Great discussion about an often glazed over topic which most people think you should just know about when dealing with electricity in electronics. It's more than just a place we refer to to get an led to blink for instance.
Great video. I feel that anyone working in the field needs to learn all this and understand it thoroughly. Always understand where your references are, and also be aware of potential ground loops. Ground loops can be compared to the secondary side of a transformer and will conduct current. If we're not sure, break out a meter and check it.. Better safe than sorry.
Enjoyed this topic very much. Especially the brief explanation of negative voltage. I had wondered about it and I was making it to difficult. Looking forward to the Brymen-Fluke comparisons.
Great video!👍 One thing I realized most people miss about system/safety grounding is it's secondary purpose of static dissipation and transient spike protection from lightning or switching etc in power lines. A lightning strike to a nearby power line can induce thousands of voltage and this can be dissipated through the transformer, distribution or consumer side ground directly or by surge arrestors/protectors. Of cos any static buildup in the system is automatically dissipated to ground too.
Hi Eddy, awesome video. I am learning so much from your tutorials. As you said floating a scope is dangerous. That’s why many T&M companies developed memory recorders. Memory recorders are like scopes but have isolated inputs. Usually a lot more channels than scopes, usually 12 or 16 bit samplers and you can choose amongst a variety of different input modules to meet specific test configurations.
Nice video - thanks. I appreciate these professional engineering concepts that you include in your videos. An idea for a follow up - good schematics vs poor schematics.
Another excellent video, Eddie. Thank you. It would be great if you could show a (simple) schematic that has 2 (or more) different earth symbols and how they relate and connect to each other.
Thanks so much! I just posted a new video showing an example of a grounding map: A Ground Map Example - A system Design for Grounding th-cam.com/video/IhzX1T8JwrU/w-d-xo.html
@@KissAnalog I remember trying to find a comprehensive book on grounding several years ago and couldn't find one. So, I had to look for pieces all over the place and try to put it all together. Dave Jones has at least one video where he goes into grounding. And Paul at Mr. Carlson's Lab has talked about it some.
Nice explanation. Yes a video about oscilloscopes plugged and the safe used of them compared with the use of a battery operated oscilloscope could be nice. It is difficult to understand that problem with the probes grounded.
Thank you! You are so right - that is an issue and some are too worried to use their scope because of potentially damaging them... I'll have to do more videos on how to use your scope;)
11:40 You should get an isolation transformer if you do such things and connect the probed equipment to it. That way it cannot short to ground. Also it is safer as you will not get shocked if you touch a wrong place inside. An isoation transformer creates a separate circuit that is isolated form the ground so you cannot get shocked from either of the wires - however, if you touch both you will get shocked.
Great stuff. Could you demystify voltage "drop" at some point? I hear it used as voltage drops across, and the voltage drop at, etc., but what is the drop exactly? A lowering of voltage? Just another way of saying voltage? Confused.
So true John! Thank you! Audio is a great example, and even if there are not ground loops - there can be more noise and/or cross talk with poor grounding.
When I build a tube amplifier I use a "Star ground" where all grounds are tied into 1 area where they all come together. Now I am going back and checking the resistance of my earth ground for my Amateur radio equipment for RFI. Ground can sure get complexed when it comes to earth ground and ground rod systems.
Thanks for your feedback. That's the problem, these symbols are used for all kinds of global connections. It is common to use the T symbol for voltages - whether they are positive or negative, and sometimes they are upside down, but don't need to be.
Hi Eddie, Nice videos on grounds. Why do you have split phase or two lines and one neutral in North America instead of having all three phases plus ground? Cheers Mark
Great question Mark. I think it is because 120Vrms at 15 or 20 Amps (common breaker sizes) is able to power a lot of things. In a hope the panel will have 20 or so breakers, so in that case you can have 20 runs with multiple outlets off each run (maybe a run for each room for instance). Half of these breakers are on L1 and half on L2 with Neutral down the middle. Then that keeps voltage lower/safer and current isn't so high to require large wires. Also, it only takes 3 conductors (2 hot and 1 ground). Then there will be several breakers that provide 240V by using L1 and L2 with the ground, and used for Appliances and larger power users.
@@KissAnalog HI Eddie, In Europe (generalization?) They have 3 phases and 5 wires: L1,L2,L3,N,Grd. The phases are about 230V and between two phases there are 400V. I suppose that 3+1 current carrying wires is more efficient than 2+1? Cheers. Mark
I have read sooooo many PCB schematics for simple low power DC 5V / 3.3V / 1.8V circuits, and NEVER did i see the proper symbol for signal ground.. Not once… I now understand what you’re talking about the lass of the art of electronics……. Do you have a rant video specifically on “the art of electronics, what it is, what it isn’t, and why it’s an increasingly lost art”.
Thank you! You are right - it is not a great conductor, it can be 100s or 1000s if 0hms, but this is good enough when you are just talking about referencing voltage points and not sending current across;)
When upgrading a 240 line/150 amp panel the inspector made me install another grounding rod six feet from the existing one to prevent possible fire from lighting strike.
Great video with very detailed demonstration but I have got one question. If the Ground wire is actually tied to the Neutral wire then won't this cause any issues with isolation between primary and secondary? Because in SMPS, their chassis are grounded and their negative terminals are tied to the same chassis.
10:45 "a little bit of voltage..." Here in Europe where we use 230/240V , that "little bit" of voltage can go up to 120V, depending on the quality of the X and Y capacitors in the EMI filter. That leakage voltage has a low current, but enough to light up a 3V LED very bright. This leakage voltage/current is more then enough to damage sensitive electronic parts like FET transistors etc....
Thanks Bjorn for this example. That’s why I say it’s not recommended to Float your scope, and why I recommended a 2 wire power cord for a plastic box. Leakage current creates a touch voltage that can be dangerous. Thanks for expressing this!
@@KissAnalog , floating a scope is not good for anything. When you float a scope by removing the earth connection, you have the voltage/current leaking due the X and Y capacitors, but because there is no earth connection, your measurings are also wrong, because your scope probe normally measure against your negative connection which is connected to earth at 0 volts. But because the chassis part of the BNC connectors is not tight to earth, but a higher voltage, you create a offset of your readings. The scope thinks his chassis is at 0V, but it isn't , and doesn't know because it has no other reference point to check if his chassis is at 0V ground potential.
It is a bit confusing how this can change the scope readings or if it does;) I know many people float scopes as I’ve seen this done in many power labs. If the thing you are measuring has no connection back to earth ground then your ground connection on the scope only references to the chassis on the scope frame. It’s floating so no current flow so no voltage offset. The Y caps still form a series path between the two power lines but there’s no current flow from this chassis thru the circuit monitored if there’s no return path. But it does result in a potential - so not safe;)
@@KissAnalog if have experimented with ground and no ground connection to my scope, as a test, i placed a white power LED in the ground lead (between de grounding of the scope and the groundpin of the powerwall socket), and this LED burns really bright due the leakage of the X and Y caps. But after a few minutes, the LED is dead due overvoltage. For a extra safety on a scope, you can place a very small value of fuse in your ground lead (exp 5mA or so) , that way you have a extra protection when you clip the ground clip of your probe to the hot wire of the mains in a circuit. Tektronix advised this back in the mid 80's to use a scope probe, with a fuseholder in the ground lead (between the probe and the alligator clip). Tektronix has also a neat device for extra protection , the Ground Isolation Monitor A6901 (1986), in short words, this is a sort of RCD that trips to +40V on the ground lead, and trips on 0,5mA/3,5mA/5mA ground lead current. Full specs on this monitor : w140.com/tekwiki/images/e/e0/070-3618-00.pdf
I have a question. What happens if your operating an appliance during a thunderstorm such that the appliance has a fault and uses the ground terminal to shunt the electricity to earth and at the same time your hand is on the metal housing connecting that to Earth Ground when lightning strikes the ground nearby? Will you feel the full force the electrical engergy since this there is no circuit breaker connecting to earth ground? Since the ground is most likely saturated and water can conduct electricity it could be several hundred yards away.
That's a great question! Hopefully, the metal housing of the appliance is grounded safely. If you are touching it when there is a fault, with or without a lightning strike near by, this should not be dangerous if the person is not standing on something that can be conductive. However, with lightning - it is difficult to say how good the insulation is and lightning storms can cause strange safety issues. This is why the power system is actually 'grounded' to earth ground - to keep all metal at the same potential as the earth that a person might be standing on. Earth ground can be somewhat - an unknown. The impedance of the earth is often higher than we would like for this system. All we can do is follow the proper grounding methods per local agency standards - and possibly use lightning protection devices. As for faulty appliances, this can be tricky at times too. I once felt a tickle when an air conditioning unit had a motor that was only somewhat shorted to the housing. It was compromised in a way that let some current flow, but not enough to trip the breaker. So not every fault can be detected all the time, and I think that's why GFCIs are becoming so popular. These help catch faults where there's just higher leakage current.
Thanks John! I would agree, a floating voltage isn't necessarily dangerous. There are lots of voltage systems that are better off floating. And once a line is tied to earth ground - it gets labeled as Neutral;)
I noticed you have rearranged your gear, maybe even removed some. There are a couple of pieces I do not recognize and was curious. For example between your leader sweep generator and you sencore. The other device I do not recognize is the two below your gwinsteck scope. I tend to watch all your equipment reviews and recommendations, so when I saw these changes I thought I would ask what new equipment you have added and why.
If a human was the device being grounded, i.e. a person standing in the mud barefoot, would the human qualify for the earth ground symbol or the protective earth ground symbol? Like would the human body act as the protective box around the energy flowing from the ground inside the human or would he/she be considered a regularly earth grounded object with energy leakage?
All because of wrong grounding. When I moved into my house it had previously been owned by a HVAC guy, he built a terrific piece meal airconditioning system off used commercial refrigeration kit. It used the swimming pool and some buried pipes as a heat sink instead of having an energy intensive fan to cool the compressed gases, very clever and well ahead of his time, I believe this technique is now used in some cool climates as a low energy heat pump. However he had some shortfalls in his knowledge of electrical design, he obviously knew enough to build the system, connect and disconnect various parts, but he didn't identify the different types of ground between commercial and residential equipment. So one of the first things I found when I moved in was floating voltages on bits of metal like TV antenna amplifiers or RF filters that had me stumped for a long time. In the end I discovered he had inadvertently bonded the ground of the refrigeration kit, via the copper pipes, to created a second earth and a potential difference between the residential earth stake and the refrigeration plumbing. We have 3-Phase so as a result a some points we had differentials showing 80 or 90v AC in the house, enough for a person to easily feel it in humid weather if they touched the wrong thing. Also because of the different impedance in various paths it would cause problems with interference on things like TV, radio or even the phone lines and back then the old ADSL internet! There must be lots of DIY problems like this that exist in homes around the globe, and people won't know about it until hopefully they find out in some safe manner.
Thanks for that great example! Unfortunately some serious (fatal) accidents have happen due to these types of issues. I need to do another video explaining how to do some tests to be sure your wiring is safe - especially exposed metal that kids can touch!
@@KissAnalog Yes I should have mentioned how potentially(no pun intentded) serious this was, and people might buy a cheap meter and test between a chassis and a nearby bit of metal and get zero volts. So I think your idea of a video on how to make safe tests would be very useful to amateurs, as well as perhaps a little bit of discussion about floating voltages. That multi-earth problem must be very common, because people would think they are making things safer. PS; I liked your comments about vintage cars and the different uses of polarity, it reminded me of working on early CO2 gas lasers and other HV Rf systems that were designed to be intrinsically safe. There must be a few radio / TV guys that watch your vlog and are well aware of this for commercial broadcast equipment, it must be a trap for people who buy used commercial equipment and just think it's a bigger version of retail stuff!
Thanks Justin! I think these videos will get a good healthy discussion going to help others with these safety concerns. I think you are right that people don’t realize that there are different safety levels for commercial vs residential…
I just got a Hanmatek 2 channel scope-meter and it's pretty kool. Have you ever checked them out? Just for clarification, it's not a Hantek.... it's a Hanmatek HO52. Looks like a pretty nice meter but I haven't used it a lot.
@@KissAnalog well, thanks for doing the videos and encouraging folks to play with electrons ;) The school system in the states should be teaching this stuff along with math.
The more NEC advances the more and more GFCI devices are required (eventually every circuit will need to be GFCI protected).. I wonder how all these devices will work when that happens or if they will cause tons of nuisance tripping, (related to the leakage you are talking about)
Where I reside there's always a 300mA RCD with appropriate overcurrent protection as the first breaker and a 30mA RCD powering around 1/3 of the breakers. (That's also how a standard apartment electrical cabinet looks like here, there can be a third or fourth RCD as well if there are more circuits). No real problems with tripping them that I know of.
I think GFCI is a great idea. It is possible to get a high leakage that is unsafe but will not trip a breaker. So the GFCI or RCD is designed to allow for some leakage, but is greatly limited making things even safer I think.
The average suburban house in the US has a stick of metal stuck somewhere on the backyard as ground. Spot the problem here. Compare that to the same type of house somewhere in the EU, where ground is connected to the metal pillars of the house. I remember at some point seeing some refrigerators with linear compressors having reliability issues, where the compressor would break its valve... and then noticed that almost all of the reports were coming from the US. In case of severe surge (ie: nearby lightning) the ground wire was too small or missing and the fridge was ending up working at so high power that the resulting force would break the valve.
Thanks for the great feedback! Yes, plumbing can be dicy, so they added the grounding rod;) It still may not be the best connection;) I'll have to cover the different methods;)
U'r feet touch it, & walk on it all the time!! though U don't take it with U, you rest with it. 4 eternity!! no mater how U try 2 explain it, it still lies beneath U!! it's good 2 stay grounded, and not let it all go 2 U head!!!there R a few companies that know how 2 ground their electronics. but it looks so elementary!! I believe that both the + & - must be hooked up accordingly!! the only thing is, a small % of EE's practice this!! all electronics need 2 hook up 2 the ground!! but ''most'' electronics never thought about it!! sad!! hey!! 3 prong!! yup!! chasse is the electronics ground.. but!! U need an example using a vna with a 2 way dx/tx + a house grounding plane!! ever wander how they ground in space??? no dirt up there!! illustrations, not sports illustrated related!!
Yes, yes, holy fack yes .. it's insanely confusing. I'm just getting into electronics and no where does anyone discuss how the different grounds relate and the history of grounding. I watched various videos get an overall basic understanding but I still feel a bit lost sometimes. I do think the history surrounding the topic is helpful; see th-cam.com/video/VxvrLydy6PA/w-d-xo.html ; at one point ground was even outlawed in New York. Even the relationship between hot, neutral and ground is a bit confusing ; my understanding is that one side of the a/c connection is "neutral" only when it has been "neutralized" by a ground connection ; otherwise, the concept doesn't apply. Even the idea of hot would only seem to apply when one side has been neutralized otherwise it would all be floating?
Thanks for this awesome feedback!! That's crazy that they had to outlaw it;) You are right - what's neutral but yet another name to explain what is what:)
@@KissAnalog Supposedly the initial grounding outside homes wasn't so much for safety as it was to solve other problems ; obviously that then created a problem with any exposed electrical inside the home; thus, extra ground points got added to stop people getting zapped. It really only started to make sense to me when I heard the reasoning / historical version of it all :-)
Question though, about floating a scope and still getting a zap. I know its bad practice but was the thought that it's possible that the DUT is earth grounded? sorry, I'm a newbie
![일상 속 기분 좋음 [Proto disco meme]](http://i.ytimg.com/vi/DwmEIaZ7XGQ/mqdefault.jpg)
Great video! Often such "basic" concepts are not taught in detail. I now have a greater understanding of ground planes and reference points. Thanks!
I appreciate you! Thank you!
I'm happy to see new video on different types Ground ,
Mainly safety & protection job!
it's great explanation details 👌
Thank you very much
I really appreciate you!
Thanks for Bob Pease reference!
I love it! I love Bob, and I want to help keep his memory alive;)
I'm really impressed with your every videos
Congratulations & welcome 🙏
Thank you! 😃
Great discussion about an often glazed over topic which most people think you should just know about when dealing with electricity in electronics. It's more than just a place we refer to to get an led to blink for instance.
Thanks Joey - great feedback!
HI Eddie, thank you for the exemplary video. Your video’s are excellent.
Thank you so much!!
Great video. I feel that anyone working in the field needs to learn all this and understand it thoroughly. Always understand where your references are, and also be aware of potential ground loops. Ground loops can be compared to the secondary side of a transformer and will conduct current. If we're not sure, break out a meter and check it.. Better safe than sorry.
Thanks for the lesson. Always good to cover the basics for new viewers.
Thanks Tron!
Enjoyed this topic very much. Especially the brief explanation of negative voltage. I had wondered about it and I was making it to difficult. Looking forward to the Brymen-Fluke comparisons.
I think you mentioned another video on proper ground for oscilloscope. I know I have watched your previous one but that’s another good topic.
Thanks Jay! I'm glad that I added the negative voltage example;)
Great video!👍 One thing I realized most people miss about system/safety grounding is it's secondary purpose of static dissipation and transient spike protection from lightning or switching etc in power lines. A lightning strike to a nearby power line can induce thousands of voltage and this can be dissipated through the transformer, distribution or consumer side ground directly or by surge arrestors/protectors. Of cos any static buildup in the system is automatically dissipated to ground too.
LOL Joey!
Excelente analisi, I believe that symbolism determines the area or type of land that the circuit requires.
Thank you for your feedback! I appreciate you!
Hi Eddy, awesome video. I am learning so much from your tutorials.
As you said floating a scope is dangerous. That’s why many T&M companies developed memory recorders.
Memory recorders are like scopes but have isolated inputs. Usually a lot more channels than scopes, usually 12 or 16 bit samplers and you can choose amongst a variety of different input modules to meet specific test configurations.
Thanks Chris for your awesome feedback!!
Thank you for grounding us.
LOL that’s perfect! Thank you!
Nice video - thanks. I appreciate these professional engineering concepts that you include in your videos. An idea for a follow up - good schematics vs poor schematics.
Thanks for the feedback! I just posted a follow up video to show and example grounding map;) Let me know what you think.
Another excellent video, Eddie. Thank you. It would be great if you could show a (simple) schematic that has 2 (or more) different earth symbols and how they relate and connect to each other.
Thanks so much! I just posted a new video showing an example of a grounding map: A Ground Map Example - A system Design for Grounding
th-cam.com/video/IhzX1T8JwrU/w-d-xo.html
Nice video! Grounding is an important subject.
Thanks Robert! You are so right - and I'm sure that a subject as important as this will be talked about in more videos;)
@@KissAnalog I remember trying to find a comprehensive book on grounding several years ago and couldn't find one. So, I had to look for pieces all over the place and try to put it all together. Dave Jones has at least one video where he goes into grounding. And Paul at Mr. Carlson's Lab has talked about it some.
Nice explanation. Yes a video about oscilloscopes plugged and the safe used of them compared with the use of a battery operated oscilloscope could be nice. It is difficult to understand that problem with the probes grounded.
Thank you! You are so right - that is an issue and some are too worried to use their scope because of potentially damaging them... I'll have to do more videos on how to use your scope;)
11:40 You should get an isolation transformer if you do such things and connect the probed equipment to it. That way it cannot short to ground. Also it is safer as you will not get shocked if you touch a wrong place inside. An isoation transformer creates a separate circuit that is isolated form the ground so you cannot get shocked from either of the wires - however, if you touch both you will get shocked.
Thanks for your feedback! Yes an Isolation transformer can help with safety but be careful how the ground is connected.
Thanks for this video on ground symbols it was well done it helped me out alot
Thank you George! I appreciate you!
Another great video! So what would be a good reference book or materials to learn the proper way to annotate schematics?
Thank you! Great question:) Maybe I need to write one!
Great stuff. Could you demystify voltage "drop" at some point? I hear it used as voltage drops across, and the voltage drop at, etc., but what is the drop exactly? A lowering of voltage? Just another way of saying voltage? Confused.
Thank you! That's another great and related issue!! I'll do it;)
great video and indeed a very important safety message
Thanks Colin! I'm glad that you thinks so!
Very interesting video. Grounding can be an issue with HIFI equipment at times with ground loops.
So true John! Thank you! Audio is a great example, and even if there are not ground loops - there can be more noise and/or cross talk with poor grounding.
When I build a tube amplifier I use a "Star ground" where all grounds are tied into 1 area where they all come together. Now I am going back and checking the resistance of my earth ground for my Amateur radio equipment for RFI. Ground can sure get complexed when it comes to earth ground and ground rod systems.
Thanks James! Those are great examples of how important proper grounding is!
the up side down triangle is used for the negative supply, so it would be confusing to use it for ground
Thanks for your feedback. That's the problem, these symbols are used for all kinds of global connections. It is common to use the T symbol for voltages - whether they are positive or negative, and sometimes they are upside down, but don't need to be.
Hi Eddie,
Nice videos on grounds.
Why do you have split phase or two lines and one neutral in North America instead of having all three phases plus ground?
Cheers
Mark
Great question Mark. I think it is because 120Vrms at 15 or 20 Amps (common breaker sizes) is able to power a lot of things. In a hope the panel will have 20 or so breakers, so in that case you can have 20 runs with multiple outlets off each run (maybe a run for each room for instance). Half of these breakers are on L1 and half on L2 with Neutral down the middle. Then that keeps voltage lower/safer and current isn't so high to require large wires. Also, it only takes 3 conductors (2 hot and 1 ground). Then there will be several breakers that provide 240V by using L1 and L2 with the ground, and used for Appliances and larger power users.
@@KissAnalog HI Eddie,
In Europe (generalization?) They have 3 phases and 5 wires: L1,L2,L3,N,Grd. The phases are about 230V and between two phases there are 400V.
I suppose that 3+1 current carrying wires is more efficient than 2+1?
Cheers.
Mark
I have read sooooo many PCB schematics for simple low power DC 5V / 3.3V / 1.8V circuits, and NEVER did i see the proper symbol for signal ground.. Not once… I now understand what you’re talking about the lass of the art of electronics……. Do you have a rant video specifically on “the art of electronics, what it is, what it isn’t, and why it’s an increasingly lost art”.
I'm glad to have you here!! I do need to do a Rant - I think I will soon;)
If you take a meter outside to the earth it shows it's open. It's amazing that it can be a conductor for ground to return to the transformer neutral.
Thank you! You are right - it is not a great conductor, it can be 100s or 1000s if 0hms, but this is good enough when you are just talking about referencing voltage points and not sending current across;)
@@KissAnalog I appreciate your reply, helps my understanding.
When upgrading a 240 line/150 amp panel the inspector made me install another grounding rod six feet from the existing one to prevent possible fire from lighting strike.
Great video with very detailed demonstration but I have got one question.
If the Ground wire is actually tied to the Neutral wire then won't this cause any issues with isolation between primary and secondary? Because in SMPS, their chassis are grounded and their negative terminals are tied to the same chassis.
Thanks Johnny for the great question! I made a video for you. I’ll post it tomorrow;)
@@KissAnalog Woh! That's amazing, thanks for the super quick response :)
10:45 "a little bit of voltage..." Here in Europe where we use 230/240V , that "little bit" of voltage can go up to 120V, depending on the quality of the X and Y capacitors in the EMI filter. That leakage voltage has a low current, but enough to light up a 3V LED very bright.
This leakage voltage/current is more then enough to damage sensitive electronic parts like FET transistors etc....
Thanks Bjorn for this example. That’s why I say it’s not recommended to Float your scope, and why I recommended a 2 wire power cord for a plastic box. Leakage current creates a touch voltage that can be dangerous. Thanks for expressing this!
@@KissAnalog , floating a scope is not good for anything. When you float a scope by removing the earth connection, you have the voltage/current leaking due the X and Y capacitors, but because there is no earth connection, your measurings are also wrong, because your scope probe normally measure against your negative connection which is connected to earth at 0 volts. But because the chassis part of the BNC connectors is not tight to earth, but a higher voltage, you create a offset of your readings. The scope thinks his chassis is at 0V, but it isn't , and doesn't know because it has no other reference point to check if his chassis is at 0V ground potential.
It is a bit confusing how this can change the scope readings or if it does;) I know many people float scopes as I’ve seen this done in many power labs. If the thing you are measuring has no connection back to earth ground then your ground connection on the scope only references to the chassis on the scope frame. It’s floating so no current flow so no voltage offset. The Y caps still form a series path between the two power lines but there’s no current flow from this chassis thru the circuit monitored if there’s no return path. But it does result in a potential - so not safe;)
@@KissAnalog if have experimented with ground and no ground connection to my scope, as a test, i placed a white power LED in the ground lead (between de grounding of the scope and the groundpin of the powerwall socket), and this LED burns really bright due the leakage of the X and Y caps. But after a few minutes, the LED is dead due overvoltage. For a extra safety on a scope, you can place a very small value of fuse in your ground lead (exp 5mA or so) , that way you have a extra protection when you clip the ground clip of your probe to the hot wire of the mains in a circuit.
Tektronix advised this back in the mid 80's to use a scope probe, with a fuseholder in the ground lead (between the probe and the alligator clip).
Tektronix has also a neat device for extra protection , the Ground Isolation Monitor A6901 (1986), in short words, this is a sort of RCD that trips to +40V on the ground lead, and trips on 0,5mA/3,5mA/5mA ground lead current. Full specs on this monitor : w140.com/tekwiki/images/e/e0/070-3618-00.pdf
I’m looking to learn more about grounding and there’s so little available information so thanks
Thank you! I've been so close to doing another grounding video on grounding - I think I might just do that tonight;)
I have a question. What happens if your operating an appliance during a thunderstorm such that the appliance has a fault and uses the ground terminal to shunt the electricity to earth and at the same time your hand is on the metal housing connecting that to Earth Ground when lightning strikes the ground nearby? Will you feel the full force the electrical engergy since this there is no circuit breaker connecting to earth ground? Since the ground is most likely saturated and water can conduct electricity it could be several hundred yards away.
That's a great question! Hopefully, the metal housing of the appliance is grounded safely. If you are touching it when there is a fault, with or without a lightning strike near by, this should not be dangerous if the person is not standing on something that can be conductive. However, with lightning - it is difficult to say how good the insulation is and lightning storms can cause strange safety issues. This is why the power system is actually 'grounded' to earth ground - to keep all metal at the same potential as the earth that a person might be standing on. Earth ground can be somewhat - an unknown. The impedance of the earth is often higher than we would like for this system. All we can do is follow the proper grounding methods per local agency standards - and possibly use lightning protection devices. As for faulty appliances, this can be tricky at times too. I once felt a tickle when an air conditioning unit had a motor that was only somewhat shorted to the housing. It was compromised in a way that let some current flow, but not enough to trip the breaker. So not every fault can be detected all the time, and I think that's why GFCIs are becoming so popular. These help catch faults where there's just higher leakage current.
I look at safety ground as a way of forcing floating AC to work as DC, otherwise there would be no polarity. Floating AC is not inherently dangerous.
Thanks John! I would agree, a floating voltage isn't necessarily dangerous. There are lots of voltage systems that are better off floating. And once a line is tied to earth ground - it gets labeled as Neutral;)
I noticed you have rearranged your gear, maybe even removed some. There are a couple of pieces I do not recognize and was curious. For example between your leader sweep generator and you sencore. The other device I do not recognize is the two below your gwinsteck scope. I tend to watch all your equipment reviews and recommendations, so when I saw these changes I thought I would ask what new equipment you have added and why.
That's a great idea James! I'll have to do a video about my bench;)
You can get zapped pretty well between ground & neutral as well, its not as bad but it still sucks enough to fall off a ladder or something.
Must watch.......
Thanks so much!
If a human was the device being grounded, i.e. a person standing in the mud barefoot, would the human qualify for the earth ground symbol or the protective earth ground symbol? Like would the human body act as the protective box around the energy flowing from the ground inside the human or would he/she be considered a regularly earth grounded object with energy leakage?
All because of wrong grounding.
When I moved into my house it had previously been owned by a HVAC guy, he built a terrific piece meal airconditioning system off used commercial refrigeration kit. It used the swimming pool and some buried pipes as a heat sink instead of having an energy intensive fan to cool the compressed gases, very clever and well ahead of his time, I believe this technique is now used in some cool climates as a low energy heat pump. However he had some shortfalls in his knowledge of electrical design, he obviously knew enough to build the system, connect and disconnect various parts, but he didn't identify the different types of ground between commercial and residential equipment. So one of the first things I found when I moved in was floating voltages on bits of metal like TV antenna amplifiers or RF filters that had me stumped for a long time. In the end I discovered he had inadvertently bonded the ground of the refrigeration kit, via the copper pipes, to created a second earth and a potential difference between the residential earth stake and the refrigeration plumbing. We have 3-Phase so as a result a some points we had differentials showing 80 or 90v AC in the house, enough for a person to easily feel it in humid weather if they touched the wrong thing. Also because of the different impedance in various paths it would cause problems with interference on things like TV, radio or even the phone lines and back then the old ADSL internet!
There must be lots of DIY problems like this that exist in homes around the globe, and people won't know about it until hopefully they find out in some safe manner.
Thanks for that great example! Unfortunately some serious (fatal) accidents have happen due to these types of issues. I need to do another video explaining how to do some tests to be sure your wiring is safe - especially exposed metal that kids can touch!
@@KissAnalog Yes I should have mentioned how potentially(no pun intentded) serious this was, and people might buy a cheap meter and test between a chassis and a nearby bit of metal and get zero volts. So I think your idea of a video on how to make safe tests would be very useful to amateurs, as well as perhaps a little bit of discussion about floating voltages. That multi-earth problem must be very common, because people would think they are making things safer.
PS; I liked your comments about vintage cars and the different uses of polarity, it reminded me of working on early CO2 gas lasers and other HV Rf systems that were designed to be intrinsically safe. There must be a few radio / TV guys that watch your vlog and are well aware of this for commercial broadcast equipment, it must be a trap for people who buy used commercial equipment and just think it's a bigger version of retail stuff!
Thanks Justin! I think these videos will get a good healthy discussion going to help others with these safety concerns. I think you are right that people don’t realize that there are different safety levels for commercial vs residential…
I just got a Hanmatek 2 channel scope-meter and it's pretty kool.
Have you ever checked them out?
Just for clarification, it's not a Hantek.... it's a Hanmatek HO52.
Looks like a pretty nice meter but I haven't used it a lot.
Thanks for bringing this up! I have looked at it but need to save some Money;)
@@KissAnalog well, thanks for doing the videos and encouraging folks to play with electrons ;)
The school system in the states should be teaching this stuff along with math.
@@aurthorthing7403 TH-cam has been a great learning tool for me. I hope to help others and make it fun;)
The more NEC advances the more and more GFCI devices are required (eventually every circuit will need to be GFCI protected).. I wonder how all these devices will work when that happens or if they will cause tons of nuisance tripping, (related to the leakage you are talking about)
Where I reside there's always a 300mA RCD with appropriate overcurrent protection as the first breaker and a 30mA RCD powering around 1/3 of the breakers. (That's also how a standard apartment electrical cabinet looks like here, there can be a third or fourth RCD as well if there are more circuits).
No real problems with tripping them that I know of.
I think GFCI is a great idea. It is possible to get a high leakage that is unsafe but will not trip a breaker. So the GFCI or RCD is designed to allow for some leakage, but is greatly limited making things even safer I think.
I want to find Seesii multimeter in your video,dear friend.😀
Very soon - thank you!
@@KissAnalog If you dislike sample, I can accept returning.Please tell me directly.Thank you for your kind.
The average suburban house in the US has a stick of metal stuck somewhere on the backyard as ground. Spot the problem here.
Compare that to the same type of house somewhere in the EU, where ground is connected to the metal pillars of the house.
I remember at some point seeing some refrigerators with linear compressors having reliability issues, where the compressor would break its valve... and then noticed that almost all of the reports were coming from the US. In case of severe surge (ie: nearby lightning) the ground wire was too small or missing and the fridge was ending up working at so high power that the resulting force would break the valve.
Thanks for the great feedback! Yes, plumbing can be dicy, so they added the grounding rod;) It still may not be the best connection;) I'll have to cover the different methods;)
@@KissAnalog Good Idea!
kiss analog what is this pl. explain.
Thanks for your support! I just posted a new video on an example grounding map. Let me know what you think;)
U'r feet touch it, & walk on it all the time!! though U don't take it with U, you rest with it. 4 eternity!! no mater how U try 2 explain it, it still lies beneath U!! it's good 2 stay grounded, and not let it all go 2 U head!!!there R a few companies that know how 2 ground their electronics. but it looks so elementary!! I believe that both the + & - must be hooked up accordingly!! the only thing is, a small % of EE's practice this!! all electronics need 2 hook up 2 the ground!! but ''most'' electronics never thought about it!! sad!! hey!! 3 prong!! yup!! chasse is the electronics ground.. but!! U need an example using a vna with a 2 way dx/tx + a house grounding plane!! ever wander how they ground in space??? no dirt up there!! illustrations, not sports illustrated related!!
Always awesome feedback! Thank you!!
Yes, yes, holy fack yes .. it's insanely confusing. I'm just getting into electronics and no where does anyone discuss how the different grounds relate and the history of grounding. I watched various videos get an overall basic understanding but I still feel a bit lost sometimes. I do think the history surrounding the topic is helpful; see th-cam.com/video/VxvrLydy6PA/w-d-xo.html ; at one point ground was even outlawed in New York. Even the relationship between hot, neutral and ground is a bit confusing ; my understanding is that one side of the a/c connection is "neutral" only when it has been "neutralized" by a ground connection ; otherwise, the concept doesn't apply. Even the idea of hot would only seem to apply when one side has been neutralized otherwise it would all be floating?
Thanks for this awesome feedback!! That's crazy that they had to outlaw it;) You are right - what's neutral but yet another name to explain what is what:)
@@KissAnalog Supposedly the initial grounding outside homes wasn't so much for safety as it was to solve other problems ; obviously that then created a problem with any exposed electrical inside the home; thus, extra ground points got added to stop people getting zapped. It really only started to make sense to me when I heard the reasoning / historical version of it all :-)
Question though, about floating a scope and still getting a zap. I know its bad practice but was the thought that it's possible that the DUT is earth grounded? sorry, I'm a newbie