Knob + tube extention

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shepelec

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Palmer, MA
Whats the take on knob + tube extentions?

I saw a job today where the EC soldered romex onto k+t, taped the joint and left in the ceiling to be covered with drywall.

One tap is the continuation of a switch leg and the second refeeds part of the old circuit. There are no new loads on the k+t.

I say 394.10 applies to extentions of k+t using k+t, not romex.
300.15 for the box requirement.

but

300.16 allows "fittings" when making the transition. Of course no fittings were used. Just tape and solder.
 
shepelec said:
Whats the take on knob + tube extentions?

I saw a job today where the EC soldered romex onto k+t, taped the joint and left in the ceiling to be covered with drywall.

One tap is the continuation of a switch leg and the second refeeds part of the old circuit. There are no new loads on the k+t.

I say 394.10 applies to extentions of k+t using k+t, not romex.
300.15 for the box requirement.

but

300.16 allows "fittings" when making the transition. Of course no fittings were used. Just tape and solder.
Click to expand...

Look at 394.10 and 394.12 /110.14/394.56
 
shepelec said:
Whats the take on knob + tube extentions?

I saw a job today where the EC soldered romex onto k+t, taped the joint and left in the ceiling to be covered with drywall.

One tap is the continuation of a switch leg and the second refeeds part of the old circuit. There are no new loads on the k+t.

I say 394.10 applies to extentions of k+t using k+t, not romex.
300.15 for the box requirement.

but

300.16 allows "fittings" when making the transition. Of course no fittings were used. Just tape and solder.
Click to expand...

We do a lot of K&T REMOVAL jobs and find stuff just like you metioned.here

I saw a job today where the EC soldered romex onto k+t, taped the joint and left in the ceiling to be covered with drywall.
when the home owner is trying to have insulation installed .And some insurence companys are requesting that the home owners remove the old K&T and run new circuits.Even though K&T is not illegal insurence companys seem to be pushing its removal more and more..Thats more work for us.:)
we go in and remove the K&T and run new circuits:grin:
 
Insurance companies make money by not taking high risks. K & T were never intended to be insulated. Back in the 20's fuel was cheap and we did not have houses with air conditioning. The system if used as intended is very safe. Problem is that is grandfathered in even if it was unsafe. Insulation defeats the systems method of not getting hot by trapping in heat.
Most of the rewires i done were because owners needed or wanted insurance or got caught by an inspector while inspecting other work like remodels.
 
shepelec said:
I saw a job today where the EC soldered romex onto k+t, taped the joint and left in the ceiling to be covered with drywall. . . Of course no fittings were used. Just tape and solder.
Click to expand...
The absence of the fitting is the thing to call out, IMO. Note that the language in 300.16 doesn't require a "listed" or "intended for the purpose" rating on the fitting, and that the solder splice doesn't occur inside the fitting. Using a small 1/2" weatherhead with a romex clamp in it would seem to fit the 300.16 description of the fitting.
 
I have asked this exact question at a continuing ed class with the local AHJ, his comment was that it is fine. My only thought to add is that as long as the splice was mechanically secure and electrically continuous, I find solder to be okay.
 
300.16(F) requires to fitting to be accessible (and the lack of). I flagged the install based on that.

I admit correcting this will be a real pain but thats the way I read it.

Am I missing something?
 
shepelec said:
300.16(F) requires to fitting to be accessible (and the lack of). I flagged the install based on that.

I admit correcting this will be a real pain but thats the way I read it.

Am I missing something?
Click to expand...


IMHO (as I was taught some time ago) when performed properly, a soldered joint becomes a continuous electrical conductor with the same strength and conductive properties. There is no "fitting" to speak of, or to leave accessible.

This would follow with the standards of knob and tube.

I know that knob and tube has gotten a bad rap, largely from homeowner abuse, neglect or ignorance. From what I understand, I don't see what the harm is.

Obviously, this should be done with caution (as in lighting scenarios only) and not used to supply heavy loads or loads with motors.

I am interested in what anyone else might have to say
 
drewsserviceco said:
IMHO (as I was taught some time ago) when performed properly, a soldered joint becomes a continuous electrical conductor with the same strength and conductive properties. There is no "fitting" to speak of, or to leave accessible.

This would follow with the standards of knob and tube.

I know that knob and tube has gotten a bad rap, largely from homeowner abuse, neglect or ignorance. From what I understand, I don't see what the harm is.

Obviously, this should be done with caution (as in lighting scenarios only) and not used to supply heavy loads or loads with motors.

I am interested in what anyone else might have to say
Click to expand...

Most here agree that K & T is a safe system if no insulation or misuse.
However when adding to it we must follow NEC. Once we change over to romex the rules change and begin at the connection to the K & T so in my opinion we can not just splice into it and solder the wires. You need a box and continue it from there.
 
Jim W in Tampa said:
. . . so in my opinion we can not just splice into it and solder the wires. You need a box and continue it from there.
Click to expand...
2008 NEC
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).
Click to expand...
It is my opinion that the NM wiring method ends where the NM cable sheath is terminated in "the fitting". The open NM conductors that emerge from the fitting are now part of the K&T method and are terminated per 394.56.

The fitting cannot contain the splice.

The soldered connection of the NM conductor to the existing K&T is, IMO, specifically allowed to be as all K&T splices are, outside of boxes.
 
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al hildenbrand said:
It is my opinion that the NM wiring method ends where the NM cable sheath is terminated in "the fitting". The open NM conductors that emerge from the fitting are now part of the K&T method and are terminated per 394.56.

The fitting cannot contain the splice.

The soldered connection of the NM conductor to the existing K&T is, IMO, specifically allowed to be as all K&T splices are, outside of boxes.
Click to expand...

"
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 "
So just what fitting are you suggesting meets this requirement ? Pict ?
 
al hildenbrand said:
The absence of the fitting is the thing to call out, IMO. Note that the language in 300.16 doesn't require a "listed" or "intended for the purpose" rating on the fitting, and that the solder splice doesn't occur inside the fitting. Using a small 1/2" weatherhead with a romex clamp in it would seem to fit the 300.16 description of the fitting.
Click to expand...

That seems like it would be okay as long as some loom extended into each opening. A small weather head, a short section of EMT and a romex connector or bushing at the other end; making sure that there's a knob within six inches of both sides of each soldered connection.

But I'm wondering how far the weatherhead should be from the last support (or knob.) I think I'd go with 6", but is there something in the code?
 
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ike5547 said:
But I'm wondering how far the weatherhead should be from the last support (or knob.) I think I'd go with 6", but is there something in the code?
Click to expand...
I think it depends on where one puts the actual soldered splice. Looking at 394.30(A)(1), I'd say if the soldered splice is in the middle, the weatherhead could be as much as 12", along a conductor, from the knob. I'd arrange a specific assembly based upon the conditions present so the weatherhead to first knob conductor was as short as practical. 'Course, one has to maintain the clearances in 394.19.
 
al hildenbrand said:
I think it depends on where one puts the actual soldered splice. Looking at 394.30(A)(1), I'd say if the soldered splice is in the middle, the weatherhead could be as much as 12", along a conductor, from the knob. I'd arrange a specific assembly based upon the conditions present so the weatherhead to first knob conductor was as short as practical. 'Course, one has to maintain the clearances in 394.19.
Click to expand...

Would you agree that the weatherhead would have to be accessible after installation, or am I missing something? I'm looking at 300.15(F)
 
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al hildenbrand said:
I think it depends on where one puts the actual soldered splice. Looking at 394.30(A)(1), I'd say if the soldered splice is in the middle, the weatherhead could be as much as 12", along a conductor, from the knob. I'd arrange a specific assembly based upon the conditions present so the weatherhead to first knob conductor was as short as practical. 'Course, one has to maintain the clearances in 394.19.
Click to expand...

And are you suggesting we can conceal a wheater head ?

I got called down once for trying to use romex to feed an old K&T circuit. Was no big issue as it was only a temp feed while we were doing a rewire. I agreed to leave that open till we were finished.

Personally i think if the romex was stapled and tied in neat that it does not create a hazard. However i just can't follow what they have in mind. Perhaps someone has a picture in hand book or a Mike Holt picture.
Luckily it is very unlikely that i will ever need to do it again but am curious about it.

What does a weatherhead solve ?
 
ike5547 said:
Would you agree that the weatherhead would have to be accessible after installation, or am I missing something? I'm looking at 300.15(F)
Click to expand...
300.15 Boxes, Conduit Bodies, or Fittings ? Where Required.

A box shall be installed at each outlet and switch point for concealed knob-and-tube wiring.

Fittings and connectors shall be used only with the specific wiring methods for which they are designed and listed.

Where the wiring method is conduit, tubing, Type AC cable, Type MC cable, Type MI cable, nonmetallic-sheathed cable, or other cables, a box or conduit body shall be installed at each conductor splice point, outlet point, switch point, junction point, termination point, or pull point, unless otherwise permitted in 300.15(A) through (M).
Click to expand...
Knob & Tube isn't in 300.15. So I don't think 300.15(F) applies.
 
As far as the original post is concerned, I generally continue on with the knob and tube wiring method as necessary, installing my own tubes, knobs, loom, etc., until I reach the the next available box. I do not transition to romex in the middle of an existing run. I have vintage electrical manuals as a guide for proper technique and I've seen, studied and observed a great deal of existing K&T installations in San Francisco.
 
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