Wiring... How scared should I be

[ormsbyj (WavyGlass)]

We all have it it or had it... KNOB & TUBE wiring. Which from this point on I will refer to as KT. My home is undergoing what I thought to be a complete rewiring of the house. I just recently discovered the contractors version of updating all the wiring was to replace the accessible KT and not get behind the walls. That is with the exception to add GFCI in baths. The kitchen will be fully updated with modern wiring as well.

What will be done is all KT replaced from the newly install 200 amp box throughout the basement. Into the kitchen and the wiring hanging in the attic. To the best of my knowledge what is left behind walls will remain.

My lack of knowledge on this is making this hard for me to understand. We just cut a hole in a second floor ceiling to make room for the AC vent. When that happened an old wire did get cut. We traced it back to find it was not active. If that's not active that would indicate new wiring is running to that fixture correct?

How does it work to have new wire running then joined to KT wiring when it goes behind walls? Is having them cut into the walls to get all KT out worthwhile or if we replace the seen and leave the unseen are we okay?

Am I the only one that when doing this work the thought of putting my family at risk to any of this old technology makes you want to respond over the top. Then again this house is 100+ years old with just about all of the original features in tact and working. Including the KT wiring still in use. It can be hard to keep things in perspective...

[chooseopen (WavyGlass)]

I have read somewhere that the KT wiring by itself is quite good. Much of the time it is decent gauge wire, and the conductor's by design have lots of separation from one another. Unfortunately, most houses' KT is not intact. Instead over the years the wiring has been spliced improperly or covered with insulation or had oversized fuses installed, etc. These types of things can increase risk of fire dramatically. My house is also partially rewired. It is apparent that some circuits were just too difficult to update. That said, you may or may not have paid for your contractors to completely rewire your house. I suggest you take a second look at the contract.

[Kashka-Kat]

If you're seeing the old dead KT it would be because they don't usually bother to pull the old (dead) wiring out - why add more cost to the job. To "replace" KT means they would just run new circuits -ie wires from the circuit breaker box to the fixtures/outlets.

Why would they not run the wires behind the wall - I guess I'm not quite understanding. Did you ask the electrician what they did - they should be able to explain to you clearly in layman's terms before they even do the job what it is they propose to be doing. When I got this place I had an electrician repair some obviously hazardous connections -old wiring near outlets/fixtures tend to more frayed and dangerous because its been messed with more over the years while wiring within the walls tend to be more intact/safe. But no way was that sold to me as a "replacement", just a repair to tide me over.

[jschneider]

Ok... I tackled the wiring in my house myself with the help of an electrician friend. I was scared to death of knob and tube when we got it, and the sellers weren't willing to remedy the situation. We also weren't willing to walk away from the house. In the end KT isn't that bad, but it is an outdated method.

I rewired by pulling floor boards and running the same route as they did when electric was added to the house over a century ago... I ended up noticing that face nailed floor boards meant they were previously removed to run wires. It prevented any holes in plaster and I even managed to used some of the old KT wires as pulls.

For what it's worth, I have 4 light fixtures with KT now and I have no intention upon replacing them. What I pulled out was honestly as good as the day it was installed and has an excellent level of workmanship. Where I tied this circuit into new romex, I used a junction box. I'm pretty sure that's typical practice when necessary.

From what it sounds like you have abandoned KT in your house which is not a big deal at all. The electricians could have taken an entirely different route than the KT was run. It typically won't be pulled out of walls if its not active anymore since that would be more trouble that it's worth. I only removed it if it was visible.

[csnyder (WavyGlass)]

Our house is full of old K&T. Our initial plan was to hire electricians to do a complete rewire shortly after we bought the house, but the electrician we brought in said it was in excellent shape and recommended against replacement. Instead, they ran ground wires and installed new outlets (on new circuits) to give us more than one outlet in each room. I've examined the wire myself - the insulation is as flexible as when it was new, and the quality of workmanship is exceptional (with the amount of man-hours that had to have gone into that job, it's no wonder that electricity was still a luxury back then).

The problem with old wiring - K&T or otherwise - is that it's often been abused. When a fuse blew, many people would simply put in a bigger fuse (or use the penny trick) rather than stopping to consider why the fuse was there in the first place. The extra current caused the wires to overheat, making the insulation brittle.

There's no harm in leaving disconnected wire in the walls. One trick I learned is to use a wire-nut to short the hot and neutral wires together before pushing the wires into the wall. That way, if somehow the wire gets reconnected to a live circuit in the future, the circuit will immediately trip rather than leaving a hot loose wire stuffed in a wall somewhere.

[2ndline]

Keep in mind that K&T is not grounded or polarized, This resulted in many electrocutions back in the old days

[Ireland House]

When insuring our house for replacement cost, the company was not worried about whether or not it had KT wiring. Their only question was if it was on fuses or breakers. Our electrician suggested only replacing wiring as we had it exposed for other reasons.

[bofusmosby (WavyGlass)]

My house too as some of the old KT wiring that is still being used. The actual KT wiring was pretty good in its day, and even still, not bad at all. Of course, this is for the KT wiring that is still in good shape. The biggest problem with the old KT wiring was first, no ground. Second would have to be the currect rating. Back when that wire was installed, nothing drew the amount of current that many things draw today. THER is your problem. The original KT wiring in my house is being used for low wattage lighting, and that's it! I have a number of Scounces on the walls, and in order to replace all of this, the plaster walls would get damaged.

Just make sure that anything in your house that draws quite a bit of current is using the new wiring. I would also recommend that all power going to the kitchen and bathrooms be updated as well, with the GFCI's installed. Of course, it goes without saying that since you still have some active KT wiring in the walls, care must always be taken anytime you have to cut into the walls.

[phil]

I replaced all mine and found quite a few joints that were made and not even inside an electrical box. The wires were wrapped with that old cloth tape that was dried out and they were twisted, not even soldered and I could plainly see that the wires were all black from arcing. I also found some really iffy freyed and tattered (thin) wire near my porch light. all of this was hidden and I only found it after I rewired and was pulling old dead stuff out. I wouldn't trust any knob and tube wiring,especially stuff in the walls that can't see. You don't know what previous owners, or their contractors may have done in there.
too much to lose.

[phil]

also maybe read up on spark fault breakers and how they differ from ground fault breakers. I don't know your code but here spark fault breakers are required for all bedroom plugs. I didn't know that when I wired and so since I had bedrooms on several circuits I needed to put all these on spark fault breakers. I had to buy 3 and they are about 100 bucks each. If I had known that beforehand I would just wire all the bedroom outlets on one breaker. the only other thing I had to correct was some boxes that were wired properly but the boxes were too small. so check the box size and refer to the charts that say how many wires and wire nuts you can have for a certain box size..

a 200 amp panel will probably need a new hook up to the utility since you'll need somethign like 000 wire. so you'll need an inspection to move the meter maybe, I did it under a homeowners permit with free advice from my bro the electrician.
don't worry too much about old dead K and T. it won't hurt anythign if it is unhooked and after you re-wire you'll not be wanting to hook the K and T into the electrical, if you have a wall open pull it out.. But don't worry too much about the old stuff if it is hard to get to.
Phil