Knob & Tube Questions

[Cavie]

I personally walk away from N and T unless I replace all of it. It's a liability thing with me. All or nothing.

 

[al hildenbrand]

I personally walk away from N and T unless I replace all of it. It's a liability thing with me. All or nothing.

Your perspective provides more work for me (he says, pretending we live and work in the same jurisdiction ).

 

[Cavie]

Your perspective provides more work for me (he says, pretending we live and work in the same jurisdiction ).

Fortunately we don't have much of it here in Florida. Lot's of work without having to mess with it.

 

[al hildenbrand]

Fortunately we don't have much of it here in Florida. Lot's of work without having to mess with it.

Here, in the old housing stock of inner city Minneapolis / St. Paul I would estimate that fully 70% of dwellings have existing K&T core wiring from original electrification that is still in service and will likely continue to be in service for another century at least.

 

[kwired]

I do not read it quite that way:
Where the only wiring method is K&T, splices can be in the open. This was done during the original installation.
But in most of the pictures, the K&T is spliced to a different wiring method.

I do not see A-L applying to any of the splices pictured.

Right or wrong, there is a lot of NM (older cloth covered NM) extensions off the K&T around here, and nearly all are tapped onto the K&T in the open, so it must have been a standard practice even if code said otherwise.


When conductors did leave knobs and tubes they were typically sleeved in a non metallic tubing - maybe in places where they were fished, or even just short lengths to a switch or outlet box.

And there was a lot of exposed live parts in some of that vintage equipment.

 

[K8MHZ]

Right or wrong, there is a lot of NM (older cloth covered NM) extensions off the K&T around here, and nearly all are tapped onto the K&T in the open, so it must have been a standard practice even if code said otherwise.


When conductors did leave knobs and tubes they were typically sleeved in a non metallic tubing - maybe in places where they were fished, or even just short lengths to a switch or outlet box.

And there was a lot of exposed live parts in some of that vintage equipment.

They still sell these at Lowes

That's the whole thing. There is no cover over the screw terminals. They are called 'cleat sockets'. Notice the UL logo?

 

[Knuckle Dragger]

Open splices, usually soldered and then taped, were the preferred method of connecting K&T wire runs. Sometimes with a knob close for support, sometimes not. But what you have in the first picture appears to be a later tap of the K&T using the predecessor of NM. That connection should probably be made in a bo

The shiny boxes, open or otherwise, are later additions and are probably illegal if concealed and should be covered if not concealed (all as of the time they were installed.)

I am not sure what all of the options were for lighting fixture connections, or what type of bushing or connector is needed when entering a box with K&T wire.
Those light bulb sockets appear to be "temporary" using sockets designed for festoon lighting or construction of luminaires and need to be supported. Also the junctions have to be in boxes.

Whether the inspector requires all of these to be corrected before signing off is probably a local variation. My guess is most or all will have to be remediated, since the integrity of the original K&T has been disturbed. It may be easiest to abandon the whole thing and pull new home runs.

The First two photo examples were legal for the time they were installed. The others are not, a junction box is required now.
When installing N&T in a metal J-box:
A) use a plastic bushing and place both conductors through the same KO.
B) use two plastic bushings, you need to get a hack saw blade and notch between the KO's then install the plastic bushings .
C) use a plastic box and stick the conductors through two separate KO's
I hope this was helpful.

 

[ActionDave]

... a junction box is required now....
.

I don't know that this is true. K&T had its own section in the code and it says that soldered splices are allowed. It makes no mention of j-boxes.

 

[K8MHZ]

I don't know that this is true. K&T had its own section in the code and it says that soldered splices are allowed. It makes no mention of j-boxes.

It looks like 300.15 allows for splices in K&T to not have a box. The only place 300.15 requires a box is at an outlet or a switch point. That, to me, makes the surface mount cleat socket in my earlier post non-compliant. But splices without a box seems to be OK if soldered or using approved splicing devices.

 

[Knuckle Dragger]

It looks like 300.15 allows for splices in K&T to not have a box. The only place 300.15 requires a box is at an outlet or a switch point. That, to me, makes the surface mount cleat socket in my earlier post non-compliant. But splices without a box seems to be OK if soldered or using approved splicing devices.

They way I have practiced and interpret 300.15 is that you need a junction box or raceway with an accessible/ removable cover when splicing conductors.

 

[al hildenbrand]

They way I have practiced and interpret 300.15 is that you need a junction box or raceway with an accessible/ removable cover when splicing conductors.

You are not alone in so doing. And there is nothing wrong with doing more than the minimum that the NEC requires.

The NEC requirements for Knob and Tube still allow splicing as seen in original K & T. These K & T code requirements are the exception to the generalization that "all splices go in a box".

 

[Knuckle Dragger]

You are not alone in so doing. And there is nothing wrong with doing more than the minimum that the NEC requires.

The NEC requirements for Knob and Tube still allow splicing as seen in original K & T. These K & T code requirements are the exception to the generalization that "all splices go in a box".

I don't quite understand where I am wrong, but I'm sure someone will show me.
This is why I enjoy these forums, I get to see code interpretations other than my own.

I just don't see in the code where it is written for (lack of a better definition) an open air splice like in a basement or attic is allowed. 300.15 , require a box and (A) no box if wiring methods with removable covers, such as wireways, multioutlet assemblies, auxiliary gutters and surface raceways. The covers shall be accessible after installation. (I look at this as some sort of junction box).:huh:


(F) Is referring to the use of an approved change over fitting instead of a box right?

 

[K8MHZ]

I don't quite understand where I am wrong, but I'm sure someone will show me.
This is why I enjoy these forums, I get to see code interpretations other than my own.

I just don't see in the code where it is written for (lack of a better definition) an open air splice like in a basement or attic is allowed. 300.15 , require a box and (A) no box if wiring methods with removable covers, such as wireways, multioutlet assemblies, auxiliary gutters and surface raceways. The covers shall be accessible after installation. (I look at this as some sort of junction box).:huh:


(F) Is referring to the use of an approved change over fitting instead of a box right?

Notice that K&T is not on the list of conductor types needing boxes for splices. It has it's own requirement, which does not include splices, at the beginning of that section.

 

[al hildenbrand]

(F) Is referring to the use of an approved change over fitting instead of a box right?

No. The "change over fitting" is described in 300.16(A).

 

[mjf]

You are not alone in so doing. And there is nothing wrong with doing more than the minimum that the NEC requires.

The NEC requirements for Knob and Tube still allow splicing as seen in original K & T. These K & T code requirements are the exception to the generalization that "all splices go in a box".

For my future knowledge.... What can legally, today, be open air spliced to existing K + T ? Any type of cable (NM, MC, etc)? Or only Knob and Tube can be spliced to Knob and Tube without some type of junction box?

 

[al hildenbrand]

What can legally, today, be open air spliced to existing K + T ?

The answer is right there in 300.16(A).

2011 NEC Chapter 3
300.16 Raceway or Cable to Open or Concealed Wiring.
(A) Box, Conduit Body, or Fitting. A box, conduit body, or terminal fitting having a separately bushed hole for each conductor shall be used wherever a change is made from conduit, electrical metallic tubing, electrical nonmetallic tubing, nonmetallic-sheathed cable, Type AC cable, Type MC cable, or mineral-insulated, metal-sheathed cable and surface raceway wiring to open wiring or to concealed knob-and-tube wiring. A fitting used for this purpose shall contain no taps or splices and shall not be used at luminaire outlets. A conduit body used for this purpose shall contain no taps or splices, unless it complies with 314.16(C)(2).

The real head scratcher is how 300.16(A) says that the fitting that ends the raceway or the cable, that permits the conductors contained inside the raceway or cable to emerge into open, non-box-enclosed air, CAN NOT contain any splices. The splices have to happen outside the fitting. . . at the K & T itself. Even a conduit body "shall not" contain splices.

 

[mjf]

Thank you. I believe I understand it.

 

[Little Bill]

Sad Story Concerning my OP

Sad Story Concerning my OP

I started this thread on the knob & tube. I didn't include any information about the customer or how I was contacted.

The customer called me from where he/she lived (trying to keep the gender private for privacy sake), two thirds of the way across the country from me. The customer bought this house in my area sight unseen. I think I mentioned that the POCO rules were that if there had been no active service for one year or longer that an inspection had to be done before reconnecting. When he/she called the POCO to get the power turned on for when he/she could come in to check out the house, they informed him/her of this. In turn I was called to help.

So from just a phone conversation and email, I took the job to get it ready for an inspection. I want go into all I had to do and some things that were suggested by me to go ahead and fix while the power was off. But I got everything taken care of and passed inspection.

The person came in and called me. Was appreciative of me getting things took care of, and asked about referring some other trades for other work. I told him/her that I would contact someone and have them call.
Long story shortened, the house was made livable by me and a few others.

Now I never met the customer at all, just phone and email. I received a check by mail for my work. I didn't know the customer came to stay, I just thought he/she came to check things out. I was told by one of the other trades that he/she was moving in now. I tried to reach him/her a few times to see if everything was ok and to see if anything else was needed. Never was able to get in touch with him/her.

I was looking online for an obituary of one of my customers. I saw a familiar name on the list. It was the name of the customer for the house w/knob & tube. I thought that can't be. But when I read where he/she was from, it was truly my customer.

So sad that someone moved 2/3rds the way across the country to a house they had never seen and an area they had never been to, to just be here a few weeks and pass away!

 

[ActionDave]

Life tosses all of us some funny bouncing balls. It sure sounds to me like your customer was lucky to find someone who was honest and did what was right.

 

[Little Bill]

Life tosses all of us some funny bouncing balls. It sure sounds to me like your customer was lucky to find someone who was honest and did what was right.

My only regret is I didn't get to meet the customer face to face. The house was in a neighboring town that I don't regularly go to. But I wish I had made a trip over to meet the customer in person.