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stevefrench 10-02-2012 03:47 PM

Replace old Knob and Tube with Romex
Hello all, long time reader, first time poster here.

I appreciate in advance any responses and advice.

My wife and I recently purchased a house built in 1909. We were told the electrical had been "updated" and that was also confirmed by the pre-sale inspection.

The other day, I was up in the attic, and discovered that there is still active knob and tube wiring in use. This alarmed me, because the previous owner blew in insulation all over the wire. I guess that's why the home inspection didn't report it.

From what I can tell, there is no knob and tube going down to the (updated) breaker box. There is Romex going up into the attic from the box, which goes into a junction box and then knob and tube connected from there. There are several junction boxes throughout the attic, in which there is romex connected to knob and tube wiring. It appears as though the knob and tube wiring is what is being used on longer runs to carry power throughout the rooms, and then that is connected at junction boxes to romex which is going down to lights, outlets, etc.

So obviously I need to replace the knob and tube, because everything that has turned up in my research indicates that it can be dangerous when covered with insulation. I've identified long runs of the knob and tube between junction boxes that should be fairly easy for me to swap out.

My plan is to:

1 - Identify the hot knob and tube wire with my voltage detector.
2 - Shut off all power at the breaker box.
3 - Disconnect the knob and tube wiring at each junction box.
4 - Run 12/2 Romex between the junction boxes, connect them to the other wiring in the boxes with high quality wire nuts wrapped with heavy duty electrical tape.
5 - Where there is wire tapped in to the knob and tube without a junction box, install a junction box and connect the romex inside the box.

There are a couple of two prong outlets in the house that we don't use that I have identified as having knob and tube run down the walls to these outlets. I plan to disconnect the knob and tube for these outlets at their respective taps, pull the wire up out of the wall and put a blank plate over the hole in the wall.

Does this sound like a decent plan? Is there anything else I should consider?

Thanks in advance

daveb1 10-02-2012 09:56 PM

First and foremost would be permits and inspections. Doing this much wiring renovation without both might jeopardize your home insurance. Are you in an area where home owners are allowed to do their own electrical work?

Talk to your local inspector about your intentions. Most of them are very helpful to DIYers if approached before the work starts.

Be honest with yourself about your wiring abilities. Asking if you should tape your wire nuts hints at inexperience.

If you do go ahead with this (and I think it should be done) map out your home wiring (what breaker feeds what area and what wire feeds to where). Devise a plan that breaks the project into small areas. It's easier to go without power to a couple of bedrooms rather than no power to half the house if you hit a snag.

You will probably be required to bring all areas that you work on, up to today's standards. This will likely mean adding a lot of receptacles and possibly some new circuits. Plan accordingly. Those receptacles you don't use could be used to extend a circuit.

Don't forget to upgrade your stove, clothes dryer and water heater wiring if required.

I'm sure you will get lots more advise from others here.

AltaSparky 10-02-2012 10:18 PM


We were told the electrical had been "updated" and that was also confirmed by the pre-sale inspection.

There are a couple of two prong outlets in the house that we don't use that I have identified as having knob and tube run down the walls to these outlets. I plan to disconnect the knob and tube for these outlets at their respective taps, pull the wire up out of the wall and put a blank plate over the hole in the wall.
Kind of concerning in my opinion. I think a 2 prong outlet should raise flags with a "home inspector".

Dave gave you lots of good advice and I would follow all of it. I think if you have wires running down walls you likely have the issue of trying to fish wires and add new receptacles in the walls to replace what you are removing. First thing I would do is get a good idea of where all the K&T is that is still active. If you have to replace any K&T going down walls it might get tricky fishing wires and retrofitting boxes.

Well, 12-2 romex is probably overdoing it, unless we are talking really long runs (50-100'). Generally whatever size wire is feeding from the panel should be enough.

stevefrench 10-03-2012 12:32 AM

Hi guys, thanks for the reply. A bit more detail...

I am definitely getting a permit to do the work. My state/area does allow home owners to do this type of work with an over the counter permit. They require a post-work inspection. I will talk to the inspectors there when I go get the permit, that is good advice.

I am confident that this is something I can do. I'm going to take my time and do it over a couple of days. For the last few days, I have been locating all of the K&T under the insulation and following to where and what it runs to. I have mapped it out and come up with my game plan of what I'm going to do at each junction box. I've checked the receptacles that I plan on decommissioning and they do not appear to be feeding other circuits.

The positive thing is that this is only one circuit that is fed by K&T. There is romex coming up from the breaker box, and that feeds the K&T in the attic. The 240v for the stove and dryer are new runs that are romex going directly to the breaker box. The water heater wiring is updated as well. Everything else in the house is romex and has been updated. I've had new circuits installed for my TV/computer/other electronics. This one K&T circuit just feeds a few outlets and 3 ceiling lights/fans. Whomever did the previous work did install several 3 prong outlets that they left ungrounded. The ground wire is inside the box in the wall disconnected. In the attic, the ground wire is just disconnected in the j-box. When I update the wiring with romex, I plan on also connecting the ground to these outlets.

During all of this investigation, I have uncovered some pretty scary stuff. There was a hot wire that was spliced to romex and K&T that was bare and stuffed under a beam. I also found a few spots that the K&T insulation is hanging on for dear life.

As far as the length of the run, this circuit services 3 separate rooms, and the total length of the run is about 50ft, so I figure the 12-2 should be good.

In terms of my "home inspector", I had an e-mail exchange with him about this and he basically told me that since he saw an updated breaker box and insulation in the attic, he figured there was no chance of there being K&T in the attic :

Glennsparky 10-03-2012 12:49 AM

I believe the work you describe was done illegally. I'd like to see the "electrician" burn in hell:furious:. I mean, compensate you for his misdeeds. Maybe even the previous owner was complicit in the scam. Once you do the work, they'll skate and jeapardise the life and finances of the next person. If you have any chance of making them pay, all the paperwork and documentation has to be done professionally (lawyer) before you touch anything. Rant over. Good luck.

stevefrench 10-03-2012 12:55 AM

No doubt in my mind that it was done illegally. All of this has just come to light in the last week for me, and I am starting to wonder if I have any recourse here. The previous owner stated specifically in the disclosures that there was all updated copper wiring in the house. I am 99% sure he did this work himself without permits. And my home inspector sure did seem to drop the ball on this one too. Had I known about these wiring issues during closing, I would have definitely demanded that they were fixed before we bought the house.

Glennsparky 10-03-2012 01:01 AM

Oops, just one circuit? Forget my last post. It's not worth it. I am concerned about you blanking off some receptacles. If memory serves, receptacles can be no more than twelve feet apart and any wall space over twenty-four inches must have one. Check if your inspector will enforce this.

k_buz 10-03-2012 05:09 AM

Don't fool yourself into thinking this will be an easy job. I have done some KT removals that have taken a week with two electricians. If you don't have any help, this will take you a long time to complete. Keep in mind that there very well could be splices you don't see in walls. You can think you have it all mapped out, cut the wiring out, then a room on the opposite side of the house doesn't work.

Also keep in mind that you may be required to bring all the wiring you touch up to current code, which means, AFCI protection, GFCI protection, tamper resistant receptacles, proper outlet spacing, fan rated boxes.

daveb1 10-03-2012 06:48 AM

As k-buz says, don't think this will be an easy job. I replaced the K&T from my son's 800 square foot house with the kitchen and basement upgraded already and took 4 weekends (not including wall repairs). Fishing walls is tough without proper tools and experience. Code violations are easy to make. Take the time now to do it all properly, not just the easier replacement in the attic. It seems that what was replaced was not inspected. You will feel better knowing that everything is done right.

Squished 10-03-2012 07:07 AM

I feel your pain. I just replaced an entire house worth of K&T, not a single wire had been updated except for the one that went to the boiler. Each and every light switch, light, and receptacle in the entire 1600 sq ft house was K&T. We almost didn't get homeowner's insurance because of it when we bought the property and the single company that offered us insurance gave us 30 days to remove every piece of it. $15,000 later, we're signed off and inspected on rough electrical for the whole house. K&T is a beast to remove, there's so many ceramic isolation blocks on a single run it gets real annoying real fast.

ericb1960 10-03-2012 08:18 AM

I would not pull the wiring from the outlets that you do not plan to use. Those wires can be used to pull Romex WHEN you or someone later decides they need those outlets. For that matter, I'm not sure you need to remove any K&T equipment as long as its properly disconnected.

Fix'n it 10-03-2012 09:05 AM

i am doing K&T replacement right now. i my walls, you ARE NOT pulling the K&T out, without opening up the walls. as the are knobs inside the wall. this clamps the wire. the wire is basicly nailed to the studs.

stevefrench 10-03-2012 01:18 PM

As always, thanks very much for all the replies. I am definitely not looking at this as an easy or simple job. I plan on taking at least 2 weeks to fully prepare for this, and a few days to a week set aside of doing nothing but this. I also do have a helper. Part of my planning is also developing a contingency plan. I plan on labeling all of the wiring first and leaving the existing system in place in case i have to fall back on it. I'm also photographing every part of the current system.

In the worst case scenario, if this circuit is disabled for a few days because of a snag, we have other circuits in the affected rooms that can run lights, etc.

It seems as though the consensus is to not disable the existing receptacles wired with K&T, and I am definitely in agreement with that now. I did speak to the building department here and they did seem to think (although didnt give me a definite answer, wasnt speaking to an inspector) that I do need to have at least one outlet on each wall. So I will leave those existing outlets wired with K&T, and as part of my "phase 2" of the project, either run myself or have someone run romex down to those outlets. It's only 2 outlets total. All other outlets in the house have romex running down to them. At the time that I have that done, which should be either immediately or shortly after replacing the circuit, I will make sure all of the outlets are tamper resistant. Where I believe I am required to have GFCI (bathroom, kitchen, laundry area, outside), there are already GFCI outlets there that are wired with romex to a seperate circuit(s) to the one that is in question here.

As far as AFCI breakers, I don't believe my breaker box has any of those. That is something I am going to contact an electrician about. I don't plan on doing any work inside the breaker box myself.

daveb1 10-04-2012 06:59 AM

You have listened to the given advise and seem as well prepared as you can get over the internet. Good luck with your project and keep us posted. Come back with more questions as they arise (and they will).:thumbsup:

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