16 gauge stranded Knob & Tube?

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titan1021

Senior Member
:huh:

I'm doing some work on an old house that is wired primarily with Knob & Tube. One of the switch boxes has (2) 16 gauge stranded wires that are wrapped with white threads and a black line running the length of the wire. I figured someone must have spliced the wire in the wall or attic. (It resembles the old bell wire only a little larger) So, I went up into the attic and discovered that this wire is run throughout the attic and house. It is splice and taped like the rest of the knob & tube, so I assume it is original wiring. Has anyone come across this before?
Aside from rewiring the house which I don't think the owner can afford, I figure on removing the 20amp breakers currently in place and trying to track down some 10amp breakers. Any info on this kind of wiring would be greatly appreciated.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I would not do this and imo this install is probably not legal with a 10 amp breaker. You would have to follow all the provisions of 240.4(D)(2). I don't that can be done and 210.23(A) allows a 15 or 20 amp branch cir. for lighting
 

LEO2854

Esteemed Member
Location
Ma
:huh:

I'm doing some work on an old house that is wired primarily with Knob & Tube. One of the switch boxes has (2) 16 gauge stranded wires that are wrapped with white threads and a black line running the length of the wire. I figured someone must have spliced the wire in the wall or attic. (It resembles the old bell wire only a little larger) So, I went up into the attic and discovered that this wire is run throughout the attic and house. It is splice and taped like the rest of the knob & tube, so I assume it is original wiring. Has anyone come across this before?
Aside from rewiring the house which I don't think the owner can afford, I figure on removing the 20amp breakers currently in place and trying to track down some 10amp breakers. Any info on this kind of wiring would be greatly appreciated.

I would submit a proposal to remove and replace that #16 wire.


And if they do not give you the green light then i would wright a detailed letter to the Electrical inspector to cover your self in case something goes wrong.
 

renosteinke

Senior Member
Location
NE Arkansas
From an academic point .... when did the NEC first require branch circuits to be 15A or larger?

From a historical angle: Has anyone else ever seen either wire like this, or stranded wire used for K&T?

For the OP: What's the service size? Any idea when it was installed?
 

Besoeker

Senior Member
Location
UK
:huh:

I'm doing some work on an old house that is wired primarily with Knob & Tube.

I have seen knob and tube mentioned a few times.
Being from across the pond it's jargon that isn't used here.
Tube I assume is conduit.
But knob?

Educate the ignorant Brit please....
 

iMuse97

Senior Member
Location
Chicagoland
I have seen knob and tube mentioned a few times.
Being from across the pond it's jargon that isn't used here.
Tube I assume is conduit.
But knob?

Educate the ignorant Brit please....

knobs are ceramic, thumb-sized insulators mounted to structure with a nail around which free-air conductors are attached. Tubes are ceramic tubes used to run these free-air conductors through building frame members. Check this for picture. http://en.wikipedia.org/wiki/Knob_and_tube_wiring

Also see this for additional information related to code: http://artisanelectric.net/blog/tip-of-the-day/knob-and-tube-wiring-what-you-should-know/
 

jaylectricity

Senior Member
Location
Massachusetts
Occupation
licensed journeyman electrician
I have seen knob and tube mentioned a few times.
Being from across the pond it's jargon that isn't used here.
Tube I assume is conduit.
But knob?

Educate the ignorant Brit please....

edit: unappropriate response
 
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al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
I'm doing some work on an old house that is wired primarily with Knob & Tube. One of the switch boxes has (2) 16 gauge stranded wires that are wrapped with white threads and a black line running the length of the wire . . . . (It resembles the old bell wire only a little larger) . . . . this wire is run throughout the attic and house. It is splice and taped like the rest of the knob & tube . . . . I figure on removing the 20amp breakers currently in place and trying to track down some 10amp breakers.
I work in the center of a seven county metro area, and, as a result of the housing stock that was built from the 1870s, on, have had a lot of experience with K&T.

The only time I have run into 16 gauge conductors strung in a classic K&T method has been when the conductors were part of a signaling circuit (doorbell or servant call), part of an early tube based radio antenna system, or a scabbed in handy person illegal install. -- Bare in mind that my seven county area has a history of State wide electrical inspection since the first years of the 1900s which has helped to weed out substandard installs like your client's.

The fact that you found a 20 Amp breaker protecting that circuit indicates that the insulation on the conductors has a likelihood of bad heat degradation.
 

kwired

Electron manager
Location
NE Nebraska
From an academic point .... when did the NEC first require branch circuits to be 15A or larger?

From a historical angle: Has anyone else ever seen either wire like this, or stranded wire used for K&T?

For the OP: What's the service size? Any idea when it was installed?

Sounds to me like it is old fixture wire - like what was used from the outlet to the pendant lampholder. Probably was not a proper use of the conductors to install them as branch circuit conductors.

Todays equivelant is zip cord.
 

Besoeker

Senior Member
Location
UK
knobs are ceramic, thumb-sized insulators mounted to structure with a nail around which free-air conductors are attached. Tubes are ceramic tubes used to run these free-air conductors through building frame members. Check this for picture. http://en.wikipedia.org/wiki/Knob_and_tube_wiring

Also see this for additional information related to code: http://artisanelectric.net/blog/tip-of-the-day/knob-and-tube-wiring-what-you-should-know/
Appreciated, thank you.
Historical rather than current, it would seem.
 

Volta

Senior Member
Location
Columbus, Ohio
From an academic point .... when did the NEC first require branch circuits to be 15A or larger?

From a historical angle: Has anyone else ever seen either wire like this, or stranded wire used for K&T?

For the OP: What's the service size? Any idea when it was installed?

NEC 1897 said:
GENERAL RULES - ALL SYSTEMS AND VOLTAGES.
14. Wires.
(For secial rules, see Nos. 18, 24, 32, 38 and 39.)
a. Must not be smaller size than No. 14 B. & S., except as allowed under Rules 24 t and 45 b.

24 t refers to fixture work, and is limited to #18, and 45 b is for pendant lamps.
 
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