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#25469 - 05/09/03 07:13 PM Knob and Tube?
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
What exactly is Knob and Tube?.
I've heard this term used around ECN a bit and I was wondering if someone could tell me what this is?.
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#25470 - 05/09/03 07:43 PM Re: Knob and Tube?
circuit man Offline
Member

Registered: 11/05/01
Posts: 287
Loc: saluda,s.c.
trumpy, it was a real old type wring using single conductors where when went through a joist you drilled a hole & inserted a porcelain tube for the wire to go through.the knob was put on the sides of a joist & the wire fit under the top. there are some pics here on the site but just not sure. they will show ya what i'm talking about. :-)ERWIN

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#25471 - 05/09/03 08:05 PM Re: Knob and Tube?
spkjpr Offline
Member

Registered: 12/01/00
Posts: 226
Loc: Sedalia,MO, USA
Trumpy, go to the electrical nostalgia board and check on "knob and tube wiring". It is a good picture.

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#25472 - 05/09/03 08:10 PM Re: Knob and Tube?
mamills Offline
Member

Registered: 11/30/01
Posts: 739
Loc: Wharton, Texas, USA
Hi Trumpy:
Go to the "Electrical Nostalgia" section here at ECN. There are several threads dealing with Knob and Tube wiring, along with excellent photos.

Mike (mamills)

...OOOOPPSS!! Like Spkjpr said...I guess I was composing about the same time he was...

[This message has been edited by mamills (edited 05-09-2003).]

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#25473 - 05/09/03 08:29 PM Re: Knob and Tube?
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Hey Thanx Guys!,
Have just checked it out and all I can say is that, this has got to be the strangest wiring method I've seen in a while!.
Are those insulators attached to the sides of them joists?.
I take it that this type of wiring is no longer used?.
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Let's face it, these days if you're not young, you're old - Red Green grin

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#25474 - 05/09/03 08:53 PM Re: Knob and Tube?
mamills Offline
Member

Registered: 11/30/01
Posts: 739
Loc: Wharton, Texas, USA
Trumpy:
The insulators are nailed into the ceiling joists or wall studs. The insulator comes in two pieces - the wire is sandwiched between the two pieces and the nail holds the entire affair in place. A great many homes still contain Knob and Tube wiring - some in pristine condition, and most in varying degrees of hazardous disrepair (due to physical damage, poor maintenance, and deterioration/overheating from overfusing).

There may be areas of the country where this method of wiring is still permitted, but it is mostly outdated now, in favor of non-metallic sheathed cable, also referred to as "Romex" (a trade name). Knob and tube wiring, as you can see from the pics, is quite a labor-intensive wiring method. Splices are also performed in the open (in violation of modern day NEC codes), along with the fact that there is no provision for grounding of devices such as light fixtures and receptacles.

Mike (mamills)

[This message has been edited by mamills (edited 05-09-2003).]

[This message has been edited by mamills (edited 05-10-2003).]

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#25475 - 05/09/03 10:07 PM Re: Knob and Tube?
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Mike,
Thanks for the info,
You say that this type of wiring is still permitted in some areas, where?.
When I first saw the pictures, I thought it was a leaning over power pole, with all them insulators.
Also, what type of wire was used?, it looks to me like black rubber, as this was in fashion in the old days, am I right?, are them wires single cores?(1 wire stranded)
You'd have to be careful using the hammer around them Porcelain insulators, one wrong hit and it would be all busted to pieces!.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

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#25476 - 05/10/03 07:29 AM Re: Knob and Tube?
Obsaleet Offline
Member

Registered: 04/05/03
Posts: 361
Loc: Pa
Trumpy,
I was talking to my inspector yesterday about k&t. He tells me it is still in use down south in flood prone areas. Romex gets wet and doesn't dry out inside. It grows mold and the paper rots degrading the insulation. Knob & Tube can dry out and is fine. The just run 3 wires instead of 2, like the old stuff.

I have no idea were they get the supplies. They aren't available in my area.


Ob
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#25477 - 05/10/03 07:58 AM Re: Knob and Tube?
mlk682 Offline
Member

Registered: 04/14/03
Posts: 46
Loc: Foley Mn
I ran into a house a few years ago that they ran the nuetral down one side of the house and the hot down the other side. They would make a joint in the ceiling light fixtures and drop out the one or two outlets they had in the room along with the switch legs. They had the service panel and metering mounted inside the house on the side of a kitchen cabinet and the whole house had been fed from 2 20 amp circuits. They had tapped one little disconnect for a dryer.I wish I had taken some pictures. The house was a depression era house and the inside walls were made from old dupont powder boxes (There was an old explosives plant from the war era nearby)

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#25478 - 05/10/03 08:24 PM Re: Knob and Tube?
harold endean Offline
Member

Registered: 02/16/02
Posts: 2248
Loc: Boonton, NJ
Trumpy,

Here in Northern NJ it is very common in homes that are over 100 years old. We will work with it if we have to but for the most part we will rip it out and install new wiring. It is a nightmare to work with. It is old, sometimes frayed, Sometimes mice chew on the insulation, and if it is exposed in the basement some people will even use it for a clothes line! Above all, there is no grounding conductor run with it.

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