Overcurrent +14/2 + Fiberglass in a 2x4 Wall
ฝัง
- เผยแพร่เมื่อ 8 ก.ย. 2024
- As requested by so many of you, I made a section of 2x4 wall with a 14/2 wire running through it in both a hollow section (interior wall) and a pink fiberglass insulated section (outside wall) and then passed increasing amounts of current though it to simulate a dangerous overcurrent situation.
Also as you suggested, I did some crude temperature measurements with a IR thermometer gun.
For those of you not in Canada or the US, this type of wall is very typical over here, and the 14/2 wiring strung though holes in the center of the studs is how a lot of wiring is done. We have 120V household power and #14 wire is rated for 15 Amps in most situations although 12A is the max continuous load that should be on a 15A circuit.
In this test we try 20, 30, 40 and 50 Amps to see when and how the cable fails. This might represent a situation where a circuit breaker malfunctions and fails to trip even when for example someone has plugged in a bunch off heaters on the same circuit which also shouldn't happen.
This is a great test that really shows the massive safety margins built into the code for wiring. In nearly all cases the end device, receptacle or what not will fail well before the wire does. I speak from CEC rules, but wire is rated based on the insulation temperature of the cable, and parts of the code restict temperature table you can use for that application. For exmaple, 14/2 is rated for 25, 20, 15 amps at 90, 75, 60c. For nearly all cases in a house, you have to use the values under 60c which would be 15amps. However for hardwired heating loads, like a hot water tank, you can use the 75c values. With the heating rules you can load 14/2 right up to 20 amps of continuous load, on a 25a breaker.
It has a great safety margin - although in a following video with even better (spray foam) insulation ( th-cam.com/video/lFdSXTKsKwA/w-d-xo.html ) 30A becomes the point where the wire insulation begins to melt. Not a huge surprise since with enough insulation you can get any amount of heat rise, but a close particularly for situations like a cable in a hot attic that have been covered with insulation and is feeding something like an air conditioner at close to rated current.
CEC rule 14/2 allowing 75C/20A for hardwired heating loads. Any idea why that is deemed acceptable? I would think a heating load that can often be on for long periods of time would be worse than for things plugged into outlets etc with usually more sporadic usage? I have also hear the higher temp ratings are also permissible in some industrial situations. For the record, I'm an electrical eng who doesn't deal with code issues very often so its neat to come across someone who really knows it (electrician?)
I had a guy run his RV out my shop on 14/2 for months, pulling close to 30 amps consistently. Wire got a little warm, but didn't have any issues even in arizona summer. This is also an old brick building with no insulation. When checking the wiring ratings, I noticed 14 gauge was rated for almost 50 amps in "chassis" wiring, but substantially less for demonstrated reasons in residential
30A on 14/2 in Arizona! Wow! I wouldn't have guessed that! There are different temperature ratings for non residential wires. Maybe the idea is in a metal chassis, as long as the wire insulation remains intact, there nothing flammable near the wire to cause a problem?
The good news - the house didn’t burn down. Remarkable when you think about it. Great summary.
It is! Good that there is a nice safety factor!
This was really cool. You put in the extra effort and made a nice accurate picture of how these real world factors effect it, and why they give such conservative ratings to cables.
It’s easy to imagine how even 30A would ruin it if it was in an even longer path of insulation, running an air conditioner all day long on a hot day. Eventually it would be mushy enough to short circuit itself.
Again, thanks for doing such an extensive test for all of us. It’s amazing to see the stark difference of what it can handle in different environments.
So glad you liked it. The charring of the plastic insulation inside the fiberglass area was interesting to me and as you said compared to the other area. And imagine if the AC was supplied though a wire embedded in insulation in a hot attic.
I will do a similar one with spray foam in a few days when is stops being rainy. All tests are outside due to smoke and fire!
@@ElectromagneticVideos you also often have a bundle of wires stapled on top of each other or all zip tied together possibly buried in fiberglass or spray foam in a hot attic. Or lots of wires stuffed into conduit. This is why we have a large safety margin and say 15 amp for 14ga instead of saying it's good to 30-40 amps.
Use case, setup, and conditions can be way worse than your test setup.
I was at a house with over stuffed junction boxes with old oxidized wires buried under insulation in an attic and the wire nuts melted clear off. Scary.
The above situation is what led me here.
@@libtrs838 I do want to test the bundle of wire: I once bought a house and almost all the wires were tied in a bundle maybe 3 or 4 inches diameter and against a beam that ran the length of the house under the main floor. The house was electrically heated, so a lot of the cables could have carried 15 amps at the same time. On advice of an electrician, I was able to spread them out. But always wondered what could have happened. They had been in a bundle for 20 or 30 years, but still!
Im a electrician that was a nice explanation on this video, keep up the great work👍
Thanks! Glad you liked it - I certainly thought it was interesting to seeing how close the safety factor is for various combinations of cables and insulation.
Good setup on the experiment. The similar video that only tested the wire in the open air wasn't particularly useful because it didn't mimic real-world conditions. This is great info.
Thanks. Yes! Unfortunately due to the TH-cam algorithm, the other "more exciting" video gets way more hits than this one. But hopefully people who are really interested in something other than seeing a wire burn up end up here!
Nice job on this test. Thanks for putting so much effort into this video. It shows. I have a feeling your channel is going to start growing pretty quickly!
It will be interesting to see if that happens, or if I am using my '15 minutes of fame" . Its been great fun in so many ways. And so many comments have been so interesting!
Very nice job. I've always wondered about how hot these wires get in insulated walls, so it's nice to see someone do the experiment. I'm glad to see there's still quite a safety margin with 14/2 wire even in insulation. It's likely worth pointing out that ambient temperature of the air makes a difference as well, so the safety margin is likely tested at something more like 38C/100F ambient air.
It's curious you had such a non-linear increase in temperature at 40 amps. One possible reason is that the resistivity of metals increases with temperature. So maybe at 40 amps, this start a positive feedback loop where the wire starts getting hotter, which increases the resistance of the wire, which gets the wire hotter. Rinse, repeat.
I'm surprised it hasn't been put on TH-cam before. Good point about ambient air. Yesterday was about 30C outside, but in an attic in the southern US you might hardly need current flowing in the wires at all.
The non-liner increase: on the previous videos I did see the resitivity increase - after setting a certain current the voltage drop would increase as the wire heated up (sometimes I had to re-adjust the voltage to the welder). But it wasn't that much. I first thought it was heat from the plastic insulation and/or pink stuff around the fiberglass smoldering but I think that happened later and contributed to the really high temp. Maybe next time it would be worth measuring the voltage at each side of the fiberglass region and same for the hollow area an see if there is an exaggerated runaway effect as you describe in the insulated region. That could make things way worse for a wire going from insulated to uninsulated areas in a house. What a great observation! I think you may have really discovered something there!
The resistance rise in copper due to heat rising is only adding some heat and quite far away from run-away. At least that is what I figure when I look at it this way. If you have a awg16 and run 40 amps through it. At 20 degrees Celsius (C) there will be a power loss of 20 watts per meter heating the cable. Lets say that awg16 with 40 amps reaches roughly 70C without taking into account the resistance rise due to temp. Then we calculate what the power loss would be for same wire at 70C we get a power loss of 25 watts. So it added 5 watts. Then I would draw the conclusion that 20 watts is needed to heat it up to 70 and an extra 5 watt will only heat it up some more, roughly 10 degrees.
@@Jonas_Aa Thanks for doing the math.
I'm not really completely sure what's causing the runaway, but it sure seems to happen. The other possibility is the insulation just starts to break down, and arcing occurs. From your math I'd imagine that's _probably_ what's going on. I'm not sure how you'd properly test though. THHN wire has higher temperatures, but the outer jacket in romex provides insulation (and can catch fire itself)
I'm sure someone out their has to know what's going on since this isn't exactly anything new. I just find it a curious effect.
FYI !
Metal plates are only required when hole for romex is less than 1 1/4 inch from stud edge.
per National Electrical Code.
I didnt know that - I assumed they were always required for wires in 2x4s. I have used them over water pex water pipes at times just to be safe.
There's nothing like a good old practical representation of what happens in the real world regarding all things electrical.
Although the current passage in this demo, through 14-2 isn't typical, at all, but not impossible.
Exactly. To get to this sort of extreme sustained current one would really need multiple failures at the same time. But as you said, not impossible. Somewhere there must be statistics about the likelihood of this sort of thing happening.
@@ElectromagneticVideos There was a comment indicating that the situation is not realistic due to such low voltage. Is there any way to test how long the 14/2 cable would last powering up a 120v 30amp appliance?
@@hippo-potamus Well I respectfully disagree with a few comments that have said that. There would be a small difference towards the end of the experiment: the initial approx 50A heating of the wire would be the same. 50A through the same wire resistance will always produce the same heating along the length of the wire. The difference would occur after the plastic has softened considerably or begun to melt. The higher voltage might punch through some weakened or thin insulation and char the plastic and as more power flows that path make things even hotter till a full short occurs or really bad things happen like a huge current burning up the wire. The charring we saw in the fiberglass area might also allow the higher voltage to push some current though the carbonized plastic adding heat. So depending on how things as setup in such a test it might be different towards. All I want to do here is get a sense of at what current does the plastic start melting and really bad things start happening. And it does that.
I would think 30A continuous is in a grey zone where a lot depends on the circumstances. Outside my house near Ottawa on a -30C winter night it might do fine! In a hot attic between insulation in a Texas summer it might not! Even if it were to do OK the prolonged high temperature may cause a gradual deterioration of the plastic insulation. There is a good engineering reason for a significant safety margin.
So I realize the 30A in your question is for illustrative purposes but to anyone reading this, PLEASE always use the approved size of wire rated for the current! You cant beat 100 years of hard lessons learned by the various approval agencies and manufactures. And you dont want to become one of those "lessons"!
@@ElectromagneticVideos Do you think the 15amp breaker would reach its thermal disconnect point before the wire sheathing began to melt?
@@hippo-potamus It should! But things can fail. Another commenter pointed out that Federal Pioneer breakers have a reputation for not tripping.
Thank You! Very interesting and entertaining!
Thanks! Will be interesting to see if spray foam insulation is just as "entertaining". Or more so!
@@ElectromagneticVideos Haha! Lights, camera... Action!
@@lgg2304 You got it!
The "goo" in the fibreglass is probably the plasticizers in the NMD cable. It's rated 90C max.
..New subsciber
It could be. 90C - I heard that older cable was 60C - from these simple tests I'm glad today's NMD 90C! Thanks for subscribing!
Have you tested the transmission of the plexiglass to the wavelengths involved for the non-contact IR temperature sensor you're using (typically 8-14um)? To get an accurate temperature measurement of the wire you'd want to add an access hole in the plastic with a removable cover to prevent drafting from affecting the heat accumulation.
Good point!
Dude you’re work is great!
Thanks! Glad you enjoyed the video!
Many, many years ago there were separate amperage ratings for knob-and-tube wire ran in an open cavity space vs. insulated, open space ratings significantly higher.
I didn't know they did that by makes perfect sense! You wouldn't happen to know what the "official" current ratings were for various knob and tube wire sizes by any chance?
@@ElectromagneticVideos I don't know it off the top of my head, but one or more of my older electrical books has the info. There might be a resource on-line that also has it. I want to say that 14 AWG was rated for 20 amps, 12 AWG was 25 amps, not sure about 10 AWG...
@@NipkowDisk Given the air cooling of the wire, the slightly higher than we are used to is not surprising.
spray foam experiment would be very interesting
Actually I did spray foam - here it is! th-cam.com/video/lFdSXTKsKwA/w-d-xo.html
Interesting video! Well done and presented....this could be shown in vocational schools..
Thanks! Yes - it would hopefully would give people a better appreciation of the rules/regulation intended to keep wiring safe and also that in some cases the safety margin isn't as great as one might like.
Very cool. Instead of a wire nut, could have put a box and outlet in the end and jumpered the hot and neutral with a cord cap (a plug) using a piece of #12 or even #10 to jumper the sides so to minimize its effect on the experiment. Would be interesting to see what happens to the outlet.
I would also suggest that when you take your temp readings, go to the backside and check the temp of the Sheetrock.
Damm! I should have checked the back! Next time. I had thought about putting in an outlet box but end the end decided it might complicate or confuse the results. But maybe an experiment to see how well a box contains a massive overload sometime .....
Glad to see you get a thermometer.
15 minutes is not enough time to reach anywhere near static condition, especially where insulation is involved.
Any idea what the time constant or time to essentially reach equilibrium might be? I do have thermocouple on order and it might be interesting to repeat with the thermocouple next to the wire deep in the insulation and plot the temp vs time graph. Although might not make the greatest video! Also am seriously looking at infra-red cameras.
@@ElectromagneticVideos My guess is going to be difficult to calculate from theory when you'd reach an equilibrium, and it's going to be highly dependent on conditions. You'll note resistivity of wire goes up with temperature, so that will produce some feedback.
Your idea of testing is experimentally with a thermocouple in the wall, and by plotting it on a graph is likely the best approach.
@@ElectromagneticVideos In my own experience running circuits near maximum allowable under NEC operating crypto miners at home, thhn and the connected breakers would take over 24hr at the rated current to reach equilibrium. Being 10% over breaker rating but under wire rating often takes multiple days before a breaker trips for instance as the wire can conduct heat away from the breaker when oversized.
I did some experiments out of concern as I had outdoor mounted load centers feeding wires running indoors and was concerned about risk in winter time for continuous maximum loads.
Definitely changed my perspective on how much current wires can really carry and how much safety is being kept in the code.
One main consideration is wires exposed to extreme ambients in an attic for instance. That would be an interesting test, 14/2 wire under 20 amp load in a 160-180deg F ambient condition with some of it laying in blow in insulation. To mimic someone swapping a 15a breaker for a 20a to operate an 1850watt window AC during a grid voltage sag/brownout in the 95 volt range in the middle of a summer day.
@@mediadaemon I never thought of wires conducting the heat away from the breaker but it makes total sense - good electrical conduction usually goes hand in hand with thermal conduction.
So how consistent were long term trip levels from breaker to breaker? Spec sheet from some breakers show a huge allowable variation in trip current/time from breaker to breaker.
Question: so why so close to the current limit for crypto mining? I is just to minimize cost of additional circuits or did I misunderstand?
Yeah - it must be real rough on the wires in an attic as you describe.
@@ElectromagneticVideos I never did comprehensive tests between brands other than Siemens and SquareD homline. Consistency was poor, 2 different new breakers would have noticeable differences in trip time at that slight overload setting. But more so, ambient conditions had major impact. A breaker at 110% by itself in an empty panel can nearly run indefinitely if the ambient is room temperature or below. But put that breaker surrounded by also 80% or more loaded breakers and it's much more likely to trip. Same with leaving the cover off, it improves the likelihood of the breaker holding much longer.
My testing all involved the fear of a breaker in an outdoor panel in freezing weather not being able to prevent a wire overload in the interior of my home.
There were two factors for 'pushing' the limits. One was that I initially wanted to have neat clean installs in server racks using server PDUs that were 30amp 240v, the ASICs at the time would draw 1400-1600 watts at 240v but like an induction motor, when the voltage sags on a switchmode power supply the current will increase to compensate. Having a continuous rating of 24 amps I wanted to know exactly what the weak link was.
Worse yet, is as ambient temperatures increase the ASICs become less efficient and can creep up in the current draw. Also, software is what was controlling the current limit of each ASIC and it was a concern if some sort of bug or firmware update/reset would cause them to draw the maximum of the power supplies.
I wondered too if the ventilation were to fail, a breaker in cold outdoor ambient, receptacles and cords in an ever increasing indoor ambient at the same time the current draw increases, what would happen.
I learned that wire and sockets can get incredibly hot before failing. The weak link in my basic tests was typically the rubber cord around the plug on the PDUs connecting to the 30 amp outlets. But not really in a burst into flames way, just a melt, char and eventually lose contact kind of way. (I had ceiling mounted receptacles with hanging cords)
The second factor, I had migrated everything out to a shed that was already fed with 6 awg thhn in conduit underground. My continuous draw at that point was 55 amps @240v. thhn in oversized conduit takes a lot to get hot unlike 6awg in nmb cable in enclosed walls. Ran that load for years before my current setup which is 2/0 copper.
The next generation of ASICs changed from ~1400 watt draw to ~3800 watt draw using dual Nema 6-15p cords, making the 30 amp PDUs no longer viable. I painted myself into a box trying to be "neat" and currently just put sub panels directly on the racks with several metal boxes that can easily be swapped out if the next generation changes it's power requirements yet again. It also solves the other concerns as the breakers are subject to the same ambient of the wire, receptacles, plugs and load devices it's protecting.
Just subscribed to your channel. Very interesting videos. Thanks for your efforts.
Glad you enjoyed it! Thanks for subscribing!
Thanks again 😉👍
Your welcome!
I'm waiting for the spray foam insulation version. Spray foam, or at least some types, burns vigorously. That should be interesting. I just subscribed to your channel
Unfortunately due to scattered showers today and the next few days I will be delayed doing the foam one : I'm doing it outside for smoke and fire reasons, and I really need 3 hours or more of good weather and dry driveway. Wednesday afternoon is the first break in weather - so if my real job permits I will do it then. If not, hopefully next weekend. I used plain old "great stuff" to fill in the area of the wall last night. I'm sure the 2 component commercial stuff and the fire retardant stuff all acts differently. But they would all hinder any air flow, so as you said the results should be interesting. Thanks for subscribing!
Great test. I will add though that the plexy glass will throw off your temp readings quite a but. I do this type of work and have to remove all plext glass to get accurate reading. I understand you are trying to keep the heat in. I am not trying bust your but by any means. Just wanted to give you some input! Love the video
goes to show how fiberglass does stop a fire from progressing out of control
Ahh the video I waited all week for. I like that you left a section non insulated vs insulation. This is a very good real life simulation. Even though 25 to 30 amps didn't destroy the wire here, picture an older house, with a 4 circuit 60 amp fuse panel. And assume the furnace had broken down in the winter. And pretend the homeowner was low income and couldn't afford to fork out 2 grand for a new furnace right away. So in the living room they have 2 1500 watt space heaters, lamps, the television what have you. Fuses keep blowing. Homeowner runs out of fuses. In act of desperation they decided to jump out the blown fuse with a penny. Now in this example 30 amps or more, is not out of the question. Let's pretend this is going on for several hours or more. The status quote could be very bad.
It's all possible Though to be fair I'm not sure the last time I saw a house with fuses in them instead of circuit breakers. I did look at quite a few older homes in circa 2008, and I don't think a single home still had fuses. I'm sure they still exist, but they're a lot less common than they were in the 80s/90s.
I think you described the scenario perfectly. And the going on for for several hours - I could sure see insulation weakening over hours at close to is limit. And probably add to that older house with those hollow wall that open into the attic with no firestop.
Steve - interesting! I'll bet a lot of thankfully gotten replaced. But I wonder about the rust belt areas that suffered the collapse of manufacturing and house values and incomes are low these days. I could see people there not being able to afford upgrading the panel and being in the scenario Kyle described.
@@ElectromagneticVideos also in many old houses the insulation wasn't as good as in a modern home, because prior to the energy crises in the 1970s, energy efficiency and being more eco-friendly wasn't that big of deal, and since we often had coal or wood burning stoves depending on where you lived, the cost of wood/coal vs oil, natural gas or propane, etc a loosely insulated house could have been an advantage, from a health safety standpoint. In a heavily overloaded circuit, could it be possible for a strong wind gust to introduce enough oxygen in the wall cavity to go from smoldering to a deadly inferno. Maybe you could repeat the test, but with less insulation and a leaf blower, to mimic this.
@@stevesether it's been quite a while since I seen a home with a fuse panel still in use. Probably closer to 10 yrs ago. I wanna say a lot has to due with insurance. Although fuses by themselves, are a very reliable overcurrent protection, for the reason a fuse will always blow , whereas a breaker is a mechanical device and have been known to freeze in the ON position (FPE, Zinsco anybody 😉?) and are occasionally still used for AC disconnects, disconnects in commercial and industrial, etc. in an insurer's eyes, fuses are an indicator of an older system that does not meet today's strict safety standards, can have issues with brittle wire insulation etc. not to mention it's much easier for a homeowner to oversize or bypass a fuse, than a breaker which tends to only be replaced by an electrician or an advanced DIY'er. Having said all that, it's either very expensive or impossible to secure an insurance policy, hence a mortgage.
10:31 what you are seeing is the off gasses condensing on the plexiglass. The fiberglass acted like a filter and caught all the darker tars and carbon so the lighter brown color oily stuff made it to the plexiglass.
That's exactly what I thought. I'm pretty sure the only thing added to fiberglass insulation is dye.
Graet video!
It would be nice to make video with mineral wool.
Keep the great videos coming!
Thanks! Next is the spray foam one when weather permits!
Small correction: Originally all 2x4's were really 2"x4" but they were called "rough cut." They really were very rough. I know this because my first house built in the 1930's was all made of rough cut lumber. But then the mills started offering sanding and planing of the 2x4's and that took 1/4" off each side. So when you bought "2x4's" you were asked "rough cut" or "sanded and planned." Very quickly everyone opted for the later and that is why 2x4's are not 2x4's.
Also great video. Thank you for making it. 🙂
Interesting - I had heard the size between what we call 2x4s and an actual 2x4 was from thick saw blades in the old days. Seemed a bit odd to me that the blades were half an inch thick. Your explanation makes much more sense. Hals also never heard about being given the option of which size of 2x4. I have heard that in California as a result of some law or court ruling, the hardware stores have signs up indicating that 2x4s aren't actually 2x4.
Glad you liked the video!
Thanks for the videos! That 14/2 wire is a lot tougher than I would of thought.
Your welcome! I am amazed too - and find it quite comforting given that our houses are really quite flammable with so much wood in the construction even if it hidden behind drywall. I will do similar one with spray foam in a few days - will be interesting to see if that changes the results.
@@petefromdewoods5157 So the tests results are irrelevant then because if it was 120v the wire wouldn't last as long to reach thermal failure? Edit: I understand now, so basically its like powering an AC unit vs a 30watt lightbulb both at 30amps. Yea I think Im going to retract my "tough" assumption. The experiment is not realistic. I would like to see that 14/2 use to power an actual 30amp rated appliance and see how long it last before it cooks. Thanks for pointing that out!!
@@petefromdewoods5157 Yea that makes total sense! Great call. Thanks mate.
@@petefromdewoods5157 I want to see that 14/2 power up a legit 30amp appliance and see how long it would last. Im rewiring a house and not sure if I should use 14/2 or 12/2. I was thinking that 12/2 was over kill from watching his videos but now your comment is making me doubt if I should just use 12 wire throughout along with all the 20 amp corresponding outlets and switches.
@@petefromdewoods5157 Apparently "equipment getting cooked" is what is popular on TH-cam! And cat videos :)
The copper will melt long before the fiberglass melts. However, fiberglass is generally coated with a binder and dye and that is likely what is burning off. Would have to look at a specific manufacturer MSDS to know for sure what is used.
great video
Fiberglass is entirely non flammable, it's made of glass as it says in the name. I think the blackness is the smoke from the wire condensing in and on the fiberglass.
I think in some of the stuff there is a chemical gunk to help hold the fibers together but I may be wrong. I should maybe try a test with a bare copper wire (or even a nichrome heating wire) and see how it reacts.
Yes, I was thinking the same thing. Any 'gunk' would probably be evaporated from the wire prior to it even being 'smoke' and then later the heat could char that condensed hydrocarbon.
@@djmips True true
Thanks! Very interesting video!
Well kind of realistic 15 amp and 20 amp breakers provide over current protection so you wouldn't be able to draw more than that on a standard 15 and 20 amp outlets you would need special devices with 14-2 or 12-2 hooked up to it... I understand why you do this and as electrician I love and like the amount of explanation you offer thank you
Test results are what one would expect, insulation melts at high current. The data points used to determine when the conductor insulation melts are flawed. The IR thermometer cannot detect surface temperature of an object through plastic. My $30k Flir infrared camera doesn’t work through plastic either. The temperatures reported throughout the video are the average surface temp of the outside of the plastic sheathing. Actual max temp of the conductor sheathing reached somewhere near 300C as this is the temp that wood will combust. For reference, fiberglass insulation melts at about 540C and copper melts at just over 1000C.
Your right - verified this in later videos after I bought a $300 IR camera (not quite as expensive as yours!). Thanks for those reference temperatures. So what do you use a $30K IR camera for? I'm guessing it has fairly high image resolution to cost that much?
@@ElectromagneticVideos I’ll have to check out the later video. I am master electrician and reliability engineer working in an industrial environment on voltages up to 12.5kV. I use the camera to find loose connections in electrical gear. Due to working on enegerqzed gear most of the time I need to keep a safe working distance from the high voltage. The high resolution camera (1024x768) with a .2mrad IFOV give the camera a very small spot size ratio and allows me to distinguish exactly where the hot spot is located from a safe distance. This is important when there are multiple lugs bolted together or multiple taps on a buss bar. Repairs have to be scheduled when there is downtime so we need to know exactly what to tighten or replace.
@@farmerjim-fat-man-do How interesting! I never thought of that as a use for an IR camera but had heard of people checking home panels for overheating breakers. I can see how a camera like that would pay for itself many time over dealing with things like yours and minimizing downtime. I'm and EE but generally dealing with signals and much lower voltage stuff than you. My only experience with HV is from fixing TV as a teenager the HV section being in the range of 12kv to 30kv depending on tube size and bw or color and of course with mA amount of current (although the built in picture tube capacitor can store quite a punch for days or more!). I wish you would put us some videos but I'm sure many industrial places wouldn't be too happy at having their facilities shown off!
@@ElectromagneticVideos IR thermography is used quite a bit in industry for reliability purposes. IR camera technology has become much more affordable allowing hobbyists access to the technology for home and auto use. A lot of electricians can now afford to carry a low end camera on their trucks. IR technology is not as simple as point and shoot, there is a quite a bit to learn about the technology before one can expect good quantitative and qualitative results in a professional setting. I have been Level 3 certified for 10 years and still learning. I am working on some content but I travel for work and it’s hard to find time to put together a video. Maybe I’ll drop some shorts…
@@farmerjim-fat-man-do It certainly had gotten cheap - I picked up the Seek one that attaches to a cell phone for cdn$200 = $150 in your money. I completely get the time constraint thing regarding videos - you wouldn't believe how long it takes for me to make these videos of simple tests - not the least of which is because there is a fair amount of road traffic on weekend and the number of retakes and edits out I had to do to get barely acceptable audio makes everything take 2 to 3x as long. Shorts would be great and quick and they seem to be the upcoming thing. If you get chance I'm sure they would get a lot of views (then again I have never been able to predict what videos of mine got really popular and which didn't so what do I know :)
Thank you for going through all this trouble to show us these "what happens if" scenarios. Bravo, great job!!
And, to other viewers: please don't forget to click "like" and "subscribe".
Thank you so much! I looked at your page - looks like you have some great videos but unfortunately I don't peak Russian (?)
@@ElectromagneticVideos Aw, thanks! I have an English language channel, but it's not as big: th-cam.com/channels/X5NqyO-dEDx5b5DRnmL8mA.html
GREAT UPDATE!!!!
You mentioned trying that foam that electricians LOVE to spray everywhere. In fact, I have seen something that really shocked me (no pun intended): They had foamed the entire inside of the breaker box and about 18" of the wiring going inside the house from there! If you make another video, may I suggest incasing several inches of your test wire with a thick layer of this foam...this should really keep the heat in that portion of the wire. Please hold for one moment........OK the only title I could see on the can is "GREAT STUFF". BTW, I was actually referring to my house above.
THUMBS UP!!!
Inside!? You mean the actual breakers were in foam? As in you pull off the panel cover and all you see is foam? If so that's crazy. Electrician did it? Not a homeowner trying to air seal?
@@libtrs838 Sorry, bad wording. No, the back of the breaker INSIDE the house...through the knockouts and inside the back of the breakers + binding all entering wire. It will be really difficult to add, remove, or replace any of this wiring.
Also, I don't recommend using this particular stuff even for air sealing...they had it in many places aroung the house to seal gaps. It is already falling away. It's been about a year now...house damaged by hurricane Ida...I'm in Louisiana.
I guess I first learned about thermal resistance when I was in high school. I was working on a laser/holography project for the science fair. I had a small HeNe laser tube fully exposed that only slightly got warm, I put a thin handkerchief over the tube to reduce the bright glare overnight (just a single layer thrown over the top, not wrapped). Hours later, the tube could melt your skin! ...think it was quartz? The funny thing is, how long it took to get this hot! Heat was leaking out but was being generated a bit too fast inside. After removing this cloth, it cooled back down (still on) rapidly. Maybe your enclosed over-current wires would get quite a bit hotter over many hours. Perhaps the 14-2 rating is partly due to enclosed wires??? There is an old church here in town (built in 1871) whose wiring throughout the attic is VERY, VERY, VERY thin on standoffs with NO insulation!
@@dalenassar9152 ah. A breaker panel / box can be incased in spray foam as long as no foam enters the box. You would get a cold spot around the box otherwise.
Spray foam can work ok if it isn't exposed to the sun, you trim it flush after, and you don't just glob it on.
The church has what is called knob and tube wiring. That is what was used from the first indoor wiring until the end of WW2. Usually it has some cloth covering but it can fall off with age.
@@libtrs838 THANKS, any additional videos on this planned?
@@dalenassar9152 I have thought about it before, but I don't make videos.
Interesting
You did the same video IWAS going to do! HAHA Great stufff!
very interesting
Thanks! Your certainly have some interesting stuff on your channel - I have to watch some of your videos when I get the time!
I appreciate it! I'm just getting the hang of planning a video beforehand to make things a little more cohesive.
@@jankcitycustoms Funny you mention that - I'm learning that too - as well as how narrate it in a way that works for my way of doing things. Also am experimenting with the best way to do audio since I move a lot when I'm doing videos and that makes recording voice challenging.
haha yeah I saw your microphone, I think it sounds great. I have the same problem. I tried using a bluetooth mic but the one I got keeps disconnecting while I record. so I have a couple videos where you can barely hear me for an entire segment. I'm trying out a usb mic now
@@jankcitycustoms Sounds does make or break a video - more so than poor picture. I tried two different lav (lavalier) mics - the problem I had with them is I look left and right while doing things changing the volume they pick up. And they dont attach well to T-shirts. The head mounted mic stays in one place so its more consistent volume but picks up my breathing. I glad to get the feedback that the audio is better. The mic is visible and is in front of my face a bit, but I dont think the majority of people are looking at the videos to see my pretty face so thats not too big a concern :) In case your wondering the mic I am using is here is a Shure PGA31-TQG Headset Microphone - only CDN$60 so probably US$45. But it has an oddball connector that was hard to find adapter for to connect it to my camera. It is intended for the Shure wireless mic system which is way too elaborate for my use.
It sounds like your phone as a camera. If you find a good mic for use with phones, please let me know - would be good for making videos when not a home.
this shows the importance of a wires ability to dissipate heat. maybe next video on ambient temperature and number of conductors in a given raceway?
Yes - I'm thinking of a maybe a bundle of cables. Do you know what the code rules are for how many 14/2 can be bundled next to each other or go though a single hole?
@@ElectromagneticVideos pretty sure there is no limit by code but I think there is a derating. I looked up the code
4-6 80%
7-9 70%
10-20 50%
21-30 45%
31-40 40%
41 and above 35%
So first column is number of current carrying conductors (pretty sure neutral doesn't count) so 4-6 hots or 4-6x 14/2 needs to be derated 80% so 12 amps.
So you can have a bundle of 100 14/2 and run them all at 5.25 amps
@@libtrs838 I think the house I had back then would have easily been in the 10-20 in a bundle range. Maybe 8 cables for heaters, and little current on the rest of the cables, so it probably averaged out. Might not have worked out so well if all the heaters cables just happened to be next to each other. The electrician said that at the time it must have been wired, the code didnt yet require deratng for bundles like that. In wonder if derating came about after the 1970s push to install electric heating and be modern (at least that happened in Ontario).
Congrats you made a fiberglass skunk .
I should have named the video that! You sure gave me a good laugh!
I never saw protecteur plates before.
I would hope this is a lesson for people not to put in too large a fuse or breaker on residential wiring.
15 amp for 14 guage wiring and 20 amp for 12 amp wiring.
I was actually shocked to hear that people not only put in bigger fuses, but also also actually have swapped in larger breakers. Scary to put it mildly!
@@ElectromagneticVideos We need more public information on the correct sizing of fuses and breakers. Especially when it gets cold and people use electric heaters.
@@jcolumbiap Definitly! To their credit, a few years ago when when I was purchasing a replacement 50A breaker for my welder outlet, the Home Depot rep mase some gentle enquiries about what was such a large breaker for, clearly wanting to make sure I wasnt going to do something like replace a much smaller one with it. At leas with breakers pwoplw are less likly to "upgrade" them on a whim which must happen with heaters blowing fuses.
Didn't catch fire = win.
Won't miss the spray foam video. I'm wondering if I should use conduit or not with foam.
👍
👌👌👍👍
Thanks!
bet its a different fire risk in spray foam than rockwool/fibreglass
I'll bet your right! If the weather is not rainy, I will try that this weekend!
Fuking awesome
I think the spray foam will burn in a bad way if it is close enough. i think spray foam is a bad idea for fire safety or at least near places where fire could be a risk. Even the fire rated orange is bad.
I was surprised the various foams didn't simply go up in flames.But even without flames the fumes are probably deadly.
If the wire is rated for 15 amps, then it should be able to carry 15 amps continuously. I think rating the wire at 12 amps or 80% of 15 amps is wrong. while the service panel ii a residential application is usually calculated at 80% of full load.
I dont know the exact reasoning the people who wrote the electrical code used for requiring the continuous current be less than the rated, but there are good engineering reasons: If you put exactly 15A worth of load on a 120V circuit any deviation from the stated value of the voltage or device could easily push you above the 15A rated current. It is more likely than might be obvious: the 120V line voltage is in most places allowed to range from +10% to -13% at a receptacle. If you have a restive load, a voltage 10% too high would increase the current drawn by 10%. If you had an 13% undervoltage, a load like an induction motor or electronic power supply will draw around that much more current to maintain the same power. Either way, if you started at exactly 15A you would now be 10% or more overcurrent. Similarly, any device (ie light bulbs, heater) will have a certain inaccuracy as to how much power the device draws adding some more +/- % deviation from rated current. A properly working breaker is allowed to trip at any continuous current above its rated value. So by requireing continuous current to be derated from the rated current of the circuit, you prevent overcurrents as result of voltage fluctuations and other factors. You also prevent nuisance tripping of breakers which in the end may be the most practical reason for requiring the continuous current to be less than the rated.
Lets say thats happening somewhere inside my walls and all I notice is burning electrical smell. How does one figure out where exactly its coming from without tearing out entire walls?
That's a tough one - a hit at location might be looking near any large loads that are running like a heater. I did notice in some cases you could get a sense of where the overheated wire was with an IR camera - but not a foolproof solution. I would think if you thought there was something like that going on in a wall the best thing would be to treat it as a fire and call the fire department - they probably have experience locating things like that best to be over cautions than risk a house fire by not doing anything.
Cool test! How many amps can the wire handle under water?
That's an interesting one! There certainly are underground power transmission cables that depend on some sort of non-conductive cooling fluid (usually oil I think) to keep the cable cool. And its a sophisticated enough setup that there are pumping and cooling stations at the ends of the cable to manage the fluid.
What about blown in insulation? Is that more flammable? My older home is filled with it. Done in 2010.
Is it foam blown in insulation? If did one with hardware spray foam in a can here which may or may not be like two part spray foam: th-cam.com/video/lFdSXTKsKwA/w-d-xo.html
Smoking hole looks funny
I'm not convinced you are reaching Steady State in 15 minutes. I believe National Electric Code differentiates "continious" vs. "intermittent". as typically used less than 1 hour, vs running for 1 hour or more. So... It might be interesting to redo this test with 1 hour intervals, and to pull the insulation off and take a picture and temperature reading in between each 1 hour run. I doubt much interesting would happen at 15 amps, or even 20 or 25 amps... Beyond that, things might get interesting. I might expect insulation browning at 30 amps over an hour, maybe??? But your 50 amp tests, although fun to watch, (hopefully) aren't very realistic. Great Video!
I think the equilibrium time may depend a lot on the thermal mass around the wire and the amount of insulation and what the resulting time constant works out to be. Temperatures seemed to stabilize after about 15 minutes, but yes, could creep up a bit more over an hour. A forensic analysis as you describe would be the way to do it for sure! I also wonder if extended cooking at 30A might make the plastic break down over time and be more susceptible to failure as the time goes on.
And yeah - 50A is fun an hopefully not common. There is a series of vintage breakers that apparently are still installed in some homes that sometimes don't trip properly (Federal Pacific and Federal Pioneer according to Mr Google) so it may be more common than we think.
Thanks for the comment!
I have some ideas for videos you can make. Any way I can contact you?
Why not just say it here?
@@libtrs838 too much to write here on youtube.
You have clearly stated typical American home construction so why did you go with celcius vs fahrenheit?
I'm in Canada - our houses are very similar in construction to the US. And I think most cables are rated in C. Correct me if I am wrong - are they rate in F in the US?
@@ElectromagneticVideos sorry, I just assume you're from the US. I actually looked at a Romex wire and no temp info.
@@joedegorostiza8305 No worries! I think I have seen it on some cables. But it may be different from manufacturer.
You got me curious - just looked at what I think is the southwire US site - the 14/2 specs do give temperatures in C. Of course they could be geolocateing me and giving me what they think I want to see :)
He said North America, which includes more than the USA.
@@ElectromagneticVideos Southwire lists theirs as 90 C. I believe that older Romeo required only 60 C. Even so, it appears there is at least a 2X factor of safety which is pretty good. Airplanes have only 1.5. 😁
I’m in the USA and would appreciate Fahrenheit and inches if you would please ,that is still our standard even though they’ve been trying to change since 1980
Easy to convert using a browser.
Dr. J, I'm somewhat underwhelmed with your testing methodology; Particularly I'm at a loss as to why you wouldn't use a temperature probe/thermocouple attached to the cable jacket inside the fiber glass insulation instead of relying on an infrared gun trying to take measurements through plexiglass. The pocket/birds nest you carved out degrades the test and taking measurements through plexiglass further skews the results. Anyhow, after 30Amps, i started loosing interest. PS: fires are much more efficient spreading through vertical cable runs. If you tilted your rig 90 degree sideways, or even better, make a 90 degree turn simulating a vertical and horizontal cable run, typically found in many homes, would give an even more realistic picture. I bet at that 90 degree turn to horizontal would catch on fire at 40amps.
Points well taken! It was by no means (or meant to be) a perfectly done test, but more a general demo of what happens when typical house wire is surrounded by insulation and exposed to varying current below and above what it is rated for. I don't remember why I didnt use a temperature probe - its been a while since I did the video - might have been the probe I had had broken and I hadnt got the replacement yet.
You make a very good point about vertical runs. And to add to your "turn it 90 degrees" comment, having it a full 8 or 9 ft tall would add to the chimney effect even more. Would also be good to do with and without sealing the holes though the 2x4s where the wire enters/exits (as is often required by building code).
So strange for us to see a wall not made of stone or concrete. If you install wire is there pvc pipe around the cable? We normaly put wall wire in the pvc pipe.
Construction of houses is very different in Canada and the US from Europe. The little section of wall I built is typical an could be from a real house. For houses, we do not normally use conduit (English for the pvc or meal pipe for electrical wires). The wire is simply placed though holes in the wood inside the wall. There are rules that say how far from the surface of the wall the cable should be to prevent damage when people put nails in the wall. I'm sure our risk of house fires is way higher than yours!