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What was used Before K&T Wire?

Lyndon Strother

Registered
Last Subscription Date
04/21/2018
I've inspected and worked on Knob & Tube installations in: Mass, N.H. Vt, Maine, Georgia, Ohio, Ill, Texas, Montana, and a couple more states. The majority of the installations had Varnished Cambric over rubber. This was essentially rubber insulation with a cotton braided outer cover that had been soaked in Varnish. After 40 or 50 years the insulation becomes very brittle. However, due to the fact that the wires were usually separated by 18 inches to four feet, and being mounted on porcelain as well as passing thru porcelain made the installations somewhat "Bullet-proof". It was quite common to find penny's or buffalo nickels in the fuse box, so essentially NO Fuse, and to read with a clamp-on ammeter 40, and 50 amps on #14 AWG and the system still did not fail or initiate a fire.

---------- Post added at 09:19:23 PM ---------- Previous post was at 09:05:13 PM ----------

What's more is that when reworking such structures is was common to find old newspaper wadded up and stuffed in the walls as insulation. That would be how I normally start a fire in my wood stove, yet the Knob & Tube still did not initiate a fire.
In the late 70's and early 80's I inspected up to 4 residences a day that had K & T before allowing cellulose insulation to be blown into the walls. We would make them swap out the fuse boxes for Circuit Breakers so that it was more difficult to overload the system or defeat the protection. In houses built during prohibition one found empty bottles in the walls, and occasionally an electrocuted squirrel, possum, or racoon. Still no fire. In 8 out of 9 houses in New England one would find a Pair of wood skis, and corner molding stored on top of the wires in the cellar. I also came across rows of coat hangers with clothes hanging from the wires. The insulation had long since flaked off the wire and they were bare. This was most common in Attics, and having wood floors the inhabitants had not been shocked.

---------- Post added at 09:31:35 PM ---------- Previous post was at 09:19:23 PM ----------

One of the more impressive installations, an Industrial one, in Turners Falls Massachusetts that was still in operation, consisted of (3) 3/0 copper cables run way up high in the very center of a large buildings ceiling. It was 440 Volt Delta with no neutral or ground. Where ever there was a mill, lathe, press or piece of equipment requiring power they ran rigid conduit up to the K & T, put a weatherhead and had a fused disconnect at the bottom. The central circuit was protected at 600 AMPS. Not far down the road was a small Hydroelectric plant that had 4 one megawatt water wheels. Nikola Tesla had actually supervised the installation and construction of the hydro plant. It has been restored to fully operational status and had one of the largest knife switches I've ever seen.

---------- Post added at 09:45:12 PM ---------- Previous post was at 09:31:35 PM ----------

The "Gran-daddy" K&T still in operation in Chicago into the 80's, was a plant that manufactured Kilns, Furnaces, Ovens, and Industrial Heat Treating equipment. They had their own sub-station outside and in several of the "Test Bays" where they would test steel mill rolling forges, and commercial china conveyor ovens, they had: 120/208/240/440/460/480/600/2400 all racked up above the crane ways vertically stacked on the walls. Voltages above that like 4160, 13.8 KV,.... were all in conduit or special lead jacketed cable. In order to get the full 4 hour test run to be considered "Continuous", they waited until night to do the test, Not because they were using so much power, but because they often used upwards of 60,000 gallons per hour of water to cool the process and Chicago's water system ha a hard time keeping up.

---------- Post added at 09:49:47 PM ---------- Previous post was at 09:45:12 PM ----------

Finally, if one studies up on Edison's early efforts, before glass and porcelain, they use Wood as an insulator, and for Underground installations they filled pipes with tar and pulled single conductors into each conduit. This didn't work so well and resulted in Horses getting shocked on rainy days at intersections.
 

GeneratorGus

Registered
Age
72
I saw a lot of K&T in my early days of construction, and saved some and used them for various things over the years. Out of curiosity about sizes, I checked my 1926 Graybar (Western Electric) catalogue. I was kind of surprised to see an entire page.
There are also seven pages of different types of porcelain insulators.
GUS
 

Attachments

Railroads

Registered
I've inspected and worked on Knob & Tube installations in: Mass, N.H. Vt, Maine, Georgia, Ohio, Ill, Texas, Montana, and a couple more states. The majority of the installations had Varnished Cambric over rubber. This was essentially rubber insulation with a cotton braided outer cover that had been soaked in Varnish. After 40 or 50 years the insulation becomes very brittle. However, due to the fact that the wires were usually separated by 18 inches to four feet, and being mounted on porcelain as well as passing thru porcelain made the installations somewhat "Bullet-proof". It was quite common to find penny's or buffalo nickels in the fuse box, so essentially NO Fuse, and to read with a clamp-on ammeter 40, and 50 amps on #14 AWG and the system still did not fail or initiate a fire.

---------- Post added at 09:19:23 PM ---------- Previous post was at 09:05:13 PM ----------

What's more is that when reworking such structures is was common to find old newspaper wadded up and stuffed in the walls as insulation. That would be how I normally start a fire in my wood stove, yet the Knob & Tube still did not initiate a fire.
In the late 70's and early 80's I inspected up to 4 residences a day that had K & T before allowing cellulose insulation to be blown into the walls. We would make them swap out the fuse boxes for Circuit Breakers so that it was more difficult to overload the system or defeat the protection. In houses built during prohibition one found empty bottles in the walls, and occasionally an electrocuted squirrel, possum, or racoon. Still no fire. In 8 out of 9 houses in New England one would find a Pair of wood skis, and corner molding stored on top of the wires in the cellar. I also came across rows of coat hangers with clothes hanging from the wires. The insulation had long since flaked off the wire and they were bare. This was most common in Attics, and having wood floors the inhabitants had not been shocked.

---------- Post added at 09:31:35 PM ---------- Previous post was at 09:19:23 PM ----------

One of the more impressive installations, an Industrial one, in Turners Falls Massachusetts that was still in operation, consisted of (3) 3/0 copper cables run way up high in the very center of a large buildings ceiling. It was 440 Volt Delta with no neutral or ground. Where ever there was a mill, lathe, press or piece of equipment requiring power they ran rigid conduit up to the K & T, put a weatherhead and had a fused disconnect at the bottom. The central circuit was protected at 600 AMPS. Not far down the road was a small Hydroelectric plant that had 4 one megawatt water wheels. Nikola Tesla had actually supervised the installation and construction of the hydro plant. It has been restored to fully operational status and had one of the largest knife switches I've ever seen.

---------- Post added at 09:45:12 PM ---------- Previous post was at 09:31:35 PM ----------

The "Gran-daddy" K&T still in operation in Chicago into the 80's, was a plant that manufactured Kilns, Furnaces, Ovens, and Industrial Heat Treating equipment. They had their own sub-station outside and in several of the "Test Bays" where they would test steel mill rolling forges, and commercial china conveyor ovens, they had: 120/208/240/440/460/480/600/2400 all racked up above the crane ways vertically stacked on the walls. Voltages above that like 4160, 13.8 KV,.... were all in conduit or special lead jacketed cable. In order to get the full 4 hour test run to be considered "Continuous", they waited until night to do the test, Not because they were using so much power, but because they often used upwards of 60,000 gallons per hour of water to cool the process and Chicago's water system ha a hard time keeping up.

---------- Post added at 09:49:47 PM ---------- Previous post was at 09:45:12 PM ----------

Finally, if one studies up on Edison's early efforts, before glass and porcelain, they use Wood as an insulator, and for Underground installations they filled pipes with tar and pulled single conductors into each conduit. This didn't work so well and resulted in Horses getting shocked on rainy days at intersections.
Interesting stuff.

Robert
 
Last edited:

cornbinder89

Subscriber
Last Subscription Date
05/11/2020
coal gas!

My brother still has active K&T wiring in part of his house. right above the washer and drier, I am worried someone will hang wet clothes on a hanger off of it! I don't know how much remains in the rest of the house, but there is a fair bit in the basement.
 

Power

Registered
The home insurers around here have gone a bit:bonk:.

They no longer insure structures with active K & T.
I complained about insurance going up. Agent told me there are less expensive companies, but if I want to change companies, and house wiring is over 12 years old, they require an inspection report from a licensed electrician before they will issue a policy! (Their choice of electrician at my expense)
 

JoeCB

Subscriber
Last Subscription Date
03/19/2020
What NDmeter man said about significant rooms only having a single suspended socket for a light bulb. I have seen early electric (bread) toasters that had a threaded male plug like from a light bulb on the end of the cord rather that a normal male two prong plug. I guess you got either light or toast, not both for breakfast.

Joe B
 

Frank DeWitt

Subscriber
Last Subscription Date
12/17/2019
What NDmeter man said about significant rooms only having a single suspended socket for a light bulb. I have seen early electric (bread) toasters that had a threaded male plug like from a light bulb on the end of the cord rather that a normal male two prong plug. I guess you got either light or toast, not both for breakfast.

Joe B
The outlet was invented later. At first all small appliances screwed into a light socket. Later Edison sockets were mounted low on the wall to be used as outlets. The evaluation of outlets is a interesting history. For a while, there were quite a few choices.
 
In my former life as a telephone repairman, I was in an attic running wire, when I noticed a faint, glowing straight line running the length of the structure. It was the original K&T, sans insulation from age, glowing from the overload being imposed on it. Still worked fine, but I sure wouldn't insure that house for fire!

I wired one 32 volt lighting circuit in my shop using K&T, supported on porcelain cleats up the wall from the batteries then changing to knobs. It's completely exposed on the ceiling (for show off purposes) and powers two 32 volt, 100 watt bulbs. The wire is modern, black plastic insulated 12 gauge. Works just fine.
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
That shows you the principle superiority of knob and tube! Obviously the fuse had been replaced with a penny or similar, and the insulation burned away. If that had been Romex, it would have long ago shorted out. The only problem with knob and tube is morons bypassing fuses or physically damaging it etc. :brows:
 

DustyBar

Subscriber
Last Subscription Date
01/14/2020
... morons bypassing fuses ...
Where I worked in South America, fuse material was available on rolls. Material was a ribbon of rather soft metal you cut to length. Fuse holder had clips to grip the ribbon.

Photos are of a K&T installation in a museum I saw in Winnipeg.
 

Attachments

Railroads

Registered
I personally really like K&T. If I had it my place, I'd keep it as long as the wiring was physically ok and fit for service. I got about 50 feet of 12 AWG cloth covered wire from Frank Dewitt. Sometime I am going to setup a K&T display board I think. Or keep the wire and use it to wire my future generator shed for lighting.

Robert
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
Yeah, I'd love to build a place entirely with it, but sourcing that many of the parts would be difficult.

When I was a kid a neighbor gave me a good long length of #10 solid cloth covered rubber wire. I strung it up to send power out to my fort. Even made a power pole on the way that made the wires take a 90* turn. :D I'm sure I don't have it anymore though. :(

Keith
 

Railroads

Registered
Yeah, I'd love to build a place entirely with it, but sourcing that many of the parts would be difficult.

When I was a kid a neighbor gave me a good long length of #10 solid cloth covered rubber wire. I strung it up to send power out to my fort. Even made a power pole on the way that made the wires take a 90* turn. :D I'm sure I don't have it anymore though. :(

Keith
Keith, I salvaged about 10 feet of the old cloth covered service entrance cable. The conductors are rubber with cloth sheathing in red and black. The wire is 6awg. My intentions are to cut up the wire and use it for my battery bank so it looks like something from the Delco light plant days.

I can't find it on the web now, But I swear I saw soft iron wire and wood or porcelain insulators as a setup? Maybe it was telegraph?


Robert
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
I have a book, "Electric Lighting", published 1920 that discusses iron wire. As with aluminum, the resistance can be delt with by higher voltage / larger cross section, but the reactance is notably worse than non-ferromagnetic conductors, obviously even more so at higher frequencies as say 60 vs 25 cycles. Wouldn't think it would be an issue with dc telegraph lines though...

Keith
 
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