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Knob & Tube Wiring Picture

B

Bryan Holland

Silver Member
Joined
Oct 18, 2009
Messages
241
Location
SW Florida
Here is a nice knob & tube wiring picture in case you have never seen this type of installation before.

(Provided by Paul Cameron of Pasco County, FL)

528.jpg
 
Wow! I'm sure electricians are glad they don't have to do it that way anymore. Most of what I've seen is in old house's after it has been messed with over the years. # 18 lamp wire used to wire recepticles etc. Had one where the electric range had been spliced into the entrance cable before the disconnect. Don't know how that one didn't burn.

Gary J
 
yeah, I've never seen an industrial/commercial installation with K & T being used. Looks pretty, cool, although that's the operative word, it stayed cool.
 
I've been around a long time and have never seen anything like that before. From the days when craftsmen practiced.
 
That installer was an artist. Look how similar it is to a modern printed circuit.
 
Wow, wow, & WOW! Thanks! I have seen many residential applications but never commercial. Say what you want but if it gave service over what ever years without burning the electrician did good. Thanks again!
 
Cool, thanks for sharing! The first house I ever owned was built in the 1920's and had it throughout.
 
that is nice. if i could get electricians around here to nmc as nice, i' be SOO happy. like others, have seen and removed alot of this in the past, but never a commercial appilication. clean!
 
That's pretty wild, looks like an art project for school. WPA project?

pc1
 
Bryan, Is this wiring system still in use? Any idea about what year it was installed. What company and what type of business? Thanks!
 
Believe it or not, K&T wiring is still in use today. (See Article 394 of the NEC)

The "heyday" of K&T wiring was from 1880 - 1930. The picture above appraently came from a "textile factory" built in the early 1920's.
 
Wow, now that's some craftmenship. Looks like some three pole switches too. Hopefully this gets preserved in some type of museum somewhere.
 
I remember seeing some panels with slate backs, knife switches and screw-in fuses in the attic of an early 20th century college building. I wonder if the lighter panels here are asbestos board, which was also used.

I also remember seeing an historic house that was electrified in the early 20th century and had electric panels where the fuses were lengths of wire with a low melting point that were screwed into the terminals. They had spools of this fuse wire, in different gauges for different amperages, and when a fuse blew they would cut a length and replace the piece that had just blown.

The main problem I've seen with K&T wiring was that the old cotton-wrapped rubber insulation would dry out and crack. The one exception was a 1920s building where the K&T wiring was still good 60 some years later.
 
That is impressive. Thanks for sharing. I can't imagine the amount of thought that had to go into installing that such that wires never crossed.

I wonder if the electrician designed it himself, or if there was a drawing.
 
Open Wiring on Insulators

Shouldn't this be classified as "Open Wiring on Insulators" i.e. not concealed like knob and tube.

398.2 Definition.

Open Wiring on Insulators. An exposed wiring method using cleats, knobs, tubes, and flexible tubing for the protection and support of single insulated conductors run in or on buildings.

Open wiring on insulators is an exposed wiring method that is not permitted to be concealed by the structure or finish of the building. It is permitted indoors or outdoors, in dry or wet locations, and where subject to corrosive vapors, provided the insulation choice from Table 310.13 is suitable for use in a corrosive environment.

This wiring method is no longer permitted for temporary lighting and power circuits on construction sites but is permitted for lighting and power circuits in agricultural buildings [see 547.5(A)]. It may also be used for services (see 230.43).
 
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