in the brick structure. My hunch was that the mortar around the bricks had weakened, then the weight and bouncing of so many people dancing

It took almost months for the investigation to conclude that weakened mortar was to blame. I could have used the several hundred thousand dollars they spent to find out what I had suspected.

All that to say, it helps to pay attention to the structures you're working in. It can come in handy down the road.

abc17news.com

Jefferson City Building Official: No known cause of partial building collapse

Officials have not pinned down what caused part of a building to collapse onto Madison St. in Jefferson City Thursday morning. Larry Burkhardt, a building official with the Jefferson City Department of Planning and Protective Services, said the last time the building was worked on was in 2013...
abc17news.com abc17news.com
 
jeffelectric1992 said:
We have to be careful were I work. If we replace or modify fifty percent or more of a dwelling units electrical system then we must bring it up to current code standards for residential outlet placement and switching requirements for hallways stairwells and closets.
Click to expand...

What a backwards requirement. Granny's wire insulation is turning to powder but have to tear her house open completely in order to fix it, vs just pulling in new NM.
 
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