Grounding - Safety Fundamentals (1hr:13min:19sec)
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- เผยแพร่เมื่อ 25 ส.ค. 2024
- www.MikeHolt.co.... Learn Grounding - Safety Fundamentals with code expert Mike Holt in this excerpt from his best-selling library - Grounding vs. Bonding video program, www.MikeHolt.com/bonding.
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This man has dedicated his life to educating us so we can be safe and do safe work. God bless you Mike Holt
I cant believe this video has been on TH-cam for 9 years and I'm just now watching it. This is the absolute best explanation of electrical grounding I have seen to date. Thank you sir! I am an industrial combustion technician and try to absorb knowledge on everything I work with and around. Subscribed and liked 👍
He knowledge never gets old....even after years. I took one of his live courses through the union years ago and I have never learned so much in one day. Not even in college. You truly never stop learning in this trade.
9 years passed and still taking me to school.... thanks for the knowledge mike
After many decades, changing just one word, from 'connect equipment to ground' to 'connect equipment to source', has finally clarified in my mind exactly what it is I want to achieve. Thanks!!!
Exactly. Many many decades for me too.
Long story short. 2 Months ago I saw this video by Mike Holt. 1 Month ago I bought Mike's Master Comprehensive Library program. Yesterday I passed my Ohio state Electrical test on the first attempt. But better than all that I have been trained better than I even knew was possible. AND I am teaching the other guys in my company things we were never taught! I am a very practical low key type of person. I don't recommend things lightly. This program is worth far more than it sells for. Thanks Mike, I'm truly thankful for all your efforts in these video's and the awesome text books.
Thank you Eric for the feedback about our products. We strive to make the books easy to read with great graphics and the video that accompanies the books is really a must to take your life to the next level.
Larry Haun and Mike Holt. Top hands.
Did you not go to electrical schooling before.. I did and my electrical exams seemed very easy.. I think holt is good for guys that had poor training or no schooling
@@possibility28able not necessarily true. I’m a journeyman with 4 years of a top trade school. I’m pretty knowledgable in commercial and industrial applications and I still learn bits and bobs from these videos. You can never ever think you know it all in electrical. There is always more to learn. Cheers🍻
@@J_M3444 There's always more to learn, but in regards to exams.. They were relatively easy for me after work experience and some schooling.. I'm still learning as well
Thank you for making this available to the public, I am happy that you cleared up my misconceptions. You have probably saved some lives....
Great video very enlightening. After 42 years of system design, panel building, power design and control system design, I can say this is the best 1 hr presentation on the subject matter I have ever seen!
+John Goodman Thank you John
Mike Holt easily makes the best NEC video. The man really knows how to teach!
John Ward UK electrician does it just as well his videos on grounding, equipotential bonding are excellent like Mikes presentation.
PHENOMENAL! Mike, you are the ONLY person who ever explained that "grounding" actual means that the earth is being used as a CONDUCTOR to get electrons BACK to the SOURCE. I was so confused about how the current would just "die" or get "absorbed" by the earth. This FINALLY makes it clear. THANK YOU SO MUCH!
Blew my mind
Do you mean during a fault or during regular operation?
when power companies began connecting the neutral from the primary and secondary there is a uncontrolled amount of power going back to the source which is the generating station numerous electrocution's have occoured because of this
+
So is grounding good or bad not An electrician. Is my grounding sheet going to hurt me or help me? Too confusing. Please help
Everyone in the electrical industry should watch this video.
Everyone should watch this video.
This is so good. Mike and the team are truly a blessing. You can't safely execute your job without having this knowledge and understanding about grounding and bonding.
Thank you for putting this video on the internet. You are saving lives.
+Terry Pullen Also saving copper!
Thanks for the laugh.
if you don't have an earth rod how can you trip the differential switch? yep with your body and you will have some pain.
@@SM-ok3sz Mk mm NM n
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This was a really FANTASTIC video! I'm an apprentice and I have to say, "From one analytical mind to another, I greatly appreciate your thoroughness in your program!"
Thank you Leo for the kind words and I'm blessed that I can be part of your career.
I worked for 30 years as a welder. We hooked up as many as 50 to 100 Diesel driven welding machines sometimes as far as 200 yards from the work directly to columns hoping the current would get to the stinger via welding cable and the ground through the numerous metal in a structural steel yard inside of a steel mill. I never once thought that there was anything strange about turning the welding machine as high as I could to generate 120 DC current to the stinger. I thought the cable was frayed or buried and nearly cut. I carried a kit to cut and splice welding cables because they often got damaged on the construction site. We would have welding projects that lasted weeks with people welding 8 to 12 hours a day like this. No one ever thought about putting the machines up closer to the welding project. No one got killed that way but I remember having to get down in a pool of water to do some overhead welding with a DC current with my body soaking wet. I couldn't load an electrode in the stinger. I had an assistant with dry gloves load the stinger and I would take the stinger to do the overhead welding. I got numerous current waves if everything didn't coordinate seamlessly. It was a one day rush job and we were shorthanded. We did what the boss told us to do. I also worked as a welding inspector. There were numerous times when the magnetism of the current flowing through the welding cable blew the metal out of the weld. I believe welders need a whole lot more training about currents. I didn't see anything in the welding codes about dealing with electromagnetism. This was a good eye opening piece of instruction. I was of the belief that the more grounding rods the better. I learned something helpful today.
I believe I need a good book on the fundamentals of current, RF oscillations an heat generated by currents and RF oscillations as well as electromagnetism in welding circuits.
I'm amazed that more people aren't killed or injured by the conditions you describe. There is a lot to learn in order to be a good welder, it's amazing that electrical fundamentals aren't the first thing you learn before you ever put an arc to metal. Gas torch welding is obviously a whole different principle but all arc welding whether it's Mig, Tig or Stick welding, it's all using electrical resistance and plasma arcs with very high amperage to heat metal. A/C welding is a bit more complicated but most welders are DC and the principles are quite simple to understand. It's all pretty well explained in this video even though it's not focused on welders specifically. Step 1 is to stop referring to the work clamp as a grounding clamp. And there is no reason to ever drive ground rods as part of a welding setup. Simply connect your welder to the work piece with a short and low-resistance path. Big copper cable with a good clamp attached to clean metal. Nothing more and nothing less. Electrical grounding considered harmful.
@@mukundamodell My welding instructors didn't really know anything from a welding school. They just welded or supervised welders. My brother was a welding superintendent and one of his guys got killed in a puddle of water with welding cables running through it and the victim also walking through it. Too many times construction contractors are so hungry for paying jobs they don't really know what they are doing. It's about having connections, a good "blow" and luck. Just like a war. The guys making the tactical decisions never get to the front lines of the death machines.
A voice of reason in the wilderness. The fundamentals of ohm's law always hold true. Thank you.
If we stay focused on the basics, then nothing is really complicated. Thank goodness for Mr. Ohm.
Mike Holt you deserve millions of views, appreciate all content will be watching all of them. 3rd year apprentice here really wanting to grasp every theory and aspect of the trade, learn the code book well and continue my hands on work.
You will do great things in this amazing industry. I'm honored that my work can be part of your journey.
I have worked on industrial electronics for thirty years; I thought I understood the power system pretty well. Thank you for this.
I've been an electrical student for a little over a month now and this is the best resource i've been able to find so far! going to watch many of your videos.. thank you for providing this information !!
Welcome to a wonderful industry. Maybe one day we'll meet.
Every ground rod obsessed inspector needs to see this video!
I wish I had these when I was going through school to really appreciate the concepts of electricity that any good designer should carry with them :( And simple to understand too!!
Omg, wish I had internet going through school in general. Learning right hand rules and left hand rules for current flow in windings, going to library to take out reference books, learning the ol slide rule to make calculations in electrical/science class was a class itself ( then next year calculators came out, what a god send that was). My point, to learn what’s in this video took a whole semester of time and a lot of effort to review; now it’s instant review and learning! Of curse, because we have people like Mike H who love to share their knowledge. God bless him.
Great video. I'm an Electrical Engineer and I can testify that many Engineers out there have learned this stuff incorrectly.
I hate these and some other false concepts: "Electricity takes the path of least resistance, current goes to ground, it's the amps not the volts that kill you."
Thanks for this video Mike. It’s actually pretty simple if you really think about it. You did a great job of explaining this and it makes so much more sense now.
When Mike said "I have 5 daughters and a wife" I understood a part of his character. Aside of this note good job, It seems the only one to have a goal of teaching and openly discuss the understanding of the code.
Your best video mike. You made it easy to understand. I liked the just go drive a ground rod and hook it up . plz keep putting these on TH-cam. We don't make enough money to buy all your videos
Thanks Mike, I'm glad to hear you in the instruction for the correct and incorrect ways to safety of electrical workings of all types from a to z.
some of this was a bit confusing. You produced some excellent graphs and explanations though, and furthered my understanding of grounding potential. This more or less confirmed my thoughts, as we always worked with sensitive audio equipment and occasionally we would pull a ground to reduce noise. It is an absolute nightmare working in large buildings, and some of the older houses have very strange and ignorant grounding situations. I appreciate you raising awareness to this... Sometimes people would randomly ground racks to strange areas of the building with only partial connections to ground, etc. Or improper connections to ground.. etc... so you'd get these weird potentials and backfeeding over audio lines... yeah it can be a nightmare. Def have pulled ground once or twice just to prevent backfeeding and to try and get equivalent voltage/impedence from each piece of equipment, to the ground at the panel. I Like how you specified that there are occasionally reasons to have ungrounded systems, or unique grounding solutions. In some circumstances in complex, hybrid circuits and in low-voltage situations, or when connecting communication lines to racks with different grounding potential, it can create difficult situations which require a lot of creativity to solve without putting people at risk of shock.
Great video , I am just now getting more into electrical work after 40 years in home improvements. I thought watching a " Grounding Basics" would be a good video to start with . I had no idea how important this is to know ! Thanks !
Wow…. It’s clear that your passion is about saving lives and not just for personal gain. Thank you Mike and keep doing these videos/public service
I love 'making a difference' and I'm pleased that you noticed.
Thanks Mike, it’s been many years since I first heard this video and it is such a great video that I am sure that has helped save the lives of others. All, the best, Steve from ElectricalTime
MIKE HOLT, THE MOST KNOWLEDGEABLE ELECTRICAL INSTRUCTOR EVER, THE BEST!!!
HYGRADE ELECTRIC INC.
Thanks dude....you probably saved my life.....I get it now and understand the voltage leaks into the ground giving me a tingle in the soil in and around remote distribution boxes That I grounded and bonded to neutral too....WRONG.....I get it now. How could I have learned something so wrong for so long from so many people who believed the wrong thing...GROUNDING CAN'T CLEAR A FAULT.... no matter how many ground rods you drive, it won't bleed off that much current
Thanks for drinking the kool aid...
You are absolutely correct at timestamp 52:30 . Ben Franklin created the "ground rod" that becomes 'connected' to the system and attracts lightning. But the PROPER way to do it is to repel the huge field. You will see this totally explained in one of Nikola Tesla's patents. The protection system looks somewhat like semi-domes above the protected "place" This is one of my favorite patents of his...but everyone choose Ben's way. It's a short patent with a main diagram that you probably would have shown here if you saw it. The patent title is something like: "Lightning Protector" I don't remember exactly.
Sir! You just increased my basic knowledge about electricity. I salute you on this educational video presentation. Thank you for sharing your skills. God bless your heart
You are most welcome, and God Bless.
How was I not taught this!!! Mike! You are blowing my mind! No wonder guys IN THE INDUSTRY treat electricity like it is as random and crazy as lightning. They don't know why they are even driving ground rods! Yikes! This is huge! I feel like knocking on all the electrician shops in my town and telling them all to watch this video! Yikes this is important!
I am studying for my test right now. 15 years experience. My boss of 9 years died suddenly last month and everyone (his wife and 6 employees) are looking to me to take up the company. These videos will be a huge part of me retraining all of us in the proper understanding of WHAT WE ARE DOING EVERYDAY! Yikes! God bless and thank you!!
I know... scary stuff. Eric, if you want to pass the exam the first time, please give my office a call at 352.360.2620. They will take good care of you. Ask them for a discount on the Master Library program.
Thanks Mike!
MikeHoltNEC. I ordered it today! Thanks again! Every time I tell guys in our field about ground rods in light of this video, and the false sense of safety we were trained in, it blows their minds.
Eric Bacon did you pass?
@@toyawest4817 Yes! On my first attempt! See my above comment. These materials from Mike's company are fantastic!
Best video explaining grounding on TH-cam, even the entire internet.
Everything is going ok with
Everything is going good with
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Yes
This is the most important video about mains electrical safety on the internet. Watch it several times. Thanks @MikeHoltNEC
I agree, it's so important for all to watch and understand.
THIS IS WHY MIKE HOLT IS THE VERY BEST TEACHING ORGANIZATION,,...............................
Mike,
Excellent, best video I ever watched regarding the two (usual) misconceptions...!!
A must watch. Thanks Dale.
This is a theory all homies should have down pat.
Hi Mike - I’m the guy that worked for SquareD and we shared interest in surge protection! Great to find you here:)
What do you recommend for contactor coil surge suppression
On a DC coil or an AC coil?
I hate to argue with him, but I install CNC machines and we ALWAYS DRIVE AN EQUIPMENT GROUND. I can’t get my job signed off without acknowledgment that I drove a ground rod
I have to say this is one of the most wake up calls for our business. we will be having a class base on this video. thank you.
This Sir was an exceptional presentation, thank you.
This video was so informative. Thank you Mr Holt, your an excellent teacher, I only wish I had this knowledge before I installed numerous ground rods all over the backyard :)
You are most welcome.
Anyone who gives a thumbs down on a mike holt video should go be a plumber.
RockyHamella don't send those folks to my industry, we are already stocked 110% with idiots.
Casey Thornton You plumbers make more money and are busier than electricians
hear hear
What all he is talking about is crap. He is taking up examples to support all his myths explanation. For example the earthing resistance will never be 25 ohms. The people who have given thumps down are the people who know electricity in depth.
I think the numbers you're referring to are meant only as a rough guide, not to be an exact measurement. There are countless other factors in the real world. You can't put an exact value in a book or video and say "this is the resistance of the earth". Please correct me if I'm misunderstanding your argument here.
Excellent ability to convey information for a laymen with minimal electrical training. Very knowledgeable and experienced.Explains fundamentals in electrical safety that's easily understood. I look forward to more of your videos.
Thank you, Mike and colleagues. I am watching this video again as review.
Education and science are there to prove the experts wrong! a paraphrase from Dr. Richard Feinman.
Thanks, this really helped me gain a deeper understanding of grounding!!!
Always add as many ohms as you can. Dry gloves, dry boots, and think about yourself in the circuit. Even when I work at my home, I work on live circuits only when I must. Pulling a wire tomorrow in my home, but will kill the panel and cover it with cardboard anyway. You die once.
I'm glad Eric said what he did about welding leads. I've always heard the work lead referred to as a ground lead, but calling it a work lead that allows the electrons to flow back to the machine makes so much more sense! I mean you're using heat to bond metal parts together. Awesome point. This whole video was such an awesome video. As an apprentice, years ago, I was really confused about the differences between grounding and bonding, and I can only contribute that to the fact that so many Journeymen are still confused as to what does what!
Great Video y'all!
Years ago (early 1970s) the welders did a repair on an automated riveting machine, when they were finished it would not run so I was called. I found that about 30 feet of conduit had become so hot all the conductors inside melted together and all the fuses had blown at the disconnect. The welders had attached the work lead to a painted surface!
Thank you Mike for this detailed video.
Hi Mike thank you so much! I work around electricity in an industry where the training is far far too basic to remain consistently safe and this as a supplementary form of education is fantastic! I plan on checking out your site and looking into your books as I aspire to do more work in electronics going forward and this was an phenomenal explanation that really helped me understand certain things I have seen in my own work. We do bonding all the time in our practices but everyone always called it grounding which is incorrect and the way in which we view our equipment grounds is horribly misunderstood in our industry where both are important you explanation regarding system and equipment grounds was the most helpful part of this for me in my work!
Thank you, and God Bless
Seriously this was the best explanation of grounding and why you get electrocuted
Qq
54:05 still my favorite part "look at this cute lil ground wire" rofl
'Me too!'
Thank you Mike, you are giving us a starting essential knowledge that ends overall on staying safe and protect our own life and others too.
You are most welcome.
Wow this is really a great video, I am so happy to have come across Mike Holt and his videos. This is the second time watching this and am learning so much in this alone. I plan to purchace his entire series of videos.
1. 0:55 Current leaves the source and returns to the source.
2. 2:20 Current does not go to ground.
3. 4:03 Voltage in a parallel circuit remains the same.
4. 15:18 How do you make the system safe? Turn the circuit off.
a. 17:38 How do you turn it off? Have an effective ground fault current path to every piece of metal that has an electrical circuit to it or that could energize it.
5. 21:45 We have system grounding and equipment grounding.
Love the video, we’re lucky to have access to this for free! Wealth of information here, I’ll probably play this back several times to sink in all this info... near the end it sank in good: electrons want to go back home not to ground... Kirchhoff’s loop equations!
Excellent point on Kirchoff's Loop equations. Never thought about that.
I concur.
Robust explanation. Fantastic!
I must review electrical service and equipment again. No were better to go then to Mike H.
Awesome, I recently started my career in the U.S in construction industry and so grateful that I found your page/channel and website. Thank you so much, your videos are awesome.
Great information.
How does this translate into an IT (Isolated Terra) power distribution system, like we have in the older systems in Our conutry (Norway)? We still get shocked if we touch an electrical conductor and ground at the same time.
I need to watch this video again, so much great information, thank you for sharing your knowledge
Thanks a lot for this presentation and explaining the fundamentals. im rethinking the way to use ground rods with my solar system. 👍
Is this Mike D'Antoni??
IF current leaves the source and returns TO the source, then why do we pay electrical utilities when this statement shows that they get back everything the deliver?
Electrons move in that system's wires, and they have to create that movement, which costs money. You pay for how much movement is used.
You Pay for the Work done to make those electrons move back and forth…. “Your killing me Smalls”
I undestood everything after having watched this video over and over again. Now I am going to continue sharing this valuable information to others, I even have to translate it into Spanish for people here in Colombia.
Yes!
One word Brilliant.......Mikes teaching is next level on this topic.
Thank you.
@@MikeHoltNEC no Thankyou sir, you have saved lives with this video. And btw just bought the excellent Donald Beeman book.
@@mathman0101 You are most welcome.
I've been an electrician since 2008 and I still feel like I don't have a clue what I'm doing.😞
Ditto, except as an engineer! Lol
Don't feel bad, since '89 Learn something new everyday
I've been in the trade since 1977 and an apprenticeship instructor for many years. Retired now.
I'm living on a fixed income, but its fixed pretty good, haha IBEW.
The issue as I see it is simple. The subject matter is pretty straight forward as
the master "Mike Holt" has just laid out for you. Don't complicate it.
Where the problem arises is when someone tries to fix your understanding of the subject
ie: inspectors, other journeyman, ect.
And you don't trust your knowledge on the subject. Stand firm and study this until you can
teach it.
I'll leave you with this...
I had just completed a similar seminar in the mid 80s by another very gifted instructor.
Shortly after that I had installed a multiple service installation (multiple
use large building) and the inspector turned down my grounding and bonding and I showed
him the workbook I had from the seminar (I won't mention the instructor but another well known
respected individual) and he looked at me with a puzzled look. Went back to his truck then returned
with a green tag (passed inspection). The real kicker on the whole deal is when he left, my workbook
was gone.
J-AMG AZ And you've stayed employed? You give me hope.
J-AMG AZ Sorry for my late response, I just found your comment. Interesting that you made the comment... exactly what part of the video do you think I'm wrong (I don't have a clue what I'm doing)?
50:00 is the meat and potatos, thanks for posting this!
12 years later and finally a clear explanation. Better late than never. Thanks
I passed NYC master electrician exam with Mike Holt Exam preparation DVDs . Very Helpful
That makes me so happy to hear the wonderful news!
After I learned basic electrical theory I always cringe when someone says, "electrons are trying to get to the ground." Once I sat through a lecture given by a woman from a utility company (who was likely their PR and not an electrician/lineman) who said this very thing. Long story short, I barely made it through the lecture without standing up and shouting, "No, No, NO! You've got it all wrong lady!"
Dear +MikeHoltNEC, your video discussed an interesting topic, which we would like to share with several Spanish-speaking professionals, so I request please activate the subtitle function in this video, so that the youtube automatic translation help us to people who only talk spanish. Thank you very much.
This is an incredible video. Seriously, this is the best conversation on grounding / bonding I've witnessed.
Thank you, it took me over 40 years to figure this all out.
I've always wanted to get into electrical work, so I've been watching Mr. Holts video's, and holy shit, this man knows sooooooo much! Wow.
JBJ, I have dedicated over 43 years to the study and teaching of electrical and business practices. I have to admint, I'm shocked at how much I do know... Have a great day and please get into the electrical industry. Give my office a call, ask for Jeff for him to get you some training material as a gift.
So your saying a 240 circuit returns to a source just as 120 returns thru a neutral?
Yep
Yes.. a 240 volt system is just 2- 120 volt legs. You still have a neutral and a gnd. Instead of 3 wires coming in, you have 4. 2 hot legs a neutral and Gnd.
Dam...I always thought ground rods we're life savers. Turns out their shit.
That's one way to summarized what I was trying to say..
It's better than not having one.
You are a great teacher. Thank you for sharing your knowledge. Much appreciated.
how energetic & genius you are! wow!God bless you Mike.
I'm on fire buddy... I love life, what I do, and helping others!
Mike got me at 54:05, haha just COME on! You can't possibly....
And at 13:18 ? :D
I want to be an electrician
+Kevin Spann Great to hear Kevin. Call the office and we help you get your education started 888.632.2633
OK THATS WHAT IM TALKING ABOUT ILL CALL YOU SOON, I BUSY TRYING TO OBTAIN MY OSHA 10 FIRST
+MikeHoltNEC Kevin, we have our program ready for you! Get me your phone number - Mike@MikeHolt.com.
only email kevinspann53@gmail.com
Thank you for your question Dan. Please watch the video again, it contains the answers to your questions.
This video was so enlightening. Now anytime someone ask I'll be like "dude it doesn't take the path of least resistance to ground, it's trying to get back to the source". Thanks for the information.
You are most welcome.
These videos are fantastic. My new obsession. It's frankly terrifying to know how close to death all of us are all day everyday.. as a kid we stuck metal in receptacles, touched electric cattle fencing, wired up old cords to old air compressors and so on. I've been shocked maybe 10 or 20 times and one time I couldn't let go and didn't know I had to for a long few seconds as everything went to vibration land and my buddy standing next to me started talking robot gibberish. Pretty scary. Respect. I want to know all the code and theory. Can't wait to get your books in my hand. Just hope they don't shock me into becoming an electrician.
"The Earth doesn't come with terminals"
100 years from now, I'm on my way traveling to mars... "where's the nearest earth terminal"?
If ground rods worked the way people think they do, we could all just drive them around our house and get free power from the earth.
but.... you actually can get free power from the environment around you. it's just such low amounts of power, it's pretty useless. between any 2 points in a circuit loop you'll have a voltage potential.
Great Video! really clarified the very important differences between (earth) grounding and equipment grounding conductors.
I find this video is really helpful even to people who don't plan on taking an exam on the NEC... or want to be electricians... or plan to do any electrical work... or live in the US in the first place. If one finished high school, has an inkling of what AC actually is, then this video can clear up many common misconceptions and help one not to kill themselves by blindly relying on them.
I consider myself to be knowledgeable about physics, and have a good intuition for it , but I never considered that a ground fault can _actually_ send current back to the power station through the earth, it seems magical at first. But it's fact, it made me look up single-wire earth return systems. I also never considered the mechanics of lightning restrikes before either. To be honest, this video started a fascination that made me consider taking a 12 month state-approved electricians certification course in my country... without any plan to work in the field.
Excellent!
Ive been watching this video for the past 2.5 hours rewinding back and fourth... cause im new to the trade i must say i enjoy the way explained it all... i can tell ya definitely passionate about ya skill as well as your teaching method is on point.... i definitely subscribed to your page and your my goto guy from hear on out.... Thank you for being Passionate about this Trade and Helping us not be misguided.
Thank you for the kind words.
Mike I undestood Now thank you very very much. Mike you are a beast at teaching. I admire you Mike. Truly you are from this world, you are not a human at explaining electrical concepts. You are definately a real expert.
How sweet, you are welcome.
Lightning is neither DC nor AC. It is more like an impulse signal or a series of occurrences of impulse signals. A DC signal should have constant magnitude throughout the entire time. Mathematically its magnitude must be same in -∞
DC current is not required to be constant, actually it's often pulsating after a switching power supply (full wave bridge rectifier). See www.electronics-tutorials.ws/diode/diode_6.html
But I do like the term 'impulse current'.
@@MikeHoltNEC well, I guess it could be considered mostly DC. However, it also has large transient current pulses before and during the main stroke. The main discharge is a massive flow of electricity that neutralizes built up regions of charge within a cloud, between clouds, or between a cloud and ground. The actual lightning flash is actually the culmination of a very complex process that involves the formation and growth of propagating conductive plasma channels (called leaders and streamers) as the air separating the charged regions begins to break down and become electrically conductive. These propagating leaders move in a series of discontinuous jumps, each accompanied by sudden spikes of current through the developing channels. Current spikes in these channels, as well the huge pulse of return current in the main discharge, radiate large amounts of broadband electromagnetic (EM) radiation (radio waves). You can clearly hear this as static in an AM radio. EM radiation is emitted from conductive plasma channels whenever rapid changes in current occur. DC does not radiate EM radiation. The radiated EM radiation before and during a lightning strike is clear evidence that the phenomenon is considerably more complex than a simple flow of DC current...
Some years ago the organization that I worked for in IT purchased a building and re-designed it to suit our needs. The existing "transformer pod" from the electical utility provider was deemed adequate and was not inspected. We installed our switches and routers and servers and PC's etc. One of the systems we had implemented was a high speed digital radio that connected to our main branch some 60 Km's away. We were having alll kinds of issues with disconnects, PC's crashing, noise on the phone lines. After several engineers came and diagnosd, all said noisy ethernet, don't know why. Turned out there was a short in the cable (underground) that energized the grounds all over the building with a potential to deliver over 30 amps of current. Instead of digging up the cable and replacing it, they put a #4 copper cable from the server/switch rack back to the equipment ground. It's a wonder they didn't kill some one!
I learned that I should not mess with electrical stuff. Thanks for the potential life lesson algo
FINALLY--a clear and concise explanation of grounding. Well done!
You are most welcome.
Placing grounding devices in places that are not usually frequented - is true not false, if you still making the path to the conductor as short as possible.
Because the grounding in case of lightning hit and equipment grounding are requiring two things that are quite opposite. As it creates the gradient voltage we need to place it as far as possible to reduce the consequences for step potentials, the same time we need to place it as close as possible to avoid internal building damage during ground path seeking time.
Correct me if understood your lecture wrong. Excellent videos! Thank you!
This is gold! I’m an electrical engineer and thought I understood this. Wrong. Thank you very much!
Thank you, yea another engineer that 'get's it!'
Im with ya!
Havent retaken the county test yet til im 100% clear on all the aspects in our trade.
Man! So helpful thankyou!
As an accountant...i understood this gentleman the first time! Well articulated!
Wow, I wished the electricians understood this!
Lovely attitude, tone, and presentation. Would make a great college professor for such topics.
Thank you!
God bless, going to start a pre apprenticeship program for electrical in September, and this is great knowledge!
We have a program for that, please email Mike@MikeHolt.com so I can get you some Free stuff for your students.
I'm watching this in 2020. And believe me, its very difficult to go back to the perception I had before watching this video.
I know, when you try you say to yourself - how is even possible I thought those things...
I agree with Chris below. Thanks for the insight.
Awesome video. 40 years in the trade and I've driven a lot of ground rods. Light poles, services, generators, outbuildings and many cnc machines. I was involved in the aftermath of a lightning strike to a utility pole adjacent to a factory full of cnc machines that I had grounded per code and drove rods per mfg specs. There was a blue flash of energy throughout the building when the strike occurred. It was described to me as I wasn't there. Most of the machines with rods were damaged and now I know why!! The flash was all that energy finding its way home and going up through the machines as you described. I never thought a little piece of #6, any wire really, would solve anything. My thoughts on light poles were the same too. 2' diameter x 10' of steel reinforced concrete is a hell of an electrode planted in the earth. What is that Itty bitty wire gonna do! But we follow what the engineer has on the plans instead of common sense and electrical theory. Bravo Mike, for making us all better electricians!
Yes! I'm so happy that you drank the cool-aid!
I love the way you teach and explain ! 👏🏿👏🏿👏🏿👍🏿❤❤