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  #1  
Old 10-13-2009, 01:09 AM
spinky spinky is online now
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Safety issues with knob and tube wiring

I have an old house, built in 1920, which still has a lot of old "knob and tube" wiring left in certain parts of it. Ultimately, I would like to spend some money and have it all ripped out and replaced with modern wiring, but in the meantime, I am curious about just how sketchy the stuff is. In particular:

1) I am thinking about installing a thermostat in the hall. This will require me to fish a wire through a wall which shouldn't have any wiring in it, but I can't be 100% sure without ripping it open. I have tried circuit finders and they don't work very well through the lathe and plaster. Is it safe to run a metal fishtape through a wall that may have 80 year old K&T in it? Obviously I can cut the power while I'm doing the fishing, but I also wonder if the wiring is easily damaged.

2) in the attic, there are places where the wiring is exposed and looks very brittle. Is this dangerous? If I were to go up there and put in fiberglas bats for insulation, do I need to take any extra precautions to keep from disturbing the wiring? Should I turn off the breaker if there is any chance of me touching it? Should I turn off the breaker and also make sure not to touch the wiring because it's fragile? I am very cautious around it because it looks like it could break if you breathe on it wrong, and the insulation on it is all cracked and doesn't look very ... insulating. Am I being silly?
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  #2  
Old 10-13-2009, 01:49 AM
gotpasswords gotpasswords is offline
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You're not being silly at all.

First of all, we can definitively say that you can not put more attic insulation over the KT wiring. Since 1987, the National Electrical Code has forbidden this. The two main hazards are that the wiring can overheat to the point of starting a fire, and that insulation may get damp and short-circuit the wiring.

As for running wiring for a thermostat - yes, shutting off the power would be prudent before sticking a steel fish tape into the wall if you're not sure that there's no KT wiring in there. At the very least, you could hit a bare spot and get shocked. As you suspect, KT wiring is very easily damaged. One alternate to fishing wires and worrying about what's inside is a wireless thermostat such as this one. Not cheap, but sometimes it may be a better option for retrofitting an old building instead of drilling, fishing and cussing.

Generally, if it's left alone, KT wiring is safe, provided it was done right in the first place. If it's lasted this long, it probably was done right. But now, it's really fragile stuff and the sooner you can get rid of it all, the better.
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  #3  
Old 10-13-2009, 02:01 AM
spinky spinky is online now
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I'm not considering putting insulation over the wiring, just mostly concerned about bumping the nearby wiring while I'm shoving the bats around. Sounds like a reasonable concern.

On the subject of a rewire... When doing wiring replacement, how exactly do you know when you've got it all? Much of the wiring goes through spaces that are easily accessible and/or mapped, but I have run across some spots where it makes some really unexpected turns, so I can't be sure it doesn't do something like that inside a wall. I'd hate to go to all the effort only to miss a chunk on a leg I didn't even know existed. I would think the insurance company, who I'd definitely want to contact for my new K&T-free rates, would want some kind of assurance that it's all gone, right?
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  #4  
Old 10-13-2009, 03:49 AM
boytyperanma boytyperanma is offline
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Originally Posted by ntucker View Post
I'm not considering putting insulation over the wiring, just mostly concerned about bumping the nearby wiring while I'm shoving the bats around. Sounds like a reasonable concern.

On the subject of a rewire... When doing wiring replacement, how exactly do you know when you've got it all? Much of the wiring goes through spaces that are easily accessible and/or mapped, but I have run across some spots where it makes some really unexpected turns, so I can't be sure it doesn't do something like that inside a wall. I'd hate to go to all the effort only to miss a chunk on a leg I didn't even know existed. I would think the insurance company, who I'd definitely want to contact for my new K&T-free rates, would want some kind of assurance that it's all gone, right?
Just remember the 'insulation' on KT is not very 'insulating' so it does not contain the heat generated by the copper the way moderns wires do and will not protect you from being shocked.

For rewiring the path the KT runs is largely irrelevant. The new wires can't typically follow the same path(KT goes through joists, new wires are run under joists) When you rewire you provide new power to all the points previously powered by the KT. The insurance companies are kinda lax on checking out whether the KT is replaced. Most home owners just end up faxing a copy of the bill for the rewiring and they are good with that. The old KT and tube is cut out to the best of the electricians ability and abandoned in a manner that prevents it from being usable in the future.
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  #5  
Old 10-13-2009, 07:56 AM
jtgain jtgain is offline
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Originally Posted by ntucker View Post
On the subject of a rewire... When doing wiring replacement, how exactly do you know when you've got it all? Much of the wiring goes through spaces that are easily accessible and/or mapped, but I have run across some spots where it makes some really unexpected turns, so I can't be sure it doesn't do something like that inside a wall. I'd hate to go to all the effort only to miss a chunk on a leg I didn't even know existed. I would think the insurance company, who I'd definitely want to contact for my new K&T-free rates, would want some kind of assurance that it's all gone, right?
Ten years ago I did a rewire from knob and tube in the house I owned back then. It was a fun project with the old man when he was still around.

We did what the previous poster suggested. It is impossible to track the path of the old circuits, so you just start with new. Run a fresh circuit from the box and start attaching the lights/outlets that are currently serviced by the knob and tube. Usually you luck out because the old knob and tube didn't run to too many outlets. Back when it was popular you didn't have microwaves, computers, TVs, etc. and it was mainly only for electric lighting. You didn't have the modern setup with an outlet every four feet along the wall.

In my case, it fed the overhead lights and one outlet in each room. Modern wiring had supplied the other outlets. Best of luck
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  #6  
Old 10-13-2009, 07:59 AM
Wheeljack Wheeljack is offline
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If it's practical, I'd suggest that when you have the K&T disconnected you leave it all in place. It'll make the house that much more interesting for future owners.
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  #7  
Old 10-13-2009, 08:00 AM
johnpost johnpost is offline
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Originally Posted by ntucker View Post
1) I am thinking about installing a thermostat in the hall. This will require me to fish a wire through a wall which shouldn't have any wiring in it, but I can't be 100% sure without ripping it open. I have tried circuit finders and they don't work very well through the lathe and plaster. Is it safe to run a metal fishtape through a wall that may have 80 year old K&T in it? Obviously I can cut the power while I'm doing the fishing, but I also wonder if the wiring is easily damaged.
yes the K&T can be damaged by fish tape. air as insulation is required to make it safe, you don't know that you wouldn't bend it or dislodge it from a knob, knock a knob loose or cause some building material to fall against it where it is bare or insulation damaged.

consider a wireless (radio wave connection) thermostat.

Last edited by johnpost; 10-13-2009 at 08:04 AM..
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  #8  
Old 10-13-2009, 08:04 AM
billfish678 billfish678 is offline
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Originally Posted by ntucker View Post

Should I turn off the breaker if there is any chance of me touching it? Should I turn off the breaker and also make sure not to touch the wiring because it's fragile?
You should TURN OFF the breakers anytime you are doing ANYTHING with wiring. AND you need to BE SURE you are ACTUALLY turning off the power to the parts you are messing with. IF you CANT be sure, turn off the power to the whole house.

Mini safety freakout over.
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  #9  
Old 10-13-2009, 08:15 AM
johnpost johnpost is offline
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Originally Posted by ntucker View Post
I have an old house, built in 1920, which still has a lot of old "knob and tube" wiring left in certain parts of it. Ultimately, I would like to spend some money and have it all ripped out and replaced with modern wiring, but in the meantime, I am curious about just how sketchy the stuff is. In particular:

2) in the attic, there are places where the wiring is exposed and looks very brittle. Is this dangerous? If I were to go up there and put in fiberglas bats for insulation, do I need to take any extra precautions to keep from disturbing the wiring? Should I turn off the breaker if there is any chance of me touching it? Should I turn off the breaker and also make sure not to touch the wiring because it's fragile? I am very cautious around it because it looks like it could break if you breathe on it wrong, and the insulation on it is all cracked and doesn't look very ... insulating. Am I being silly?
the insulation is very brittle, if undisturbed and in place it can still remain safe barring rodents and building damage (rain leaks and so on). i would turn the breaker/fuse off, it is easy to turn around and bump into. just brushing it lightly, or vibrations on wood structure that normally doesn't move much (stepping on the ceiling joists) can cause brittle cloth and rubber insulation to fall off. use good lighting and know well where it all is before hand.

you can abandon old K&T in place and route new wires through the walls when you want to replace it.
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  #10  
Old 10-13-2009, 09:33 AM
Wheeljack Wheeljack is offline
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Originally Posted by billfish678 View Post
You should TURN OFF the breakers anytime you are doing ANYTHING with wiring. AND you need to BE SURE you are ACTUALLY turning off the power to the parts you are messing with. IF you CANT be sure, turn off the power to the whole house.

Mini safety freakout over.
If I may expand the mini safety freakout just a hair: particularly on a house that old, you need to make sure "turning off the power to the whole house" actually turns off the power to the whole house. People have a nasty habit of neglecting to keep labels current, such as the genius at my father's old place who jumped the innards of a switchbox and then painted it closed. The switch still moved, but it did nothing to interrupt the power.
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  #11  
Old 10-13-2009, 10:15 AM
Munch Munch is offline
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Originally Posted by johnpost View Post
you can abandon old K&T in place and route new wires through the walls when you want to replace it.
The OP pretty much described my house - built in 1920, plaster and lathe, K&T wiring.

For a newcomer to rewiring, how difficult is this to do on my own? Say I take a weekend, cut the power in the morning, and start running new lines down to the breaker. What would I be in for?

Are there any books/websites you'd recommend to really read up on this before I begin?
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  #12  
Old 10-13-2009, 10:40 AM
gotpasswords gotpasswords is offline
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Quote:
Originally Posted by Munch
For a newcomer to rewiring, how difficult is this to do on my own? Say I take a weekend, cut the power in the morning, and start running new lines down to the breaker. What would I be in for?
You're in for a lot of work. Also, if you don't draw up plans and get a permit from your city or county, you'll be in for a lot of grief. Different jurisdictions have different rules on whether or not this kind of work can be done by a layman or if a licensed electrician must do it.

I really wouldn't recommend rewiring a house and upgrading the service entrance and main breaker panel as a first project. If youre new to wiring, this job is best fixed with the checkbook tool - hire an electrician who will know the various code requirements. You don't want to get through it all then have the inspector come in and ding you for subtleties like not enough outlets in the kitchen, or not using arc-fault breakers on bedroom circuits, etc.
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  #13  
Old 10-13-2009, 11:20 AM
johnpost johnpost is offline
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Originally Posted by johnpost View Post
you can abandon old K&T in place and route new wires through the walls when you want to replace it.
Quote:
Originally Posted by Munch View Post
The OP pretty much described my house - built in 1920, plaster and lathe, K&T wiring.

For a newcomer to rewiring, how difficult is this to do on my own? Say I take a weekend, cut the power in the morning, and start running new lines down to the breaker. What would I be in for?

Are there any books/websites you'd recommend to really read up on this before I begin?
you are allowed as a home owner to repair old electrical with like. so you can replace receptacles, switches and light fixtures for a 2 wire system as long as the K&T wiring holds up. once you start to upgrade then all that circuit has to be brought up to electrical code.

for a big job like that i would recommend an electrician do it. you would want to plan a new circuit map for your house and bright it up to current electrical code. knowing the electrical code for residential and safe wiring practice (there are unique concerns to doing a rewiring) is no small deal, also doing so with minimal disruption to the structure and plaster/lathe walls takes experience (other wise you get to do lots of wet plaster repair). you might be able to work as the electricians helper, it will take two people to do quickly and that way you will never be without electricity overnight if the job is done right.

for someone who is good at DIY you could try it with lots of preparation. i would get every book on DIY wiring at your library and read them all until you understood them all. Consumer grade DIY wiring books do have errors in the code and sometimes don't explain well to each person, multiple books help things come out in the end. Wiring Simplified by H. P. Richter, i think is the best book for a DIYer to explain doing things to the code, though other books may have good diagrams, drawings and photos to help you understand the techniques (you will do a lot of working blind in walls and some access hole making).
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  #14  
Old 10-13-2009, 11:54 AM
Kevbo Kevbo is offline
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Originally Posted by Wheeljack View Post
If it's practical, I'd suggest that when you have the K&T disconnected you leave it all in place. It'll make the house that much more interesting for future owners.
Check your local electrical code for rules related to "abandoned circuits" before acting on the above suggestion.
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  #15  
Old 10-13-2009, 01:09 PM
boytyperanma boytyperanma is offline
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Originally Posted by Kevbo View Post
Check your local electrical code for rules related to "abandoned circuits" before acting on the above suggestion.
National Electrical Code covers it. You can not leave abandoned wiring in a manner that it could be reused in the future.

I would not recommend rewiring a house as a DIY project. Specifically one with horsehair plaster. While snaking wires is simple in concept in practice it takes a lot of skill to do it effectively and in a timely way. If you can avoid cutting holes in the plaster it is always best and an experienced electrician will know the best methods to avoid damage.
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  #16  
Old 10-13-2009, 01:12 PM
HongKongFooey HongKongFooey is offline
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Originally Posted by Munch View Post
The OP pretty much described my house - built in 1920, plaster and lathe, K&T wiring.

For a newcomer to rewiring, how difficult is this to do on my own? Say I take a weekend, cut the power in the morning, and start running new lines down to the breaker. What would I be in for?

Are there any books/websites you'd recommend to really read up on this before I begin?
I'll third or fourth the recommendation to hire a pro for this. With a lot of old homes the main breaker needs to be upsized to to meet all the requirements of the code so you might not even be able to strip it back to there and start anew. Add to that the difficulty of fishing wires through all the layers of old renovations that you run into with an older home and you'll be glad to have someone experienced with you.

Around here the knob-and-tube is just disconnected and left where it is. I didn't know there were areas where it all had to be removed. That would be a huge pain in the ass.
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  #17  
Old 10-13-2009, 01:19 PM
HongKongFooey HongKongFooey is offline
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Originally Posted by boytyperanma View Post
National Electrical Code covers it. You can not leave abandoned wiring in a manner that it could be reused in the future.
Do you have to remove it all or just remove the feed from the panel out to the branch circuits?
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  #18  
Old 10-13-2009, 01:36 PM
Munch Munch is offline
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Originally Posted by HongKongFooey View Post
I'll third or fourth the recommendation to hire a pro for this. With a lot of old homes the main breaker needs to be upsized to to meet all the requirements of the code so you might not even be able to strip it back to there and start anew. Add to that the difficulty of fishing wires through all the layers of old renovations that you run into with an older home and you'll be glad to have someone experienced with you.
Thanks - that's kinda what I was hoping.

Two additional questions: I plan on renovating my bathroom from a half bath to a full bath (second floor). There will be rewiring needed, in addition to plumbing and carpentry. (1) Do I contract each of those jobs out (plumber, electrician, gen. contractor), or will a general contractor be sufficient? (2) When I put in new wiring for that bathroom, does that then obligate me to upgrade everything else?
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  #19  
Old 10-13-2009, 01:38 PM
spinky spinky is online now
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I don't know what the code says, but I think it would be a good idea to remove it as much as possible. It's no fun to run across wires that you must assume are live until proving otherwise.

Then again, it might be common for people to cut corners on that. I recently had a repipe done (the galvanized pipes were as old as my wiring), and at one point I was lucky to be standing there watching because the plumber held up a sawzall to recklessly hack through a pipe and what he assumed was dead wiring immediately next to it. I said, "don't cut that wiring. It's live." He tried to argue that there was no way it was live because there was some romex nearby so obviously the house had been rewired. I pointed out how you could actually follow that wire he was about to cut back to a live junction box fed by new wiring. No dead plumbers in my basement, please.
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  #20  
Old 10-13-2009, 01:58 PM
HongKongFooey HongKongFooey is offline
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Originally Posted by Munch View Post
(1) Do I contract each of those jobs out (plumber, electrician, gen. contractor), or will a general contractor be sufficient?
A good general contractor will hire the right guys for each job. Ask to see the permits or get them yourself. If he's getting the appropriate permits and inspections that's a good sign.
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Originally Posted by Munch View Post
(2) When I put in new wiring for that bathroom, does that then obligate me to upgrade everything else?
Around here, if a licensed guy touches it he has to bring everything up to code. I'm not familiar with American codes.

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It's no fun to run across wires that you must assume are live until proving otherwise.
Not a bad point but it sounds like that circuit shouldn't have been connected to anything as the plumber said.
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  #21  
Old 10-13-2009, 02:02 PM
johnpost johnpost is offline
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Originally Posted by Munch View Post
Two additional questions: I plan on renovating my bathroom from a half bath to a full bath (second floor). There will be rewiring needed, in addition to plumbing and carpentry. (1) Do I contract each of those jobs out (plumber, electrician, gen. contractor), or will a general contractor be sufficient? (2) When I put in new wiring for that bathroom, does that then obligate me to upgrade everything else?
1) a general contractor would hire the others and do the carpentry their self if that was their trade. you could also find someone in each trade yourself.

2) you will have to upgrade everything on that circuit, everything fed from the fuse or breaker that circuit is on needs to get upgraded. alternately you could run new wiring for just the bathroom back to the main breaker/fuse box; this would require properly terminating the old wiring somewhere (remove it to a junction or cap it in an accessible box (which could be in the bathroom or brought to a wall in the adjacent room).
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  #22  
Old 10-13-2009, 02:18 PM
boytyperanma boytyperanma is offline
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Originally Posted by HongKongFooey View Post
Do you have to remove it all or just remove the feed from the panel out to the branch circuits?
NEC wants the wires removed. Older wires in themselves can be a hazard do to the smoke they can cause in a fire. This is more specifically related to wires in plenum space.

All wiring powered or not must terminate in a box. KT presents a problem in doing so because you can not terminate the ends in the conventional 'box'

Say I have a Romex circuit running from one of the house to the other. If I decide it is no longer needed. My options are to remove it completely or if I can not or do not want to remove it I can box it on each end. It would be unacceptable to cut it and leave it unboxed at any point even if it is completely unpowered.
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  #23  
Old 10-13-2009, 02:45 PM
spinky spinky is online now
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Originally Posted by HongKongFooey View Post
Quote:
Originally Posted by ntucker
It's no fun to run across wires that you must assume are live until proving otherwise.
Not a bad point but it sounds like that circuit shouldn't have been connected to anything as the plumber said.
Are you saying he was making a valid assumption? Because I assure you he was not. Maybe it "shouldn't" have been connected to what it was connected to, but it most definitely was.

It's weird to me how many people make assumptions about wiring they have no actual knowledge of. Given the amount of do-it-yourself wiring I've seen, the only approach that makes any sense to me is to assume that whoever worked on the wiring before you might be a color blind amateur who has no knowledge of wiring conventions, let alone codes, and may in fact be trying to kill you.

Last edited by spinky; 10-13-2009 at 02:46 PM..
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  #24  
Old 10-13-2009, 03:40 PM
HongKongFooey HongKongFooey is offline
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Are you saying he was making a valid assumption? Because I assure you he was not. Maybe it "shouldn't" have been connected to what it was connected to, but it most definitely was.
I meant it shouldn't have been connected and I can see why he made that assumption, not that it was a good idea to do so.
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  #25  
Old 10-13-2009, 03:45 PM
t-bonham@scc.net t-bonham@scc.net is offline
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I don't know what the code says, but I think it would be a good idea to remove it as much as possible. It's no fun to run across wires that you must assume are live until proving otherwise.
Also, that wire can be sold for recycling. Given the current prices, it it's copper wire, selling it can help pay some of the costs of rewiring.

K&T wiring is safe, & works fine, as long as you leave it alone. Even if the insulation is old & brittle and falls off, the wires are physically separated and won't touch each other to short out. But if somebody shoves cardboard storage boxes up against the wires in the attic, or pushes insulation bats around them, or anything else that disturbs them, you can have problems.

If you're already up there where you can see the K&T wiring, it should be easy to replace it. And after you remove the tubes, you can often use those holes to run new romex -- can save a lot of work. But you generally have to replace the whole circuit. Fishing through the last 6 feet, where it runs down inside the wall to a wall outlet, may be more work than the whole attic rewiring part.

-------------------
A suggestion for the OP: there's a handy tool for this. It consists of a short (3-4') fiber optic cable, with a built in light, and an eyepiece at one end. You just drill a hole in the wall, insert the cable, and then look through the eyepiece to see what is really there inside the wall. Search for terms like "wall eye" or "wall scope". They aren't cheap, but could be worthwhile if you plan to live in an old house for a while and renovate it. You might also be able to rent/borrow one from an electrician or plumber.
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  #26  
Old 10-13-2009, 03:47 PM
spinky spinky is online now
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Originally Posted by t-bonham@scc.net View Post
A suggestion for the OP: there's a handy tool for this. ... They aren't cheap, but could be worthwhile if you plan to live in an old house for a while and renovate it. You might also be able to rent/borrow one from an electrician or plumber.
Sounds like an excellent excuse to buy a toy.
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  #27  
Old 10-13-2009, 03:55 PM
HongKongFooey HongKongFooey is offline
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Search for terms like "wall eye" or "wall scope".
or "flexible borescope". I think fiberscope is the proper term. They cost about $150.
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  #28  
Old 10-13-2009, 03:57 PM
billfish678 billfish678 is offline
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I meant it shouldn't have been connected and I can see why he made that assumption, not that it was a good idea to do so.


If an assumption is not a good idea to make, then should it not be made ?
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  #29  
Old 10-13-2009, 04:07 PM
Wheeljack Wheeljack is offline
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Originally Posted by boytyperanma View Post
National Electrical Code covers it. You can not leave abandoned wiring in a manner that it could be reused in the future.
I don't know if this is consistent with other aspects of the code, but whoever rewired my house accomplished this by cutting the wiring for the K&T every five feet or so and letting the ends hang where they may. It's very visibly disabled so no worries about it being powered.
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  #30  
Old 10-13-2009, 04:17 PM
HongKongFooey HongKongFooey is offline
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If an assumption is not a good idea to make, then should it not be made ?
I never said he should have I said I can see why he did. If you work with people who do professional work you get used to that level of quality. It sounds like the electrician in that case did a poor job or overlooked something, that's all. That's the type of thing that leads to unsafe situations arising down the road.
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  #31  
Old 10-13-2009, 04:35 PM
The Great Sun Jester The Great Sun Jester is offline
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Originally Posted by ntucker View Post
I recently had a repipe done (the galvanized pipes were as old as my wiring), and at one point I was lucky to be standing there watching because the plumber held up a sawzall to recklessly hack through a pipe and what he assumed was dead wiring immediately next to it. I said, "don't cut that wiring. It's live." He tried to argue that there was no way it was live because there was some romex nearby so obviously the house had been rewired. I pointed out how you could actually follow that wire he was about to cut back to a live junction box fed by new wiring. No dead plumbers in my basement, please.
Is it even code to ground a circuit to a water pipe (was it ever)? I can see this causing two problems: 1) as noted above, 2) you might be attempting to ground onto a decommissioned pipe that was just never removed and which no longer has contact with ground.

Like I would know what's code or not, but if you're grounding a 2-wire romex circuit from 1950 wouldn't you just run that ground wire right to the nuetral bus bar?
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  #32  
Old 10-13-2009, 04:58 PM
spinky spinky is online now
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Is it even code to ground a circuit to a water pipe (was it ever)?
The K&T was not grounded to the water pipe. It was simply running along beside it. They weren't touching. There's actually a seperate ground wire that runs parallel to all of this, but I don't see how it's tied to the wiring at all. How is K&T supposed to be grounded?
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  #33  
Old 10-13-2009, 05:15 PM
HongKongFooey HongKongFooey is offline
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One of the biggest reasons for getting rid of it is the lack of a grounding conductor.
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  #34  
Old 10-13-2009, 05:45 PM
johnpost johnpost is offline
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Is it even code to ground a circuit to a water pipe (was it ever)? I can see this causing two problems: 1) as noted above, 2) you might be attempting to ground onto a decommissioned pipe that was just never removed and which no longer has contact with ground.

Like I would know what's code or not, but if you're grounding a 2-wire romex circuit from 1950 wouldn't you just run that ground wire right to the nuetral bus bar?
in the USA where the NEC applies all metallic plumbing has to be grounded to the house electrical grounding system.

previously it was common for those on city water to use the metallic water service entrance pipe as the household grounding electrode. now since in some locations the water service entrance is nonmetallic or the continuity of the house plumbing system being metallic is no longer certain a grounding rod or plate is used now as the grounding electrode.

the plumbing system isn't used as a grounding conductor in subcircuits though it may be a grounding conductor for the whole system if the water service entrance is the grounding electrode..

the neutral is grounded at the meter and then not after that in most circumstances.

running a third wire separate for a grounding conductor is not to code. if you want a grounded circuit then you must run new cable or conduit.
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  #35  
Old 10-13-2009, 06:19 PM
billfish678 billfish678 is offline
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Originally Posted by HongKongFooey View Post
I never said he should have I said I can see why he did. If you work with people who do professional work you get used to that level of quality. It sounds like the electrician in that case did a poor job or overlooked something, that's all. That's the type of thing that leads to unsafe situations arising down the road.
His WHY was stupid IMO.

EVEN in my limited exposure as DIY handyman as needed for myself, close family and friends, I have seen more than my share of WTF / dangerous electrical, plumbing and whatnot home stuff. And most of that crap was probably done by "professionals".

If this guy hasnt seen anything NOT to code as professional plumber, he must live in an alternate universe.

The SAFE asssumption is to assume it was done wrong.

The type of thing that leads to unsafe situations is one person doing it wrong AND some other idiot assuming it was done right.

That plumber had no GOOD reason to NOT assume the wires were hot, besides his own laziness and ego.

You ask any "professional" in just about any profession and they will tell you there are significant number of their bretheren that are idiots.
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  #36  
Old 10-13-2009, 06:32 PM
HongKongFooey HongKongFooey is offline
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When I say "professional work" I mean the level of work. I know all too well about "professionals" who don't meet that level, they're everywhere. It doesn't exonerate the plumber, if the worst happened it's he who would suffer. Anyway, forget the plumber. The original point was about removing the knob and tube wiring or disconnecting it and leaving it in the walls. The inspectors here will pass a job where it's disconnected and the reasonably accessible wiring is removed. In that case it should have been removed or at least disconnected, that's all.
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  #37  
Old 10-13-2009, 07:52 PM
Jamicat Jamicat is offline
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all that old wiring goes to a fuse panel...take the fuses out...should be a main fuse and sub fuses.

When the electricians do additions they tend to leave the fuse panel and tie to a breaker in the new panel if they didn't change that part of the house.

When they do full house re-wiring...they snip at the panel, leave much of the old wiring there, and run new wires, unless it is contractual to take out the old stuff.

The old wires should be dead then.
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  #38  
Old 10-13-2009, 08:42 PM
spinky spinky is online now
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What they seem to have done in my case is snip everything off the old panel, put in a new panel, run lots of romex around for new circuits, but leave some of the old circuits active and tied into a new circuit. I don't think anything is attached to the old fuse box (this, of course, needs to be verified).

On the piece that the plumber almost cut, the entire thing is visible from the new panel to where he was going to cut: new panel -> romex -> jbox -> 6-inch romex (?) jumper connecting to K&T -> dead plumber. The jbox also has another leg of romex coming out of it for the rest of the new circuit.

So I guess someone did a partial rewire and didn't follow the "once you touch a circuit you bring the whole thing up to code" rule.

There are lots of baffling things about the way the wiring is run in this house. For example, this particular circuit splits at the jbox into a romex leg and a K&T leg, as I mentioned before. Both halves run along the basement ceiling and are completely exposed, and they go almost exactly the same place. So why replace one and not the other? Most of the length of this old wiring is running right next to new wiring that it's actually directly connected to back in the other room! Furthermore, the ceiling of the room with the panel in the basement is a twisty maze of romex and K&T, some of which zig-zags across the ceiling and then goes into another room only to split and come back into the room it started in. I don't have a lot of experience with this stuff, so maybe there are good reasons for that, but it seems completely random to me.

I sort of hope to someday cut my teeth on household wiring by tackling these crazy basement circuits. I can be pretty handy when I want to, and these have the advantage of being pretty well isolated and almost completely exposed, so there's no fishing in walls or living without a kitchen for weeks if I take a long time. I have a friend who's a journeyman electrician who just got laid off, so I figure I can hire him for a saturday consultation to feel out whether this is a job I really want to do myself. But I know plenty of people who are dumber and less cautious than me who have done it successfully...
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  #39  
Old 10-13-2009, 08:52 PM
HongKongFooey HongKongFooey is offline
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Household wiring is pretty easy once you get a few basics down. If you have a journeyman who can help you get started you're good. Where do-it-yourselfers get in trouble is when they get outside their comfort zone but don't realize it. Buy the man a case of beer and get learning. You probably have most of the tools you'll need but buy a decent meter if you don't have one and learn to use it. Everything else you can pick up as you need it.
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  #40  
Old 10-13-2009, 09:06 PM
johnpost johnpost is offline
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I have a friend who's a journeyman electrician who just got laid off, so I figure I can hire him for a saturday consultation to feel out whether this is a job I really want to do myself.
your friend seems like a real good start to plan what has to be done. given time he could explain some of what was done and why. that experience is good for good planning and evaluation of the project. and fishing wire takes two people to do it in a short time, consider him to do the work with you.

Quote:
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But I know plenty of people who are dumber and less cautious than me who have done it successfully...
just because they didn't die, the building didn't burn and the power flowed doesn't mean it necessarily done correctly. there is a lot of details in making an installation that won't fail in a year or two and need rework, won't develop a fire or shock hazard in a few years, bad quality work might look good in the short term and takes a few years for the problems to show up.
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  #41  
Old 10-14-2009, 12:10 AM
t-bonham@scc.net t-bonham@scc.net is offline
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How is K&T supposed to be grounded?
Grounding had not been invented yet when K&T wiring was done. So there's no standard way to ground it.
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  #42  
Old 06-07-2014, 04:22 PM
mc5w mc5w is offline
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Killing All The Knob and Tube

If the only wiring that is energized off of your electrical service is the NEW wiring, then all of your knob and tube is deenergized. You do not have to rip it all out - abandones is OK as long as you have chopped it up enough that the next owner cannot reuse it.

Theoretically, abandoned wiring could conduct electricity if it is accidentally energized but if you have chopped it up or better yet grounded out all of the abandoned wiring that cannot be removed similar to how when the power companies do deenergized maintenance the put grounding jumpers across all the wire you do not need to worry.

If you put in enough new wiring nobody will need to try to reuse the old K&T.

Mike Cole, Ohio electrical contractor license number EL45,008
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  #43  
Old 06-07-2014, 05:06 PM
Broomstick Broomstick is online now
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Originally Posted by HongKongFooey View Post
A good general contractor will hire the right guys for each job. Ask to see the permits or get them yourself. If he's getting the appropriate permits and inspections that's a good sign.Around here, if a licensed guy touches it he has to bring everything up to code. I'm not familiar with American codes.
I've worked for a general contractor who was also a licensed electrician. Really, it depends on the contractor if he'll do the work himself or contract it out. Either way, ask for references, ask to see his/her contractor's license, ask to see relevant permits, make sure the proper inspections are performed. You have a right to know who will be working on your property and their qualifications so feel free to ask about sub-contractors as well. A good and ethical contractor will not have a problem with any of that.

We had some customers who just up and left while we were working. We had others that were frequently dropping by/looking over our shoulders and asking the boss questions. We didn't have a problem with either (well, OK, the boss did get testy about the one guy who was doing this to the point of disturbing/distracting the workers - not a good thing when you're working on scaffolding with power tools), but really, it never hurts to double-check on anyone working on your home.
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  #44  
Old 06-07-2014, 05:08 PM
Chefguy Chefguy is offline
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Around here, if a licensed guy touches it he has to bring everything up to code. I'm not familiar with American codes.
Pretty much the case in the US also, but code and permitting rules vary from city to city. Codes must meet or exceed the latest accepted national codes. Permits are dictated by the city/county rules where the work is being done. Where I am, if the electrician is merely extending an existing circuit, no permit is required. If he's running a new circuit, a permit is required.
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  #45  
Old 06-07-2014, 05:26 PM
bob++ bob++ is offline
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I had never heard of this wiring system before. I gather it must be at least 60 years old. On that basis alone I think that on safety grounds alone it should be ripped out as much as possible and professionally replaced with a complete modern circuit.

In the UK, a house with wiring that old would never qualify for a mortgage or get insurance. If anyone (visitor/friend/child) was electrocuted, the householder would be fully liable.

That said, I have no doubt that there are houses still in use with wiring even older. When the house my mother lived in was rewired prior to her moving in, some of the wiring was lead sheathed. The plumbing (one cold tap in the kitchen) and a flush lavatory) was entirely lead. Mind - the house was built in 1457. I guess it had no wires or plumbing then

In case you were wondering - http://www.victoriacountyhistory.ac....houses-burford

Last edited by bob++; 06-07-2014 at 05:26 PM..
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  #46  
Old 06-07-2014, 05:30 PM
johnpost johnpost is offline
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zombie or no

i think it has been denergized.
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  #47  
Old 06-07-2014, 06:27 PM
engineer_comp_geek engineer_comp_geek is offline
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In the UK, a house with wiring that old would never qualify for a mortgage or get insurance. If anyone (visitor/friend/child) was electrocuted, the householder would be fully liable.
It varies in the U.S.

A lot of places will let you keep the knob and tube stuff. There's no requirement to replace it, and technically it should be fine as long as it is properly maintained. If something breaks you can generally replace it with exactly what was there before, but in most places if you actually change something to something different then everything in the affected area has to be brought up to current code.

While the NEC and local codes may not require knob and tube wiring to be replaced, sometimes insurance companies will. I've known more than one person who had to have the wiring replaced because their insurance company refused to insure it as-is.

I've said this before in other threads, but personally, knob and tube wiring gives me the willies. If I moved into a house that had it, it wouldn't be there for long.

ETA: And the proper way to handle unused wiring that has been left in walls is to short the two wires together (twist them together and wire nut it). Don't ever leave bare wires hanging.

Last edited by engineer_comp_geek; 06-07-2014 at 06:31 PM..
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  #48  
Old 06-08-2014, 05:36 AM
bob++ bob++ is offline
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I also saw upthread somewhere a comment about using plumbing as an earth. Until recently that was common and in code in the UK. It was the advent of plastic plumbing pipes that triggered a new code which now requires a robust earthing circuit throughout the house.

I also saw where cables are routed underneath joists - in the UK they are required to go through the centre of joists.
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  #49  
Old 06-08-2014, 10:39 PM
mikecc69 mikecc69 is offline
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I'm an electrician...if u have to question anything about what u r looking at..best advice is to. Leave it alone..and pay. Someone that knows what they r doing...getting shocked I'd least of ur worrys...can burn ur house down!!!
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  #50  
Old 06-08-2014, 10:54 PM
MikeG MikeG is offline
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I have a good bit of electrical experience. Ive installed boxes, run emt and bx, wired all sorts of fixtures including 3 phase.

That said, I would not attempt to redo the KT in a house I owned. Let a pro do it and assume the liability.

There's frugal and there's foolhardy. Know when to spend the money.
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