# Splicing knob and tube



## FastFokker (Sep 18, 2012)

Box and wire nuts?


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## 480sparky (Sep 20, 2007)

*394.56 Splices and Taps*
Splices shall be soldered unless approved splicing devices
are used. In-line or strain splices shall not be used.


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## forsaledun (Nov 15, 2012)

480sparky said:


> 394.56 Splices and Taps
> Splices shall be soldered unless approved splicing devices
> are used. In-line or strain splices shall not be used.


Can this be behind a wall or does it need to be in a box? I've seen a lot of hoaky things done with k&t.


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## wireman64 (Feb 2, 2012)

Your repairing this right ? Can't extend k &t Or any ungrounded circuit for that matter .Any way like 480 said twist solider and tape just like they used to is what i would do. We always replace though. Don't have my book on me but it does have an article on k&t .


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## forsaledun (Nov 15, 2012)

wireman64 said:


> Your repairing this right ? Can't extend k &t Or any ungrounded circuit for that matter .Any way like 480 said twist solider and tape just like they used to is what i would do. We always replace though. Don't have my book on me but it does have an article on k&t .


Yes, repairing. Homeowners budget won't allow for replacing. Sounds like I'll do some soldering.


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## RGH (Sep 12, 2011)

pull it back if you can to a place (basement or attic)where you can repair it by using a jbox..:thumbsup:...remember you can not extend it...re-read 480's post...you dont have to solder...as he said...only if you cant nut it...


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## forsaledun (Nov 15, 2012)

RGH said:


> pull it back if you can to a place (basement or attic)where you can repair it by using a jbox..:thumbsup:...remember you can not extend it...re-read 480's post...you dont have to solder...as he said...only if you cant nut it...


Can't pull it back either. So am I understanding that I can wirenut it, tape it up, and leave in the wall? No slack to put a box in.


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## Wirenuting (Sep 12, 2010)

Do it the old fashioned way. 
If you have never done it, please don't try.
To save a HO $$ is a bad time for you to learn.


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## Mshea (Jan 17, 2011)

The Approved method for Canada is the splice must be done in a box. 1 wire into 1 knockout. you also need to Loom the single wire and as you know wire loom is not easy to find. I have seen it for Automotive wiring. I will accept a few layers of rubber tape and a few layers of vinyl tape in the connector spliced onto normal loomex inside of a box that remains accessible. 1 K&T wire per KO. 1 Ko for the loomex (canadian romex)
No you may not bury the box in the wall and no you may not make sp[lices like they did in the original methods as these are no longer code defined wiring methods.


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## kennydmeek (Sep 12, 2009)

Mshea said:


> The Approved method for Canada is the splice must be done in a box. 1 wire into 1 knockout. you also need to Loom the single wire and as you know wire loom is not easy to find. I have seen it for Automotive wiring. I will accept a few layers of rubber tape and a few layers of vinyl tape in the connector spliced onto normal loomex inside of a box that remains accessible. 1 K&T wire per KO. 1 Ko for the loomex (canadian romex)
> No you may not bury the box in the wall and no you may not make sp[lices like they did in the original methods as these are no longer code defined wiring methods.


That's pretty much what I've always done as I never had anybody to tell me otherwise....and it's always passed inspection. Sort of is what it is with K&T..


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## forsaledun (Nov 15, 2012)

My plan was to put a box in the wall and splice, but. There's no slack there. Can't pull back as it's finished above and below. Thought about 2 boxes with romex between. Trying to make the cleanest and safest option for the homeowner.


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## wireman64 (Feb 2, 2012)

Mshea said:


> The Approved method for Canada is the splice must be done in a box. 1 wire into 1 knockout. you also need to Loom the single wire and as you know wire loom is not easy to find. I have seen it for Automotive wiring. I will accept a few layers of rubber tape and a few layers of vinyl tape in the connector spliced onto normal loomex inside of a box that remains accessible. 1 K&T wire per KO. 1 Ko for the loomex (canadian romex)
> No you may not bury the box in the wall and no you may not make sp[lices like they did in the original methods as these are no longer code defined wiring methods.


When i rip k&t out i always save the loom thats in good shape , ya never know when your gonna need it


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## big2bird (Oct 1, 2012)

Mshea said:


> The Approved method for Canada is the splice must be done in a box. 1 wire into 1 knockout. you also need to Loom the single wire and as you know wire loom is not easy to find. I have seen it for Automotive wiring. I will accept a few layers of rubber tape and a few layers of vinyl tape in the connector spliced onto normal loomex inside of a box that remains accessible. 1 K&T wire per KO. 1 Ko for the loomex (canadian romex)
> No you may not bury the box in the wall and no you may not make sp[lices like they did in the original methods as these are no longer code defined wiring methods.


Let me get this straight. One phase per K.O., spliced in an ungrounded metal box. That right?


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## big2bird (Oct 1, 2012)

wireman64 said:


> When i rip k&t out i always save the loom thats in good shape , ya never know when your gonna need it


Antique auto supply is a source. Just FYI.


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## wireman64 (Feb 2, 2012)

big2bird said:


> Antique auto supply is a source. Just FYI.


Im not going searching for it if its right there in front of me . But good to know


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## forsaledun (Nov 15, 2012)

big2bird said:


> Let me get this straight. One phase per K.O., spliced in an ungrounded metal box. That right?


I'm assuming he is talking about a plastic box.


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## Elephante (Nov 16, 2011)

forsaledun said:


> I'm assuming he is talking about a plastic box.


KT through same hole in metal box,through separate holes in plastic box.


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## RePhase277 (Feb 5, 2008)

A scrap of romex sheathing is a pretty good substitute for loom... Jus' sayin'....


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## big2bird (Oct 1, 2012)

Elephante said:


> KT through same hole in metal box,through separate holes in plastic box.


So what grounds the box?


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## macmikeman (Jan 23, 2007)

big2bird said:


> So what grounds the box?


What grounds the branch circuit? It's knob and tube....... Two wires. I use plastic boxes for the repairs. But mostly I replace it.


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## Elephante (Nov 16, 2011)

big2bird said:


> So what grounds the box?


I think metal boxes shouldn't be used for knob and tubingnly plastic.that metal box can become energized if the insulation is in bad shape or because poor workmanship. If your going to ground the metal box use a gfi on the circuit.


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## RePhase277 (Feb 5, 2008)

Elephante said:


> I think metal boxes shouldn't be used for knob and tubingnly plastic.that metal box can become energized if the insulation is in bad shape or because poor workmanship. If your going to ground the metal box use a gfi on the circuit.


What about every other box? They are all metal. There were no plastic boxes in 1915. I don't understand the last sentence in the quote.


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## retiredsparktech (Mar 8, 2011)

big2bird said:


> Let me get this straight. One phase per K.O., spliced in an ungrounded metal box. That right?


I was taught in trade school, that one conductor per K.O., with a length of loom on each and a Romex connector per K.O.
They refered to a Romex connector as a two screw connector. This was in the 1959/61 time frame. :blink:


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## TOOL_5150 (Aug 27, 2007)

one conductor per KO causes inductive heating. use a 3/4" 2 screw romex connector, loom the 2 K&T wires and jam them BOTH in the same hole.


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## Wirenuting (Sep 12, 2010)

TOOL_5150 said:


> one conductor per KO causes inductive heating. use a 3/4" 2 screw romex connector, loom the 2 K&T wires and jam them BOTH in the same hole.


This is how I also do it. It makes the greatest sense. 

But like retiriedspark said, the way he explained it is how I was also taught it by the old guys in the old days.


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## BBQ (Nov 16, 2010)

TOOL_5150 said:


> one conductor per KO causes inductive heating. use a 3/4" 2 screw romex connector, loom the 2 K&T wires and jam them BOTH in the same hole.


Code violation, the NEC requires we enter K&T in separately bushed holes. 

You can kill the inductive heating issue by cutting a slot between the two holes.


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## Jlarson (Jun 28, 2009)

BBQ said:


> Code violation, the NEC requires we enter K&T in separately bushed holes.
> 
> You can kill the inductive heating issue by cutting a slot between the two holes.


That's how I rolled the less then 5 times I've had to mess with K&T. 

Those evil plastic snap in bushings work good. :laughing:


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## RePhase277 (Feb 5, 2008)

TOOL_5150 said:


> one conductor per KO causes inductive heating. use a 3/4" 2 screw romex connector, loom the 2 K&T wires and jam them BOTH in the same hole.


Barely. We are talking about 15 and 20 amp receptacle and lighting circuits, not 100 amp furnaces. The amount of inductive heating caused by a couple of amps in a 1900 box is likely undetectable except by measuring equipment. Probably couldn't feel it with your hand.


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## BBQ (Nov 16, 2010)

Code section



> *300.16 Raceway or Cable to Open or Concealed Wiring.
> (A) Box, Conduit Body, or Fitting. *
> 
> A box, conduit body,
> ...


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## BBQ (Nov 16, 2010)

InPhase277 said:


> Barely. We are talking about 15 and 20 amp receptacle and lighting circuits, not 100 amp furnaces. The amount of inductive heating caused by a couple of amps in a 1900 box is likely undetectable except by measuring equipment. Probably couldn't feel it with your hand.


That is also true.


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## Elephante (Nov 16, 2011)

InPhase277 said:


> What about every other box? They are all metal. There were no plastic boxes in 1915. I don't understand the last sentence in the quote.


Sorry I thought the op was tapping off the knob and tube wiring with new wiring.well anyway this happened to me once awhile back.I extended knob and tube wiring with romex.i grounded the metal 4in box and I guess there was a some bare wire on my knob tubing and it energized my new old work metal box that I just installed as well as the the 4in.I found this out when I got putting on the cover plate.ouch


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## Wirenuting (Sep 12, 2010)

BBQ said:


> Code violation, the NEC requires we enter K&T in separately bushed holes.
> 
> You can kill the inductive heating issue by cutting a slot between the two holes.


That's right, I forgot about that. Thanks. 
I did see back in 95, in a 90yo hospital, were they had added a metal box in the 40's during a rehab. 
That black iron 1900 box did have the K&T entering thru 2 KO's. It did show signs of being burned between the openings. To bad it was before cell cameras. 

I think 480 posted a link 2 years ago to an old K&T installation instruction booklet. 
I'll try to find the link later tonight. I know I saved it as a PDF.


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## chicken steve (Mar 22, 2011)

I can recall 'slots' as well, but also forget....

BBQ, where did you get this?


~CS~


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## RePhase277 (Feb 5, 2008)

chicken steve said:


> I can recall 'slots' as well, but also forget....
> 
> BBQ, where did you get this?
> 
> ...


I can't speak for Bob, but I first read it in the American Electrician's Handbook. The physics is pretty simple. The gap gives a path for the field lines with no steel in the way, and hence a great reduction in eddy currents.


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