Knob and Tube Wiring

[Rickmar]

Hey Guys,

In the northeast, we are still infested with older homes with knob and tube wiring. The other day at my code update class, I brought up on why knob and tube wiring does not go straight into the electrical panel and onto a breaker. There might be homes that still does have that, but I have yet to see it. I was told that there was a code that stated that if you are going to replace the electrical panel the knob and tube wiring must not go back into the new panel. That is why I always see the black junction box with the hinged door next to the electrical panel. The electrician ran BX or Romex cables from the panel to this junction box and made up the splice to the knob and tube wires there.
Does anybody know what year code book did this go into effect?


Thanks,
Rick

 

[Ponchik]

Did the instructor give you a code reference?
I have never heard of "the knob&tube can not go into new panel"

 

[Rickmar]

I did not ask at the time. On my drive home I thought that I should of because I get a lot of jobs removing knob and tube and it would be great to tell the customer when or if this went into effect.

 

[kwired]

I'd guess most K&T ran straight to the fuse panel it was supplied from when initially installed. Some of those were nothing more then an open bladed 2 pole knife switch and fuse holder on a porcelain base. One fuse was in grounded and one in ungrounded conductor.

Some time later when a bigger fuse panel or even a circuit breaker panel was installed it often was relocated - and K&T was not typical wiring method used anymore so extensions to the new panel were often NM cable.

 

[Sierrasparky]

I worked for a guy a few years back that replaced K&T and we did nothing special , ran the K&T directly into the panel.
Never saw issue with that.

 

[kwired]

I worked for a guy a few years back that replaced K&T and we did nothing special , ran the K&T directly into the panel.
Never saw issue with that.

Isn't it hard to run it directly into the panel if you are replacing it?

 

[Rickmar]

Years ago before the volt stick came out and I wanted to find the hot K&T wire, I would role out a piece of THHN and touch the faucet or closest pipe. Then stick the Wiggy tester in between.

 

[don_resqcapt19]

Years ago before the volt stick came out and I wanted to find the hot K&T wire, I would role out a piece of THHN and touch the faucet or closest pipe. Then stick the Wiggy tester in between.

The old neon voltage testers worked for that purpose. One lead on the wire and your fingers on the other lead. It would glow a bit on the hot, and not any on the neutral.

 

[mopowr steve]

The old neon voltage testers worked for that purpose. One lead on the wire and your fingers on the other lead. It would glow a bit on the hot, and not any on the neutral.

Still keep one of those with me just for that purpose.

 

[GerryB]

Hey Guys,

In the northeast, we are still infested with older homes with knob and tube wiring. The other day at my code update class, I brought up on why knob and tube wiring does not go straight into the electrical panel and onto a breaker. There might be homes that still does have that, but I have yet to see it. I was told that there was a code that stated that if you are going to replace the electrical panel the knob and tube wiring must not go back into the new panel. That is why I always see the black junction box with the hinged door next to the electrical panel. The electrician ran BX or Romex cables from the panel to this junction box and made up the splice to the knob and tube wires there.
Does anybody know what year code book did this go into effect?


Thanks,
Rick

Around here if we do a service upgrade and there is visible K&T we are usually required to remove it and box it where it goes up the wall, so if you did that you would have no K&T going into the panel.

 

[Pizza]

Around here the original service to the older homes was brought to the 2nd floor, sometimes in the stair way, attic, or even a bathroom. Usually a 30 amp service.
As the decades went by, homeowners had more electrical needs and a 100 amp service was put in the basement with the meter socket outside.
That old 30 amp service was gutted and was refed with like four circuits or whatever or completely abandoned.
Basements didn't have any original K&t but maybe a light. As chit was added by that time BX and Emt had came out so that was used.

So that's why around here you normally don't see K&t in panels.

And maybe the installer didn't want to booger up the panel by having knob and tube in it?


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[ptonsparky]

Still keep one of those with me just for that purpose.

I had, have, a long time customer using one of them on his 480 Pump panels. After I chewed his butt for the second or third time I bought him a Fluke T+Pro and considered it a "free hat" for his years of business.

now back to our program

 

[user 100]

Around here the original service to the older homes was brought to the 2nd floor, sometimes in the stair way, attic, or even a bathroom. Usually a 30 amp service.
As the decades went by, homeowners had more electrical needs and a 100 amp service was put in the basement with the meter socket outside.
That old 30 amp service was gutted and was refed with like four circuits or whatever or completely abandoned.
Basements didn't have any original K&t but maybe a light. As chit was added by that time BX and Emt had came out so that was used.

So that's why around here you normally don't see K&t in panels.

And maybe the installer didn't want to booger up the panel by having knob and tube in it?


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Or he simply may not have had the length available when the original can was replaced/moved. And I agree with the others that there is no prohibition to running k&t to a panel-you can legally secure loomed/sleeved k&t to a junction box using the right connectors, so why wouldn't you be able to do the same when entering a panel?

 

[goldstar]

Part of the problem (especially in the Ridgewood and Glen Rock areas) is that many insurance companies will not insure you if you have K&T in the house. A big problem for a home seller and/or a 1st time home buyer. K&T is still in the code book in Article 394. Sometimes if you're compliant with 406.4(D)(2) and GFI protect the circuit and replace the receptacles with grounded type they'll accept it and let you leave it in place.

I've already had situations where I've cut the plaster and lath right down an entrance hallway, replaced the K&T and had the ceiling re-plastered. It all depends on how badly the sellers want to unload the house or how badly the buyers want to buy the house.

I'm guessing the reason insurance companies want the K&T removed is because splices in K&T were soldered when they were installed. If you have someone like my daughter living in the house who runs her curling iron and/or hair dryer for a half hour at a time that soldered splice will soften and possibly start to arc

 

[user 100]

I'm guessing the reason insurance companies want the K&T removed is because splices in K&T were soldered when they were installed. If you have someone like my daughter living in the house who runs her curling iron and/or hair dryer for a half hour at a time that soldered splice will soften and possibly start to arc

Provided the solder splice was done correctly (pretwisted/coated w/rcs) the overheating due to current would have to be a pretty extreme event to damage the integrity of the joint-something would have to cause the wire temp to approach 400 degrees or higher before the solder even begins to loosen up.

I think the bigger concern is with the often seen hackery the old stuff falls victim to and the general deterioration (80 year old rubber cloth insulation/loose friction tape).

 

[Frank DuVal]

Yes, soldered connections are just fine. Especially since if done by the "method of the day", the joint was mechanically secure first (twisted like a wire nut joint would be) then solder was added.

 

[Pizza]

Part of the problem (especially in the Ridgewood and Glen Rock areas) is that many insurance companies will not insure you if you have K&T in the house. A big problem for a home seller and/or a 1st time home buyer. K&T is still in the code book in Article 394. Sometimes if you're compliant with 406.4(D)(2) and GFI protect the circuit and replace the receptacles with grounded type they'll accept it and let you leave it in place.

I've already had situations where I've cut the plaster and lath right down an entrance hallway, replaced the K&T and had the ceiling re-plastered. It all depends on how badly the sellers want to unload the house or how badly the buyers want to buy the house.

I'm guessing the reason insurance companies want the K&T removed is because splices in K&T were soldered when they were installed. If you have someone like my daughter living in the house who runs her curling iron and/or hair dryer for a half hour at a time that soldered splice will soften and possibly start to arc

Also a main reason is in attics or crawl spaces where home owners have tossed insulation over it and it can't dissipate heat.


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[K8MHZ]

Yes, soldered connections are just fine. Especially since if done by the "method of the day", the joint was mechanically secure first (twisted like a wire nut joint would be) then solder was added.

The same method is allowed today, and is in the code. Solder is allowed but it cannot be used as a means of mechanical connection.

110.14(B)

"Conductors shall be spliced or joined with splicing devices identified for the use or by brazing, welding or soldering with a fusible metal or alloy. Soldered splices shall first be spliced or joined so as to be mechanically and electrically secure without solder and then be soldered."

So, if I wanted to, I could use soldered connections on NM cable. Note the 'or' in the above.

Most wire nuts are labeled indicating no pre-twisting is required. For example, the below:

http://www.idealind.com/products/wire_termination/twist-on/twister.jsp

One 'method of the day' that is not mentioned in the code is the use of 'Western Union' splices, which are incredibly strong and were part of our trade a century ago.

 

[K8MHZ]

Also a main reason is in attics or crawl spaces where home owners have tossed insulation over it and it can't dissipate heat.


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And walls with blown in insulation.

 

[goldstar]

....the overheating due to current would have to be a pretty extreme event to damage the integrity of the joint-something would have to cause the wire temp to approach 400 degrees or higher before the solder even begins to loosen up.

How many women live in your house ?????

I think the bigger concern is with the often seen hackery the old stuff falls victim to and the general deterioration (80 year old rubber cloth insulation/loose friction tape).

I'm sure you are correct.