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maximumpower: Knob and tube, junction boxes and insulation question

maximumpower: Knob and tube, junction boxes and insulation question

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  #1  
Old 08-25-12, 12:12 PM
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maximumpower: Knob and tube, junction boxes and insulation question

I know you can't insulate around knob and tube. I also know that if you install a junction box (for example, to connect loose wire together to complete a circuit) that you must have access to the junction box. That is, you can't hide a junction box behind drywall.

Having said that, I had an electrical contractor do some work in the attic to remove knob and tube. He spliced into the knob and tube with romex. These connections are in junction boxes that he added. The boxes are under the insulation.

I am doing more remodeling where there will be more knob and tube I have to deal with. I want to install more junction boxes and another electrical contractor told me this is the way to do it. However, I am confused, I thought you had to provide access to any added junction box. Is that just the case if it is behind drywall? Can I "bury" a junction box under insulation?

Thanks
 
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  #2  
Old 08-25-12, 12:55 PM
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Can I "bury" a junction box under insulation?
No. And, if the junction box is for connecting Romex to knob-and-tube, you can't have it down where the K&T is. Or, IOW,
you can't insulate around knob and tube.
But you already said that, didn't you?

What is it, specifically, that you're planning to do? And what is it, specifically, that the electrician did? undisturbed K&T can be left in place and used in most jurisdictions, but there's a very specific procedure that should be followed when feeding it into a modern J-box.
 
  #3  
Old 08-25-12, 04:12 PM
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If you've already had work done tying into the knob and tube and are getting ready to do more just rip it out. It's old and done it's job well... now bury it. Use your remodel as an opportunity to rip it out. It's out of date and prevents you from properly insulating your home.

So far in my rental houses I've found evidence of two fires started by the knob and tube that self extinguished without anyone ever knowing. I don't like the stuff and remove it whenever I encounter it.
 
  #4  
Old 08-25-12, 04:43 PM
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You don't really need to rip it out, just disconnect at both ends and cut it short enough it can't be reconnected and abandon in place.
 
  #5  
Old 08-26-12, 07:58 AM
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I will take it out. That is what I want to do but it is a lot of work. I have to re-run 1 outlet, 3 lights and 3 switches. It is going to be very difficult to get into the switch boxes into the walls. They are all plaster and lathe. But I will get it done.

As far as what the other contractor did...

There is K&T running under my bedroom (the bedroom is in the attic, so to speak). As the K&T exits out from under the bedroom, it was cut and terminated in a junction box. Then romex is tied to that in the junction box. The box is in the floor joist with insulation over it. This is how I found it.

Like I said, it is coming out but it makes for a huge electrical job. That is why I wanted to avoid running new romex. However, like you said, this is the time to do it.

Thanks!
 
  #6  
Old 08-26-12, 08:43 AM
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Yeah you would be better off taking it out,like Ray said you don't have to rip it all out just cut back what you can see to the insulators.I know running new wiring in old houses is a pita but the benefits of it are well worth it.Back in the day k&t was a good set up because it mainly powered lights,clocks and small radios but with all the new devices and appliances out today even wiring in houses built in the 80s is considered inadequate.Most of the newer houses just require a service upgrade without replacing the wiring unless it's aluminum.but anything built before the 1950s most likely will require a complete rewire.My house that was built in 1940 didn't have k&t but it had the old tar and oil insulation romex with no ground the way I replaced it was removing the switches and receptacles,taking a hacksaw blade wrapped halfway up with tape and cut the nails holding the old metal boxes to the studs.If you have k&t then the boxes you have are probaly screwed to the wood lath,just replace those boxes with newer metal boxes.
 
  #7  
Old 08-26-12, 11:34 AM
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Most knob and tube wiring was only attached at insulators or where it passed through a framing member with a ceramic insulator so you can often use the old wire to pull the new through wall cavities. If you have access and good luck it can sometimes be pretty easy to attach your new wire or a pull cord to the old wire in the box and then pull it up to the attic.
 
  #8  
Old 09-24-12, 06:28 PM
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I just wanted to follow up and let you know that I have replaced all the knob and tube in my attic/bedroom!

I also moved the dining room chandelier (had to cut a new hole in the plaster and lathe), which gave us a more open walk way through our dining room. I also added a hall way light.

I was able to replace two of the three old metal switch boxes in the bedrooms below the bedroom/attic. I liked the idea of using a hack saw blade but these were not mounted with nails or screws on the sides. There were brackets at the top and bottom, buried behind the plaster and lathe. I got them out but I need to touch up the plaster now :-)

I was able to reuse the third switch box and keep it in place :-)

It took a lot of work and I had to rip up a lot of flooring and sub flooring in the bedroom to re-wire it all but it was worth it!

Thanks again for all the help!!!
 
  #9  
Old 09-24-12, 07:31 PM
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Glad you got it done, Mike, and thanks for letting us know!
 
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