Knob and Tube Wiring

One area you may find tons of information on this is from the fire department. They have put out tons of fires caused by this and surely have data on it as well. Oh! you might also check with the folks FM (factory mutual). I am sure they also could help you with some information.

Good Luck.

PS. If I can remember ( getting older) I will look up a couple of book titles that may give you some insight as well. Post these later.

Who are FM (factory mutual)? I'm from the UK.

Hadn't thought of fire departments as I'd like to see working instalations. But it's worth following.

Thank you.

Sorry I should have stated that FM is the under-writer for some of the industrial insurance companies here in the US. Not sure who the UK uses.

im surprised to read this, since ive seen lots of knob and tube installations still serving well 90 years after their were installed. its a very basic and simple installation, what can do wrong with it?

Knob and tube had it's day for sure. My house (circa 1869) was/is full of it. The basic problem, as I understand it, is if the installation is disturbed, the insulation will easily come off the wires themselves, a fact I know very well when I removed one floor's worth, some of the insulation just dropped off the wires. Another problem is rodents, they like to chew on the insulation, thereby baring the wires, not a safe condition.

Having worked with Knob and tube myself, I have seen almost everyone who had this type of wiring do some very dangerous things. The main panel rarely did not have 30 amp plug fuses instead of the 15 amp fuse due to overloading each circuit. That is the main cause of damage (fire) I had to deal with.When doing a service change, the first thing I did was to replace the 30 amp fuses with 15 amp. Most home owners baulked at the change until I asked them if the preferred to have a " nuisance" of blown fuses as opposed to talking to the insurance company about why their house burned down.

The second amendment to BS7671 2008 has just been published. It covers car charging points.

Some more of the stuff I worked on in my early years

Reyrolle Class D & E OCB's

Ellison OCB's

Switching this gear on to load was bad enough (it fights back!) I had the misfortune to close a Reyrolle Class D on to a fault. Being Dependant Manual Operation (DMO) there is now an embargo on any live switching in the UK.

So how do they make it non-alive to be able to switch it?

Drop out the MV breaker first. It's a pain in the backside but safer.

The place I worked as an apprentice all the DMO 11KV OCB trucks were replaced with spring assisted rapid close trucks. The original panels were retained. The 3.3KV system retained the original trucks until the end of our 3.3 distribution network.

The Reyrolle and Ellison gear shown above was on 550V

That is a switching operation, isn't it, on a piece of live gear?

(There's a hole in the bucket, dear Liza.....)

TonyS meant "live switching on DMO breakers".

Seeing that gear reminds me of the safety officer's stark warning before leading us to a 1928 vintage slate panel breaker - "You don't have accidents at 11 kV - you die!". Safety precautions were white lines on the floor around safe routes and rope barriers.

Sigh!

Does anyone know why CR4 now rejects comments "unable to process form...", except just after I have logged-on?

You can believe this or not. Early 11KV ACB's, the arc chutes were lined with elephant hide.

Do you have any manual for the Class 'D'? As i still work with it and never had a manual.

Any infomation would be good.

My company has a warehouse, and it is old.

Some of controls for an electric motor is still on the wall, was surprised to see it, my younger colleague had no clue as what it was　

I have pictures of it somewhere.

Found it

We had old lift (elevator) around 70 years old with similar control panel. Contacts were toggle type and of carbon. Brake linner of cotton fabric. We disposed off all as scrap and installed new machine.

Do you have any interest in the actual knobs and tubes themselves?

We gutted and rewired our whole house. I think I discarded most of the knobs/tubes; but I may have a few.

I imagine I have some before pictures as well. I will see what I can find.

For my sins I seem to have got involved in an electrical museum in the UK. If you would forward you're e-mail address via the mesanger service I'll pass it on to the curator.

Photographs would be great, the real thing……………….

As for the insulation, I know exactly what you mean, "I'll just move that to one side" only to find yourself with a handful of bare live copper.

That being said, I rerouted a 550V 0.3' PILC-SWA cable to a new switchboard. The cable was installed in the 1930's, it's still in use to this today. The IR test results were as good as I would expect from a new cable of its size and length.

Try ElectricianTalk.com or MikeHolt's Forums.

They have sections dedicated to this topic.

As a General Building Contractor in Southern California for many years I encountered Knob and Tube wiring all the time. As a matter of fact the first house in Burbank I bought had Knob and Tube wiring in the attic.

This is what I learned when working with Knob and Tube wiring:

1. Don't touch it unless you are going to replace it.
2. If you are repairing it then replace the Knob and Tube wiring from the breaker box to the device it serves.
3. The most common failure on Knob and Tube wiring is that the wire insulation dries out and flakes off.
4. It's easy to damage Knob and Tube wiring if you have to crawl over it. I would usually catch my foot on it and yank it out of the Knob.
5. If you see any Knob and Tube wiring that is frayed or damaged, replace it right away.

It's not difficult to work with Knob and Tube wiring and many installations are still being used to this day without issue.
BA

I've got some K&T wire that's still perfectly good, I can curl it up and straighten it as much as I like. I've tried to break the insulation and failed, even tried to light it and barely got it to burn for more than a few seconds, seems like it may down to what the home owners did to that curcut over the 90 so years? I'm not sure, I'd like to reuse the wire and make a "new" circuit with it but don't have a proper excuse to yet

My old house (built 1920) has K&T. I dont worry about it. When I upgrade the 100A panel to 200A, I'll probably upgrade the K&T. Nice little project.