Home Improvement Stack Exchange
Home Improvement Stack Exchange

Questions tagged [knob-and-tube]

For questions about Knob and Tube electrical wiring throughout the home. Sometimes abbreviated as K&T.

Knob and tube wiring uses two separate copper conductors, each isolated by cotton cloth or soft rubber. The conductors are strung tightly through the cavities of your walls and floors, and depend on being separated by air in order to avoid overheating. When going through joists, the wires pass through porcelain tubes. In the wall and floor cavities, they are attached intermittently by porcelain knobs.

Knob and tube wiring was commonly used in North America from the 1880s through the 1930s. Existing knob and tube installs are permitted by the NEC to remain; however, it is possible for a variety of improper conditions to occur in a knob & tube wiring system, such as inappropriately shared neutrals, excessive EMI from loops, and makeshift open splicing of newer wiring methods into the K&T.

Source: What is Knob and Tube Wiring

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Should old knob and tube wiring be replaced?

I have been doing some electrical work in my house and I noticed it has old knob and tube wiring that is still hot, should this be replaced as found or is it fine to just leave it? It seems really old and brittle, so I'm a little concerned.
Tester101
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What is "knob and tube wiring"?

I assume this is some USA wiring system, am I right?
Walker
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Can disconnected knob-and-tube wiring be left in place?

The house I recently bought (over 100 years old) has had almost all of its wiring replaced with a new elctrical board. However, in two cases the new wiring has been connected to existing knob-and-tube wiring in a junction box, with the ground wire…
Nicholaas de Bruyn
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Should I use a GFCI or AFCI circuit breaker with knob and tube wiring?

My American house was built in 1942, and much of the wiring is still knob-and-tube wiring (2-wire, no ground). Over the years new modern wiring has been added to the house, but we still have some KnT wiring for the ceiling lights, and a few branch…
Stefan Lasiewski
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Can I replace an outlet that uses knob and tube wiring with a grounded outlet?

Can I replace an outlet that uses knob and tube wiring with a grounded outlet? Obviously the best choice would be to replace the old wiring. Is there a standard way to ground these outlets? Do I need to run a wire back to the circuit breaker box? Do…
Joe Phillips
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In knob and tube wiring, how to identify neutral wire vs a dead wire?

I'm in the US, Ohio if that matters. I have an old house with many circuits still on K&T wiring. I haven't been able to find information on how to identify a neutral wire - most guides just tell you how to identify hot wires, and whatever is left…
cjrobe
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How can I attach modern fixture to knob & tube wiring?

I have a modern external light fixture that needs to be attached to an existing exterior electrical 'box'. The older parts of the house have knob & tube wiring and there is evidence of gas plumbing for lighting before the knob & tube was installed.…
Meltemi
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Leaving lost neutral wire

I am in the process of clearing out old random wires from my 100 year old house (think multiple layers, modern, knob and tube and everything in between). In the process of doing this, I tried to remove a knob and tube circuit that disappeared…
Simon
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Box in knob and tube wiring between ceiling and cellulose?

I know that code says no cellulose insulation with knob and tube wiring because of possible heat build up. I also know that evidence of it causing fires because of this is scarce and a few states allow cellulose if an electrician says it's in good…
user20127
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Would knob and tube be used with modern conduit wiring?

Recently bought a single story house that was built in 1925, it has a basement and an attic space. I've doing some updates in it, and have noticed some confusing things with the electrical wiring. There is a fuse box in the basement, but only has…
Travis
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Looking for some guidance on knob and tube

I have recently moved into a 1920s apartment in Chicago. My landlord has only owned the building for a few years and does not know the details of the electrical system. I have some electrical devices that I know use a bit of electricity and want to…
osteichthyes
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I am removing some Knob and Tube wiring. Can I leave the NEUTRAL wires hanging in the walls?

I am renovating my bathroom. I am bringing in new circuits for all the electrical, and replacing the boxes. I will have no problem capping off/removing the live (black) knob and tube wires in boxes. However, I won't be able to cut the neutral/white…
user870
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Why are ungrounded GFCIs required to be labeled?

I discovered in my new house that someone had incorrectly connected grounded outlets (without any ground connected) to the knob and tube wiring. I have read that the outlets can be made safe by adding a GFCI upstream. However, electrical code…
glenviewjeff
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Is it safe to put insulation next to knob & tube wiring?

I have a room that has some really ugly cheap panelling on the walls. I want to rip it out & replace with drywall. While I'm at it, I'd like to add soundproofing insulation between rooms & thermal insulation on the outside walls. However, the house…
tomwhipple
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Remove a light switch to an outlet - knob and tube

I have an outlet with a light switch that currently controls it. What I would like to do is remove the switch so the outlet is always hot. I considered just removing the switch and connecting the two wires, but it's knob and tube and changing…
Michael
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