Where Does Grounded Electricity Actually Go?
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- Опубликовано: 7 май 2024
- Grounding is one of the most confusing and misunderstood aspects of the grid.
Errata:
At 10:40, the meter is set to resistance (not voltage). Since current is constant, it is also an indication of differences in voltage, but the script should have been a little clearer.
Current doesn’t flow to the ground; it flows through the ground and back up. If there is electricity moving into the ground from an energized conductor, go back to the source of that conductor and see what’s happening. For the grid, it’s probably a transformer or electrical generator, in either case, a simple coil of wire. And, the electrical current flowing out of the coil has to be equal to the electrical current flowing into it, whether that current is coming from one of the other phases, a neutral line, or an electrode buried in the ground.
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Great channel very very well explained sir!
Got the book and I love it. It is the perfect coffee table book.
Also... that Henson razor is a game changer. I love it.
It would have helped if you spent a bit more time explaining how three-phase AC power works. You glossed over that so quickly I bet most people completely missed the most critical issues here. I'll admit this is something that could take a video all on its own to explain properly, so go do that!
Hi, Does Hello Fresh Ship To Outside The US? Say To Kenya?🇰🇪 Avid Fan From Kenya 🖐
I think Hulk Hogan messed around with Zap's mom. There's a striking resemblance.
it goes into the ground
I can't believe it
don't believe it
russian misinformation
i see, thanks
@@GOOD_FARMERYes, the ground is made of ground. 👍
@@interstellarsurferNo it's made of earth
@Practical Engineering: at approx 19:30 you mention hopping to limit the chance of step potential - this is no longer the case, at least in the Australian electricity industry. The reason is that a person hopping (one or 2 footed) is very prone to overbalance and accidentelly step or fall, thereby creating the step potential and possibly injuring themeselves as well.
Current training is to keep both feet together and 'shuffle' by sliding one foot forward no more than 3/4 of the length of the foot so they stay together, then shifting the other foot in the same manner. In this way, while some 'step potential' will potentially still exist it will be small, and the feet / ankles / legs touching provides a path for any currect without transitting through the torso.
Another thing to note is to avoid any sudden ground condition changes where possible - don't move from dry ground to wet, concrete to grass, etc.
Great content!
For anyone interested in the real life consequences of poor grounding and floating Neutral wires, here is a link to an incident in New South Wales, Australia in 2014. The report is quite a detailed investigation and highlights what this video is discussing quite well. www.resourcesregulator.nsw.gov.au/sites/default/files/documents/iir15-01-fatality-at-house-near-quarry.pdf
Not from the electrical service industry but I was taught another (still different) way of getting away from ground potential: short hopping with both feet together
That's recommended in electrical training in the US, too. (At least what I had.)
could you attach a wire to the boots, running along the pants to give a lower resistance path?
@@anwyl42 Exactly what I was thinking - can't we just "ground" the shoes to each other?
I worked as a journeyman lineman for 36 years. I have found your videos to be interesting and accurate. I think your comment about electricity following all the paths available is very important. Many have been killed thinking the the path of least resistance. I started in 72 and the rule then was to work "between grounds.". Time went by and "singlepoint' grounding became a thing. Grounding from the conductors to the tower or pole below the linemans feet making for no differential.
It was a hard sell, still might be, but it works.
Im going to watch this one a few more times to see if I can learn more.
I think you are one of a few people, who sre not in the electrical industry, who understand what goes on here.
What do mean by "between grounds".. and "singlepoint" ?
I was a defensive lineman when I was younger, but when I got to high school, I became a linebacker. I know what it’s like to be a lineman, though, so I can totally relate to what you do. It’s a tough job, for sure, but it’s a very important one. I’m sure your team appreciates all your hard work.
"Im going to watch this one a few more times to see if I can learn more."
Good. I was feeling very ignorant about electricity while thinking about how many times I will need to watch this. Thank you.
obvious joke, silly @@chriswebster24
I helped an electrician completely overhaul the electrical system at a large multi-building facility originally built in 1906. All the lines in on building were just single wires that ran the length of the building and at the far end connected to a steel pipe that ran along the top of the wall; that was the return line.
We made a bizarre discovery, though: the men's restroom in one corner of the building still had the old steel trough as a common urinal, which was bolted to a frame of steel pipe inside the wall. Somewhere in the decades between the original construction and the electrical overhaul, for some reason the steel pipe serving as the return electrical line had been cut and a section removed -- and when that section had been replaced it hadn't gotten connected back to the return line but instead to the steel frame for that trough urinal, and then a heavy wire had been run from that frame back to the main electrical panel. So for years, probably decades, that men's restroom had an electrified urinal.
BTW, the 'hot' wires were only insulated on about eight inches on either side of where they were attached to glass mounting insulators, and the wire insulation was just tar paper wrapped around the copper wire.
A hot urinal trough has the potential (see what I did?) to cause serious injury if the bathroom floor is somewhat conductive, like from being wet. It's similar to pissing on the third rail.
@@soaringvulture Cute pun.
We figured either people had been very lucky or there was a shorter path to ground somewhere, or the steel urinal was itself grounded well. The general manager wasn't interested in paying what it would have cost to trace things to find out, though, so we just did the overhaul and made sure the electrical system was no longer using any connections to plumbing as a ground. Later when a plumber was dealing with an issue not even twenty feet from that restroom I mentioned the electrical silliness, so we traced pipe, ended up pulling sixty feet or so that wasn't actually attached to any water lines plus used PVC sections to join lines on a couple of T-connectors so the only thing flowing would be water.
@@traildude7538 COLD water pipes were considered acceptable ground points for decades, but that is changing due to PVC and other plastics used in plumbing.
Besides, having a solid wire from ground to point of use is much better than pipes with many joints!
Excellent
You'd be surprised how many electricians I work with think the neutral is always a non hot wire
I like when ground is Earth. Grounding to the Moon is just so difficult.
You're just not using the right ladder
@@kiriuxeosa8716It's a step ladder. The real one died.
I wonder if the english artemis astronauts will call the 0v potential on base "mooning"
Smh... Words aren't toys.
Definitely need a bonding cable run at some point.
I am an electrical engineer (in the US) that designs the grounding grids for substations to limit touch and step potentials. I can confirm that there are tons of calculations & analyses that go into the design, including simulations of worst case faults to make sure there is a near zero chance of injury. However, ground grids are not designed to eliminate potentials, only to reduce it enough to prevent arrhythmia. So if you happen to be at a substation during a ground fault, you may still get zapped, but it won't be fatal!
Great video Grady!
What is the typical voltage potential at these subs?
An even more difficult concept for many here to understand is Prospective Instantaneous Fault Current.
As an electrical engineer (In Israel), I can confirm what ZZZZ271 said is just partially correct. But too tired to explain why now lmao.
I have carried out such calculations, although not for a good few years. In the UK we would find the Earth Potential Rise (EPR) and from there calculate the step and touch voltages. The areas where the touch and step voltages were above required levels (referred to as the ‘Hot zone), would require additional earthing and bonding.
How many people do you know who have, "shuffled to safety". I bet it's zero.
That's so cool, @zzzz271! I was always amazed to see how much detail, planning, and regulations/standards you have to adhere to with substation grounding grid analysis and recommendations, just to make sure any human life inside and slightly near the fence line has a chance to survive if a fault occurs. It's so much more than just welding a bunch of copper grounding grid into the earth and saying "done!"
I never felt like the concept of electrical ground was very well explained in any of my electronics or physics classes; and I still don't feel like I totally understand it, but this video helped at least a little bit, so thanks!
It's magic and I don't care... until it stops.
Yes, he actually isn’t good at explaining things
@@jimleigh7781 When someone is not good at explaining something it’s often because they don’t fully understand it themselves.
Haha, you caught him😂@@alfredopampanga9356
I work at an insurance company, and a major fire loss came in where the client had installed an electric fence on their balcony to ward off pigeons/birds, and it required grounding.
They put the wire into a plant pot on their balcony.
Really spices up the petunias
Now that's a bird brained set up.
Well done! You stepped in my territory, and you managed to survive! 😁
Ahhh!! I love this! This is hilarious
Yeah! He was on the safe side and did make a really good explanation video.
Hi mate how are you?
If you were there Grady would have been cleaning for hours to get the sand off the floor... and the walls, the ceiling, and....
I was tempted to leave in some inaccuracies to try to start another RUclips EE debate!
When I started at the power plant, I asked about where all it fed power to. A guy told me it’s pretty much like throwing a cup of water in a stream & someone else pulling a cup of water out down stream. Yea it could’ve been your water, but more than likely, it was a combo of all the tributaries.
So when we are billed to a single power company, how do they know how much of "their" power we actually used?
@@danpro4519 That has to do with distribution. Your local utility, co-op, or municipality was the one that installed all of the equipment in order to deliver you power, aka the feeders (power lines), the protection equipment, the substations, and more. They can generate power themselves, or they can purchase their power in order to deliver you yours.
@@danpro4519 that's not a question since both are entirely different entities. a power company is engaged in the field of producing electricity and then also in distributing it. those are separate things. with different revenue flows and balance sheets. more often then not, the distribution even inflicts an internal loss. meaning, would they just sell all their electricity to current brokers instead of the consumers, they'd be better off even.
@@danpro4519 Here in the UK, power companies are meant to charge you based on grid usage rather than supply usage as the national grid controls the flow of the entire grid including from all sources, imports and everything. The engineer/TV presenter Guy Martin took over the national grid for a short time in learning how it all works in a series - "Guy Martin's Great British Power Trip"
But, that's the UK, so I don't know how it works for others.
@@danpro4519 as far as generators are concerned. They just get a demand from the grid operators, & then try to meet that demand. Renewable & Fossil plants both put power onto the same grid, as the person above mentioned, it’s the transmission operators & distributor’s that actually deliver the power. Sometimes it’s all the same company but such as in my case, our plant is owned by a different company than the one that operates the grid. So customers pay them, & they keep some & pay us whatever the agreed upon price was per Megawatt when we produced it.
Grady you do a fantastic job of education and explanation of your subjects. I lived in Cambodia which has a 220/380V or so system. Each house was connected to one hot leg of a 3 wire wye and the common. Common was NOT grounded. Middle of the night one phase was 280, in the heat of the day with all the air con running it was 160 or so. Across the street was a welding shop which was on a different hot leg of the wye. I has incandescent lights in my bathrooms, and whenever he struck an arc it would drag the common towards him and increase the brightness of my lamps A LOT. I finally replaced those fixtures with electronic ballast fluorescents, which eliminated the change in luminance. Some fluorescent light switches in the house broke the common instead of the hot, so the input capacitor in the ballast would charge and then flash the lamp about every 5 minutes. Interesting experience living there.
can someone just spoil the video instead of commenting “i have 40 years of experience in this field and i must say this is a fantastic video!”
As an electrician I see a lot of apprentices get confused with grounding, grounded and bonding. In school and generally out in the world we hear a lot of "electricity wants to flow to ground" without really understanding whats happening. Easiest way I explain it, electricity doesn't want to flow to ground, it wants to return to the source, through the ground, in a grounded and properly bonded system.
That is a good explanation because this way it's very easy to see that there won't be any electricity flowing from the battery to the earth.
Whatever leaves the source must return to the source
Call it return path instead of ground and it will make a little more sense.
ruclips.net/video/jRy_YzvDv5Q/видео.html
ruclips.net/video/jRy_YzvDv5Q/видео.html
13:00 Grady, fun fact.
The early telegraph system in outback Australia used a single wire system as the iron ore content in the soil was high enough to use as the earth return.
It's what gives the outback the classic red/orange colour.
That fact is indeed fun. Australia is neat.
i think i saw snippets of Australia in this video tbh..looked like home to me
@@Liveleadplayer70 yep we have SWER in parts.
Australia is the mars of earth
yes I'm an Australian electrician. This is called SWER and it still exists
Man I love your calm, clear, and inviting speaking tone. It’s easy to listen to & because of that (and the highly technical based videos) you have a new follow!
I'm aware of a number of cases where cast iron water mains developed leaks due to electrical grounds from a business like a welding shop. The grounds weren't on the main itself, but there was enough current to slowly strip iron from the pipe eventually causing leaks.
As a chemist I'm used to deal with elements exchanging electrons to make things happen, but when it comes to electricity in a circuit & insulation I'm as a smart as a wood door, save from battery cells. Thanks for sharing this with us.
Glad to have a chemist in the room for once.
While you are here, I have been meaning to ask if with the discovery of Quantum "Spin", have Chemists come up with anything in elemental electron exchange?
I find all the analogies confusing. For me, electricity is easier to understand from first principles. Unfortunately, that involves quantum mechanics, which I guess many feel is too complicated to explain. But only after I saw some videos explaining that electricity is all about the movement of fields and not electrons flowing through the wire like little balls in a pipe, it all clicked. AC is extremely difficult for me to understand if I try to understand it using the traditional analogies.
I must suspect there are similarities. As I understand , in order for an electron to move to a higher orbit it needs to have 'enough energy'. An electron following its designed path would be the equivalent of a circuit. Insulation refers to the amount of 'enough energy' required to exceed its normal path to reach a higher orbit(s). To say, insulation=resistance, the distance of, 'enough energy', required to reach higher orbits becomes equivalent to the amount of insulation (resistance) that must be overcome. From Gradys sand example: dry sand offers the most insulation, wet sand offers an amount of insulation, yet salt water offers little insulation. (Different salt((s)) offers different abilities.)
@@MR-nl8xr Honestly, after getting to know the basics of quantum in college I figured out it’s just too much for me. The probabilistic behavior of wave-particles in confined orbitals blows my mind every time I think of it, in the end always going back to physics and tons of math (which is a marvelous way to describe and understand reality). Channels like PBS Space Time, Veritassium, The Science Asylum, Physics Videos by Eugene, Arvin Ash and many others would give you a much better response to your question. As far as I know, genius scientists are using the quantum properties to improve computing power. I’m a simple man.
@@deelowe3 Can you suggest those videos.
In the Navy even though it can be more dangerous, we often use ungrounded 3 phase distribution systems so that they continue operating even in the event of a ground fault (like a missile blows a hole in the side of the ship)
Really that's cool!
Hawaii EJ
This (ungrounded 3-phase delta) is also fairly common in industrial applications, especially for wet processes where ground faults could be common.
ruclips.net/video/jRy_YzvDv5Q/видео.html
i think it is pretty common not only in the navy but most of merchant ships today just monitor ground fault and have an alarm system for it, instead of interrupting the service, in the power generating side however(in the generator) it is still necessary to monitor ground fault current
I was a welder in the navy. Most of the time we only needed to carry/run one lead to the work area/parts, as the ship was the return path, AKA ground.
Great video! One extra thing, related to the example at 7:09: in some countries, such as Italy, France and Japan, the neutral and ground/earth are kept entirely separate in the home, and never connected together.
In that case, during a fault (like in the toaster example) the current will in fact flow through the physical ground, and thus will be fairly low - too low to trip a breaker immediately. Because of this, an RCD/GFCI is required to make sure that power gets cut immediately after a fault.
This is called the TT system, and is nowadays considered to be fairly safe and reliable, provided that an RCD is actually used (which is the case in the countries that make use of it).
I was wondering, "what does he mean by a return path?" because the ground connectors absolutely do not reconnect to the grid at any point here in the UK. If your device has a ground fault, the current will simply... Go into the ground. At which point your RCD will detect that the return current is lower than the supply current and open the circuit.
The American electricity system is strange. Not to mention their outlets and plugs.
@@RaunienTheFirst Generally speaking, the UK does in fact use a TN earthing system - generally a TN-C-S one, the same one used in the US, so the same principles apply (especially since houses in the UK aren't required to have earth rods).
The exception is in rural areas, where TT supplies like I described are in fact common - but generally speaking, the TN-C-S system is the predominant one.
The main difference with the US, really, is that the split (from combined neutral and earth into separate neutral and earth conductors) is done by the supplier, while in the US this is done at the breaker panel.
@@samstech963 huh
@@samstech963The old breaker panel in my basement connected the ground wires together and connected them to a copper rod that ran through the seam between the main basement concrete slab and the slab for the exterior stairway. When the wiring got updated at some point the copper rod got pulled, which took a serious amount of pulling power because, as it turned out, the rod was over seven feet long. I thought that was amazing, but an electrician had one of those copper rods on the wall in his shop as a bit of history; it was twelve feet long! The explanation was that anywhere between six and fifteen feet down under much of this town there was a natural gravel layer that water flowed through that was an excellent conductor due to the fact that except for the town the entire valley area was dairyland, which meant that the water flowing underground towards the bay was far from pure.
studying to become an electrician here in australia, and we have the same system. we just call it "earth". but just like yours our ground/earth cables go straight into a copper rod submerged a metre into the ground, with an RCD to detect leakage to earth. i was very surprised to hear that their connects to neutral. is it less safe?
I am master electrician and I have watched your video more than once and everything l learned in the 20 plus years about grounding feel I have just started to understand abit more how grounding really works..! Very interesting and I will continue to follow practical engineering; thank you and Mike Holt as well for the email. God bless 🙏
My electronics professor was explaining 3 phase, 4 wire motors. He had a diagram of the 3phase generator connected to the 3phase motor and kept emphasizing the “4 wire” part of it. Finally a student asked, “where is the fourth wire?” Then he pointed to the ground symbol and added a ground layer to the diagram connecting the generator and the motor.
Three phase may be configured in a "Y" or "Delta" configuration. In Delta configuration there is no phase to neutral connection. At terminations a transformer makes the conversion Y to Delta or vice versa.
How long the class suffered trying to understand until one mind could not take it any longer and had to let his soul get satisfaction in answer form.
Technically, the term “three-phase four-wire” *never* refers to the use of a ground wire, only a neutral wire. If I have a three-phase motor that for some reasons used a neutral wire, as well as a ground wire, it is a four-wire grounded motor (not five-wire).
@@MR-nl8xrOr he's trying to let students think for themselves instead of just blindly accepting everything he says. "Ah yes, three does equal four, because teacher says so."
If using an ounce of brain power to ask why something seems wrong is considered "suffering," then it's no wonder our education system doesn't work.
I would try and get students to understand the difference between a neutral and a ground before I got too far into a discussion . That would clear up the confusion. And I have been guilty of using one term when the other was correct.
I'm in charge of a power transmission grid and always enjoy your videos. The accuracy of the information makes me trust your videos on topics for which I'm not an expert. Your channel is a gift to the world.
Hi man, in this case maybe you can help me with the question that has been bothering me for a long time - where does an extra current generated by a house solar panel go? It circulates in the local grid up to the transformator, right? It can not go up onto the high voltage grid, right?
@@andreismirnov7200 it can go up into the high voltage grid if you were to make enough. We have a solar installation not unlike a home installation, but a bit larger at around 500kW. It goes through the 11kV to 415V transformer, thus feeding the local medium voltage grid. Yours is likely flowing to your neighbors, but if you're on your own transformer, it's also getting there on the medium voltage grid. But like this video says, it's not practical to tell which current comes from where exactly. It flows where it can based on impedances.
@@michaelcarr2466 first of all, big thanks for your professional opinion! So, transformers work both ways without limitations, so all theoretic excess electricity can go up the grid? I was asking more about regular home solar installations, all big solar farms probably a totally different story. My big problem with solar is that nobody knows if any of this excess electricity generated in the summer is needed, to what extent and how it is used. It is generated and just "goes somewhere". In the winter everybody still gets power from grid and consumer is stuck with the bill for all these solar experiments that nobody knows economics of.
@@andreismirnov7200 You are correct; transformers work in both directions, and thus excess electricity would flow into the grid. You are also correct that the economics of residential solar installations can be complicated, and also result in unintended consequences. There are additional concerns regarding the reliability of the grid when solar and wind become a large portion of the supply, and more traditional generation goes offline. A traditional generator provides physical inertia to the grid which improves the grid stability.
@@michaelcarr2466 thank you very much again for your valuable clarifications and confirmations.
I found the diagrams a bit confusing, but I appreciated your combined use of them and other teaching methods (theoretical explanations, demos, practical examples, etc.) to make your point. This is a difficult subject, and I think that my chances of properly understanding electrical circuits is higher from watching this channel than it would be from any other source.
video looked great! I definitely noticed the refinement in the illustrations and of course content was top quality as usual. i really love what you guys do, keep up the great work!
My job has a high resistance ground on our 480v distribution system. It’s wild to realize one phase is at 0 volts during a fault and non of the equipment cares because phase to phase doesn’t change.
Yet 2 of those phases in such a fault condition will be much higher voltage to ground, easily exceeding the rated voltage of insulation. That high ground/Earth impedance is a matter that should be addressed.
@@BTW...Is the wire only rated for 600V in these applications?
@@BTW... the ungrounded phases go from 277 to 480 phase to ground and the phase to phase voltage is unaffected. Still below the common 600v rating of most insulation.
Ah yes the high impedance grounded system. The Cadillac of electrical systems. Are you by any chance in a hospital...??
@@MrMaxyield Glass plant. The furnace requires similar reliability to a hospital.
Great video. Despite having a degree in electrical engineering for 21 years, this is the first time someone completely explains the concept of ‘ground’ in all its aspects in one single go.
Technically he explained earth, not ground, and got the two confused
@@youtube_omaro1879 Let me guess... European, right? In North America, the thing you guys call earth (the green wire, the spike into the dirt, etc.) is commonly called ground. So is the common/return/reference point in an electronic circuit. Yes this can lead to confusion.
Yeah, long time EE here too, and no I too was never taught much about grounding systems in school. I've been told they teach it in trade/tech schools. Or you learn it by working in for an electrical utility co. Actually very little of the knowledge I use to earn my living was taught in my "higher" education.
@@sootikins
Australian. But I learnt that nitpick off American textbooks, or at least I think I did.
Circuit ground is not the same as the Earth. Perhaps this is a more Electronics than Electrical distinction, but I'm pretty sure that we always call our green wire earth too.
@@youtube_omaro1879 If I'm talking to an electrician I usually say "ground". But if I'm talking to an electronics person I try to say "earth ground" to avoid confusion with system ground aka common. Then there's stuff like servo controllers where you may have "analog ground" and "digital ground" and "ground " (aka protective earth) all on one unit - lol!
This was the first video of yours I stumbled across and I’m glad I did. Amazing video with great detail. Keep up the great work.
This is an excellent video - for those with a background in the field. For the rest of us, it was too much, too fast. You could do a series on this subject.
Your tap water must be ridiculously good. At my high power lab, we would use city tap water as a salt water source when mixing into DI water to set water conductivity.
That must taste disgusting!! His water comes from the Edward's Aquifer...and it's taste is pretty good...but the city has added flouride like 20 years ago, and so now it's taste is only okay imo. (maybe it's in my head)
A few years back my old house was having problems such as the washer not able to spin dry sometimes, dim lights at times etc. The cable TV would also fuzz up and checking that connection to the house I discovered the cab;e connection outside was warm. I called the electric company. They found an intermittent bad neutral at the pole. They redid the connection and things went back to normal. The cable was acting as an interment ground/neutral.
I work for a cable company and years ago when we would physically disconnect customers at the pole you were supposed to check with a probe for voltage, occasionally someone would be in a hurry and not check and when they would disconnect the cable lights in the house would go out and sometimes things exploded because the neutral to the home was no longer connected and the home had been using the cable drop as the return path.
Intermediately losing your neutral means various things in your house would be getting anywhere between 0 and 240 volts depending on how loads are balanced
One more thing. Some (maybe most) modern relays have oscilloscopes built into them, so they can detect not just the intensity, but also the waveform of the current. This allows enhanced protection, because some low-level faults may not get enough current to trip out the relay, but if the oscilloscope detects a waveform indicative of a fault it can still trip the station or distribution circuit.
If there is no waveform acreen then it is not a scope. It is a microprocessor controlled relay.
I guess it uses a current transformer in series with an ADC to sample the waveform of the current. Then, some DSP is applied to detect problems
Thank you for another outstanding learning experience, sir. And it's not just your depth of knowledge and easy to understand explanations, but also a wholesomeness that is just bubbly refreshing! I am sure that this old-school guy isn't the only one that feels it.
May God continue to bless you and your family.
i like to learn
I remember working with a friend of mine on my home electrics. I mentioned to him that the circuit was live, so be careful. He said not to worry because he wasn’t grounded. He grabbed the hot wire and got a shock. I explained capacitive coupling with AC.
"so be careful" would have been to have shut off the power before the circuit was exposed and a risk of shock was non negligible.
@@ianallen738 That only applies if the work can be done on a cold circuit. If they were troubleshooting a circuit, they might not be able to find the problem if it was cold. Sometimes hot work cannot be avoided, and so other methods have to be used to maintain safety.
@@ianallen738 We were just getting started. I did mention that the breaker wasn’t off. I wasn’t expecting anyone to work on a live circuit or anticipating anyone to reach in a grab the hot line after I warned that it was live.
I literally have to double bag my hands in certain areas of my job because there's so much capacitive coupling that turning off the power INCREASES the voltage you can measure. It's wonderful every time, changing out an old light fixture and getting 300V+ not even 5 seconds after shorting all wires.
The shock from capacitively-coupled mains and L-N/L-G mains are two completely different things though. The capacitively-coupled one (about 100pF of human body capacitance, 26Megohms at 60Hz), is only an unpleasant but otherwise harmless tingle while L-N/G is painfully sharp and potentially lethal. In both cases, I'm more worried about over-reacting to shocks than the shocks themselves on 120V.
Those single wire earth return systems are quite commonplace here in Australia. I remember being fascinated by them as a kid and asking my dad, who is a physicist, how they worked. I recently purchased a pair of local battery magneto crank telephones, which I have setup as a novelty intercom system. I was recently reading about how some remote telephone lines used a earth return system, so at some point, I plan on doing a little experiment with the phones to see if I can get an earth return system to work between them.
You may be interested in the open-wire telephone system from the rim to the bottom of the Grand Canyon in Arizona! It's on the historic register.
Ground-return is how a lot of magneto-based phone systems worked, cheaper to use one wire per phone, and, if you have long wire fences on reasonably insulated posts, you could even use your fenceline as the main wire, just by clipping onto it and connecting the other terminal to the ground... :)
I have a photo I took of a public phone box at Yaraka QLD, when booking a hotel room, I rang this long phone number and asked for “Yaraka 4” and spoke to a manual exchange. This phone box had an A and B button and a crank handle. People I showed this photo to said they wouldn’t know how to make a phone call. This was in 1987. As a kid in the 1960s I had an uncle who was an electrician who had a whole bunch of hand crank generators as he was involved in upgrading the telephone system.
@@darylcheshire1618 Fascinating! I had always thought that the last manual magneto exchange in Australia was near Geraldton WA and closed in late 1985. The two PMG 403MT handsets I have were made by British Ericsson in 1957 and 1960 respectively, but both have Telecom Workshop Hobart test tags on them from 1979 and 1982, meaning they were probably last in service on remote exchanges in Tasmania until sometime in the mid 1980's.
@@pulsecodemodulated Yes there were a few in Queensland, also in Yaraka the freight train service still carried passengers until 2004 in a passenger compartment in the guards van. This was a car-goods which is different to a mixed which was a passenger car attached to a freight train.
This was the reason I travelled to Yaraka 3-4 times from 1987-1999.
There was a rail fan called Richard who drove around and took photos of all the remaining manual exchanges and spoke to the old ladies that ran them, he would exhibit these photos on rail enthusiast slide nights. Mostly delapidated tiny buildings in rural areas.
Love watching this channel. As a mechanic I always enjoy finding out how these things work.
This was really good to watch. Answered a lot of questions I had about how grounds work
As a high voltage engineer I know how difficult it is to explain how earth works, but this is an amazing explanation. Great job Grady! (Can you make a Dutch version for new colleages? 🤭)
I having teaching myself designing circuits and ground is a difficult concept to understand as there is more than just one type of ground and how should different types of ground be connected to prevent ground loops and EMI noise
You can try auto translating the captions to Dutch
Agree this is an excellent video introducing the topic
@@latticepoint5245 This. I have auto-translate set to Polish for fun, and it's certainly _interesting_ to see what videos seem like po polsku...
aren't you Dutch very good at english tho?
In the sixties my dad was converting our house from a furnace, which at some time in the past had been modified from burning coal to oil, to electric baseboards. Part of the project also involved moving and updating the fuse box to circuit breakers.
Dad worked for the local power company and got a former lineman, certified for such work, to come make the change over. He had lost the lower part of both arms in a work accident. I was young and fascinated and he did not mind showing me how the hooks split apart and closed using wires that were controlled by shoulder shrugs.
I have been very, very careful around wiring ever since.
A scaffolder in New Zealand recently lost both arms after the metal pole he was holding to assemble the scaffolding touched the overhead power lines. He spent 6 months in the burns unit recovering. Electricity is nasty stuff. It makes me think how lucky we all are that electrical tradespeople risk their lives at work so the rest of us can relax with electricity at home to watch TV and make coffee.
I have my degree in electrical engineering with a focus in utility technologies, and I’ve been a journeyman lineman for 15 minutes. I am always thoroughly impressed with your level of understanding and what is a relatively complex focus. It’s rare I see a RUclips video that talks about electrical without me finding errors in the theory as it’s explain, however, your work is very impressive!
I suppose the only bone I’d have to pick is the lack of specifications regarding Delta and wye circuits in relation to grounds or short conditions. However, the diagrams clearly showed Delta or wye configurations 🤷🏻♂️ so all good!!
it goes to its room to think about what its done, only then can it have dinner
Professor in college: Today we're going to talk about electrical grounding.
Me: ugh boring.
RUclipsr: Today we're going to talk about electrical grounding.
Me: fascinating!
I'm not gonna lie, when I first saw the video title I thought "this is a question that does NOT require a 20 min answer." But now that I'm watching it, this video is so fascinating and I'm learning a ton. Thanks for making it!
I'm glad you mentioned the PDCI. I can elaborate more on HVDC grounding. In a balanced bipolar mode the ground currents cancel each other out.
Grady, a potential video idea...
Dry pouring concrete has become quite a rage lately. There is an ongoing argument on the internet about whether or not dry poured concrete is as strong as wet pour.
Since I know concrete is one of the things you've covered very well in the past, a video from you showing the strengths and weaknesses of both dry pour and wet pour would be great. Might help to answer a few of those wet vs dry questions floating around the 'net.
You’re a great teacher Grady. It’s crazy to think that you don’t have professional teaching experience. You’ve taught me so much about the world around me. From full sized dams, to weirs, and even the dynamics of water pipes. It’s amazing how much more interesting the world is when you know how it works. I really appreciate you as a person bro. Thank you
Back in 1997, a nasty October storm knocked down some power lines near my home. One of our dogs ended up getting her back legs paralyzed after going outside and had to be put down. We thought she stepped on a downed line, but after seeing your demonstration with the Hulk Hogan figure, I think I have a better understanding of what happened. Just going near the downed line would have been enough to do the damage.
There are back leg wheel chairs....
@@tungsten2009we don't know if that was the only issue with the dog after the incident
@@samsunguser3148 That's fair
@@tungsten2009oh brother. I'm sure they loved their pet and did what they could. Sure, in 1987 maybe they could have gone to a machine shop to get a custom wheelchair built for their dog, but I dont fault them if they didn't.
@@FreejackVesa Well, in any case, RIP little doggy, fly high.
An effective approach toward understanding one of the most misunderstood concepts of electrical distribution. I particularly appreciated that you demystified grounding as simply adding another connection to the neutral to complete the circuit.
I wish we had more courses for engineers in school on grounding! Great video and wish I had seen this years ago!
As someone who has spent days in the field sticking electrodes in the ground for geoelectric measurements, I really appreciate the (saturated) sand experiment. It's a good visualisation of how applying voltage to the ground can be used to measure its conductivity and therefore draw conclusions about its composition.
As a surveyor who has asbuilt and checked ground rods/ground grids it also helps illustrate why I was correct to scold guys trying to put gravel in instead of washed/clear rock when they were going shallow with the ground grid.
I've also done some line locating in the past too, and that principle works really well when doing line locating too. There was a really deep water line that had tracer line on it that was still not being located by most guys. I noticed a pond/big pool of water at the riser location where the pipe and tracer line came out of the ground. Instead of just using a spike to connect my negative lead, I just used a large steel tow rope, attached my lead to it and threw it in the pond. I found that line that 2 line locating companies (remind you, I'm a surveyor) spent two weeks not able to locate without much problem. That was pretty satisfying.
I actually caught myself asking myself this question during a road trip this past week. I found myself sleeping on the floor of a one room (10x12) cabin, on top of a ridge at 6,000 ft in elevation, while a big storm moved in. At the sound of approaching thunder, I began to consider how the cabin was grounded... or if it was. I hadn't been ready for rain, so ended up sleeping on the floor at the base of the loft, an aluminum ladder pretty much right at my back heading up to the loft, under a gabled metal roof. Now I have been in a fire lookout tower during a storm, and knew how the grounding worked on those with metal wires that ran over the roof, down the sides of the tower, and into the ground below. But, this wasn't a tower up in the air, and I was rather close to that ground. Now I knew the guy who built the cabin, he is a bridge engineer, so, figured, this was grounded sure thing. But.... I have not seen any metal wires running down the outside of the cabin walls, or along the roof. Maybe there were grounding rods in the walls Suddenly not sure, decided sitting against the bottom of an aluminum ladder, on the cabin floor, maybe wasn't the best spot with lighting coming. Got home and found this video and now have come to the conclusion.... yeah, wasn't the best spot. Turned out the cabin was not grounded.
If it wasn't grounded then it would be somewhat less likely to be struck by lightning than a grounded cabin would. Swings and roundabouts.
Thanks for making this video! I learned a lot from it. This helped me understand some things I had kind of intuited but didn’t know for certain.
I always liked how it's explained in circuits 1. Ground is just whatever you want to be your reference as 0v. So theoretically you could make the live wire the ground and ground would be -120v.
This dude worked SO hard to make this basic and accessible and my dumb self still missed all of it 😂
I'm glad you make these videos sir, and I hope better minds than mine can get something from it
What did you not understand?
@@kayakMike1000 Man, I don't even know the difference between current and voltage. I only clicked because I watch a lot of videos from the Chemical Safety Board and WorkSafeBC. The WSBC vids talk about what to do if you're digging and strike a wire, so I thought maybe I would get this topic.
Nope. Multivariable calculus? No problem. Basic electricity? I'm hopeless
@@blacktimhoward4322voltage: difference in potential (think pressure)
Current: flow of electricity (think how much water goes thru a pipe in a given amount of time)
Yeah, when the Dominos logo started spinning, I lost it. I am NOT an engineer. ✍️
@@blacktimhoward4322 If you are really good in multivariable calculus then you should be able to derive everything from the Maxwell's equations 😉. 😁JK
This is the first time I’ve ever left a comment. I’ve been watching practical engineering for a few years and I’ve always enjoyed and appreciated your videos. I am an electrician and you did a really good job explaining where grouted electricity goes .
I would like to see more videos on electricity !!!
Good ol grouted electricity
@@yeahmon215 Hey, it's his first comment.
@@simonruszczak5563nobody does a first comment without a spell check, nobody...
Even his lathe and wooden bowl videos?
@@yeahmon215nobody is perfect, including you 😂. lol
All your videos have been great. Very interesting and educating. Keep up the good work
Well done explaining this. Im an electrician and learnt this at trade school. Its a very complex topic and difficult to explain but you did well
As an EE who much prefers embedded systems and low voltage stuff, the idea of grounding into the actual earth has always seemed very odd, so I appreciate you making a video all about how it works and where it's used. Your videos are much more engaging than the power distribution class I had to take, maybe if I had you as a professor I'd be more interested in the field.
I would definitely be interested in seeing a video on HVDC transmission systems, I run across a lot of people with misconceptions about why we primarily use AC for distribution instead of DC, and I'm not really up to date on the state of HVDC projects, so it would be cool to see your take on how the technology is progressing and what benefits it gives us.
re: why we primarily use AC for distribution?
It comes down to MONEY. If we had DC power lines, we would need more copper.
@@pisspee2099 I don't think the primary factor is more material in the lines, but the expensive electronics required to increase or decrease the voltage in a DC system. Compared to a transformer they're much more complex. My understanding is that because DC transmission is significantly more efficient, it can make sense when you have few conversions, like long distance connections between grids, or when supplying power to customers that can use DC directly, but for things like household distribution the cost of the equipment and the cost to retrofit everything exceeds the savings from improved efficiency
There are only a couple of HVDC lines out there, mostly in China because they have a *huge* distance between population and production sites. DC outperforms AC only on very very long distances. The main issue with DC line is safety equipments.
Last year I was driving down the road during a storm. There was a tree that had blown over and leaning on some power lines. The part of the tree that was in contact with the power lines was smoldering, and I saw flames too. The fire department was on scene, but the guys were still sitting in their trucks. Pretty neat to see.
yeah, nothing the fire crew can do except tell people to keep clear until power gets there to shut down the line.
LOL, yea they were "F that", we'll wait until it's off.
@@kenbrown2808 Actually some german fire crews now have spray nozzles that allow them to treat fires near train lines without having to wait for the power to get shut off and someone to come out and manually ground the line. The key is ensuring droplets instead of stream and enough distance to prevent arcing.
@@namibjDerEchte train lines run a little bit lower voltage than our overhead power lines.
I appreciate these videos so much. And shout out to a fellow Texan! Was surprised to see the wurstfest cup and blacks reference too. Keep up the great work!
I like your videos with explanation. I am terribly interested in the area of electricity, its distribution, etc. But, this information went over my head. Anyhow, thank you for such professional and slick videos.
I'm a senior undergrad in EE, this video is great! You did a great job explaining the many many different meanings of ground without waving your hands about semi-true analogies, and you did it in an easy to understand manner. As a kid I used to be confused about neutral vs ground in typical house wiring, after all they are bonded at the panel so shouldn't they be the same? No, of course not! Current flows in a closed loop, ground vs neutral vs return path or whatever you call it is just whatever loop that current happens to be flowing back through. Now just wait till yall get to class and learn that all the electrons move backwards...
Or wait until you start learning about it from the physics side and find out the electrons aren't flowing at all in either direction! There are so many abstractions we apply to complex systems to make practical assumptions that can actually be applied.
That line: "you may have heard that electricity takes the path of least resistance" followed by pointing out that in fact, it follows ALL available paths at various levels determined by their individual conductivity. Yes! That jolted(lol) my brain a bit, and makes a lot more sense to me now. Well of course it does - we all know that we can design a circuit that splits into X number of parallel paths, each having a different resistance, and the electric potential will flow through all of those paths simultaneously at levels that are based on the individual resistance of each path. Excellent descriptions in this video. Much goodness.
thank you for reinforcing knowledge on these difficult topics!
As an electrical engineer I've always seen your videos talking, most of the time, about civil's but with this video I'm really surprised, you've digged into one of the most unknown and hard to explain topics in the matter of power systems and made it really comprensive, which is not that easy. very nice work!
PD:I see also that You have good food taste as well hahaha, try to make ceviche I think you have the skills for it!
electrical engineer that considers grounding as one of the modt unknown😅
@@omniyambot9876 As is not part of the main topics, commonly is assumed and not deeply explained. Which is impresive because of the importance of the matter, maybe for an EE not but for some professionals of the sector.
As a kid we had a Crystal radio which uses a ground wire and runs off the electricity in the radio waves.
Super helpful ! Extraordinary detail !!
I learned lots of new things !!! Thanks mate !!!!
I'm so glad you all do the Hello Fresh this way, the other RUclipsrs don't show them using the products they advertise.
In your generator thought experiment, there could be a current of about 2 microamps due to capacitive coupling. Of course if you drove the hot line into the ground, then you would get a pretty bad shock if you touched the generator, stopping which is ultimately why we have earth bonding.
If there is no flow of current, what would happen with the energy (if any) produced by the generator? would the generator spin super fast?
@@evanc1721 The generator itself wouldn't be producing much if any power. With no current flowing there would be no torque on the shaft and it would spin relatively freely. With no load the engine would likely rev up, but most generators have rpm governors that would reduce the flow of fuel to keep the motor spinning at the same rate. There would be some energy produced in the form of waste heat from combustion and some going to frictional losses in the both the engine and generator portion but there wouldn't really be any power produced.
@user-oj9iz4vb4q Thanks a lot, this is very helpful
As an engineering student I was lucky to get a job working on the construction of a small power plant for a big manufacture in Buffalo NY. the construction of the switching yard for the plant was fascinating to me and involved a lot of copper rope and rods, plus three or four feet of crushed rock. It always seems kind of crazy to me that after months of construction and connecting a million dollars of equipment that it all comes down to one person covered in protective gear throwing a three-foot lever to make the connection.
I'm an engineer on the civil/structural side of a company that designs transmission lines and substations, and I always love when I can learn and understand more about what the electrical engineers on the other side of the building do! Thanks for this!
You should do a video about using generators and whether it has a bonded Neutral or not. And When you want to ground the generator frame its itself to the ground and when you don’t want to. It’s crazy how many people don’t understand that concept but it is a bit Of a hard concept to understand. Awesome video thanks for posting:)
The top wires on a transmission line are called shield wires, often a smaller steel cable or now days a Fiber Optics cable ("OPGW") which can be used for telecom purposes. These are used to protect the conductors in the event of a lightning strike as they are grounded to the structure and consequently the actual ground. If the structure is steel, it itself is the ground "path" which is then usually tied to some sort of grounding rod or cable buried next to the foundation of the structure. If it is a wooden pole, then usually there is a ground wire that runs the length of the pole into the ground near the base of the pole. One of the lesser known issues with this is that people will attempt to steal the grounding wires off of structures because they think they can get money for the copper scrap. What they don't know is that it's actually just aluminum or steel coated with a thin layer of copper, so it's hardly worth anything in scrap.
You answered a question I had for along time and never asked. I kinda had figured the wire going down the wooden pole was ground but didn't know why. Thanks
We use 25mm2 copper in our city for the 20kv poles. and well all the other stuff too. No idea about the 110kv and 400kv lines tho
A remarkably well done video - an EE specialising in grounding.
I am an Architect in Germany and with our often used fully insulated water impermeable concrete basements... the mandatory solution for grounding (and lightning protection) seems a bit overkill.. as usual. Can be seen in this video (I don't know if you can link non youtube stuff on youtube..) ruclips.net/video/XYzJL2ujOa8/видео.html
Oh, you're an engineer? Explain ferroresonance in ungrounded systems then.
Thank you for sharing and clarifying few things. I love it
I worked in grounding and this video brought back much of what i learned at the time. We had an area that gets ice storms and the weight of the ice on the high temtion line and the return would cause the poles to break so we removed the reyurn and improved all the grounds in the areacfor earth returns. I remember working on a hill of shale and having to drive 100 feet of ground rod to reach the water table and get adequate grounding. Another time i could not get it and we realized that we were in a valley completely surrounded by rock and thus insulated from the world. We run half a million volt dc lines from up north with earth returns and they can tell in the US what we are doing. I remember being told how material from the ground rods slowly dissolves at one and builds up on the rods at the other. We reverse polarity every so often to reversevthis effect. I hope I've got this right as it was over 40 years ago when i learned this.
I asked my cousin (a railroader) what the metal straps I saw between sections of platform at a passenger station on the electric train line were for. He said it was for grounding, and that you could sometimes measure quite a voltage between structural elements and neutral on the line. Presumably these were generated by induction. Eventually I found the similar straps from these structures to earth grounds. If any sections became electrically isolated, they could present quite the hazard -- for instance for someone walking from one section to another. The straps kept all the sections at the same potential.
This is basic equipotential bonding. Everything in a substation or similar high voltage installation, even the fences and gates, are bonded like this, and they have steel grid mats beneath the gravel so that the ground itself is all the same voltage as the metal structures.
Excellent vid. It's not just a safety issue. If people knew just how much hell, poorly grounded buildings and ungrounded shields, can play with electronics, computer networks and security systems, they'd pay more attention.
Shielding is a subject worthy of a separate video. And would have to touch on how power returns and shielding works in situations like cars and aircraft don't have any earth connection.
@@mikebarushok5361 If the installers and tecs I used to talk to are any indication, it would probably be too boring a video for anyone to watch. I lost track of all the systems that had problems that were traced back to ground loops, unshielded cables and un-bonded building additions.
you're so trucking cool brady. Its not often I'm asked a question and find myself am unable to stitch some guess together. You asked, and all I knew was I had no idea, Rad! ty ty
This was incredibly informative. Thank you. :)
Nice video! Answering questions I would never think of but are so interesting
That's the best instructor! Telling you something that is interesting, but you didn't have enough base knowledge to even ask.
A video or a short on grounding methods might be worth doing. It's possible to ground in sandy soil using an Ufer ground (rod embedded in a block of concrete) because of how much surface area it creates.
Got me to sub with this video. Thanks . Make more this grid flow subject is awesome
great video! hope you keep putting out such quality content.
You should bring up the term "potential difference" for voltage; it makes things a lot simpler to visualise
did you watch the video? 10:36
@@blackkissi oh. I still feel like it could be better if they explained the term more fully in describing how voltage is a difference.
Once again you and your team have produced a very informative and easy to understand video. I have been in the heavy construction industry for almost 20 years and you STILL manage to teach me a thing or two in almost every video you make. You ROCK Grady!
love you pfp matthew
I have tried to learn as much as possible about electricity for 3 years and this has made me again more curious and smarter, thanks
Thanks for your clarifications. Great video
Love the content. I’ve been a industrial electrician for 8 years. I worked ungrounded and grounded systems and I love how you have demonstrated it. Good work and thanks for sharing that very cool knowledge with the world.
Wow! Excellent job describing everything here. I’ve been doing ground grid design in substations for about 4 years now and honestly couldn’t have described it any more intuitively myself. So cool to see my line of work actually get a mention!
Nice pine of work
11:30 In high school electronics class, our teacher always told us to test new circuits with ONE HAND, giving the example of if you touch with two hands, the path is _directly_ through the heart.
This was 50 years ago, but Hopping Hulk Hogan seems to illustrate the same point.
Makes no sense it will still go from hand to ground
@@KuroYKT I guess you missed the part about "directly through the heart."
Pure of heart and great if mind. Thank you for your effort good sir
The voltage drop across a SWER distribution system is substantial. The remote farm at the end of the line is going to need a very different transformer than one nearer to the source.
That's odd, they claim it doesn't matter how far apart two ground rods are, the resistance is the same because you're actually measuring the bulk resistivity of the earth which doesn't change. The farther apart the rods are, the more area there is to carry the current between them.
Hi Grady,
I always enjoy your videos. Thanks so much for taking the time to create & produce them!
As an industrial/commercial electrician for nearly 40 years (recently retired but still "working"), I found this video particularly interesting.
As a note: Nearly all modern transmission & distribution systems (with exception of rural SWER systems) always keep a grounded/neutral conductor present with the phase conductor(s), and that ground/neutral conductor is bonded to the earth at every line pole, and every transformer/switch/breaker/recloser location, thus enhancing the earth-ground "connection" on the neutral conductor sytem, which keeps the potential difference of the neutral & ground minimized, in the event of a physical failure of a transmission/distribution line (like a downed pole). I.e., lots of connections to the actual "ground" to minimize resistance and differential potential.
Anyway, great video! I always learn something new!
Keep 'em coming!
All the best from west Texas!
~Alan
also worth mentioning that there are ungrounded circuits that use isolating transformers, I want to say in hospitals or certain classified areas where arcs are a concern, definitely for pool lighting i think. And also that while these ungrounded circuits are indeed safer, if a neutral somehow becomes grounded, then a human could be unexpectedly energized, which was a concern in the early days of electricity, when most if not all circuits were ungrounded. The topic of grounding is very interesting, it blew my mind when I first learned the neutral and ground were bonded in the panel. I was going to school to be an industrial electrician but then covid hit... sadly never learned what I wanted to because the school shut down (programming PLCs and HMIs and that sort of thing)
Thanks for another great video. Speaking of the grid and substations, I know the purpose of circuit breakers, transformers and other electrical equipment, but I have to admit that except for transformers, I have trouble identifying those parts in a substation. Things look different when they are so big. Have you explained these things in a video? If not, would you consider including that info in a related video?
Grady, I love your videos and bought your book, I really loved reading it. Glad you are still finding things to make videos about, your passion speaks out wonderfully.
Another superbly-done presentation, thanks!
I hadn’t been aware that ground-return was a backup conduction method for HVDC transmission lines, it was fascinating to learn about the massive grounding array in the northwest and the ocean-based ground at the southern end.
I had some confusions when we learned this in school. I now understand it quite well. Thanks for the explanation
Loved the video. To detect a grounded phase in an ungrounded system, Neutral Voltage Displacement (NVD) protection is used.
at 10:40 you are measuring the different between resistance, not voltage =D
Whoops! Well with a constant current, it's essentially the same thing ;) I'll make a note in the description. Good catch!
@@PracticalEngineeringChannel haha yep , V = I x R , with constant current, variable resistance is equal to variable voltage =D
love your video so much, keep going!