I was honestly surprised at the amount of current that the 12/2 NM-B cable handled bundled like that. As an electrician, that is a BIG NO-NO! 😠 I have seen panel boards with wires melted because of bundling. Excellent video with a lot of important safety tips! Great job! 👍😁
I was surprized too. And yes - a big no-no :) fascinatging that you saw the effects of bundling. If youliked this, look at some of my videos from a year or two ago, I did some with 14/2 embedded in 2x4 stud walls with and without insulation. For some insulation such as spray foam, the margin of safety goes way down as one might expect. So much so that I would go to the next bigger wire size for any runs where cable is in insulation. Glad you like the video - means a lot to hear it from an experianced electrician who has seen so much of this in the real world. One of my friends who is a retired electrician often comes over to watch and help when I do these types of video and is also amazed and fascinated how much overcurrent a lot of things can handle. He also takes some of the video for me since he is also a great photographer. Great to have friends like that.
Great video. Thank you. Around 20 years ago a friend who owned a big convenience store with gas pumps and a big canopy with lights called me to see why the lights were not working. The lights required a 30 amp circuit... 10 gauge wire. The electrician boys ran 12 gauge wire. The wire nuts in the box at the bottom of the support going to the lights completely melted. I had to pull new wire to repair the problem.
Thanks! Interesting that wirenuts melted. I wonder if besides the cable being undersized, the wirenuts were installed poorly or if the copper ends were oxidized and formed a poor, somewhat resistive connection generating more heat than normal? Strangely enough for large commercial lighting circuits like that over here (Canada), 347 volts is often used to reduce the current and wire sizes needed. Not sure if the US does something similar?
@@ElectromagneticVideos Yep, have worked both in US and UK (and canada briefly not for payment :) ) , and the terminations are always the weak point if not done right. Actually poor stripping practices cause more damage because it creates a weak point in the cable
We had one when i was running motel maintenance in wisconsin. BRAND new sign, installed by a professional sign company. Turn the breaker on, half the sign lit and half didn't (it was on 2 phases of 120/208)... and after a second or so the breaker would trip. The manufacturer had trapped a wire behind a ballast. Felt sorry for the sign guy, he was almost home when we called him back LOL
@@TheChipmunk2008 Amazing a defect light that would get though quality control. Such a small thing but a great example of how a defect like that can have significant costs.
@@ElectromagneticVideos So for the USA it is 277V. It is the line to neutral voltage for a 480V Y transformer. I have been redoing a bunch of 8 ft fluorescent's to LED at work and have pulled so many of these out of them that had gotten hot enough to melt to wire an inch or more back. I abhor seeing then on 12V trailer wiring much less in 277V lighting. i.redd.it/cs2al46csxr01.jpg
Thanks - thats really great to hear - appreciate it! You would be amazed at how small a fraction of a video typically gets watched. On average 50% or less! People usually skip to the parts that most interest them .
@@ElectromagneticVideos I tend to skip around a lot but usually to REWATCH segments, so my view time will be HIGHER than the video length :) I am also on a technical discord so often share such videos there
@@TheChipmunk2008 Thats interesting. I'm not sure how youtube counts that. Besides views, I also see total time watched so its probably included in that . Interestingly, this video has had many more hours actually watched in proportion to views than many others, so people are matching more of it (even if not in order :). If you share the video, thats really appreciated - really helpful for a small channel like this one. You'll notice I don't bug people to subscribe, share, like - I find it annoying when channels repeatedly bug views to do that.
@@ElectromagneticVideos As an asside, I am loving this conversation, i was so happy to see a new video. You do your research, do the scientific method right (as a pHd you would), and social media needs more of this content.
@@ElectromagneticVideos I like dave plummer's attitude to it, just a note, if you make it to the end of the video, that he only does it for subs and likes, so leave one of both if you got anything. That's not obnoxious but can help build your channel
Thanks! Whats even more amazing is how hot cables get when surrounded by modern insulation in a typical (Canadian/US) 2x4 stud wall. I did a bunch of videos with fibreglass, rigid foam, and spray foam a few years ago - a bit of an eye opener!
Thanks again! Well I am an EE. What really made all of it possible was the vintage old style AC arc welder which is a a great high current source that provides a fairly constant current that is somewhat immune to resistance changes of the load.
Man, even for something so simple (the concept I mean, compared to deeper fields of knowledge) the setup and work to make your video is through the roof. Basically, I am just letting you know that I know. Awesome video. You have a nice aura for a video - regular people talk. Rock on.
Thanks! I really appreciate that! You know, you probably one of the few who understood how much time and setup it takes to do something like this. My setup for this type of test has also improved over time - bigger variac, more instrumentation, and most notably a really good thermal camera kindly provided by a manufacturer (Kaiweets) who saw some of the previous videos. "You have a nice aura for a video - regular people talk" - wonderful to hear - thats exactly what I am going for. In particular, trying to trying to demo science, engineering, or technology in a way that is understandable to everyone without the need of years of in-depth science and math background. Its taking a while but I'm gradually learning what works best for TH-cam viewers.
Bunching is allowed in Australia but it incurs a derate. The more cables, the lower amp rating of the cables. 2.5mm cable with V90 insulation - PVC max temp 75c in normal installation - each wire is 2.5mm, line (active), neutral, earth) clipped to a surface drops from over 25A single cable to 15A if bunched up with 5 others at normal ambient max 40c. Even stacking cables vertically on a surface too closely allows radiant heat and localised air temperature to incur a derate. There is no real concept of a given size wire being associated with a particular amperage but typical installation situations means an electrician doesn't have to reach for tables / calculators to know (s)he can stick 2.5mm 'there', put a 16A breaker on it and everything is good thermally, while a different situation may call for 4mm2 wire to do the same job.
Always interesting to hear how things are done elsewhere! It would be interesting to compare derating rules from different places. but probably would be hard to an apples to apples comparison given the variations on what currents are expected in normal house wiring, construction materials etc. "Even stacking cables vertically on a surface too closely allows radiant heat and localised air temperature to incur a derate. " We need more thinking like that over here - in particular cables embedded in insulated walls.
@@cashewABCD Yes - I just looked up #14 is almost exactly 2sqmm. #12 is 3.3 sqmm. Really gives a lot better sense of the relative size of wires rather than what seem like arbitrary numbers.
Watching your demos regarding how much safety factor is really built into our wiring certainly helps me sleep easier every night 😂 Jokes aside, I've discovered for myself on how the resistance of copper rises when very hot, a couple years back when I was measuring the current on the soldering tip of my Weller 200/260 watt professional soldering gun, using my Ideal 400 amp AC/DC clamp meter. When the gun is first turned to high temp, i don't know how many amps are really flowing because it shows "OL" on the meter, but when the tip reaches it's rated temperature of approximately 1,100°F after about 15 seconds give or take a few, the current seems to stabilize at around 150-160 amps. The current may have dropped slightly more if I continued reading, but I was afraid I would melt the jaws around the meter and I wouldn't be a happy camper after paying a little over $100. I don't know if I was dissipating the stated 260 watts because I never took a voltage reading along with the current although I certainly may buy a cheap meter just to do that sometime down the road.
So I guess I guess I could say my videos help ut people to sleep :) I'm a little less optimistic than you are - what really concerns me is how small the safety factor gets when cable is embedded in (really good) modern insulation. I do think a revision in the electrical code should be considered to de-rate cable in that situation. Soldering gun - I never thought of that as an example of resistance of copper going up with heat - what a neat experiment you did. When the tip is cold and the current is huge, I wonder if there is a significant inductive lag on the current reducing the amount of real power transferred. If so, it would make it harder for for the tip to heat up in the beginning. That resistance rise with increasing temperature is typical of conductors. Semi-conductors are often the opposite - as they heat up, the resistance drops as more electrons have a enough energy to get into the sparsely populated conduction bad. Now that I think of it, I what what material combinations are used by manufactures of precision resistors that presumably should keep their value reasonable well as temperature rises.
@@ElectromagneticVideos you're right about the insulation factor. Guess I haven't really thought about that quite as much but I would also have to agree with you on that as well that there should, possibly in the next code cycle or two, have a derating factor when wiring is surrounded by insulation over a certain R value and while this certainly wasn't as big an issue many years ago, even with 60°C conductors when energy costs were cheaper and homes weren't as well insulated , but today with energy cost often rising faster than our paychecks not to mention the impact on the environment, we tend to be far more mindful of our electricity/gas/fuel oil consumption habits than we were 40 years ago, and new homes have gotten much more airtight as a result and many jurisdictions in the US have minimal R value requirements as well that homebuilders are required to meet.
@@Sparky-ww5re Well the only reason I'm aware of the issues with insulation is the videos I did a while ago with 14/2 in insulated walls - results were too close for comfort in terms of a safety factor. Completely agree with you assessment of how energy costs and greater insulation changed things. Even worse up here in Canada. Is there any effective way for real practising electricians to provide advice to the code update committees? I'm a bit dubious that manufacturers seem to have had an undue influence promoting expensive high tech solutions (ie arc fault breakers on most circuits) rather rather than looking at what the best bang for the buck in terns of additional cost vs amount of additional safety achieved might be.
The are fun to do :) I see HVAC in your profile name - I'll bet you see lots of interesting stuff like that in shall we say "less controlled" conditions .
Interesting, here in the UK we're allowed to do the derating calcs ourselves, so we CAN bundle cables like that, but we have to oversize them in some instances
I guess I implied we didn't do de-rating over here - sorry if I mislead anyone. We actually do it too. In the old house I lived in where the cables were in a bundle, they were certainly not de-rated and used close to their full (unbundled) capacity. What probably helped was that the bundle was in an unheated basement and on average not all the heaters would be on at once. The big steel ungrounded I-beam they were tied to probably also helped cool them :)
I used to work on old Arrow Hart circuit breakers. They could be "fused" with what we called heaters. These were resistors that could be replaced. One per terminal, so the three phase breakers naturally had three. They were modifiable because you could change the resistence just by putting different heaters in the breaker. But that was also potentially bad because you could put a 50 amp resister in a breaker only rated for 20. Also the breakers were twice the size of a standard breaker from Square D or Seemans. Newer Seemans breakers had a small slotted dial with an amp range. Say 1.5 to 4 amps. These could be safely adjusted in that range.
I had never heard of Arrow Hart and didnt know about adjustable circuit breakers. How interesting. I really like the idea of a fused breaker - assuming the resistors were designed to open like a fuse - last resort safety feature. Although looks like size could be an issue. Also like the idea of adjustable ones - a great safety feature for the right situation. I'll have to keep that in mind. Thanks for posting all of this!
@@ElectromagneticVideos They stopped making them in the late 80s. I cut my teeth on a lot of weird systems. Some naval ships used to use something called Delta Y power. That was even more strange.
@@bobbressi5414 Interesting! Delta Y as in the transformer that rotates phase by +/-30 degrees? I'm sure that can cause much confusion when people are trying to interconnect things. Or is it something even different from that,.
@@ElectromagneticVideos Fortunately for me I did not have a lot of experience with Delta Y. Most of my work was on fairly typical 3 phase systems. My father dealt with Delta Y and I don't think the Navy uses it anymore.
@@bobbressi5414 The only reason I instantly remembered it was when I was a student had to take a required power/machines course which I wasn't thrilled about. Turned out the Profs who taught it were amazing and it became one of may favourite courses, and we a full size power lab with multi-horsepower AC and DC machines, 600V three phase power, transformers etc. There were some characteristics of Delta and Y configured transformers that had to with harmonics, circulating currents etc. I'm now intrigued - will have to look that up some.
Interesting to think about how temperature will be affected by shoving this bundle through some studs in an insulated wall where there is little/no free air to cool the NM jackets. Thermal runaway is very real and should be regarded with much caution. Yeah, the NEC (National Electric code) is very real (in the USA) and exists for many very good reasons.
"Thermal runaway is very real and should be regarded with much caution." YES!!!! I actually think the code should require derating of cable ampacity when in insulation. Actually did some tests of that in 2x4 wall sections: Fibreglass th-cam.com/video/Df7bAEdIILI/w-d-xo.html Spray Foam th-cam.com/video/lFdSXTKsKwA/w-d-xo.html Extruded Foam th-cam.com/video/4k0xLiokNsc/w-d-xo.html
Thats interesting - over here(near Ottawa, Canada) usually the individual cables to each branch circuit generally exit though many individual cable glands along the sides of the panel and are not in conduit. Although sometimes they are quite bunched up. And the main entry conduit only has the giant 200A supply cable. Hopefully that is able to dissipate enough heat under full load to keep cool enough.
@@ElectromagneticVideos Where I live in the southern US most panels are placed on the exterior of the home so most if not all of the cables from the house enter the main panel through the largest center knockout.
@@hippo-potamus Thats so different from us in the cold white north :). I am amazed that moisture (rain , hurricanes) is not an issue. Maybe you have better sealed panels than ours which are certainly not weather rated. Unless of course you are in the SW desert area. Are you panels locked somehow? I could see teenagers thinking it would be fun to go down a street in the middle of the night randomly turning off peoples breakers. I wonder if in the north east US (near me, similar weather), the panels are indoors or outdoors.
@@ElectromagneticVideos The panels have the ability to padlock but rarely is that ever done. Yes in the northern US and randomly throughout depending on area main panels are placed inside the home as well. However now with the new NEC change to mandating primary means of disconnect panel be exterior any new builds that want to put panels inside the house will have to wire them as a subpanel. The external panels are built differently and actually do a very good job protecting against rain incursion. The main issue I have with mine is dust.
@@hippo-potamus Interesting. I'm enough of an electrical geek that I will have to keep my eyes out for outside panels next time am in the US. I'm also wondering if we do that anywhere in Canada. Interesting about the mandatory outside disconnect. Probably a good idea for firefighters to be able to turn off power from the outside, particularly in case of gas leaks.
Thanks for the video. I have an off topic question. You mentioned in the beginning of the video that you had a home with electric heat. Ive seen videos on a type of electric heat called "radiant ceiling" or "Ceil-Heat". My understanding is the heat cabling is sandwiched between sheet rock. How can this be practical and not a fire hazzard?
I had to look up "radiant ceiling"! My home had wall mounted electric heaters (not baseboards) in each room. My initial googling showed hydronic panels, but then I came across this: blog.technicalsafetybc.ca/ask-electrical-safety-officer-are-radiant-ceiling-heating-panels-allowed-canada So your concern about electrical ones is well founded! I would be very concerned about such a system - something goes wrong and panels could easily overheat. Interestingly, where I live (Ontario, Canada) electricity seems to have become cheaper than propane (what I currently use) or oil heat. I'm actually in the process of installed an electric boiler in parallel with with the propane one. I wonder if relative prices are similar elsewhere? Natural gas is still the cheapest, but you have to be near a gas line.
Oh. My maternal Grandmother was from Leamington. If could give me a hand, I googled an couple images that I would like to share. My grandother had base board heat.
@@andrewclarke3622 The tomato capital of Canada :) Electric base board seemed to be very common in the 70s in Ontario. Then as prices changed it went out of favour. Apparently common in Montreal where even today electricity is really cheap. There doesn't seem to be a way of sharing images here unfortunately. Only what is to post a link to the image or page.
Excellent video! Very nice thermal camera. I like many of Kaiweets tools. They sent me a small electric screwdriver set to review recently and it's nice. I am not jealous that you got a thermal camera at all though 😂. Funny that you pointed out the Manfrotto tripod. I got one last year at a local bargain center outlet and I absolutely love it. I never would have believed the Manfrotto is that much easier to setup and use than the cheaper versions.
Did it a few years ago! Here it is : th-cam.com/video/lFdSXTKsKwA/w-d-xo.html Also did it in various other typical situations. Here is playllist with those videos. th-cam.com/play/PLHUfJmsprIcTVwSgCkTJnkinJSWrZY7DY.html
It does at the higher output currents. I think it was for significantly over 100A output. 15A to 60A currents I was using (at probably less than 5% of it normal output power) is so low for the welder that overheating wasn't a concern. Not even any noticeable heat rise on top of the welder which usually gets warm after normal use.
Would you/have you experimented with bends in wire? There are codes about bending radius of wires. The idea is a weak point of higher resistance is created if you bend a wire too sharply. Maybe investigate work hardening and bending radius!
I havent done that so far. An interesting idea for a test - particularity for solid wire (like used in the video) which is more vulnerable to that than stranded. Would be interesting to see if the plastic on a sharp bend melts first and if the bend is noticeably hotter.
Bending radius of cables is 100% related to insulation damage and slip between conductors in a multi core cable. ZERO to do with any resistance change. To measure such a change, if any due to a reduction in cross sectional area you will need an instrument and test leads that measures microohms. Frankly, there would be more resistance at connections points and long cable runs in a domestic installation.... and DIY butchery. If this speculated 'localised resistance change due to sharp bending' was a 'thing', every high current main switchboard would show faults at those locations under High kA type testing procedure, where the board is in a dead short circuit condition prior to dumping up to a 100kA fault current at the rated operating voltage. 100kA fault current... think about that. The item under test may achieve a 10kA rating... perhaps 25kA... perhaps 45 or more kA without exploding. If this 'bend resistance' were a 'thing' it would show up under such extreme testing. It doesn't. Such boards have large copper busbars... main bus may have 3 bars of 100mm x 10mm per phase. A good 2500A rating. They are full of heavy bars with numerous bends. No high kA approval testing or thermal In-Service testing has ever shown localised heating at bends.... at connection points yes.
Next one is testing Wago connectors rather than cables - had numerous requests for that. I think Wagos have been getting more common in North America over the last few years.
If only service providing companies, device manufacturing companies and big tech across the board would take this consumer safety, derating approach with their products and services. But they're greedy so we're screwed. 🥴
Sounds like derating is done well in the UK. I actually get the impression in the US an Canada there is a lot of lobbying from manufacturers to add things like arc fault breakers rather than cheaper solutions!
The test actually shows mainly the importance of good quality TESTED breakers. In any home all wall sockets should be tested with a shorting switch to be sure the breaker blows instantly. In actual situations house fires happen from things plugged into the wall socket rather than from internal wiring.
You make a very good point. Federal Pacific breakers were apparently notorious for not tripping. I'm not sure that testing with a direct short is the best solution - if the breaker doesnt trip it could vaporize the branch circuit cable, cause a fire etc. Perhaps a specified load big enough to magnetically trip the breaker - but still small enough to maintain the integrity of the cable for a few seconds might be the solution. Maybe with a timed switch that provides the overload for say 1 second. If the breaker doesn't trip in that period., replace it. I wonder if anyone makes some sort of device like that?
@@ElectromagneticVideos It is a point but my opinion is the likelihood of any problem with the breaker not tripping blowing things up before the operator opens the switch or yanks the plug is not an issue. Maybe with DEI electricians now days everything must be made automatic, removing the operator from the test.
@@glasslinger Hi mate... love your glass and experimental work. Yep... proper effective protection please. Less DIY please.. often that is the root cause of issues. I for one wouldn't want to full overload test a CB or RCBO in situ using a short circuit method, as I read that. CB on a test bench setup... maybe.... one that captures instantaneous fault current and time.... like every respectable manufacturer does under QA regimes. Modern Field testing equipment is far from 'automated'. A single microprocessor based instrument for this application provides data for interpretation / diagnosis of wiring systems and protection devices. A host of tests that include HV insulation resistance, Earth/Ground impedance, and importantly, RCBO trip currents (mA)... all done by actual progressive loading. You get a calibrated reading... not a 'pass' /'fail' lamp.... not a 'zone' on a mechanical meter dial. They do not do Thermal/Magnetic on a time base overload trip test.
@@glasslinger I'm still not convinced that once could switch off a dead short in time to prevent damage if the breaker failed - or that a normal switch could handle the dead short current. But thinking a bit more about it maybe put a second breaker in the tester that is rated at say twice the current of the breaker under test. If the breaker being tested fails, the second breaker would save the day.
@@ElectromagneticVideos I use a two foot piece of cord with a heavy wall plug and a 30 amp pushbutton switch to test my circuits. I have never had the idea fail. Fear is a treacherous emotion that can irrationally shut you down from harmless situations.
Very interesting and informative video however what about the Elephant in the room ! . I refer to the coiled extension reel that appears to be feeding the Variac . ooooops. I have found several which have been coiled up whilst transporting too many angry pixies resulting in melted insulation, as the cable cannot liberate heat easily even at 50% of duty load can cause significant heating. Best from UK. Thermal camera, the temperature indicated was the high end of the level and span not necessarily the peak temperature, if you go to settings the camera will give spot temperature and max min. For future experiments you may like to adjust the level and span the focus into a specific temperature range o interest this then shares the pallet colour for that range providing more contrast to the I radiation. Example looking at a component running at 150 C (expected material failure to be 250) then set range for 140 to 300 this will not blow out the image and the source heating is more visible. These budget camera are pretty good but remember the laws of thermodynamics and black body radiation before assuming the temperature seen is correct, watch out for reflections. For ourself and others go and check out the infraredtraining for free tutorial. Retired Thermographer
Oooops is right - great observation on your part! I actually clued in on that at the end and felt the extension cord reel and it was warm but thankfully not hot. I think the max power sent to the cable we were testing was 200W (except the 200A part where the welder was plugged into 240V 40A) so assuming significant loss and reactive current from the welder, maybe only about 4A went though the extension cord. Like you indicated, much more than that and the extension cord may have become the star of the video! Your point is something many people are not aware of - and I haven't seen any warnings about that anywhere. I should maybe sacrifice an extension cord and make a video demonstrating that. Best wishes to you from Canada!
@@ElectromagneticVideos It would make an interesting experiment especially if you can undertake a hight potential insulation test at the same time. Over the years a number factory sites provided extension leads for my kit and several showed heat damage. PVC is a poor conductor so the core temperature can rise quickly under modest loads. Another issue for contractors or men in shed's is they either ignore or do not understand cable voltage drop. As you alluded to current goes up for induction motors, one chap chooched two drill motors a chopsaw and was rather ticked off, when I measured the voltage at the end of 50 meter (160 feet) extension to his shed it was 180 volts should have been 240. For those in the comments using TI cameras take this advice from a retired Thermographer of 15 years don't jump to conclusion just because something looks to have heat remember bright surfaces are reflecting heat so you may be seeing a reflection. These budget cameras are as capable as the operator, I have one myself as it is more convenient than my £35k Agema. Many on YT make measurement errors or jump to the wrong conclusion, have a think before you give your report ......... Q; if you covered a TI with a Kellogs cornflake bag or bin liner (useful trick when things get messy) 1/ What is the temperature you register 2/ Would you see an image. If you can't answer this go to : Infrared Training Centre or FLIR for basic understanding and free tutorials
@@WOFFY-qc9te Interesting idea about adding in a an insulation test - I could set up a relay to periodically switch between current source and leakage tester during the course of testing. 180 volts should have been 240 - huge drop! Terrible for a an induction motor, particularly for a single phase one trying to start! Thermographer ? Interesting! Great points about thermal cameras/sensors. You'll notice that I was also using a temperature probe embedded in the cable and it agreed amazingly closely to the camera. I was debating about saying something about reflection and IR emmisivity but one thing I have learned is to keep videos confined to a a limited topic on youtube. I'll have to look up those sites sounds like they have good material!
@@ElectromagneticVideos True good call things can get complicated, yes the temp tracks nicely. Emmisivity 0.95 is good for anything oil based and skin, brass, copper, stainless is a nightmare which is why I suggest others do a little homework. HiPot test switching sound good may also be spiced up by testing imported cable on a reel with that made by a responsible manufacture. I worked on a test for AEI cable UK on some counterfeit cable from China, it failed early with toxic smoke, on closer inspection the first 10 meters was copper the remainder was aluminium, conductor and insulation thickness was variable. 60 Volt drop, yes horrific his solution was run another extension in parallel I suppose that is easer than moving his shed.
@@WOFFY-qc9te "the first 10 meters was copper the remainder was aluminium" Wow - thats crazy - I am always surprised at the effort some Chinese suppliers take to do things like that. Worked at Rockwell Collins years ago - apparently they had an issue with counterfeit (military?) cables being returned for warranty repair.
The sent me the camera in a very complete kit - camera, USB cable, charger, carrying case, 32G SD card. The stand is a standard tripod I normally use use for my DSLR. Great thing about the camera is it has a standard tripod thread hole at the bottom of the hand grip so that makes mounting it on a photographic tripod really easy - perfect for this sort of thing. Its funny - sometimes little things like a tripod screw hole can really make something way more practical to use as this demonstrates.
after watching your previous videos each heating circuit in my house has 2.5 mm clipped direct rated at 27A for each 2kw heater . I couldn't stand the idea of current flowing through the ring circuit that I couldn't see and monitor. I measured a heater and it draws around 8 A and the clipped direct cable is cold .
That sounds like your house was very nicely wired - plenty of safety margin. Ring circuit - I gather that's uniquely British - neat idea for saving copper. Question - you mentioned 2.5mm cable (which seems to be close to our #10. which we would use for a 30A circuit). I see charts showing both diameter in mm and area in sqmm for wire. If you go into a store in the metric world, do you ask for cable in terms of diameter or area?
@@ElectromagneticVideos There's a twist to the UK's 2.5mm2 in that it typically has a thinner earth wire, 1.5mm? It varies from country to country. Australia, 1mm, 1.5mm and 2.5mm the earth wire is the same CSA as the others. Over 2.5mm it starts reducing relative to the conductors. 4mm and 6mm uses 2.5mm earth, 10mm uses 4mm earth, 16mm and 25mm uses 6mm earth and so on. 2.5mm and lower keep the CSA of the earth up for mechanical and resistance reasons. Once the wire is heavy enough to put the mechanical/resistance aspect aside it can be lower CSA than the conductors as the heat gain in the wire under a high current fault, and the requirement for the earth fault/short circuit protection to work in no more than 0.4 seconds ensures the wiring/insulation isn't damaged.
@@ElectromagneticVideos We rate it at 27 amps in free air, but like i said elsewhere, we have to apply derating factors. We have listed 'installation methods', in free air is a 1.0x derating factor, but if it's buried in deep insulation it can be derated to 50%. The point of a ring main is the current divides along the 2 paths back to the distribution board. a 32A circuit can have a cable rated for 20 amp on each leg, to provide a margin of safety if the current doesn't divide equally, for example a heavy load close to one end of the ring. Rings are dying out, 4mm radials on 20 or 32A breakers (again depending on derating) are more common now. The 32A breaker is the reason we have fuses in plugs by the way :)
Yes - exactly! All the power (watts) lost in the resistance of the cable becomes heat. The power calculation is current squared times resistance, so more current results in much more power and heat. In a real circuit with a load attached, the bigger the load, the more current it draws an its that current that generates heat in the cable and is the current though the cable that we mimicked in this test.
You should have connected the bare Earth cable to neutral... for earlier fireworks. I still find it hard to believe a solid strand bare Earth conductor cable in still used anywhere.
Your right! Quite possible the live touched the unconnected ground in this test. So next time! I'd be interested to hear the reasoning against this sort of ground wire. From your using the term "earth" I'm guessing your in the UK or one of the other for British colonies besides Canada/US. Do you use individual wires in conduit, or cables like ones we use (ie as in the video).
@@ElectromagneticVideos In Australia we use stranded for active (live/line/hot), neutral and earth in all size flat/round cables (equates to romex) except for 1mm which has solid for A+N. Before 2000 it was solid for A+N but still stranded for earth. More accurately those are the default go to types. I think it is still possible to use solid but solid is essentially unobtainable since stranded is much more flexible and easier to pull. Even when solid was in vogue larger CSA flats were still stranded. Pulling what would have essentially been a copper rod would not have been fun at all. Singles can be solid depending on the application. The reasoning behind stranded is it's more resilient. If you knick solid it can easily fracture completely during handling, while with stranded you will just break a strand. That's still not good since potentially losing 1/7 of the wire CSA depending on the number of strands decreases the current carrying capability of the wire at the point of the break considerably, but countering that the localised heat at the point of the break is dissipated by all the copper in the area so it's not as bad as it seems up front. You still have to be careful preparing stranded of course as it is comparatively easy to cut a strand off, paying attention to torque applied to terminals etc remains quite important. Wiring can be flats, rounds and singles with singles also being available double insulated (SDI) if needed. Single insulated wiring must be in containment, conduit, boxes, etc to ensure double insulation between people and current. Flats, rounds and SDI can be run in conduit too and must be in circumstances where it is likely to be exposed to mechanical damage.
@@ElectromagneticVideos Probably Aus or Nz, because the UK still does use a bare earth wire but we have to sleeve it for identification. I think the reasoning is our boxes are WAY smaller than US style boxes (aus and nz use US size boxes I believe), so it's more likely to compress a bare wire against a terminal when folding the cables back into the box. For this reason we fit 35mm boxes now for everything rather than the standard 25mm
Oh and UK uses T&E, (twin and earth) but with no paper barrier, very similar to your type UF. It has an undersized ground wire though, typically 1 size below the live and neutral, reasoning being it doesn't carry current except under fault, and the overcurrent protective device should cut power in a fault to prevent ohmic heating. We even have adiabatic equations for that in our regs book to see if you need an extra earth. We also use armoured cable (steel wire armoured, not the type BX that north america uses) for outdoor work and submains (feeding sub panels) as it's exempt from the requirement for ground fault protection which is on almost everything here domestically now, and most things commerically. We also use metallic and non metallic conduit, and cable trunking (I believe you don't have an exact equivalent in north america, but closest is 'trough'
@@TheChipmunk2008 Interesting about box size! I knew they were different dimensions. I should have thought about the bare ground being jammed up against a live terminal. I'm sure it happens here sometimes. I guess with our "larger" box sizes it not enough of problem to change things although a sleeve sounds like a great idea and would be so simple to do.
Thats true: ) Strange - once again TH-cam didnt show me this comment alongside the others under the notification bell, but it did show up in TH-cam Studio. Happens occasionally, but seems to happen more for you comments.
Indeed. We have to use this argument with customers sometimes when they say 'it works doesn't it?' Yes, till it doesn't, and your insurance company won't pay out if DIY dave has run the upstairs sockets in whatever scraps of ancient 1mm cable he found in the shed!
@@TheChipmunk2008 I have buddy who renos houses one the side. You should seen one house he had - coax and speaker wire to some outlets, and a kitchen lamp that kept burning out (wired with 240V rather than120). To his credit and on my urging he got an electrician in to clean up the mess. I'm sure you see lots of stuff like that!
@@leetucker9938 We will work with customers on a budget, i can save time by reusing existing cable that tests out ok at 500V, using slightly cheaper accessories, or whatever, but absolutely no regulation deviations. More than our NICEIC membership is worth
The guy coughed during the voice over of him being close to the smoke in the video.. thats pretty weird.. he kinda reminds me of methias wendell the wood gear dude on youtube for some reason..
I had never heard of methias wendell - looked up his channel funny I do see a similarly in how he presents his videos. Cough - there were a few more coughs which were ll edited out - but that one came at the perfect time to mention how bad the burning plastic smoke is.
They seem to do amazingly well under extreme conditions. I do pre-twist the wires before putting on the wire nut which I think makes a better, longer lasting connection. Thats not a universal opinion though - about half the planet vehemently feels that one should not pre-twist.
@@DrD6452 Agree completely - and adds mechanical strength so if the plastic weaken from heat or age, one is not depending on the spring in the nut to hold everything together. Apparently some are made with spring wire being square and biting into the cable to be more secure and better conductive. Even with those I would still pre-twist unless the manufacturer specifically said not to (as is the case for some apparently). I have some of those clamping (for lack of better word) Wago connectors that are getting very popular because if their ease of use. Going to test those and compare to wires nuts - will be interesting to see how they hold up.
A typical extension cable - thinner wire and often in a tighter bundle is certainly more vulnerable to this. Bottom line - the implications of any bundle of cables carrying significant current should be considered carefully.
This is not a real world test. If you have a bundle in a house not all cables would be carrying the max current (or 50% over) at any one time. If you have a concern use a thermal gun to check the temp.rise. Or use your hand to check for heat. Warm is normal, hot is not. .
Your right - it is that way now. I think it was about 25 years ago that they standardized to yellow for 12/2 to make its presence more obvious. Before that it was white just like 14/2. So thats a good indication of how old the scrap of cable used for the video was.
![ค้างคืนโรงเก็บกระสวยอวกาศร้างกลางทะเลทราย [Around The World Ep. 3]](http://i.ytimg.com/vi/E5bWZQhABJE/mqdefault.jpg)
I was honestly surprised at the amount of current that the 12/2 NM-B cable handled bundled like that. As an electrician, that is a BIG NO-NO! 😠 I have seen panel boards with wires melted because of bundling. Excellent video with a lot of important safety tips! Great job! 👍😁
I was surprized too. And yes - a big no-no :) fascinatging that you saw the effects of bundling. If youliked this, look at some of my videos from a year or two ago, I did some with 14/2 embedded in 2x4 stud walls with and without insulation. For some insulation such as spray foam, the margin of safety goes way down as one might expect. So much so that I would go to the next bigger wire size for any runs where cable is in insulation.
Glad you like the video - means a lot to hear it from an experianced electrician who has seen so much of this in the real world. One of my friends who is a retired electrician often comes over to watch and help when I do these types of video and is also amazed and fascinated how much overcurrent a lot of things can handle. He also takes some of the video for me since he is also a great photographer. Great to have friends like that.
Great video. Thank you. Around 20 years ago a friend who owned a big convenience store with gas pumps and a big canopy with lights called me to see why the lights were not working. The lights required a 30 amp circuit... 10 gauge wire. The electrician boys ran 12 gauge wire. The wire nuts in the box at the bottom of the support going to the lights completely melted. I had to pull new wire to repair the problem.
Thanks! Interesting that wirenuts melted. I wonder if besides the cable being undersized, the wirenuts were installed poorly or if the copper ends were oxidized and formed a poor, somewhat resistive connection generating more heat than normal?
Strangely enough for large commercial lighting circuits like that over here (Canada), 347 volts is often used to reduce the current and wire sizes needed. Not sure if the US does something similar?
@@ElectromagneticVideos Yep, have worked both in US and UK (and canada briefly not for payment :) ) , and the terminations are always the weak point if not done right. Actually poor stripping practices cause more damage because it creates a weak point in the cable
We had one when i was running motel maintenance in wisconsin. BRAND new sign, installed by a professional sign company. Turn the breaker on, half the sign lit and half didn't (it was on 2 phases of 120/208)... and after a second or so the breaker would trip.
The manufacturer had trapped a wire behind a ballast. Felt sorry for the sign guy, he was almost home when we called him back LOL
@@TheChipmunk2008 Amazing a defect light that would get though quality control. Such a small thing but a great example of how a defect like that can have significant costs.
@@ElectromagneticVideos So for the USA it is 277V. It is the line to neutral voltage for a 480V Y transformer.
I have been redoing a bunch of 8 ft fluorescent's to LED at work and have pulled so many of these out of them that had gotten hot enough to melt to wire an inch or more back. I abhor seeing then on 12V trailer wiring much less in 277V lighting.
i.redd.it/cs2al46csxr01.jpg
Absolutely enjoy the work you are doing here! One of the only channels making videos to which I watch every second, to the very end!
Thanks - thats really great to hear - appreciate it! You would be amazed at how small a fraction of a video typically gets watched. On average 50% or less! People usually skip to the parts that most interest them .
@@ElectromagneticVideos I tend to skip around a lot but usually to REWATCH segments, so my view time will be HIGHER than the video length :) I am also on a technical discord so often share such videos there
@@TheChipmunk2008 Thats interesting. I'm not sure how youtube counts that. Besides views, I also see total time watched so its probably included in that . Interestingly, this video has had many more hours actually watched in proportion to views than many others, so people are matching more of it (even if not in order :).
If you share the video, thats really appreciated - really helpful for a small channel like this one. You'll notice I don't bug people to subscribe, share, like - I find it annoying when channels repeatedly bug views to do that.
@@ElectromagneticVideos As an asside, I am loving this conversation, i was so happy to see a new video. You do your research, do the scientific method right (as a pHd you would), and social media needs more of this content.
@@ElectromagneticVideos I like dave plummer's attitude to it, just a note, if you make it to the end of the video, that he only does it for subs and likes, so leave one of both if you got anything. That's not obnoxious but can help build your channel
That was very educational for me. Never thought about being limited on bundle size due to heat. Great video!
Thanks! Whats even more amazing is how hot cables get when surrounded by modern insulation in a typical (Canadian/US) 2x4 stud wall. I did a bunch of videos with fibreglass, rigid foam, and spray foam a few years ago - a bit of an eye opener!
Just great content sir. That was very nice of the people giving you that thermal camera.
Yes! I had a small android dongle that attached to to phone as a thermal camera, but having a dedicated one is so much better.
This was very technical and I’m impressed by your knowledge and setting all that up very impressive
Thanks again! Well I am an EE. What really made all of it possible was the vintage old style AC arc welder which is a a great high current source that provides a fairly constant current that is somewhat immune to resistance changes of the load.
Man, even for something so simple (the concept I mean, compared to deeper fields of knowledge) the setup and work to make your video is through the roof. Basically, I am just letting you know that I know. Awesome video. You have a nice aura for a video - regular people talk. Rock on.
Thanks! I really appreciate that! You know, you probably one of the few who understood how much time and setup it takes to do something like this. My setup for this type of test has also improved over time - bigger variac, more instrumentation, and most notably a really good thermal camera kindly provided by a manufacturer (Kaiweets) who saw some of the previous videos.
"You have a nice aura for a video - regular people talk" - wonderful to hear - thats exactly what I am going for. In particular, trying to trying to demo science, engineering, or technology in a way that is understandable to everyone without the need of years of in-depth science and math background. Its taking a while but I'm gradually learning what works best for TH-cam viewers.
29:35 "That's what a fire looks like" 🤣🤣
I thought maybe some people didn't know :)
Bunching is allowed in Australia but it incurs a derate. The more cables, the lower amp rating of the cables. 2.5mm cable with V90 insulation - PVC max temp 75c in normal installation - each wire is 2.5mm, line (active), neutral, earth) clipped to a surface drops from over 25A single cable to 15A if bunched up with 5 others at normal ambient max 40c. Even stacking cables vertically on a surface too closely allows radiant heat and localised air temperature to incur a derate. There is no real concept of a given size wire being associated with a particular amperage but typical installation situations means an electrician doesn't have to reach for tables / calculators to know (s)he can stick 2.5mm 'there', put a 16A breaker on it and everything is good thermally, while a different situation may call for 4mm2 wire to do the same job.
Always interesting to hear how things are done elsewhere! It would be interesting to compare derating rules from different places. but probably would be hard to an apples to apples comparison given the variations on what currents are expected in normal house wiring, construction materials etc.
"Even stacking cables vertically on a surface too closely allows radiant heat and localised air temperature to incur a derate. " We need more thinking like that over here - in particular cables embedded in insulated walls.
Australia - count your blessings. 2mm makes a lot more sense than 12 gauge / 16 gauge / 20 gauge.
@@cashewABCD Yes - I just looked up #14 is almost exactly 2sqmm. #12 is 3.3 sqmm. Really gives a lot better sense of the relative size of wires rather than what seem like arbitrary numbers.
Greatly informative. I love it. Thanks.
Thanks! It was fun to do - and a bit disconcerting given that there was a bundle of cable like that in a house I once lived in!
You really are a very intelligent person
Watching your demos regarding how much safety factor is really built into our wiring certainly helps me sleep easier every night 😂
Jokes aside, I've discovered for myself on how the resistance of copper rises when very hot, a couple years back when I was measuring the current on the soldering tip of my Weller 200/260 watt professional soldering gun, using my Ideal 400 amp AC/DC clamp meter. When the gun is first turned to high temp, i don't know how many amps are really flowing because it shows "OL" on the meter, but when the tip reaches it's rated temperature of approximately 1,100°F after about 15 seconds give or take a few, the current seems to stabilize at around 150-160 amps. The current may have dropped slightly more if I continued reading, but I was afraid I would melt the jaws around the meter and I wouldn't be a happy camper after paying a little over $100. I don't know if I was dissipating the stated 260 watts because I never took a voltage reading along with the current although I certainly may buy a cheap meter just to do that sometime down the road.
So I guess I guess I could say my videos help ut people to sleep :)
I'm a little less optimistic than you are - what really concerns me is how small the safety factor gets when cable is embedded in (really good) modern insulation. I do think a revision in the electrical code should be considered to de-rate cable in that situation.
Soldering gun - I never thought of that as an example of resistance of copper going up with heat - what a neat experiment you did. When the tip is cold and the current is huge, I wonder if there is a significant inductive lag on the current reducing the amount of real power transferred. If so, it would make it harder for for the tip to heat up in the beginning.
That resistance rise with increasing temperature is typical of conductors. Semi-conductors are often the opposite - as they heat up, the resistance drops as more electrons have a enough energy to get into the sparsely populated conduction bad.
Now that I think of it, I what what material combinations are used by manufactures of precision resistors that presumably should keep their value reasonable well as temperature rises.
@@ElectromagneticVideos you're right about the insulation factor. Guess I haven't really thought about that quite as much but I would also have to agree with you on that as well that there should, possibly in the next code cycle or two, have a derating factor when wiring is surrounded by insulation over a certain R value and while this certainly wasn't as big an issue many years ago, even with 60°C conductors when energy costs were cheaper and homes weren't as well insulated , but today with energy cost often rising faster than our paychecks not to mention the impact on the environment, we tend to be far more mindful of our electricity/gas/fuel oil consumption habits than we were 40 years ago, and new homes have gotten much more airtight as a result and many jurisdictions in the US have minimal R value requirements as well that homebuilders are required to meet.
@@Sparky-ww5re Well the only reason I'm aware of the issues with insulation is the videos I did a while ago with 14/2 in insulated walls - results were too close for comfort in terms of a safety factor.
Completely agree with you assessment of how energy costs and greater insulation changed things. Even worse up here in Canada. Is there any effective way for real practising electricians to provide advice to the code update committees? I'm a bit dubious that manufacturers seem to have had an undue influence promoting expensive high tech solutions (ie arc fault breakers on most circuits) rather rather than looking at what the best bang for the buck in terns of additional cost vs amount of additional safety achieved might be.
Love these videos.
The are fun to do :) I see HVAC in your profile name - I'll bet you see lots of interesting stuff like that in shall we say "less controlled" conditions .
Great video, thank you
Well thank you! Glad you liked it!
Interesting, here in the UK we're allowed to do the derating calcs ourselves, so we CAN bundle cables like that, but we have to oversize them in some instances
I guess I implied we didn't do de-rating over here - sorry if I mislead anyone. We actually do it too. In the old house I lived in where the cables were in a bundle, they were certainly not de-rated and used close to their full (unbundled) capacity. What probably helped was that the bundle was in an unheated basement and on average not all the heaters would be on at once. The big steel ungrounded I-beam they were tied to probably also helped cool them :)
I used to work on old Arrow Hart circuit breakers. They could be "fused" with what we called heaters. These were resistors that could be replaced. One per terminal, so the three phase breakers naturally had three. They were modifiable because you could change the resistence just by putting different heaters in the breaker. But that was also potentially bad because you could put a 50 amp resister in a breaker only rated for 20. Also the breakers were twice the size of a standard breaker from Square D or Seemans. Newer Seemans breakers had a small slotted dial with an amp range. Say 1.5 to 4 amps. These could be safely adjusted in that range.
I had never heard of Arrow Hart and didnt know about adjustable circuit breakers. How interesting.
I really like the idea of a fused breaker - assuming the resistors were designed to open like a fuse - last resort safety feature. Although looks like size could be an issue.
Also like the idea of adjustable ones - a great safety feature for the right situation. I'll have to keep that in mind. Thanks for posting all of this!
@@ElectromagneticVideos They stopped making them in the late 80s. I cut my teeth on a lot of weird systems. Some naval ships used to use something called Delta Y power. That was even more strange.
@@bobbressi5414 Interesting! Delta Y as in the transformer that rotates phase by +/-30 degrees? I'm sure that can cause much confusion when people are trying to interconnect things. Or is it something even different from that,.
@@ElectromagneticVideos Fortunately for me I did not have a lot of experience with Delta Y. Most of my work was on fairly typical 3 phase systems. My father dealt with Delta Y and I don't think the Navy uses it anymore.
@@bobbressi5414 The only reason I instantly remembered it was when I was a student had to take a required power/machines course which I wasn't thrilled about. Turned out the Profs who taught it were amazing and it became one of may favourite courses, and we a full size power lab with multi-horsepower AC and DC machines, 600V three phase power, transformers etc. There were some characteristics of Delta and Y configured transformers that had to with harmonics, circulating currents etc. I'm now intrigued - will have to look that up some.
Interesting to think about how temperature will be affected by shoving this bundle through some studs in an insulated wall where there is little/no free air to cool the NM jackets. Thermal runaway is very real and should be regarded with much caution.
Yeah, the NEC (National Electric code) is very real (in the USA) and exists for many very good reasons.
"Thermal runaway is very real and should be regarded with much caution." YES!!!!
I actually think the code should require derating of cable ampacity when in insulation.
Actually did some tests of that in 2x4 wall sections:
Fibreglass th-cam.com/video/Df7bAEdIILI/w-d-xo.html
Spray Foam th-cam.com/video/lFdSXTKsKwA/w-d-xo.html
Extruded Foam th-cam.com/video/4k0xLiokNsc/w-d-xo.html
That bundle and worse is certainly found in the main panel box entry conduit.
Thats interesting - over here(near Ottawa, Canada) usually the individual cables to each branch circuit generally exit though many individual cable glands along the sides of the panel and are not in conduit. Although sometimes they are quite bunched up. And the main entry conduit only has the giant 200A supply cable. Hopefully that is able to dissipate enough heat under full load to keep cool enough.
@@ElectromagneticVideos Where I live in the southern US most panels are placed on the exterior of the home so most if not all of the cables from the house enter the main panel through the largest center knockout.
@@hippo-potamus Thats so different from us in the cold white north :). I am amazed that moisture (rain , hurricanes) is not an issue. Maybe you have better sealed panels than ours which are certainly not weather rated. Unless of course you are in the SW desert area.
Are you panels locked somehow? I could see teenagers thinking it would be fun to go down a street in the middle of the night randomly turning off peoples breakers.
I wonder if in the north east US (near me, similar weather), the panels are indoors or outdoors.
@@ElectromagneticVideos The panels have the ability to padlock but rarely is that ever done. Yes in the northern US and randomly throughout depending on area main panels are placed inside the home as well. However now with the new NEC change to mandating primary means of disconnect panel be exterior any new builds that want to put panels inside the house will have to wire them as a subpanel. The external panels are built differently and actually do a very good job protecting against rain incursion. The main issue I have with mine is dust.
@@hippo-potamus Interesting. I'm enough of an electrical geek that I will have to keep my eyes out for outside panels next time am in the US. I'm also wondering if we do that anywhere in Canada.
Interesting about the mandatory outside disconnect. Probably a good idea for firefighters to be able to turn off power from the outside, particularly in case of gas leaks.
Thanks for the video. I have an off topic question. You mentioned in the beginning of the video that you had a home with electric heat. Ive seen videos on a type of electric heat called "radiant ceiling" or "Ceil-Heat". My understanding is the heat cabling is sandwiched between sheet rock. How can this be practical and not a fire hazzard?
I had to look up "radiant ceiling"! My home had wall mounted electric heaters (not baseboards) in each room.
My initial googling showed hydronic panels, but then I came across this: blog.technicalsafetybc.ca/ask-electrical-safety-officer-are-radiant-ceiling-heating-panels-allowed-canada
So your concern about electrical ones is well founded! I would be very concerned about such a system - something goes wrong and panels could easily overheat.
Interestingly, where I live (Ontario, Canada) electricity seems to have become cheaper than propane (what I currently use) or oil heat. I'm actually in the process of installed an electric boiler in parallel with with the propane one. I wonder if relative prices are similar elsewhere? Natural gas is still the cheapest, but you have to be near a gas line.
Oh. My maternal Grandmother was from Leamington. If could give me a hand, I googled an couple images that I would like to share. My grandother had base board heat.
@@andrewclarke3622 The tomato capital of Canada :) Electric base board seemed to be very common in the 70s in Ontario. Then as prices changed it went out of favour. Apparently common in Montreal where even today electricity is really cheap.
There doesn't seem to be a way of sharing images here unfortunately. Only what is to post a link to the image or page.
Sounds good thanks.
Excellent video! Very nice thermal camera. I like many of Kaiweets tools. They sent me a small electric screwdriver set to review recently and it's nice. I am not jealous that you got a thermal camera at all though 😂. Funny that you pointed out the Manfrotto tripod. I got one last year at a local bargain center outlet and I absolutely love it. I never would have believed the Manfrotto is that much easier to setup and use than the cheaper versions.
What about a Romex cable encased in spray foam insulation?
Did it a few years ago! Here it is : th-cam.com/video/lFdSXTKsKwA/w-d-xo.html
Also did it in various other typical situations. Here is playllist with those videos.
th-cam.com/play/PLHUfJmsprIcTVwSgCkTJnkinJSWrZY7DY.html
does the welder have a duty cycle ?
It does at the higher output currents. I think it was for significantly over 100A output. 15A to 60A currents I was using (at probably less than 5% of it normal output power) is so low for the welder that overheating wasn't a concern. Not even any noticeable heat rise on top of the welder which usually gets warm after normal use.
Would you/have you experimented with bends in wire? There are codes about bending radius of wires. The idea is a weak point of higher resistance is created if you bend a wire too sharply. Maybe investigate work hardening and bending radius!
I havent done that so far. An interesting idea for a test - particularity for solid wire (like used in the video) which is more vulnerable to that than stranded. Would be interesting to see if the plastic on a sharp bend melts first and if the bend is noticeably hotter.
Bending radius of cables is 100% related to insulation damage and slip between conductors in a multi core cable. ZERO to do with any resistance change.
To measure such a change, if any due to a reduction in cross sectional area you will need an instrument and test leads that measures microohms.
Frankly, there would be more resistance at connections points and long cable runs in a domestic installation.... and DIY butchery.
If this speculated 'localised resistance change due to sharp bending' was a 'thing', every high current main switchboard would show faults at those locations under High kA type testing procedure, where the board is in a dead short circuit condition prior to dumping up to a 100kA fault current at the rated operating voltage. 100kA fault current... think about that.
The item under test may achieve a 10kA rating... perhaps 25kA... perhaps 45 or more kA without exploding.
If this 'bend resistance' were a 'thing' it would show up under such extreme testing. It doesn't.
Such boards have large copper busbars... main bus may have 3 bars of 100mm x 10mm per phase. A good 2500A rating. They are full of heavy bars with numerous bends.
No high kA approval testing or thermal In-Service testing has ever shown localised heating at bends.... at connection points yes.
Do more please!!!! How about 6mm wire and below
Next one is testing Wago connectors rather than cables - had numerous requests for that. I think Wagos have been getting more common in North America over the last few years.
If only service providing companies, device manufacturing companies and big tech across the board would take this consumer safety, derating approach with their products and services. But they're greedy so we're screwed. 🥴
Sounds like derating is done well in the UK. I actually get the impression in the US an Canada there is a lot of lobbying from manufacturers to add things like arc fault breakers rather than cheaper solutions!
The test actually shows mainly the importance of good quality TESTED breakers. In any home all wall sockets should be tested with a shorting switch to be sure the breaker blows instantly. In actual situations house fires happen from things plugged into the wall socket rather than from internal wiring.
You make a very good point. Federal Pacific breakers were apparently notorious for not tripping. I'm not sure that testing with a direct short is the best solution - if the breaker doesnt trip it could vaporize the branch circuit cable, cause a fire etc. Perhaps a specified load big enough to magnetically trip the breaker - but still small enough to maintain the integrity of the cable for a few seconds might be the solution. Maybe with a timed switch that provides the overload for say 1 second. If the breaker doesn't trip in that period., replace it. I wonder if anyone makes some sort of device like that?
@@ElectromagneticVideos It is a point but my opinion is the likelihood of any problem with the breaker not tripping blowing things up before the operator opens the switch or yanks the plug is not an issue. Maybe with DEI electricians now days everything must be made automatic, removing the operator from the test.
@@glasslinger Hi mate... love your glass and experimental work.
Yep... proper effective protection please.
Less DIY please.. often that is the root cause of issues.
I for one wouldn't want to full overload test a CB or RCBO in situ using a short circuit method, as I read that. CB on a test bench setup... maybe.... one that captures instantaneous fault current and time.... like every respectable manufacturer does under QA regimes.
Modern Field testing equipment is far from 'automated'. A single microprocessor based instrument for this application provides data for interpretation / diagnosis of wiring systems and protection devices. A host of tests that include HV insulation resistance, Earth/Ground impedance, and importantly, RCBO trip currents (mA)... all done by actual progressive loading. You get a calibrated reading... not a 'pass' /'fail' lamp.... not a 'zone' on a mechanical meter dial. They do not do Thermal/Magnetic on a time base overload trip test.
@@glasslinger I'm still not convinced that once could switch off a dead short in time to prevent damage if the breaker failed - or that a normal switch could handle the dead short current. But thinking a bit more about it maybe put a second breaker in the tester that is rated at say twice the current of the breaker under test. If the breaker being tested fails, the second breaker would save the day.
@@ElectromagneticVideos I use a two foot piece of cord with a heavy wall plug and a 30 amp pushbutton switch to test my circuits. I have never had the idea fail. Fear is a treacherous emotion that can irrationally shut you down from harmless situations.
Very interesting and informative video however what about the Elephant in the room ! . I refer to the coiled extension reel that appears to be feeding the Variac . ooooops. I have found several which have been coiled up whilst transporting too many angry pixies resulting in melted insulation, as the cable cannot liberate heat easily even at 50% of duty load can cause significant heating. Best from UK.
Thermal camera, the temperature indicated was the high end of the level and span not necessarily the peak temperature, if you go to settings the camera will give spot temperature and max min. For future experiments you may like to adjust the level and span the focus into a specific temperature range o interest this then shares the pallet colour for that range providing more contrast to the I radiation. Example looking at a component running at 150 C (expected material failure to be 250) then set range for 140 to 300 this will not blow out the image and the source heating is more visible. These budget camera are pretty good but remember the laws of thermodynamics and black body radiation before assuming the temperature seen is correct, watch out for reflections. For ourself and others go and check out the infraredtraining for free tutorial. Retired Thermographer
Oooops is right - great observation on your part! I actually clued in on that at the end and felt the extension cord reel and it was warm but thankfully not hot. I think the max power sent to the cable we were testing was 200W (except the 200A part where the welder was plugged into 240V 40A) so assuming significant loss and reactive current from the welder, maybe only about 4A went though the extension cord.
Like you indicated, much more than that and the extension cord may have become the star of the video!
Your point is something many people are not aware of - and I haven't seen any warnings about that anywhere. I should maybe sacrifice an extension cord and make a video demonstrating that.
Best wishes to you from Canada!
@@ElectromagneticVideos It would make an interesting experiment especially if you can undertake a hight potential insulation test at the same time. Over the years a number factory sites provided extension leads for my kit and several showed heat damage. PVC is a poor conductor so the core temperature can rise quickly under modest loads. Another issue for contractors or men in shed's is they either ignore or do not understand cable voltage drop. As you alluded to current goes up for induction motors, one chap chooched two drill motors a chopsaw and was rather ticked off, when I measured the voltage at the end of 50 meter (160 feet) extension to his shed it was 180 volts should have been 240.
For those in the comments using TI cameras take this advice from a retired Thermographer of 15 years don't jump to conclusion just because something looks to have heat remember bright surfaces are reflecting heat so you may be seeing a reflection. These budget cameras are as capable as the operator, I have one myself as it is more convenient than my £35k Agema. Many on YT make measurement errors or jump to the wrong conclusion, have a think before you give your report .........
Q; if you covered a TI with a Kellogs cornflake bag or bin liner (useful trick when things get messy)
1/ What is the temperature you register
2/ Would you see an image.
If you can't answer this go to :
Infrared Training Centre or FLIR for basic understanding and free tutorials
@@WOFFY-qc9te Interesting idea about adding in a an insulation test - I could set up a relay to periodically switch between current source and leakage tester during the course of testing.
180 volts should have been 240 - huge drop! Terrible for a an induction motor, particularly for a single phase one trying to start!
Thermographer ? Interesting! Great points about thermal cameras/sensors. You'll notice that I was also using a temperature probe embedded in the cable and it agreed amazingly closely to the camera. I was debating about saying something about reflection and IR emmisivity but one thing I have learned is to keep videos confined to a a limited topic on youtube. I'll have to look up those sites sounds like they have good material!
@@ElectromagneticVideos True good call things can get complicated, yes the temp tracks nicely.
Emmisivity 0.95 is good for anything oil based and skin, brass, copper, stainless is a nightmare which is why I suggest others do a little homework.
HiPot test switching sound good may also be spiced up by testing imported cable on a reel with that made by a responsible manufacture. I worked on a test for AEI cable UK on some counterfeit cable from China, it failed early with toxic smoke, on closer inspection the first 10 meters was copper the remainder was aluminium, conductor and insulation thickness was variable. 60 Volt drop, yes horrific his solution was run another extension in parallel I suppose that is easer than moving his shed.
@@WOFFY-qc9te "the first 10 meters was copper the remainder was aluminium" Wow - thats crazy - I am always surprised at the effort some Chinese suppliers take to do things like that. Worked at Rockwell Collins years ago - apparently they had an issue with counterfeit (military?) cables being returned for warranty repair.
Did you get just the camera from them, or did you give you the stand as well? I went to their website and it was not user friendly and very limited.
The sent me the camera in a very complete kit - camera, USB cable, charger, carrying case, 32G SD card. The stand is a standard tripod I normally use use for my DSLR. Great thing about the camera is it has a standard tripod thread hole at the bottom of the hand grip so that makes mounting it on a photographic tripod really easy - perfect for this sort of thing. Its funny - sometimes little things like a tripod screw hole can really make something way more practical to use as this demonstrates.
after watching your previous videos each heating circuit in my house has 2.5 mm clipped direct rated at 27A for each 2kw heater . I couldn't stand the idea of current flowing through the ring circuit that I couldn't see and monitor. I measured a heater and it draws around 8 A and the clipped direct cable is cold .
That sounds like your house was very nicely wired - plenty of safety margin. Ring circuit - I gather that's uniquely British - neat idea for saving copper.
Question - you mentioned 2.5mm cable (which seems to be close to our #10. which we would use for a 30A circuit). I see charts showing both diameter in mm and area in sqmm for wire. If you go into a store in the metric world, do you ask for cable in terms of diameter or area?
@@ElectromagneticVideos we just ask for 2.5 mm 2 , it is cross sectional area
@@leetucker9938 Interesting. So at 2.5 mm2, that corresponds to our #14 which we would rate at 15A for residential use.
@@ElectromagneticVideos There's a twist to the UK's 2.5mm2 in that it typically has a thinner earth wire, 1.5mm? It varies from country to country. Australia, 1mm, 1.5mm and 2.5mm the earth wire is the same CSA as the others. Over 2.5mm it starts reducing relative to the conductors. 4mm and 6mm uses 2.5mm earth, 10mm uses 4mm earth, 16mm and 25mm uses 6mm earth and so on. 2.5mm and lower keep the CSA of the earth up for mechanical and resistance reasons. Once the wire is heavy enough to put the mechanical/resistance aspect aside it can be lower CSA than the conductors as the heat gain in the wire under a high current fault, and the requirement for the earth fault/short circuit protection to work in no more than 0.4 seconds ensures the wiring/insulation isn't damaged.
@@ElectromagneticVideos We rate it at 27 amps in free air, but like i said elsewhere, we have to apply derating factors. We have listed 'installation methods', in free air is a 1.0x derating factor, but if it's buried in deep insulation it can be derated to 50%. The point of a ring main is the current divides along the 2 paths back to the distribution board. a 32A circuit can have a cable rated for 20 amp on each leg, to provide a margin of safety if the current doesn't divide equally, for example a heavy load close to one end of the ring.
Rings are dying out, 4mm radials on 20 or 32A breakers (again depending on derating) are more common now. The 32A breaker is the reason we have fuses in plugs by the way :)
So, what you're saying is, that I can power my electric oven which is 240v at 30 amps, with cat5 cable? :P
:) That would be one powerful POE setup!
Does higher wattage not mean higher heat?
Yes - exactly! All the power (watts) lost in the resistance of the cable becomes heat. The power calculation is current squared times resistance, so more current results in much more power and heat. In a real circuit with a load attached, the bigger the load, the more current it draws an its that current that generates heat in the cable and is the current though the cable that we mimicked in this test.
Should have protected the concrete. Now you have a burn mark on your garage floor. The high heat can degrade concrete. Cleanup on isle 9.
In hindsight, yes :)
You should have connected the bare Earth cable to neutral... for earlier fireworks.
I still find it hard to believe a solid strand bare Earth conductor cable in still used anywhere.
Your right! Quite possible the live touched the unconnected ground in this test. So next time!
I'd be interested to hear the reasoning against this sort of ground wire. From your using the term "earth" I'm guessing your in the UK or one of the other for British colonies besides Canada/US. Do you use individual wires in conduit, or cables like ones we use (ie as in the video).
@@ElectromagneticVideos In Australia we use stranded for active (live/line/hot), neutral and earth in all size flat/round cables (equates to romex) except for 1mm which has solid for A+N. Before 2000 it was solid for A+N but still stranded for earth. More accurately those are the default go to types. I think it is still possible to use solid but solid is essentially unobtainable since stranded is much more flexible and easier to pull. Even when solid was in vogue larger CSA flats were still stranded. Pulling what would have essentially been a copper rod would not have been fun at all. Singles can be solid depending on the application.
The reasoning behind stranded is it's more resilient. If you knick solid it can easily fracture completely during handling, while with stranded you will just break a strand. That's still not good since potentially losing 1/7 of the wire CSA depending on the number of strands decreases the current carrying capability of the wire at the point of the break considerably, but countering that the localised heat at the point of the break is dissipated by all the copper in the area so it's not as bad as it seems up front. You still have to be careful preparing stranded of course as it is comparatively easy to cut a strand off, paying attention to torque applied to terminals etc remains quite important.
Wiring can be flats, rounds and singles with singles also being available double insulated (SDI) if needed. Single insulated wiring must be in containment, conduit, boxes, etc to ensure double insulation between people and current. Flats, rounds and SDI can be run in conduit too and must be in circumstances where it is likely to be exposed to mechanical damage.
@@ElectromagneticVideos Probably Aus or Nz, because the UK still does use a bare earth wire but we have to sleeve it for identification. I think the reasoning is our boxes are WAY smaller than US style boxes (aus and nz use US size boxes I believe), so it's more likely to compress a bare wire against a terminal when folding the cables back into the box. For this reason we fit 35mm boxes now for everything rather than the standard 25mm
Oh and UK uses T&E, (twin and earth) but with no paper barrier, very similar to your type UF. It has an undersized ground wire though, typically 1 size below the live and neutral, reasoning being it doesn't carry current except under fault, and the overcurrent protective device should cut power in a fault to prevent ohmic heating. We even have adiabatic equations for that in our regs book to see if you need an extra earth.
We also use armoured cable (steel wire armoured, not the type BX that north america uses) for outdoor work and submains (feeding sub panels) as it's exempt from the requirement for ground fault protection which is on almost everything here domestically now, and most things commerically.
We also use metallic and non metallic conduit, and cable trunking (I believe you don't have an exact equivalent in north america, but closest is 'trough'
@@TheChipmunk2008 Interesting about box size! I knew they were different dimensions. I should have thought about the bare ground being jammed up against a live terminal. I'm sure it happens here sometimes. I guess with our "larger" box sizes it not enough of problem to change things although a sleeve sounds like a great idea and would be so simple to do.
£50 for some 2.5 mm cable and some circuit breakers is cheaper than a new house
Thats true: )
Strange - once again TH-cam didnt show me this comment alongside the others under the notification bell, but it did show up in TH-cam Studio. Happens occasionally, but seems to happen more for you comments.
Indeed. We have to use this argument with customers sometimes when they say 'it works doesn't it?'
Yes, till it doesn't, and your insurance company won't pay out if DIY dave has run the upstairs sockets in whatever scraps of ancient 1mm cable he found in the shed!
@@TheChipmunk2008 exactly , save money on your supermarket shopping not house electrics
@@TheChipmunk2008 I have buddy who renos houses one the side. You should seen one house he had - coax and speaker wire to some outlets, and a kitchen lamp that kept burning out (wired with 240V rather than120). To his credit and on my urging he got an electrician in to clean up the mess. I'm sure you see lots of stuff like that!
@@leetucker9938 We will work with customers on a budget, i can save time by reusing existing cable that tests out ok at 500V, using slightly cheaper accessories, or whatever, but absolutely no regulation deviations. More than our NICEIC membership is worth
The guy coughed during the voice over of him being close to the smoke in the video.. thats pretty weird.. he kinda reminds me of methias wendell the wood gear dude on youtube for some reason..
I had never heard of methias wendell - looked up his channel funny I do see a similarly in how he presents his videos.
Cough - there were a few more coughs which were ll edited out - but that one came at the perfect time to mention how bad the burning plastic smoke is.
The wire nut held up quite well.
They seem to do amazingly well under extreme conditions. I do pre-twist the wires before putting on the wire nut which I think makes a better, longer lasting connection. Thats not a universal opinion though - about half the planet vehemently feels that one should not pre-twist.
@@ElectromagneticVideos I always pre-twist too. It would seem to me physics states a pre-twisted connection should be better.
@@DrD6452 Agree completely - and adds mechanical strength so if the plastic weaken from heat or age, one is not depending on the spring in the nut to hold everything together.
Apparently some are made with spring wire being square and biting into the cable to be more secure and better conductive. Even with those I would still pre-twist unless the manufacturer specifically said not to (as is the case for some apparently).
I have some of those clamping (for lack of better word) Wago connectors that are getting very popular because if their ease of use. Going to test those and compare to wires nuts - will be interesting to see how they hold up.
this what would happen in a extension lead not a bundle of separate circuit cables
A typical extension cable - thinner wire and often in a tighter bundle is certainly more vulnerable to this. Bottom line - the implications of any bundle of cables carrying significant current should be considered carefully.
This is not a real world test. If you have a bundle in a house not all cables would be carrying the max current (or 50% over) at any one time. If you have a concern use a thermal gun to check the temp.rise. Or use your hand to check for heat. Warm is normal, hot is not. .
I thought 12/2 had a yellow sheath and 14/2 was white.
Your right - it is that way now. I think it was about 25 years ago that they standardized to yellow for 12/2 to make its presence more obvious. Before that it was white just like 14/2. So thats a good indication of how old the scrap of cable used for the video was.