How do i wire knob and tube wire to conventional (flooring, heat)
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okay so me and my dad are rewiring a house from the 1920s with knob and tube wiring but were trying to run it switched to conventional in the garage for some reason if im not mistaken knob and tube works as just power and ground so my question is we have a gfi that is running but it wont turn our lights on im not sure if its a wiring fault or what but if your familiar with the switch, weve tried runnin it from both the white n red wires and neither is running the lights but the gfi's light is comin on not powering anything when plugged in though if the green light is on should tht not mean tht there is power to it
Knob and Tube is considered inherently unsafe as it is well past its useful life span. There is no ground in Knob and Tube, it is Hot and Neutral only. I would recommend evaluation by a qualified electrician and replace circuit wiring as necessary. Fire is a bad thing for the house.
okay so me and my dad are rewiring a house from the 1920s with knob and tube wiring but were trying to run it switched to conventional in the garage for some reason if im not mistaken knob and tube works as just power and ground so my question is we have a gfi that is running but it wont turn our lights on im not sure if its a wiring fault or what but if your familiar with the switch, weve tried runnin it from both the white n red wires and neither is running the lights but the gfi's light is comin on not powering anything when plugged in though if the green light is on should tht not mean tht there is power to it
Hire a qualified certified electrician. Safety means knowing your limitations and when to ask for help. The copper wire used in knob and tube was of a different resistance than the copper wire used in modern wiring.
Stupidity is losing an entire family due to an amature venture into electric wiring and a house fire!
The problem I see with knob and tube occurs almost exclusively from damage or sub-standard alterations... both very likely over 90 years.
Knob and Tube is used widely today... just look at most any utility pole and you will find it.
I currently own and was raised in 1920's homes with knob and tube... nothing inherently wrong with it for basic power distribution.
Just looked at a building from the same era... it was converted into 3 units during WWII with permits and only has a single 30 amp fuse for the entire building... basically a few lights and 3 refrigerators... everything else is gas... heat water and cooking. The owner would like to rewire to put in individual meters to get out of having the electric bill in his name... all units have individual gas meters.
That said, it would be just about impossible to wire a modern home knob and tube because homes today have gone from two circuits (one 20 amp outlet circuit and one 15 amp light circuit) to typically 30 to 40 circuits and it is physically impossible to wire K&T with so many circuits because of the space required.
Also... K&T doesn't provide a ground... so there is compatibility issues with modern living... Ground for early disposals and washing machines required a separate ground wire attached to a cold water pipe and the appliance... also still run into that occasionally.
A GFCI is permissible without a ground in every jurisdiction where I pull electrical permits... it is an exception to the code because the benefit of having a GFCI outweighs not having a working ground.
Have you identified the HOT and NEUTRAL in the K&T? Also, how did you make the junction from K&T to BX or Romex?
The wiring method itself is fine and if it had a grounding conductor it would be modern; the problem with old knob and tube wiring is the conductor insulation failure due to heat and age degradation. This old insulation material may look fine for most of the long runs,but, at the junction boxes where there is heat and activity is; it can be cracked, brittle, deteriorated or non-existent; therein lies the problem. Michelin makes great tires, however, they become unreliable after a while, even if they are not used!
I have owned two houses with K & T wiring and help others with wiring in three more. Everyone has an opinion on K & T.
Some electriciaions say it is all unsafe and can only be ripped out and replaced or your house iwll burn down. These are usually people who think you are rich and want the work. There are thousands of houses still using Knob & tube wiring and they are not on fire. However, you should use your own judgment.
Other electricians will say that as long as you do not mess with it, it will be ok. If you begin to play with it, you will end up replacing it.
Others will happily tie into knob and tube systems and some will say that it is as safe or safer than romex. K & T wires are seperated by several feet. Not much liklihood of them shorting out to each other except at the terminations where the wires come together. Also they often used very heavy wire.
If you are going to keep the K & T wiring a few things that I have found are:
1. You may need to install boxes. Most electrical fires occur at junctions or terminations. This is where wires can short to each other, this is where heat tends to build up. I much prefer plastic boxes to metal, but use what you like. Just be sure that you have a fire resistand box at every termination and at every junction. You may have to improvise to get a connection into a box without taking it apart.
2. Some people say to replace all of the connections with wire nuts. While this is safer, it often does nto work becuase the wire breaks off, or it is simply too heavy. Generally I just encased the connections in fireproof materials and left them alone. You have to do your own research and make your own choices balancing cost against risk.
3. Watch out for aluminum wire. I had some circuits that were aluminium. It was not hard to get to them, so I just replaced them. One circuit could nto be replaced. Then you want to at least repalce all of the connectors with the special connectors that are made for aluminium to copper connections.
4. It is a bad idea to try to tie a new circuit into and esixting K & T circuit. Better to just run a new line. There are probably a lot of reasons for this, but the ones that I am aware of are that you do nto want to try to connect incompatible sizes and types of wire. the old wire can be brittle and inflexible and hard to get a wire nut to hold. The old systems often were substantially loaded. For example all of our second floor light fixtures were on one single circuit. In addition to loading, it is nice to have a seperate circuuit so that you still have a light working if the breaker trips. that way you do not have to stumble around int he dark.
5. It is better not to mess with it. Often the insulation will be dried out and brittle. If you bump it, it will crumble. Sometimes the wire is brittle. If you bend it, it breaks. If you try to put a wire nut or other connector on it, it breaks off. Sometimes you can cut back enough go get to some wire that is still flexible. Sometimes you have to replace the whole run once you mees with it at all.
6. Inspect it carefully for damage and any signs of heat. INspect connections and terminations expesically well.
7. Check loading. With our upstairs circuit, we found that it was figured for single bulb lights in each room. Over the years, light fixtures had been repalced with multi bulb lights. Also some billy bob had tied into the circuit to provide power to the lights and outlets in a downstairs bedroom addition. The breaker had been replaced with a higher amperage breaker, but the outlets were only capalble of 15 amps at best. It was bad. It was a simple matter to run two seperate circuits to the bedroom, and run a seperate line upstairs for some of the lights. We ran out of space int he breaker box, so we had to use those expensive double breakers (two breakers bound together in a size that fits into a single breaker slot.
8. You will have no ground on K & T circuits. We used diffrent solutions. a. Run a seperate ground. We tied one of them to the copper plumbing pipes (not sure if that is still legal). The other circuits, we tied into the romex grounds in the box. Where we could nto include a ground we put in GFCIs. That was mostly upstaids and the types of things that we plug in upstaid typically are not grounded anyway.
9. Watch for switched neutrals. This is a very dangerous configuration where the switch controls the neutral instead of the hot. It is a stupid configuration which is fortunately pretty rare.
10. If you store stuff inthe attic, keep it well away from the wires.
11. Test everything. If practical have it inspected by an electrition.
12. Get a really good book on electricity and wiring. It is really not all that complicated. Electricians want you to think it is some mysterious thing, but it is really understading some basic principals and following the rules. remember, your typical electrician did not go to college to learn their trade, some did not even graduate from high school. Many have never even read a book about wiring or about electricity. Many have not had all that much on the job experience either. Some are badly misinformed due to misinformation passed down through on the job training. Others are execellent and really know what they are doing. Those are somewhat hard to find.
If you are not confident in your ability to locate good resources and understand wiring and the principals behind the rules, then just do not do it. I found wiring to be very easy, but plumbing impossible. I wired half of our current house and had a fraction of the correction items that the "professionsal" had upon inspection (I had two, they had eight or ten). On the other hand, I know other people who do their own plumbing all the time, but would not change a light switch without an electrician. Some people are more than comfortable to do all the plumbing and wiring in their house, but will not touch a hammer or nail gun. It just depends on you.
Last edited by Coldjensens; 10-22-2010 at 08:39 AM..
There is a huge difference between the wiring on utility poles and inside houses.
Knob and tube wiring has not been used for decades in home construction, and for good reason. Sure there are lots of buildings that still have it in place, but that in no way means it is safe. I have seen many houses that I just had to wonder why they hadn't caught fire yet.
If it was my house, I would hire a professional and replace all of the K&T.
There is a huge difference between the wiring on utility poles and inside houses.
Knob and tube wiring has not been used for decades in home construction, and for good reason. Sure there are lots of buildings that still have it in place, but that in no way means it is safe. I have seen many houses that I just had to wonder why they hadn't caught fire yet.
If it was my house, I would hire a professional and replace all of the K&T.
That is obviously the best option, but if you do, then be sure to get a firm price (if they say that they cannot give you a firm price and want to proceed on T & M - send them packing). Also be sure you find out EXACTLY where and how they will cut openings into the walls and who will repair the damage. The cost of repairing walls, cielings and floors, replacing plaster, wallpaper or paint, flooring, etc will usually far exceed the cost fo re-wiring.
This is the reason that I re-wired my current house partially on my own. The "professionals" have no care for what damage they do or what it costs to repair it. They have no concern for historical value or preservation. They only think about the easist cheapest way to get from A to B. Many of them only know one way to do wiring and cannot figure out alternates. Some are complete idiots and do not know how to do much of anything. A lot of them are simply incapable of thinking outside of the realm of "normal." For example, our house has very wide door casings. Modetn door casings tend to be very narrow. When they did wiring in some areas, they did not think to consider how wide the door casings would be and put a half dozen light switch boxes too close to the door. In some cases, I had to move the boxes, in other cases, all we could do was cut the door casing around the light switch (for example where the wall was tiled), in another instance I had to cut the switch plate cover in half to get it on the box.
That reminds me. If you hire a pro, make sure that you get the guy you hire. Some of them will drop off a buynch of hung over flunkies at your house and stop in once a day at the most to look at what they are doing.
There is a huge difference between the wiring on utility poles and inside houses.
Knob and tube wiring has not been used for decades in home construction, and for good reason. Sure there are lots of buildings that still have it in place, but that in no way means it is safe. I have seen many houses that I just had to wonder why they hadn't caught fire yet.
If it was my house, I would hire a professional and replace all of the K&T.
I understand what you are saying...
I would also like to relate this case: A home 2 houses down from my Grandparents that was rewired by a Licensed Electrician with permits that turned out to be a disaster.
The new neighbors had a home inspection... very rare in the 1970's... the inspector came up with a list of items... at the top was "Antiquated K&T wiring" followed by galvanized water pipes...
The neighbors, at great expense for the time, had all the wiring replaced, including restoring all of the casings and trim. The home was also re-piped with copper... they didn't want to have problems with 50 year old wires or pipes.
The electric job was 100% in ALUMINUM... they had so many problems... hearing buzzing in the walls and outlets and fixtures not working that they did the job again 15 years later with copper... their insurance was also in question not because of K&T... only because of Aluminum Wiring.
As a side note... they were also the only home to have a busted pipe when we had a hard freeze... not typical here... seems copper is more susceptible to freeze than galvanized... at least the insurance adjuster said he only had burst copper pipe claims and no galvanized. The water damaged buckled a lot of the match-stick oak flooring.
Common sense goes a long way and determining limitations and benefits is a sound basis for making a decision... remember, Aluminum wire was code approved at one time.
The Electrical Inspectors in my city prefer/insist on using "spilt bolt" splices in most cases when splicing or joining K&T
The big push here with Insurance is no more Edison Base fuses... the glass screw in type... they want resettable circuit breakers.
Grandmother's home still has K&T and galvanized pipe... built in 1922 and no problems yet...
Last edited by Ultrarunner; 10-23-2010 at 01:03 AM..
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