Hi Susan. That is great! I hope you can find some qualified electricians in whatever area you live. Not all electricians do this kind of work properly.
I am a plumber with 25 years of experience i just removed the last knob and tube wiring that was for the lighting circuit of the entire house. No holes in drywall. Fished 4 home runs to the attic, removed a couple floor boards and removed the last of knob and tube.
To rewire this house which I just did. I had three estimates done actually five electric companies 3 gave me a estimate 2 I never heard from. One company wanted $31,000 for the complete rewire. $9,000 to just replace the one knob and tube wire that was fish through the house. $6,000 to upgrade the service to 200 amps. The cheapest estimate $23,000. What the 2 companies said it would take 3 weeks and four guys. My wife and I are the entire house in 4 16hr days with a new 100 amp panel Square D 24 spaces(double what was here), Schneider hepd 80 surge protector. Brought mostly up to code except the didn't use the ARC flash breakers,12 gauge wire, separate 20 amp outlets for kitchen and dining room. Previous wiring was stapled to bottom of joists. Major fire hazards everywhere, romex spliced into lighting circuit total of 7 outlets tied to 11 lights. Quite a bit of time reading the national electric code on certain things $5000 total cost to my customer that couldn't afford the massive amount these businesses charged. He has Cancer and I couldn't in good conscience add to his stress.
@@PatrickBuckley-ol2ok Here is an insane number. I did it myself (I worked for electricians for years), and I still spent $7,000. Everything had to go. The boxes were old, and undersized, new connectors, including wago lever nuts, a new disconnect, a new main breaker pannel, etc. Everything was $100. The rodents even messed with some 2x lumber, so, there was $300 in lumber I had to replace. etc. But, it was also during the pandemic. I'm still in denial. There is no way, it cost that much, but it did. It's what I spent. Ouch. I reused some of the outlet covers, which, jokes on me, I could get 20 for $2. I no longer use the cheapest outlets, and I buy direct from the manufacturer. $120 in outlets. Our problem, is the house sat empty, and the rodents attacked the wiring, and during the sale, since the house went to the nursing home, they sold everything, including the kitchen cabinets, and the cover to the electrical box. The house was wired by an electrician in 1950, and they did not even use junction boxes, nor nuts.
It’s so pretty to see a well run knob and tube install. Saw one in my friends house - like looking back in time…. And I tore all of it out of there! Way too dangerous. I did an extremely pretty rewire. Hopefully in a hundred years somebody will look at my install favorably, before they rewire it again.
@@DonkeyLipsDA3rd you don't think AC (possibly at much higher frequencies like 400Hz airplane wiring) will continue to be used for long runs? Or maybe high voltage DC?
It's only bad if it's in poor condition. That tends to be the case, but the people wiring homes back then weren't stupid. Those porcelain knobs and tubes will outlast most modern installations.
@@micheleemcdaniel389 Those old houses might have only had 4 circuits for the whole house. Back then the only appliances were an iron and maybe a refrigerator. There typically was one light and one convenience outlet per room. Over the years people added more appliances, lamps, and other devices to these homes on the same 4 circuits. combine that with the age of the wiring and breakdown of wire insulation and you have a fire.
@@thomasdragosr.841 You need to separate in your mind the service from the wiring within the house. You can upgrade a service from a 30amp 120, to a 240,and still use the wiring within the walls, basement , attic. You can run romax or A.C for Added circuits once you've upgraded the panel (the service) It doesn't mean there's anything automatically "wrong" with your existing knob and tube that remains In use. You need to understand about limits according to wires size about amperage and overcurrent devices and accordance with that if you have a dedicated circuit for a microwave that's gonna be something new, Or It's going to be off the existing knob & tube or t if it is, it's going to have enough Amperage to handle it or not. You need to count- up how many amps in total are on a given circuit ( A load calculation).
@@micheleemcdaniel389No one is suggesting connecting your central AC system to a knob and tube circuit. Lighting loads are far more efficient now, and we still permit an unlimited number of convenience outlets on a standard 15-amp circuit. At worst, you end up with nuisance trips, same as you would with the most modern version of the NEC.
I've only I've come across knob-and-tube was just one job. I was a bit amazed by the process it was done. I know very little about it because my time came well after in the 70s through today it was about two decades ago that I ran into it. It's a trip how they used to do it
@@kuhlmanelectricserious Craftsman for sure. Same with the Carpenters back then. The work they were able to do all by hand. Just incredible. I find so much more in older places than anything built this century..
Knob and tube goes right along with balloon frame houses...both of which contribute to house fires a lot. Old wiring and an open chase from basement to attic. Seen it where a house was engulfed in flames in the walls and never set off the detectors. Fortunately the family got out safely.
I agree 100%. I'm ripping out all the plaster and lath. Lath is nothing but kindling. I put horizontal studs in with fire resistant roxul,pyrogard plywood to replace the lath.
Enjoyed the video. I am an electrical contractor and have rewired multiple homes in historic Richmond VA and you are spot on with all your concerns. One additional thing I constantly ran into was that it was common practice to switch the neutral wire in wall switches. Three way switching was done very odd as well. Great job keep up the good work!!!
HI Lionel, thank you! Yes you are correct - look out for those switched neutrals! Electricians who have never experienced it can be in for a big surprise. I've also seen the hot and neutral wire being fused in the panels - i always found this is to be fascinating, you have to wonder why they would do that? Making this video has been a learning experience for me. I have NEVER seen KT in homes here in the northeast built past ~1932, it's really interesting to read how it continued to be installed in other states for so much longer.
Three way switches were run from a splice in the line conductors to the traveler terminals on both switches flipping the polarity of the socket or making both hot both of which are dangerous.
Great video. We replace lots of K&T here in Philadelphia. We stop agreeing to verify wiring safety after 70 years of service. It makes no sense to wait for failure. Knob and tube is due for replacement and early Non-Metallic wire is getting to that age too.
One of the best explanations I’ve seen thus far regarding K&t wiring. You forgot TWO important things to add. 1. K&T is rated for 15 amps. Oftentimes folks overload it and that’s trouble. 2. Neutral fusing Back in the day they thought if one fuse was safe adding another to the neutral would make it double safe. The problem with this is that when a fuse does blow it normally takes out the neutral fuse leaving the circuit hot. Many an electrician in the day would tell you the end result of that. That is IF they made it. K&t is safer but the facts you mentioned and the ones I added are why replacement with modern wiring is an order.
Hey thanks for the comment. I agree! Add to that, you can have neutral switching, which is mind blowing for many electricians when they first encounter it. The double fusing (Hot and neutral) was always super interesting to me.
A family member lives in a house built in 1916. The structure is original and some stuff remains from its original configuration. I wonder if there is still some parts of the knob and tube. I find it interesting how things were done in the past and the evolution of plumbing and electrical
I find it extremely interesting as well! Particularly the decision electricians at the time were making - Use K+T, BX wiring or depending on the year, ungrounded early romex wire. Then you have homes were the electrician combined them together.
Knob and Tube systems had the boxes with a separate Ground wire clamped to the nearest water pipe (Lived in 2 houses with/had K&T). for Bathrooms and Kitchens, this was the practice. My Top Issue: folk working on K&T that do not know HOW. Proper K&T was soldered after doing multi turn wraps around the main line, then well taped.
I;ve seen this many times. The ground wire was added later by someone to gain the ground and probably replace the receptacle with a 3prong. When this is done throughout a house, it can trick home inspectors (if the K+T can't be seen anywhere and they don't pull plates). They will say everything is grounded properly, even though it's not!
@@kuhlmanelectric or they do a bootleg ground, a jumper from neutral to ground and making metal case of appliance live. also saw romex with 2 wire an ground with 2 different loads using grounding wire as a return not good but one load was ceiling lite on porch other load was 2 lamps 1 on each side of garage door well within reaching height and are metal.
I used to work fire/water restoration and a lot of home had this old wire. Even if the wire was unrelated to the fire the whole house was gutted and all the old wire and associated pieces scattered along the ground and wire into a scrap copper pile. All new wiring, outlets, switches, etc. Felt kinda bad seeing this pice of history from the 1800s just going in the trash but was unsafe.
Hey Frank, Making this video has been educational, i never knew how long some states continued to install it. I will edit the video to reflect what i have learned. I do have to wonder why an electrician in the 1960's would choose KT over all the other choices at the time - i mean romex with a ground was available and would install SO much faster.. It's interesting to think about!
Excellent Video. Just discovered K&T wiring in my mother-in-laws house, as an insulation company said they wouldn't insulate the attic with it. House is from 1920, so it makes sense. The house if full of K&T. 1300 sq ft house 2 stories, what is a ballpark to replace it? Each bedroom has a single outlet(in the baseboard), so i'm thinking that each room should have more outlets as well. BTW, the house is located in Portland, Maine, a stones throw from MA.
Hey thanks for the comment! It's hard to say without knowing the total count of switches, lights, outlets that need to be rewired. I will say the average K+T job for us (single family) is 12k. I hope this helps!
Hey Joel, thanks for the comment. Doing that will add a level of safety - the arc-fault breaker should trip if there is a bad connection somewhere. This does not solve the insulation or lack of ground issue however. Installing the AF breakers should be a short term solution, buying some time before a full rewire is done. Keep this in mind if you opt to install AF breakers on the K+T - The AF breakers may trip and this is good because you want to know there is an issue and the AF breaker identified there is one. The downside is you are left with two options - spend money trying to troubleshoot where the issue is to fix it, or rewire that circuit.
@@kuhlmanelectric That sounds like a great solution to me then. A lot of homeowners will feel comfortable installing those breakers, but unable to afford all the circuits replaced at one time. It also indicates where immediate attention must be given. Also seems like gfcis can address the lack of ground.
My home is 93 years old and I’m currently removing the knob&tube in the attic. Fortunately, wiring in the walls is romex and the k&t is only in the attic. Unfortunately, there is almost a foot of insulation in the attic. I’m replacing in the walls where possible, as well, since it’s old romex and the rubber/plastic is pretty brittle. It is very slow going. The hardest part was getting new home runs from the basement to the attic. It’s not too bad, actually.
Yikes!! I’m in the buying process of a house with KnT wiring, but more in hesitant. I live in NM, this house is 83 yrs old with a newer service panel. What should I do??
Hey Angela, I wouldn't let the K+T wiring dissuade you from buying a house you like. You will need to find an electrician you can trust and have the budget to replace it of course.
Thanks so much for a thorough discussion of K&T wiring. Because of all wooden and plaster-on-lath walls, I am concerned about the prohibitive cost of new wiring, in large part because of the difficulty of access and huge amounts of wall repair to follow. I don't think any contractors are able to make such repairs without costing an absolute fortune. It's a very large house.
Hey thanks for the comment. We do the rough patching ourselves and aim for small holes overall. Take a look at our website and check out the "careful rewiring techniques" page to read more about our strategy. - you should be able to find a company that does it similarly to us. www.kuhlmanelectricalservices.com/rewiring-techniques/ Beware of companies who want to gut your walls to replace the K+T, this is not needed.
I'm not a contractor just in training but we are rewiring an old home and decided to gut the walls. It's better if you can afford it. There are options not to however.
The house I mentioned is over 100 years old and very large, with 11 rooms. If a bedroom, for example, is 15ft by 16ft in size, and has only one or two outlets, this is insufficient by modern standards. So a large number of additional new receptacles must be installed, as well as rewiring the existing K&T ones. Without a total gut and re-wall of the entire house which would cost more than the total value of the house, the only way I know to achieve proper new wiring is to cut long channels around the perimeter of every room. Having removed small sections of old beadboard walls and plaster-on-lath walls here for certain repairs, I am well familiar with just how difficult this is. The walls coverings vary in thickness, so drywall does not work well for repairs unless the rooms are gutted. Plaster does not cut out neatly in channels. It breaks loose easily and often the lath is not a solidly attached substrate, so when you try to cut it, it flaps loosely and breaks out more and more plaster. It's just a disaster to try to repair. I am not saying it is humanly impossible, just that the cost of this type of work could easily exceed the total value of an existing old house, which really suggests a bulldozer is the better option.
Hi. I live in Massachusetts in a house that was built in 1903. If you go into the basement you can see remnants of some old K&T wiring. You can also see that the house has had the wiring updated throughout the years as well with both I believe that second generation wiring (has metal casing around it) and what I believe is Romax (?) wiring. Last summer I had the electrical service upgraded to 200 amps and converted from fuses to circuit breakers. I hired a reputable electrician that got the necessary permits etc. My concern for years was whether or not that old K & T wiring still powered any of the outlets in the house. After stumbling across this video I got to wondering if between the electrician and the wiring inspector if the upgrade would've or could've been allowed if the house still had active K&T wiring?? Your thoughts would be greatly appreciated. Thank you.
Hey Matty great question! The service upgrade is a separate from the knob and tube wiring / interior wiring. Think of the 200 amp upgrade as the foundation, and the interior wiring the rest of the house. Yes, a 200amp service upgrade can happen with old wiring still in the home, it's quite common actually. We service most of the Massachusetts, From Worcester to the coast.. If you are in our service range shoot us an email or phone call and we can setup you up with a k+t inspection (if you are interested in one of course). www.kuhlmanelectricalservices.com
Hey KES! Good to see you here on RUclips. I reached out to you via email last summer when I was helping a friend on Cape Cod. We failed an inspection for not having an emergency disconnect for a 200A upgrade. Eventually I went back and the work was approved. Nice video!
I was going around with a home inspector in 1994 through a house that I was buying. The house had live nob and tube wiring. He claimed that nob and tube wasn't so bad because the conductors were separated and there was no way to short them out by driving a nail. At that time I had no difficulty getting insurance on the house, despite the nob and tube. I didn't really like the fact that the house had this antique wiring, and I worried about the modifications that were made to the wiring over the years, for the house, a small bungalow originally had just one circuit, but now had many circuits using the nob and tube. I only had 5 grounded outlets in the house and an antique key switch in the garage gave me such a shock that I would replace the garage light with the circuit breaker off so I didn't have to touch the switch. Why didn't I change out the wiring? Cost! To replace all of the wiring would have easily cost 10 to 15 thousand dollars and I was a home health nurse paid Burger King wages.
Thanks so much for the reply! The inspectors reasoning is interesting - in a modern why a short circuit would turn the circuit off / alert you to an issue. A nail into a live knob and tube wire would not short out, and you would be left with a very unsafe situation - a live nail, or a connection that is semi broken leading to heat build up etc. You are correct that replacing knob and tube wiring can be very expensive. It comes down to how much K+T is left in the home.
Knob and tube on the left coast was installed at least up to WWII, not 1932 as you say. My home was built in 1940 and originally completely knob and tube; as an electrician I can tell you this is the case in housing throughout the SF Bay Area. Most homes still have a blend of knob and tube in the bedrooms with a fuse box subpanel and modern wiring in the kitchens, leading back to a circuit breaker meter/main. Because of the age of the housing stock, there are still a lot of FPE OCPDs out there which represent the first-gen electrical remodels that occurred in the 1950s and 1960s.
Hi Steve, i learned a lot about the age of the system from everyone on here! Thank you for sharing.. It's interesting how different the east coast is from the west coast!
FPE was pretty good till it came out with the stab-lock brkrs, fuses will always be much safer. a given amount of current thru a lead wire or strip of a given gage will always melt. Old homes with pull-outs were nice for emergency generators too, 'pull the mains' and Range and u were totally isolated from the grid. As I have seen, some old panels the range would not work if the Mains were pulled. the branch ckts were off the MAINS but some panels other panels the range would work if the mains were pulled
I'm in PA and my 1940 house was also knob and tube. I've seen the knobs and tubes to verify. It was rewired in the late 60's with modern grounded wiring. I've googled and it seems (from my extensive Google research lol) that it was installed into the 1940's in some places. I
FPE made a good fuse panel, some had a main breaker but fuses for there 110 v branch circuits and pull-outs for the range and dryer circuits. Other fuse panels had two large pull-outs, one for the MAINS, one for the RANGE. FPE went str8 to hell when they came out w the stab-lock breakers. I know for a fact as one day a wire in the clothes dryer had intermittent shorts to the back panel and burned a hole thru said panel, never tripping the breaker, another time, the cord from a space heater had a white ball of an arc and the breaker never tripped. I have seen houses where KnT was used and no one hacked into it so it was kept there, that fuse panel was then used as a Sub-panel a newer panel brought in for the stove, clothes dryer and A/C
Very interesting! I have never seen a house in the northeast built after 1932 with it. I can't imagine an electrician in 1957 choosing K+T over the other options available, not to mention the supply house actually having it, crazy stuff!
1957 would be extremely odd. I would question the age of the house, and/or confirm that it was knob and tube. I haven't seen anything past the mid 40's, and there was more modern alternatives like he said above.
i wouldn't say just because something is old it's bad, I still come across knob and tube that is still in great shape even in the light box, and to solve the no ground issue you can install GFCI receptacles. granted I'm partial to knob and tube, even installed it in my shed, fuse box and all. Biggest issue i find with it would be lack of circuits of course, and the insulation issue. i've actually load tested it, new plastic wire vs. 60's vs. 40's vs. K&T all #14 and the K&T won out easily, the plastic melting and burning up while the knob and tube didn't do anything even holding 90 amps. 60's wire still melted, 40's held on fine until it got so hot the insulation became conductive and the whole thing glowed like a light bulb.
@@PostmanApocalypse yeah, and it's still standing, the wood is much better than new wood you would get today, it's old growth and full size, just the weight difference alone is substantial. A new 2x4 is puny compared to a 100 year old 2x4.
Hey, i'm not sure what you mean? The individual conductors? If the insulation has come off, it needs to be stripped back to where the insulation is good. Otherwise you need to replace the wire.
@@kuhlmanelectric I've been told the original protective layer for K&T was typically made of cotton soaked in creosote and over time it just rots away leaving a bare wire ran between the knobs. I was just curious if the original wire insulation could be replaced with the plastic wire covers that are popular to use with computer cables to collect them neatly, in order to remedy the problem you mentioned concerning heat dissipation when fiberglass batting or blown in foam is added to the walls around the wiring. The plastic tubing would allow a small air space around the wire.
I told my professor in college where I was studying electricity that if I bought a house all knob and tube wiring was coming out no matter what and that the new wiring would, if possible, would all go in some form of conduit.
1935 house in California has knob & tube wiring. I’d like to get rid of it but need an electrician willing to do it. Had an electrician do some remedial work and add some circuits. The house is concrete block so he’s not thrilled about that. Insurance is the biggest issue…expensive…high deductible.
Bought my 1920 all and I mean all brick lap and plaster home 3 years ago. A mechanic and hobby machinists the home runs a 200amp service with modern breaker box that converts to the k&t system. The garage also was k&t with 3 lights and one outlet. Also all brick. Rewired the kitchen the first year while doing a updated look. Rewired the garage the 2nd year to increase my productivity. This summer will be the attic and upstairs rooms. I'd like to get some insulation installed for next year. This house is a bit drafty.
I enjoyed this very much, Thanx. Had some exp with it, changing over to romex, a new panel was installed (service entrance equipment) weird stuff, small home and 12 fuses. they fused the neutral! I have seen this in old houses on Cape Cod on west Main street.
@@kuhlmanelectric I gave that some thought, It may have been pretty easy to borrow a neutral from another ckt. I don't know if 220 volts were around then, but I can see where a ckt rated for 10 amps would have the ungrounded conductor protected but having the neutral possibly carry twice as much. I got a jolt putting in a recep. went down cellar and sh'ed holler when the lite went out, so yeah I thot the ckt no longer HOT. backed into the radiator old cast iron job. hadda see why I got juiced an pulled cover offa the panel. 6 fuses on each of the two lines coming in. It was romexed out of the panel and when I went to the attic, her knobs were all over the place.
In knob & tube did they just run one ceiling light wire down the wall cut it at the switch on the wall, and run the one wire back up where the junction +/- was located in the ceiling light?
Sometimes yes, there would only be 2 wires in the switch, feed in and feed to the light with no neutral in the switch box. There were electricians that would run the neutral wire through the switch, creating a switched neutral, these are fun!
@@kuhlmanelectric Well the switch appears to be one wire cut in half at the switch from the light down /cut put switch in between and other half start at the neautral side of same switch and run back up to the light. doesn't matter which one they cut to the switch .it's just one wire. Off no power to the wire leading back up to the light.
First time home buyer here in windsor Canadá. I just discover I have this type of wire and man I am kinda scare on how much it will cost me to get it re wire 😶 wishing I had the budget. But it looks like there is a mix of new and old.
How does existing K&T wiring even handle all the modern appliances and computers and stuff we use today on old wiring that was designed for some lightbulbs and maybe a vacuum cleaner or something back in the 1900s I would expect that the wiring would overload pretty easy at that point and be a danger.
The current carrying capacity of #14 AWG and #20 AWG K&T is the same as modern Romex. If properly fused or with the proper sized circuit breaker it is perfectly safe. The breaker will trip or the fuse will blow long before the wire overheats.
I am in the process of buying a home with knob and tube wiring. The gfci's do not work. The seller agreed to have an electrician repair the gfci's. Can an electrician run newly updated wire to the gfci's and all of the appliances and keep the rest of the house as it is at knob and tube wiring. The home must pass inspection in order for me to buy it and no one wants to rip out all of the old plaster to remove the house of this wiring and install all new wiring?
HI Steven, Yes new wiring could be run to certain outlets while leaving the old KT as-is, this is not uncommon. I will say that if they are repairing the GFCI's, they may only be replacing them. GFCI"s can be installed on ungrounded wiring like KT by code. I'd check with the seller to see what their electrician is actually doing. If you can, push for new wiring as it's definitely better, but more expensive.
I've also read that common neutrals between circuits was done with some K&T installs, but that might be a regional thing. I have a 1915 house and some of the original K&T (with dedicated neutrals) is still in use for lighting circuits, with most of the receptacles having been replaced with separate AC (no bonding wire) or NM runs over the last half century. I think I have just about every generation of wiring in this house, although luckily aluminum is limited to range and dryer receptacles. I had no problems getting insurance, but everything was inspected before we bought the house.
Interesting! We see a lot of homes with a mix of KT, BX and romex. Aluminum going to the range / dryer / other heavy loads is no issue. I don't see many, if any, shared neutral KT around our area. I'll keep an eye out for that though going forward!
I saw it in attic of one old building it wasn’t in use but i live in Estonia where you find maximum 60 year old wiring because people change it often i changed my entire home 2 months ago
I ran into a gas pipe at a duplex unit that was hot. It ran outside of the building about 2 feet off the ground for 40 feet. I was working at a small apartment building across the alley and the heating contractor that was working at the duplex came over and told me he received a shock from the gas pipe! I was skeptical but went over and looked and sure enough I read 124 vrs to ground.😫 To make a long story short it turned out that there were no ground wires anywhere in the duplex, and and no bonding of gas and water pipes. The kitchen stove had a spark ignition and the neutral wire of the stove cord was attached to the stove frame. The outlet that this was plugged into had hot and neutral crossed! Made everything attached to the stove hot. How no child ever got killed playing out there is beyond me…. Moral of the story: Always hire a qualified electrician.
Knob and tubes do have their disadvantages- hidden behind walls and not protected but I also see significant advantages. Many are still in use- this proves their longevity. They are spliced /joined by twisting other conductors together soldered and then insulated. They are insulated with rubber and or cloth insulation, ceramic tubes and separation of conductors. They have the ability to dissipate significant heat because they are not confined hence they should be able to handle even more current. If they were modernized with a ground wire and maintained I think they will be on par with current wires. Today we have insulated copper wires that are extremely close to each other in a confined space wrapped with additional insulation- metal clad, or plastic- Romex. Tightly packaging the wires together lowers the specifications of it's awg due to fear of them melting and shorting each other.- hence another reason they add ground wire.
The ground wire is there to protect YOU.....period. In an UN-grounded system if you find a fault the "hard way"....I guarantee you'll NEVER want to repeat it.🤔
Ironically the knobs and tubes themselves are actually a safer way to mount wires and run them through joists and studs than we do now: by offsetting parallel runs with the knobs, the possibility of accidentally nicking a wire when someone is aiming for a stud is effectively eliminated while the tubes offer real protection against deep penetrations into a stud by a fastener or drill bit.
It would be interesting to imagine a modern house being wired with knob and tube. Some medium sized homes can have over 30 circuits in them - imagine what all those wires would like as K+T? Fun to think about!
Do you mean the wiring needing cooling? Modern wiring is designed with much higher temperature ratings than knob and tube was. Modern wiring does not need to be in open air for cooling for this reason. Thanks for the question!
Romex will not last as long, which is a bit sad. But, old wiring, needs to go. Not to mention, the new breaker boxes, have new safety features, like the yellow boots in the square d boxes.
Well. Some issues some lighting in series chain lights via single poles and switching neutrals via three ways . cloth. Romex . You had sometimes a color coded neutral Of course if you had a master electrician with the connections soldered. Than you it was no to as bad as other jobs .
Comments: 1. If it's getting hot enough buried in insulation, then there's another issue going on. I have yet to see any evidence of a fire from an unmolested, normally loaded K&T directly caused by covering with insulation. Millions of homes had this done. 2. Insurance companies. No surprise. What's new? 3. Ok, lack of ground. Inconvenient. Yes. Downright dangerous. Not necessarily. Depends. In your case, an handyman hack, not an original install. 4. I agree with this. Was also an issue with earlier plastic Romex. If you have attic access, one method to fix it is put a plastic jbox in the attic and cut off the burnt section of the old wires and route them into the box, then do a whip with modern NM to the fixture. I would not call this "extending the circuit". It's a repair. Other than burnt insulation in fixture boxes, the K&T I encountered had insulation in very good condition. 5. Yes it's old, but so what? These installation were almost always professionaly done and made to last. If you need to upgrade, run new circuits from the panel, leave the K&T alone, unless the house is gutted to the studs. K&T was still allowed in the 1975 NEC, although most AHJs outlawed it. The latest house I encountered with this wiring was built in 1968 in rural CA.
Hey thanks for the reply. Wow 1968 huh? It's so interesting to me to hear these late dates with K+T wire being used. I'm imagining an electrician in the 60's going to the supply house... Don't give me any of those romex wires that are WAY easier to to install, give me the OG K+T LOL. Pretty fun to consider.
Knob and tube is really the worst because it has 90 years of hack jobs and jank accumulated. If unmodified, it's not that bad for lighting circuits.. but your issues are valid for sure. Having no ground on your outlets sure limits what you can use, and having a GFCI on every outlet really only is an expensive bandaid that doesn't actually fix the problem.
its actually a well thought out system other than no ground.....both conductors are spaced apart and connections are soldered together ...he is right about the wires being baked over the years from bulbs though......disintegrate if you look at it wrong lol
@@workingshlub8861 Hi there wrkg shlub. Yes I do know that, it could lead to a loaded neutral, whatever current drawn by the load will be on the neutral. With romex the white wire of course will be in the box as well as the black and grounding wire.
This is nuts people don't want to change their electrical circuits to newer technologies - I just cannot imagine living in a house with live wires like that
@@electricianron_New_Jersey You are correct. It is much the same with auto mechanics,dentists,etc. I'm here to buck the trend. I will work with people on these older homes (usually younger couples just starting out) with a variety of options.
WTF for me as a german that is absolutely ridiculous. Do this wires even have some sort of insulation or is it just the bare copper running on the ceiling
They are insulated. And properly maintained they are also safe and still recognized by the National Fire Protection Association's publication #70, latest edition. As an American, I'm fairly confident that the Standard is sufficiently robust in its installation requirements to avoid electrical hazards. Maintenance is key though; I am sure that holds true in Germany as well.
I live in an older American home (1869) that once had knob and tube wiring including wooden surface mount conduit that had two grooves for the conductors to be placed in. My home was originally built and owned by German-Americans (Jacob Sterner a miller).
@@steveloux4709 its actually a well thought out system....conductors spaced apart....less chance of them touching and connections soldered together....better than any wire nut......if it had a ground it would be no problem...its like old style fuses....they are actually more reliable than modern breakers because there are no moving parts that can fail but it was idiots using pennies and burning down the house that ruined them...
Between outdated wiring, lead pipes, no insulation, 120yo cast iron sewer lines there should be a superfund to help people get their homes updated..lord knows this govt has the money to spend on everything else
It's really amazing to think about - Just in our area there are 100's of thousands of homes built pre 1930... All these homes will need their wiring updated, not to mention, plumbing, painting, roofing, HVAC etc etc.
@@kuhlmanelectric instead my state is pushing to ban gas stoves to improve air quality...idiots dont realize the dust I cant keep up with contains lead and asbestos? Amazing..
Was it called the Jewish electric? I graduated in 1977 from high school school as electrician... obviously I ran into this tubing and from older electricians, they called it, Jewish.....
You convinced me! My home is almost 90 years old. I think it's time.
Hi Susan. That is great! I hope you can find some qualified electricians in whatever area you live. Not all electricians do this kind of work properly.
I am a plumber with 25 years of experience i just removed the last knob and tube wiring that was for the lighting circuit of the entire house. No holes in drywall. Fished 4 home runs to the attic, removed a couple floor boards and removed the last of knob and tube.
To rewire this house which I just did. I had three estimates done actually five electric companies 3 gave me a estimate 2 I never heard from. One company wanted $31,000 for the complete rewire. $9,000 to just replace the one knob and tube wire that was fish through the house. $6,000 to upgrade the service to 200 amps. The cheapest estimate $23,000. What the 2 companies said it would take 3 weeks and four guys. My wife and I are the entire house in 4 16hr days with a new 100 amp panel Square D 24 spaces(double what was here), Schneider hepd 80 surge protector. Brought mostly up to code except the didn't use the ARC flash breakers,12 gauge wire, separate 20 amp outlets for kitchen and dining room. Previous wiring was stapled to bottom of joists. Major fire hazards everywhere, romex spliced into lighting circuit total of 7 outlets tied to 11 lights. Quite a bit of time reading the national electric code on certain things $5000 total cost to my customer that couldn't afford the massive amount these businesses charged. He has Cancer and I couldn't in good conscience add to his stress.
@@PatrickBuckley-ol2ok Here is an insane number. I did it myself (I worked for electricians for years), and I still spent $7,000. Everything had to go. The boxes were old, and undersized, new connectors, including wago lever nuts, a new disconnect, a new main breaker pannel, etc. Everything was $100. The rodents even messed with some 2x lumber, so, there was $300 in lumber I had to replace. etc. But, it was also during the pandemic. I'm still in denial. There is no way, it cost that much, but it did. It's what I spent. Ouch. I reused some of the outlet covers, which, jokes on me, I could get 20 for $2. I no longer use the cheapest outlets, and I buy direct from the manufacturer. $120 in outlets. Our problem, is the house sat empty, and the rodents attacked the wiring, and during the sale, since the house went to the nursing home, they sold everything, including the kitchen cabinets, and the cover to the electrical box. The house was wired by an electrician in 1950, and they did not even use junction boxes, nor nuts.
I bought your book. Troubleshooting residential. You did a graet job. Thank God. We need a more advanced book
It’s so pretty to see a well run knob and tube install. Saw one in my friends house - like looking back in time…. And I tore all of it out of there! Way too dangerous. I did an extremely pretty rewire. Hopefully in a hundred years somebody will look at my install favorably, before they rewire it again.
Very cool! Interesting to think to the future, when will romex wire become outdated?
@@kuhlmanelectric When DC homes take over.
Agreed, sometimes you open up an area and the knob & Tube still looks brand new.
@@DonkeyLipsDA3rd you don't think AC (possibly at much higher frequencies like 400Hz airplane wiring) will continue to be used for long runs? Or maybe high voltage DC?
@@DonkeyLipsDA3rd That contest with Edison and Westinghouse was settled a 130 years ago.
It's only bad if it's in poor condition. That tends to be the case, but the people wiring homes back then weren't stupid. Those porcelain knobs and tubes will outlast most modern installations.
Yes, but what about the point that modern day lifestyle requires far more electricity than the old system was designed for?
@@micheleemcdaniel389 Those old houses might have only had 4 circuits for the whole house. Back then the only appliances were an iron and maybe a refrigerator. There typically was one light and one convenience outlet per room. Over the years people added more appliances, lamps, and other devices to these homes on the same 4 circuits. combine that with the age of the wiring and breakdown of wire insulation and you have a fire.
@@thomasdragosr.841 You need to separate in your mind the service from the wiring within the house. You can upgrade a service from a 30amp 120, to a 240,and still use the wiring within the walls, basement , attic. You can run romax or A.C for Added circuits once you've upgraded the panel (the service) It doesn't mean there's anything automatically "wrong" with your existing knob and tube that remains In use. You need to understand about limits according to wires size about amperage and overcurrent devices and accordance with that if you have a dedicated circuit for a microwave that's gonna be something new, Or It's going to be off the existing knob & tube or t if it is, it's going to have enough Amperage to handle it or not.
You need to count- up how many amps in total are on a given circuit ( A load calculation).
Hell yes
@@micheleemcdaniel389No one is suggesting connecting your central AC system to a knob and tube circuit. Lighting loads are far more efficient now, and we still permit an unlimited number of convenience outlets on a standard 15-amp circuit. At worst, you end up with nuisance trips, same as you would with the most modern version of the NEC.
I've only I've come across knob-and-tube was just one job. I was a bit amazed by the process it was done. I know very little about it because my time came well after in the 70s through today it was about two decades ago that I ran into it. It's a trip how they used to do it
Hey Jeffrey. I think it's pretty cool too! I would love to see how electricians back then did the installs, drilling by hand etc.
@@kuhlmanelectricserious Craftsman for sure. Same with the Carpenters back then. The work they were able to do all by hand. Just incredible. I find so much more in older places than anything built this century..
Knob and tube goes right along with balloon frame houses...both of which contribute to house fires a lot. Old wiring and an open chase from basement to attic. Seen it where a house was engulfed in flames in the walls and never set off the detectors. Fortunately the family got out safely.
The knob and tube wires I have work perfectly. Zero insulation and circuit breakers.
I agree 100%. I'm ripping out all the plaster and lath. Lath is nothing but kindling. I put horizontal studs in with fire resistant roxul,pyrogard plywood to replace the lath.
@@erlycuyler mine has the 2x4 drywall lath, I replaced all the wires in the upper unit and will replace the lower ones when the tenant moves.
@@danlux4954 Excellent call.
@@erlycuyler the old horsehair plaster is fairly fire resistant but the slats will lite up real fast...
Enjoyed the video. I am an electrical contractor and have rewired multiple homes in historic Richmond VA and you are spot on with all your concerns. One additional thing I constantly ran into was that it was common practice to switch the neutral wire in wall switches. Three way switching was done very odd as well. Great job keep up the good work!!!
HI Lionel, thank you! Yes you are correct - look out for those switched neutrals! Electricians who have never experienced it can be in for a big surprise. I've also seen the hot and neutral wire being fused in the panels - i always found this is to be fascinating, you have to wonder why they would do that?
Making this video has been a learning experience for me. I have NEVER seen KT in homes here in the northeast built past ~1932, it's really interesting to read how it continued to be installed in other states for so much longer.
Three way switches were run from a splice in the line conductors to the traveler terminals on both switches flipping the polarity of the socket or making both hot both of which are dangerous.
Thanks for this great explanation. I'm looking forward to a similar list of cons with BX cable.
Great video. We replace lots of K&T here in Philadelphia.
We stop agreeing to verify wiring safety after 70 years of service. It makes no sense to wait for failure.
Knob and tube is due for replacement and early Non-Metallic wire is getting to that age too.
Very good. Thank you. Insulation was my motivation to replace it, but fear of fire was important too.
Hey Susan thanks for the comment, i'm glad to hear you had your old wiring replaced.
One of the best explanations I’ve seen thus far regarding K&t wiring. You forgot TWO important things to add.
1. K&T is rated for 15 amps. Oftentimes folks overload it and that’s trouble.
2. Neutral fusing
Back in the day they thought if one fuse was safe adding another to the neutral would make it double safe. The problem with this is that when a fuse does blow it normally takes out the neutral fuse leaving the circuit hot. Many an electrician in the day would tell you the end result of that. That is IF they made it.
K&t is safer but the facts you mentioned and the ones I added are why replacement with modern wiring is an order.
Hey thanks for the comment. I agree!
Add to that, you can have neutral switching, which is mind blowing for many electricians when they first encounter it.
The double fusing (Hot and neutral) was always super interesting to me.
A family member lives in a house built in 1916. The structure is original and some stuff remains from its original configuration. I wonder if there is still some parts of the knob and tube. I find it interesting how things were done in the past and the evolution of plumbing and electrical
I find it extremely interesting as well! Particularly the decision electricians at the time were making - Use K+T, BX wiring or depending on the year, ungrounded early romex wire. Then you have homes were the electrician combined them together.
My dad bought an old Audel's book on electrical wiring in the early 1940's that tells you how to wire with knob and tube.
Knob and Tube systems had the boxes with a separate Ground wire clamped to the nearest water pipe (Lived in 2 houses with/had K&T). for Bathrooms and Kitchens, this was the practice.
My Top Issue: folk working on K&T that do not know HOW. Proper K&T was soldered after doing multi turn wraps around the main line, then well taped.
I;ve seen this many times. The ground wire was added later by someone to gain the ground and probably replace the receptacle with a 3prong. When this is done throughout a house, it can trick home inspectors (if the K+T can't be seen anywhere and they don't pull plates). They will say everything is grounded properly, even though it's not!
@@kuhlmanelectric or they do a bootleg ground, a jumper from
neutral to ground and making metal case of appliance live. also saw romex
with 2 wire an ground with 2 different loads using grounding wire as a return
not good but one load was ceiling lite on porch other load was 2 lamps 1 on
each side of garage door well within reaching height and are metal.
I used to work fire/water restoration and a lot of home had this old wire. Even if the wire was unrelated to the fire the whole house was gutted and all the old wire and associated pieces scattered along the ground and wire into a scrap copper pile. All new wiring, outlets, switches, etc. Felt kinda bad seeing this pice of history from the 1800s just going in the trash but was unsafe.
Makes sense!
You need to come out to California, nob & tube wiring was installed here into the fifties and early sixties.
Hey Frank,
Making this video has been educational, i never knew how long some states continued to install it. I will edit the video to reflect what i have learned.
I do have to wonder why an electrician in the 1960's would choose KT over all the other choices at the time - i mean romex with a ground was available and would install SO much faster.. It's interesting to think about!
I live in Maine house was built 1940 and at one time had knob and tube still have some of the porcelain insulators in the basement
I have a house built in 1947. It still had live, cotton insulated knob and tube wiring until about 10 years ago.
Excellent Video. Just discovered K&T wiring in my mother-in-laws house, as an insulation company said they wouldn't insulate the attic with it. House is from 1920, so it makes sense. The house if full of K&T. 1300 sq ft house 2 stories, what is a ballpark to replace it? Each bedroom has a single outlet(in the baseboard), so i'm thinking that each room should have more outlets as well. BTW, the house is located in Portland, Maine, a stones throw from MA.
Hey thanks for the comment! It's hard to say without knowing the total count of switches, lights, outlets that need to be rewired. I will say the average K+T job for us (single family) is 12k. I hope this helps!
I don't know about electrical wiring but I was wondering if there could be a modern version of knob and tube wiring that is grounded?
Hey, thanks for the reply. There is no modern grounded knob and tube wiring.
Should people with K&T add arc fault breakers to make the home safer? What's the pros and cons to that solution?
Hey Joel, thanks for the comment. Doing that will add a level of safety - the arc-fault breaker should trip if there is a bad connection somewhere. This does not solve the insulation or lack of ground issue however. Installing the AF breakers should be a short term solution, buying some time before a full rewire is done.
Keep this in mind if you opt to install AF breakers on the K+T - The AF breakers may trip and this is good because you want to know there is an issue and the AF breaker identified there is one. The downside is you are left with two options - spend money trying to troubleshoot where the issue is to fix it, or rewire that circuit.
@@kuhlmanelectric That sounds like a great solution to me then. A lot of homeowners will feel comfortable installing those breakers, but unable to afford all the circuits replaced at one time. It also indicates where immediate attention must be given. Also seems like gfcis can address the lack of ground.
My home is 93 years old and I’m currently removing the knob&tube in the attic. Fortunately, wiring in the walls is romex and the k&t is only in the attic. Unfortunately, there is almost a foot of insulation in the attic. I’m replacing in the walls where possible, as well, since it’s old romex and the rubber/plastic is pretty brittle. It is very slow going.
The hardest part was getting new home runs from the basement to the attic. It’s not too bad, actually.
Yikes!! I’m in the buying process of a house with KnT wiring, but more in hesitant. I live in NM, this house is 83 yrs old with a newer service panel. What should I do??
Hey Angela, I wouldn't let the K+T wiring dissuade you from buying a house you like. You will need to find an electrician you can trust and have the budget to replace it of course.
Thanks so much for a thorough discussion of K&T wiring. Because of all wooden and plaster-on-lath walls, I am concerned about the prohibitive cost of new wiring, in large part because of the difficulty of access and huge amounts of wall repair to follow. I don't think any contractors are able to make such repairs without costing an absolute fortune. It's a very large house.
Could be anywhere between $15,000 - $30,000
Hey thanks for the comment. We do the rough patching ourselves and aim for small holes overall. Take a look at our website and check out the "careful rewiring techniques" page to read more about our strategy. - you should be able to find a company that does it similarly to us. www.kuhlmanelectricalservices.com/rewiring-techniques/
Beware of companies who want to gut your walls to replace the K+T, this is not needed.
I'm not a contractor just in training but we are rewiring an old home and decided to gut the walls. It's better if you can afford it. There are options not to however.
The house I mentioned is over 100 years old and very large, with 11 rooms. If a bedroom, for example, is 15ft by 16ft in size, and has only one or two outlets, this is insufficient by modern standards. So a large number of additional new receptacles must be installed, as well as rewiring the existing K&T ones. Without a total gut and re-wall of the entire house which would cost more than the total value of the house, the only way I know to achieve proper new wiring is to cut long channels around the perimeter of every room. Having removed small sections of old beadboard walls and plaster-on-lath walls here for certain repairs, I am well familiar with just how difficult this is. The walls coverings vary in thickness, so drywall does not work well for repairs unless the rooms are gutted. Plaster does not cut out neatly in channels. It breaks loose easily and often the lath is not a solidly attached substrate, so when you try to cut it, it flaps loosely and breaks out more and more plaster. It's just a disaster to try to repair. I am not saying it is humanly impossible, just that the cost of this type of work could easily exceed the total value of an existing old house, which really suggests a bulldozer is the better option.
Hi. I live in Massachusetts in a house that was built in 1903. If you go into the basement you can see remnants of some old K&T wiring. You can also see that the house has had the wiring updated throughout the years as well with both I believe that second generation wiring (has metal casing around it) and what I believe is Romax (?) wiring. Last summer I had the electrical service upgraded to 200 amps and converted from fuses to circuit breakers. I hired a reputable electrician that got the necessary permits etc. My concern for years was whether or not that old K & T wiring still powered any of the outlets in the house. After stumbling across this video I got to wondering if between the electrician and the wiring inspector if the upgrade would've or could've been allowed if the house still had active K&T wiring?? Your thoughts would be greatly appreciated. Thank you.
Hey Matty great question! The service upgrade is a separate from the knob and tube wiring / interior wiring. Think of the 200 amp upgrade as the foundation, and the interior wiring the rest of the house.
Yes, a 200amp service upgrade can happen with old wiring still in the home, it's quite common actually.
We service most of the Massachusetts, From Worcester to the coast.. If you are in our service range shoot us an email or phone call and we can setup you up with a k+t inspection (if you are interested in one of course). www.kuhlmanelectricalservices.com
Hey KES! Good to see you here on RUclips. I reached out to you via email last summer when I was helping a friend on Cape Cod. We failed an inspection for not having an emergency disconnect for a 200A upgrade. Eventually I went back and the work was approved. Nice video!
Very cool thank you! I'll be putting some more time into videos going forward, hoping to have a new one every 3 weeks or so! Glad things worked out!
I was going around with a home inspector in 1994 through a house that I was buying. The house had live nob and tube wiring. He claimed that nob and tube wasn't so bad because the conductors were separated and there was no way to short them out by driving a nail. At that time I had no difficulty getting insurance on the house, despite the nob and tube. I didn't really like the fact that the house had this antique wiring, and I worried about the modifications that were made to the wiring over the years, for the house, a small bungalow originally had just one circuit, but now had many circuits using the nob and tube. I only had 5 grounded outlets in the house and an antique key switch in the garage gave me such a shock that I would replace the garage light with the circuit breaker off so I didn't have to touch the switch. Why didn't I change out the wiring? Cost! To replace all of the wiring would have easily cost 10 to 15 thousand dollars and I was a home health nurse paid Burger King wages.
Thanks so much for the reply! The inspectors reasoning is interesting - in a modern why a short circuit would turn the circuit off / alert you to an issue. A nail into a live knob and tube wire would not short out, and you would be left with a very unsafe situation - a live nail, or a connection that is semi broken leading to heat build up etc.
You are correct that replacing knob and tube wiring can be very expensive. It comes down to how much K+T is left in the home.
Knob and tube on the left coast was installed at least up to WWII, not 1932 as you say. My home was built in 1940 and originally completely knob and tube; as an electrician I can tell you this is the case in housing throughout the SF Bay Area. Most homes still have a blend of knob and tube in the bedrooms with a fuse box subpanel and modern wiring in the kitchens, leading back to a circuit breaker meter/main. Because of the age of the housing stock, there are still a lot of FPE OCPDs out there which represent the first-gen electrical remodels that occurred in the 1950s and 1960s.
Hi Steve, i learned a lot about the age of the system from everyone on here! Thank you for sharing.. It's interesting how different the east coast is from the west coast!
FPE was pretty good till it came out with the stab-lock brkrs, fuses will always be
much safer. a given amount of current thru a lead wire or strip of a given gage will
always melt. Old homes with pull-outs were nice for emergency generators too,
'pull the mains' and Range and u were totally isolated from the grid. As I have seen,
some old panels the range would not work if the Mains were pulled. the branch ckts
were off the MAINS but some panels other panels the range would work if the mains
were pulled
I'm in PA and my 1940 house was also knob and tube. I've seen the knobs and tubes to verify.
It was rewired in the late 60's with modern grounded wiring.
I've googled and it seems (from my extensive Google research lol) that it was installed into the 1940's in some places.
I
FPE made a good fuse panel, some had a main breaker but fuses for there 110 v
branch circuits and pull-outs for the range and dryer circuits. Other fuse panels
had two large pull-outs, one for the MAINS, one for the RANGE.
FPE went str8 to
hell when they came out w the stab-lock breakers. I know for a fact as one day a
wire in the clothes dryer had intermittent shorts to the back panel and burned a
hole thru said panel, never tripping the breaker, another time, the cord from a
space heater had a white ball of an arc and the breaker never tripped.
I have seen houses where KnT was used and no one hacked into it so it was kept
there, that fuse panel was then used as a Sub-panel a newer panel brought in for the
stove, clothes dryer and A/C
Do a video going over issues with BX wire.
I will soon!
My house was built in 57, and I have knob and tube. Greater Cleveland area though.
Very interesting! I have never seen a house in the northeast built after 1932 with it. I can't imagine an electrician in 1957 choosing K+T over the other options available, not to mention the supply house actually having it, crazy stuff!
1957 would be extremely odd.
I would question the age of the house, and/or confirm that it was knob and tube.
I haven't seen anything past the mid 40's, and there was more modern alternatives like he said above.
It’s not odd to see knob and tube in the cleveland area. Cleveland is a historic town. We have lots of old homes.
Thank you for sharing your knowledge.
HI Vince, thank you for checking it out! I'm hoping to have some more time soon to start making videos again.
@@kuhlmanelectric Looking forward to seeing them. Thank you for sharing your knowledge.
i wouldn't say just because something is old it's bad, I still come across knob and tube that is still in great shape even in the light box, and to solve the no ground issue you can install GFCI receptacles. granted I'm partial to knob and tube, even installed it in my shed, fuse box and all. Biggest issue i find with it would be lack of circuits of course, and the insulation issue. i've actually load tested it, new plastic wire vs. 60's vs. 40's vs. K&T all #14 and the K&T won out easily, the plastic melting and burning up while the knob and tube didn't do anything even holding 90 amps. 60's wire still melted, 40's held on fine until it got so hot the insulation became conductive and the whole thing glowed like a light bulb.
Yeah I have to agree. And you know what else is really old in a house that has knob and tube? Pretty much the rest of the structure of the house!!!
@@PostmanApocalypse yeah, and it's still standing, the wood is much better than new wood you would get today, it's old growth and full size, just the weight difference alone is substantial. A new 2x4 is puny compared to a 100 year old 2x4.
@gtb81 yes and that old rough cut oak is second to none!
Is there a way to insulate over the wire with plastic tube etc ? The original covering is gone.
Hey, i'm not sure what you mean? The individual conductors? If the insulation has come off, it needs to be stripped back to where the insulation is good. Otherwise you need to replace the wire.
@@kuhlmanelectric I've been told the original protective layer for K&T was typically made of cotton soaked in creosote and over time it just rots away leaving a bare wire ran between the knobs. I was just curious if the original wire insulation could be replaced with the plastic wire covers that are popular to use with computer cables to collect them neatly, in order to remedy the problem you mentioned concerning heat dissipation when fiberglass batting or blown in foam is added to the walls around the wiring. The plastic tubing would allow a small air space around the wire.
I told my professor in college where I was studying electricity that if I bought a house all knob and tube wiring was coming out no matter what and that the new wiring would, if possible, would all go in some form of conduit.
Yay! I'm rewiring an old k&t house and I use conduit. It's obvious an industrial electrician did the rewire. Lol.
Never heard of an “electricity” major, especially taught by a professor. What kind of college is that?
Just ordered your knob and tube book bro...thx...👍
Hey Arnie, thanks so much! I hope you find it useful!!
1935 house in California has knob & tube wiring. I’d like to get rid of it but need an electrician willing to do it. Had an electrician do some remedial work and add some circuits. The house is concrete block so he’s not thrilled about that. Insurance is the biggest issue…expensive…high deductible.
Any electrician should be able to rewire a house.
@@danlux4954 the point he is making is that a concrete dwelling would be more difficult to rewire. I agree.
@@steveloux4709 yes but he should be able to place new wires where the old wires went? Concrete houses shouldn’t burn.
HI David, is it concrete block with wood studded walls on the inside?
Thank you for the straight to the point information
Bought my 1920 all and I mean all brick lap and plaster home 3 years ago. A mechanic and hobby machinists the home runs a 200amp service with modern breaker box that converts to the k&t system. The garage also was k&t with 3 lights and one outlet. Also all brick. Rewired the kitchen the first year while doing a updated look. Rewired the garage the 2nd year to increase my productivity. This summer will be the attic and upstairs rooms. I'd like to get some insulation installed for next year. This house is a bit drafty.
I enjoyed this very much, Thanx. Had some exp with it, changing over to romex, a new panel
was installed (service entrance equipment) weird stuff, small home and 12 fuses. they fused
the neutral! I have seen this in old houses on Cape Cod on west Main street.
Often times in the very early days, electricians would fuse the neutral and hot. Each circuit would have 2 fuses.. Interesting stuff!
@@kuhlmanelectric I gave that some thought, It may have been
pretty easy to borrow a neutral from another ckt. I don't know if 220 volts were
around then, but I can see where a ckt rated for 10 amps would have the ungrounded conductor protected but having the neutral possibly carry twice
as much. I got a jolt putting in a recep. went down cellar and sh'ed holler when
the lite went out, so yeah I thot the ckt no longer HOT. backed into the radiator old cast iron job. hadda see why I got juiced an pulled cover offa the panel. 6 fuses on each of the two lines coming in. It was romexed out of the panel and when I went to the attic, her knobs were all over the place.
In knob & tube did they just run one ceiling light wire down the wall cut it at the switch on the wall, and run the one wire back up where the junction +/- was located in the ceiling light?
Sometimes yes, there would only be 2 wires in the switch, feed in and feed to the light with no neutral in the switch box.
There were electricians that would run the neutral wire through the switch, creating a switched neutral, these are fun!
@@kuhlmanelectric Well the switch appears to be one wire cut in half at the switch from the light down /cut put switch in between and other half start at the neautral side of same switch and run back up to the light. doesn't matter which one they cut to the switch .it's just one wire. Off no power to the wire leading back up to the light.
First time home buyer here in windsor Canadá. I just discover I have this type of wire and man I am kinda scare on how much it will cost me to get it re wire 😶 wishing I had the budget. But it looks like there is a mix of new and old.
We often see a mix of wire in homes. Pricing will depend on how much KT is actually left in the home, hopefully not too much!
How does existing K&T wiring even handle all the modern appliances and computers and stuff we use today on old wiring that was designed for some lightbulbs and maybe a vacuum cleaner or something back in the 1900s
I would expect that the wiring would overload pretty easy at that point and be a danger.
The current carrying capacity of #14 AWG and #20 AWG K&T is the same as modern Romex. If properly fused or with the proper sized circuit breaker it is perfectly safe. The breaker will trip or the fuse will blow long before the wire overheats.
I am in the process of buying a home with knob and tube wiring. The gfci's do not work. The seller agreed to have an electrician repair the gfci's. Can an electrician run newly updated wire to the gfci's and all of the appliances and keep the rest of the house as it is at knob and tube wiring. The home must pass inspection in order for me to buy it and no one wants to rip out all of the old plaster to remove the house of this wiring and install all new wiring?
HI Steven,
Yes new wiring could be run to certain outlets while leaving the old KT as-is, this is not uncommon.
I will say that if they are repairing the GFCI's, they may only be replacing them. GFCI"s can be installed on ungrounded wiring like KT by code. I'd check with the seller to see what their electrician is actually doing. If you can, push for new wiring as it's definitely better, but more expensive.
Early Romex was ungrounded also. Houses built in the 50's early 60's are also ungrounded.
I've also read that common neutrals between circuits was done with some K&T installs, but that might be a regional thing.
I have a 1915 house and some of the original K&T (with dedicated neutrals) is still in use for lighting circuits, with most of the receptacles having been replaced with separate AC (no bonding wire) or NM runs over the last half century. I think I have just about every generation of wiring in this house, although luckily aluminum is limited to range and dryer receptacles. I had no problems getting insurance, but everything was inspected before we bought the house.
Common neutral is still done with modern circuits. It’s called MWBC. It has its advantages, but must be done properly
Interesting! We see a lot of homes with a mix of KT, BX and romex. Aluminum going to the range / dryer / other heavy loads is no issue.
I don't see many, if any, shared neutral KT around our area. I'll keep an eye out for that though going forward!
Great conclusion
Thank you!
LOL! The thumbnail caption totally has me ROFLMAO! Are fireworks safe? Is walking around a major city at night safe?
Ha! Thank you for the reply
I saw it in attic of one old building it wasn’t in use but i live in Estonia where you find maximum 60 year old wiring because people change it often i changed my entire home 2 months ago
Very interesting!
Thank you
I've turned down several side jobs because they won't replace the knob and tube
Replace it you can tap dance around this issue in the end it need's to be replaced .
Agreed!
I ran into a gas pipe at a duplex unit that was hot. It ran outside of the building about 2 feet off the ground for 40 feet. I was working at a small apartment building across the alley and the heating contractor that was working at the duplex came over and told me he received a shock from the gas pipe! I was skeptical but went over and looked and sure enough I read 124 vrs to ground.😫 To make a long story short it turned out that there were no ground wires anywhere in the duplex, and and no bonding of gas and water pipes. The kitchen stove had a spark ignition and the neutral wire of the stove cord was attached to the stove frame. The outlet that this was plugged into had hot and neutral crossed! Made everything attached to the stove hot. How no child ever got killed playing out there is beyond me…. Moral of the story: Always hire a qualified electrician.
Wow that is a crazy story! Yes these things can happen and everyone who has lived there is lucky to have not been injured! Thank you for sharing
Thanks will share
Thanks for sharing!
Knob and tubes do have their disadvantages- hidden behind walls and not protected but I also see significant advantages.
Many are still in use- this proves their longevity. They are spliced /joined by twisting other conductors together soldered and then insulated.
They are insulated with rubber and or cloth insulation, ceramic tubes and separation of conductors.
They have the ability to dissipate significant heat because they are not confined hence they should be able to handle even more current. If they were modernized with a ground wire and maintained I think they will be on par with current wires.
Today we have insulated copper wires that are extremely close to each other in a confined space wrapped with additional insulation- metal clad, or plastic- Romex. Tightly packaging the wires together lowers the specifications of it's awg due to fear of them melting and shorting each other.- hence another reason they add ground wire.
The ground wire is there to protect YOU.....period. In an UN-grounded system if you find a fault the "hard way"....I guarantee you'll NEVER want to repeat it.🤔
Ironically the knobs and tubes themselves are actually a safer way to mount wires and run them through joists and studs than we do now: by offsetting parallel runs with the knobs, the possibility of accidentally nicking a wire when someone is aiming for a stud is effectively eliminated while the tubes offer real protection against deep penetrations into a stud by a fastener or drill bit.
It would be interesting to imagine a modern house being wired with knob and tube. Some medium sized homes can have over 30 circuits in them - imagine what all those wires would like as K+T? Fun to think about!
From what I have seen as an EE, the NEC has lots of design margin against overheating built in if it is adhered to.
Thank you!
Thanks for watching!
Just being old isn't a problem. It's the degredation that happens because of that age that causes specific problems.
Why don't modern house wires need cooling too?
Do you mean the wiring needing cooling? Modern wiring is designed with much higher temperature ratings than knob and tube was. Modern wiring does not need to be in open air for cooling for this reason. Thanks for the question!
Romex will not last as long, which is a bit sad. But, old wiring, needs to go. Not to mention, the new breaker boxes, have new safety features, like the yellow boots in the square d boxes.
Well. Some issues some lighting in series chain lights via single poles and switching neutrals via three ways . cloth. Romex . You had sometimes a color coded neutral
Of course if you had a master electrician with the connections soldered. Than you it was no to as bad as other jobs .
Comments:
1. If it's getting hot enough buried in insulation, then there's another issue going on. I have yet to see any evidence of a fire from an unmolested, normally loaded K&T directly caused by covering with insulation. Millions of homes had this done.
2. Insurance companies. No surprise. What's new?
3. Ok, lack of ground. Inconvenient. Yes. Downright dangerous. Not necessarily. Depends. In your case, an handyman hack, not an original install.
4. I agree with this. Was also an issue with earlier plastic Romex. If you have attic access, one method to fix it is put a plastic jbox in the attic and cut off the burnt section of the old wires and route them into the box, then do a whip with modern NM to the fixture. I would not call this "extending the circuit". It's a repair. Other than burnt insulation in fixture boxes, the K&T I encountered had insulation in very good condition.
5. Yes it's old, but so what? These installation were almost always professionaly done and made to last. If you need to upgrade, run new circuits from the panel, leave the K&T alone, unless the house is gutted to the studs. K&T was still allowed in the 1975 NEC, although most AHJs outlawed it. The latest house I encountered with this wiring was built in 1968 in rural CA.
Hey thanks for the reply. Wow 1968 huh? It's so interesting to me to hear these late dates with K+T wire being used. I'm imagining an electrician in the 60's going to the supply house... Don't give me any of those romex wires that are WAY easier to to install, give me the OG K+T LOL. Pretty fun to consider.
Another issue is overloaded neutral wires
Knob and tube is really the worst because it has 90 years of hack jobs and jank accumulated. If unmodified, it's not that bad for lighting circuits.. but your issues are valid for sure. Having no ground on your outlets sure limits what you can use, and having a GFCI on every outlet really only is an expensive bandaid that doesn't actually fix the problem.
Hey, thanks for the reply. I agree with that!
Over demand on the circuit is true nobody has microwave oven and modern appliances back in 1902
That's true! There were not many items to plug in at all in 1902.
👍👍
its actually a well thought out system other than no ground.....both conductors are spaced apart and connections are soldered together ...he is right about the wires being baked over the years from bulbs though......disintegrate if you look at it wrong lol
Very true! I think the electricians installing it took great pride in it
when a switch was put in with KnT was just the hot wire brot into the box? and 1 wire from the lamp as well?
@@raymondgarafano8604 yes...you never put a neutral wire on a switch..
@@workingshlub8861 Hi there wrkg shlub. Yes I do know that, it could lead to a
loaded neutral, whatever current drawn by the load will be on the neutral.
With romex the white wire of course will be in the box as well as the black
and grounding wire.
This is nuts people don't want to change their electrical circuits to newer technologies - I just cannot imagine living in a house with live wires like that
same
Well, what happens is they see an estimate for $2-300.00 per opening to rewire the home and they just take their chances.
@@electricianron_New_Jersey yeah - I thought gambling is legal only in certain parts of USA, but it seems I was wrong 😅
It’s the cost.
@@electricianron_New_Jersey You are correct. It is much the same with auto mechanics,dentists,etc. I'm here to buck the trend. I will work with people on these older homes (usually younger couples just starting out) with a variety of options.
With that rhetoric you should be a NEC employee!! The NFPA/NEC sells nearly $1,000,000 worth of publications annually! The NFPA employs 600 people??
Easy bake oven in the 1980's only used a 40watt and you cld bake breads with it imagine a 100watt lol
WTF for me as a german that is absolutely ridiculous. Do this wires even have some sort of insulation or is it just the bare copper running on the ceiling
They are insulated. And properly maintained they are also safe and still recognized by the National Fire Protection Association's publication #70, latest edition. As an American, I'm fairly confident that the Standard is sufficiently robust in its installation requirements to avoid electrical hazards. Maintenance is key though; I am sure that holds true in Germany as well.
I live in an older American home (1869) that once had knob and tube wiring including wooden surface mount conduit that had two grooves for the conductors to be placed in. My home was originally built and owned by German-Americans (Jacob Sterner a miller).
It needs air space for cooling purposes. The wire is insulated. But N&T is very overbuilt compared to today's systems.
@@steveloux4709 its actually a well thought out system....conductors spaced apart....less chance of them touching and connections soldered together....better than any wire nut......if it had a ground it would be no problem...its like old style fuses....they are actually more reliable than modern breakers because there are no moving parts that can fail but it was idiots using pennies and burning down the house that ruined them...
Between outdated wiring, lead pipes, no insulation, 120yo cast iron sewer lines there should be a superfund to help people get their homes updated..lord knows this govt has the money to spend on everything else
It's really amazing to think about - Just in our area there are 100's of thousands of homes built pre 1930... All these homes will need their wiring updated, not to mention, plumbing, painting, roofing, HVAC etc etc.
@@kuhlmanelectric instead my state is pushing to ban gas stoves to improve air quality...idiots dont realize the dust I cant keep up with contains lead and asbestos? Amazing..
If your house has this youre neighbors are stealing your electricity
Wow wow 😨
K & T is too old and never safe. It's just too old
It definitely not as safe as today's electrical wiring.
Agreed!
Was it called the Jewish electric?
I graduated in 1977 from high school school as electrician... obviously I ran into this tubing and from older electricians, they called it, Jewish.....
is knob and tube safe let me see house from 1902 and still hasn't burnt down