SAN FRANCISCO (KGO) -- Few of you have probably heard of knob and tube electrical wiring. But, it turns out you should know more, because insurance companies are now canceling and denying homeowners policies for having this old electrical system.
Inside many old homes in the Bay Area is an outdated electrical system, called knob and tube.
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My first house, a Craftsman home built in 1921, had knob and tube wiring. Never had a problem with it.
I've come across knob and tube wiring in some really older homes in the past... As long as it's in good shape it's safe... If I was remodeling I would definitely change it but that doesn't mean it's not safe.. Insurance companies will look for any reason to deny it cancel you if you make a claim.
ReplyDeleteJD
knob and tube? I thought it was knob and post? Maybe it's called something different on the left coast. Heck, a lot of the boys think they're girls out there so anything is possible
DeleteI'm not on the left coast, I'm on the gulf coast and that's what it's called here as well.. I've never heard it call knob and post, not saying nobody calls it that but not around here
DeleteJD
Many old houses here in our valley still have it. Some of them done when electricity first came into the area back in the teens/twenties. Quite a few still standing with no issues.
ReplyDeleteCeramic knob and tube, split Bolt splices with friction tape, cloth insulation that mice won't chew on. Never had a problem with it. Now the screw in fuses in an old Westinghouse box may be a different story.
ReplyDeleteMy screw in fuse kept blowing but it just cost me pennies to fix the whole box...........
DeleteBiggest problem with knob and tube is the treated cloth insulation on the wiring. At this point, the shit just crumbles right off if you need to work with it (even just to replace an outlet or switch) it is also typically undersized versus modern wire gauge used since at least the mid 1950's.
ReplyDeleteReally this is an extension of the practice by insurance companies to refuse coverage for known substandard electrical system components. Breaker panels by Federal Pacific, Zinsco, and pushmatic are all considered bad news now due to mechanical failure of the breakers in one way or another. And really, after 50-60 years, these obsolete panels are well last their prime. I know it sucks and is hugely expensive to rewire a house, but at some point people are going to have to deal with modernizing these old setups.
I bought an old house that had knob and tube, cloth wiring from the fourties’ and more modern wiring from the sixties. I tore it all out including the walls and remodeled. New 200 amp service as well. Worked out nicely.
DeleteThere are A LOT of houses with Zinsco panels out here in California! They were "handy" because the panels were small, and would fit in places bigger panels wouldn't. Zinzco breakers are known to electricians as "Neverblows," and are dangerous as HELL. Reason being, the bus bars the breakers snap onto are aluminum. The connection between the breaker and the bus bar loosens due to aluminum's propensity to "cold-flow." The aluminum oxidizes at the connection point, creating resistance between the breaker and the bus. This causes the connection to get hot. This MELTS THE BREAKER in the ON POSITION. When the circuit reaches the breaking point for the breaker, the breaker can't trip because it's melted in the on position, hence, the "Neverblow" moniker. The attached circuit then heats up with predictable results.
DeleteZinsco was bought by Sylvania. Their panels were just as bad.
If you have one of these panels do yourself a favor and have it replaced. It's a ticking timebomb. It's one those "pay now or pay later" scenarios. If you can't afford this, at least have an electrician check the panel out. He can smear some antioxidant on the connection points for the breakers to keep the connections from oxidizing and heating up.
I had an old house with cotton jacket wiring. After my divorce, where my wife got the house, there was an electrical fire that burned the living room.
ReplyDeletehmmmmm fire only happened AFTER the divorce, you say? Coincidence?
DeleteHad a mix of knob & tube -and everything else right up to NM cable - in my old house, built in 1868 and wired/rewired repeatedly. Walls were lathe & plaster except where they were solid 2 foot thick brick (yes, solid- either rock fill, concrete, or just bricks). The only way to rewire would be to strip out the ceilings and some interior walls. By the way, historic register house. No question that the electrical system was iffy (heck, the original wiring box was a whole 30 amps- for the entire house). Deny insurance, and the house is unsellable, unliveable, and good only for a teardown. Try that, with a national register house. My position on insurance would be can't deny if the place has a certificate of occupancy. Charge extra for the risk? Sure. Charge enough to make it worthwhile to rewire? No problem.
ReplyDeleteDon't get me started on the plumbing. The main water line was half inch IRON pipe, from two streets away, at least 100 years old. At least, the piece we could see was. The rest might have been lead. There was abandoned lead pipe all over the place under the kitchen... Now let's talk drains, or the gas lines....
My son purchased a house in Parkersburg, Wv. Part of closing agreement was the 1920's house electric had to be updated. Banks and Insurance
ReplyDeleteThe International Brotherhood of Electrical Workers approves this message.
ReplyDeleteI ran across knob and tube wiring while pulling telephone cables through the attic of a circa-1900 Coast Guard station on Long Island. I didn't even know it was there until I got the shit shocked out of me when I crawled over it. It was STILL LIVE and buried in the blown in insulation. This stuff wasn't even insulated. It looked like an old open wire telephone line... and was just about the same gauge!
ReplyDeleteThat beats the worst I've run across, and I've seen some sketchy shit while in attics, basements and crawlspaces. Truthfully, it amazes me we don't have more electrical fires in old structures, especially with all the poor DIY work I've seen. I'm a plumber by trade, so I'm routinely in places where I get to see the ugly parts of a structure. I'm proficient enough in proper electrical practice to know when I'm looking at bad news.
DeleteOne of my favorites is finding a huge bundle of wire run alongside a 4" cast iron stack that I'm about to tear out and replace, because they used the pipe chase for the wiring too, when the house was built. Always makes my day, although that practice isn't inherently unsafe, just inconvenient to me.
Knob and Tube is as safe as any wiring. There is no increased risk of fire. It *is* dangerous if you can find the exposed wire with your hands, or if it is asked to carry too much current, like any wire.
ReplyDeleteMost Knob and Tube is about 12 gauge, so it is good for 20 amps. generally higher as it can be cooled by the air better than wires in a jacket or in conduit.
The "Dangerous" claim comes from untrained/poorly trained "electricians" who have never seen it before and do not know what to do with it.
In most states, it is legal UNTIL you want to add to or modify it, then it must be changed to meet code.
But it ain't a fire hazard. An electrocution hazard, yes.
Exactly right.
DeleteAs they should. That crap is over 100years old. Massive fire hazard especially when squirrels or rats are in the attic
ReplyDeleteNah, it's great. Kills the rats and squirrels when they chew on it. Or course the smell can be pretty bad for a while .
DeleteI am wondering how long before they begin refusing coverage for houses with aluminum wiring.
ReplyDeleteMy parents house had that kind of wiring. One of the first things that they replaced.
ReplyDeleteGrandma's house had those push button light switches. . . . . .
ReplyDelete"They dont build 'em like they used to" isn't always a bad thing.
ReplyDeleteAs the real problem seems to be the cotton insulation decaying and allowing a short to happen, Can new modern wire be pulled into the system to replace the old and keep the knobs and tubes? Legal? probably not code. But in a home/building where there would not be an inspection is it feasable. Also update the panel to breakers.
ReplyDelete"In some knob and tube homes, people have installed three prongs, which can be dangerous if there is a electrical surge potentially damaging your equipment.
ReplyDelete"That's what the ground wire does, it absorbs the electrical chock and brings it to the ground. "
BULL-SH*T....another writer who can't take the time to research things.
In the original house, built in 1746, that was one of the electrical standards inside the walls and attic. Mixed with several other later styles.
ReplyDeleteAs was the plumbing, every type and size of pipe from threaded cast iron, brass to PVC.
I called in a plumber to replumb everything. And replaced all the electric wiring myself.
I wish to firmly state that the electric wiring was NOT the reason the house burned down.