Neutral-to-Earth Voltage (NEV), NEC 2020, (44min:40sec)

[@nsh399]

Mike you've been such a blessing throughout the years...I was first introduced to your books back in 2001 I was on my 2nd year of apprenticeship. May God continue blessing you and your family. 🙏

[@MikeHoltNEC]

Thank you and now you're an adult! My wife is waiting for me to grow up...

[@that1electrician]

Yo Mike you the man. I went through one of California's most intense apprenticeship programs which included 8000 hours OJT and 200+ books from basic theory to PLCs and everything inbetween. I still am completely lost on a lot of subjects especially grounding/ bonding, and "voltage". Those 2 subjects are the hardest to fully understand in my opinion. Thank you for the content and blessing up my confusion!

[@MikeHoltNEC]

Get my Bonding Library, book/videos. MikeHolt.com/Bonding

[@ronald5728]

8000 hours?

[@driftingburrito895]

@@ronald5728 yup, California requires more hours on the job to become an electrician than a cop

[@ronald5728]

@@driftingburrito895 Wow!!! That a lot of hours; almost 4 years. It's definitely more complicated than training to be a cop. lol

[@Casualyoutubee]

Alaska is 8,000 too 😝

[@joecrozier3236]

Thanks for another great video, Mike. As a utility P.Eng. I've seen both cases over the decades: cause of high NEV on the utility side -- and the customer side. Regardless, it's ALWAYS a good idea for the utility to put its own house in tiptop shape. Avoid finger-pointing. Even if you measure less than 25 ohms at the pole or pad, improve it anyway -- get it down below 5 ohms! It might solve the customer's problem. But even if it doesn't, you're still cutting the step+touch voltage risks to your linemen and the public.

[@mernokimuvek]

Some countries in Europe require it to be under 2 Ohms.

[@TimPerfetto]

Thank you for your passion explaining these mostly unknown yet important concepts. And putting it out there for free.

[@MikeHoltNEC]

Thank you for noticing.

[@85agyoung]

Mike your videos are great. I work for a large utility in NC and I am a protection and control tech. I have a great understanding of electrical fundamentals. It is hard for people to understand step amd touch potential so I understand your explanation.

[@MikeHoltNEC]

Aww, thanks for the feedback.

[@EricDennison]

Thanks for this awesome presentation. Now I know how to think about and describe the 10v NEV that I am seeing at my rural location (enough to hurt, but not kill).

[@n4hoop]

Great presentation and explanation of NVE Mike, i really learn how it measured the NEV to a ground referencing the amperage load on equipment house I'm an a fire alarm technician on a growing industry and safety thank you and God bless you all

[@paulshephard701]

Hello Mike. Thank you for putting the Neutral to Earth voltage into perspective. A truly amazing presentation. Thank you.

[@johannesdesloper8434]

Haha, clamp a volt meter to a blade of grass. Your video's a very helpfull Mike, thank you. I've been a power plant operator and they taught me that 25 KV is the max. for powerplant generators. Has to do with air (H2) gaps and arcing over inside the generator. And indeed that grounding and bonding video is a great vid, vieuwed it many times.

[@MikeHoltNEC]

The blade of grass actually works great!

[@johannesdesloper8434]

@@MikeHoltNEC I've heard it before from certain kinds of trees in dry areas that root deep and ofcourse there are salts and water in the roots. I'll try it one day, living in the endless grasslands here.

[@ebaystars]

we used to use long grass stalks to test if electric shock fences were working by holding one end and slowly sliding it towards the wire like a variable resistor I am not sure "use a blade of grass" is worthwhile advice other than a joke comment

[@brianmcdermott1718]

Great discussion Mike. Thanks for all you and your guests work.

[@MrQualifie]

Dear Mike, I am from Mexico and I really appreciate that you can teach many people. God bless you. I got the ultimate training library 👍🏼👍🏼 it going to be profitable because USMCA agreement 🤝🏼 🇺🇸🇨🇦🇲🇽

[@MikeHoltNEC]

I am so happy to hear the great news!

[@ridefast0]

Very interesting for a UK viewer where we do things differently than that! Almost bailed at the god-credit which felt jarring, but I am glad I stayed and it made me think! We have a 3-phase transformer for each area of housing, where the low side neutral is grounded, and 3-phase+N LV runs down every street with houses connected sequentially to one of the three phases and N. Single phase is about 230V but there is about 400V difference between my live and my neighbor's live! If I want temporary 3-phase I can talk nicely to my neighbors both sides and run extension cables.

[@cwmalone]

One of the only great things about the Internet is the wealth of information that Mike Holt provides, free of charge. Thank you, Mike!

[@richardcranium3579]

Mike, the biggest difference I’ve seen between two bushing and single bushing pots (distribution transformers) is the location of the neutral connection of the primary winding. One style pot (single bushing) ties the neutral end of the primary winding (H2) to the tank grounding lug and the the other style pot (two bushing) runs the neutral end of the primary winding (H2) out through the second bushing on top. The co-ops here use single bushing pots until they build a two (open Y open delta) or three (YY, Y/Delta, Delta/Delta) pot banks. The investor utilities here use two bushing pots on single installations and transformer banks. To myself the two bushing pot is less hazardous to the lineman working on the secondary side……If a lineman cuts the ground lug connection (single bushing) to the system neutral with the transformer energized he exposes himself to a difference in potential between the neutral (pole ground) and the now ungrounded end of the transformer primary winding (which will read at primary system voltage). The two bushing pot ties the neutral connection of the primary winding to the multi-grounded neutral in a configuration with less exposure to the lineman. Thanks for the videos!

[@stargazer7644]

Those are guy wires, not guide wires.

[@gregmiller-breetz3368]

And a lot of them have insulators blocking the path to earth.

[@shaus81]

That's very sexist of you.

[@stargazer7644]

@@shaus81 It's actually rather nautical of me.

[@mmwrangler]

Great videos & content Mike . I was working on a facility years back because of workers getting shocked . The neutral grid from the power company substation that was over 1000 feet and across the road was causing our grounding systems to energize and shock the workers on everything that was grounded.

[@MikeHoltNEC]

That is true...

[@phyde1885]

@@MikeHoltNEC I'm a retired EE from ITT,worked at COBRA as a QC Inspector for 3 years,then at RANK for a spell. Wished i had stuck more with the industry,but i'm self learning MORE PC and YOU to get a better grasp at this particular subject. Also did a summer as an Union Elec. So i've got my hands dirty in all over. I've always said,"I ain't Burnt a House down Yet !" And i did save a Life by 1 of my wire schemes. This is before i ever saw your channel. Instead of putting in GFCI sockets in a bathroom of a house i was re-wiring,i decided to protect the WHOLE Bathroom with 1 Breaker. His daughter was showering in the unfinished room,reached around for the switch,stuck her fingers in it and tripped it, and SAVED her LIFE !! When i found out,i about $#!t my Pants !! Makes me kind of fuzzy inside knowing i had done the RIGHT choice !! In this instance a GFCI would have been nowhere near to the job. Then when i was on the Union site,i had a Journeyman that had wired a 4 wire Delta transformer wrong. I jumped up at sat on it,and it LIT me UP ! DAM 440 SMARTS!! And he was suppose to be the Master !?! I know,i shouldn't have jumped on a Box and TRUST it,my BAD ! So it 's "YOUR" channel and vids that i'm turning to for that Knowledge in this Vid and Field i look to,to round out my other half i didn't get. P.S You have my Brother and sons name too !

[@mernokimuvek]

Medium voltage distribution lines in Europe have only 3 wires used. The neutral at the substation is grounded through a variable inductance( Petersen coil or Bauch transformer). Resonant/ reactance grounding allows the reduction of ground fault current to 5 Amps or less and the line can be in operation under a single fault.

[@dane5167]

neutral is supposed to be 0 relative to the earth. and we make it 0 by making the ground the same as the neutral side of the transformer. the reason you start to see voltage miles away on the neutral to the ground is because the voltage drop on the neutral (KxIxD) increases, while the ground stays the same. a voltage tester is designed to measure the relative difference between two points. in other words, the neutral miles away from the source, drops volts, while the ground stays the same. so the tester is showing you the difference @mikeHoltNEC please correct me If I'm wrong I don't want to mislead anyone I only want to clarify for myself and others

[@jawaharlalkaramchetti5675]

Your explanation is Excellent. I watch your programs from India

[@daved-ds8pm]

One issue I think NEV creates is with high magnetic fields in the house. Even with NEV around 1V, the neutrals will be directly connected to ground paths in the house (like pool equipment)...which creates a one-way current of hundreds of mA...which creates AC magnetic fields in the documented unhealthy range of >5mG. If you're far enough away from the circuit wiring carrying this current, then the magnetic field will drop off and not be an issue. For me, the circuit was running in the crawl space under the master bedroom and was subjected to the higher magnetic field during sleep.

[@charlespaine987]

Mike just an experience we had (we 15 yo boy , my father , and a friend master electrician )were stripping out uor old in preparation install new electrical service. Power wires were cut at the pole ,meter was removed but common/bare wire remained intact . As we were striping out “master cutoff “switch there was a 2’ arc and the whole street went dark. It turned out our house had the only ground on the entire street. In five minutes the electric company had 5 trucks on the street repairing grounds on every pole and house . Luckily no one was injured short of a laundry issue of brown underwear. If i understand you correctly basically all those readings were stray power loses . Now i see why Europe doesn;t use the same ground system as we do theirs seem to be a little safer. Still a bit confusing but i learned some thank you. I viewed a video on emergency/aux generator “grounding “ still sorting that out in my mind.

[@comingtofull-ageinchrist6736]

I have a chart that shows what Mike is talking about resistance or impedance of the earth depending upon the soil. moist soil (swampy like conditions) has the least resistance; as soil temperatures increase, resistance or impedance decrease; as soil temperatures decrease, resistance decreases. Dry soil offers more resistance and moist soil offers less resistance. At 68 degrees F, the chart shows 7,200 ohm-centimeters; at 23 F, it's 79,000 ohm-centimeters; at 14 F, 330,000 ohm-centimeters. Depending on the soil type: rocky, sandy, clay, shale, all effect the resistance of the ground in relation to grounding electrodes. This is a study done by ABB, who offer grounding and bonding products. They have charts that will show the different soil types and the resistance that you can expect for the type of soil in the area where you have to drive a ground rod or where you. Anyone can look them up and find the same charts.

[@MikeHoltNEC]

What value do you think this document serves?

[@comingtofull-ageinchrist6736]

@@MikeHoltNEC for one, whether I need to drive that supplemental ground rod for a service if my resistance is more that 25ohms. I think that it helps to serve what to expect on soil resistance for the grounding of a service disconnect. Most new homes have steel in the slab extended up to connect the service to ground, so it won't matter in a lot of cases. You mentioned the topic in your video, so I was offering a reference for what you said mostly, Mike, so that what you said had some kind of data to back it up, so I really offered it to support your comment. Because it was data that I had saved, and ABB is a reputable supply company, so I used it to give support to your comment.

[@MikeHoltNEC]

@@comingtofull-ageinchrist6736 I understand, thank you for helping me help others!

[@dixondavies]

Was this made before GFI's were introduced ?

[@Mikecianfrocco]

I thank God for you mike !

[@kd7cwg]

Whenever I get to a new campground, I check the power pedestal outlet with a voltmeter to verify it is wired correctly. Then after plugged in measure my Converted bus to the pedestal to verify there is no voltage to create a hot skin condition. I need a better voltmeter to measure to the earth. The one I have is cheap and does not go down to tenths of a volt.

[@ronaldkovacs7080]

My take on multiple grounding points on the utility line: If the neutral is open for whatever reason upstream of a distribution transformer, and lets say the phase voltage is 13kV to ground, primary current in transformer becomes 0, voltage on neutral terminal of transformer primary winding is now 13kV to ground. If primary neutral terminal is connected to secondary (240 Volt) neutral, the neutral wire entering a house will now be at 13kV to ground.

[@MikeHoltNEC]

You my friend totally get it. Not many will understand your comment! Congratulations.

[@persona250]

This would kill an awful lot of people . The primary and secondary neutrals are not connected together .

[@D.Hozzie]

Thanks Mike…..Brian…..!

[@marktheunitedstatescitezen185]

Praise Jesus !

[@NoName-OG1]

At one point in time while I was in the military, and doing lineman work, and someone described grounding to earth as NOT bringing the transformers, panel and grounding conductor’s to the earth potential. But bringing the local areas of the earth and grounded items to the potential of the items that were grounded to as near as same. So the multi point grounding is trying to make that neutral and the local grounding at the local earth - as close as they can be to each other. A few hundred feet away - that might have a different voltage potential - and that area would have its own grounding and the ground plane in that area would be the closest it can be due to the grounding in that area.

[@MikeHoltNEC]

What you described is not the reason for a multi-grounded neutral system. But it's a nice story.

[@NoName-OG1]

@@MikeHoltNEC WOW a A response from the man himself! By the way, I’ve been on your forum for a number of years, and watching all of your work which is 100% great! With the opportunity to bend your ear, I figured I’d say that. Anyway, that’s just the way it was described to me once upon a time. And always seemed to make sense. From a utility, or a lineman’s point of view. Richard, as you know, is much different than premise wiring and grounding. Edit The other item that was also described to me back then. But she may or may disagree. What is that without local Grounding, there technically would not be a fault path if a line fell and hit the ground… so on top of making the neutral conductor, the same potential as the earth in that area. It also created a method of clearing over current protection, if a line fell in that area. Again, you may disagree, but that is how it was described to me some 30 years ago. And it always felt like it made sense.

[@bobpoortinga7352]

One of the main purposes for a multipoint ground system in the utility network is protection from lightning strikes.

[@brianmckerrow817]

Will watch later but I KNOW when knowledge is precious 😌. Thank you fir you invaluable value.

[@jimr164]

Sorry at 19.50 you start talking about water pipe. You are doing a great job.

[@matthewbeasley7765]

Just to refine the description of what happens during a phase to neutral fault: With long distances, there is considerable voltage difference between the substation and the point of fault for a distant fault. There is a drop in the phase, but in addition, there is a drop in the neutral. The neutral is pulled towards the faulted phase voltage. That increases the phase to neutral voltage of the other two phases _at the point of the fault_. The unfaulted phases do not increase (much*) in voltage with relation to the substation. By multi-grounding the neutral, the neutral becomes effectively a very large conductor, so the neutral can't be pulled towards the phase near as much. *really getting into the weeds - there is mutual inductance coupling, and the mutual can act as a transformer to boost the voltage some. But the effect is much smaller than the effect of neutral shift.

[@xenadu02]

CA tends to use delta wired transformers (two bushings, primary is connected phase to phase) to avoid high NEV. Because it doesn't rain for most of the year we have a lot of really dry soil that doesn't conduct very well so it is more difficult to keep a neutral return properly at ground potential. Delta means you don't return primary voltage through the neutral at all. Unbalanced loads can cause larger voltage changes to the phases though.

[@MikeHoltNEC]

I didn't realize that, that makes total sense! This explains why my experience with 'stray voltage' issues have only been on the East Coast of the US. Thank you!

[@GilmerJohn]

So on rural circuits, the "distribution" is simply two conductors without any attempt to ground anything until you get to the local transformer and there it's only the secondary? You save on grounds but you have to high voltage insulate both conductors.

[@brnmcc01]

@@MikeHoltNEC xenudu02 is exactly right. Also there's a lot of mountainous terrain and dry rock isn't a good conductor either. However, one advantage of using a WYE distribution system besides the unbalanced voltage problem of a Delta system, is that if there is a primary to secondary fault on a customer transformer, hopefully the small fuse to the single bushing will blow before the customers equipment blows! Also another potential problem with a delta distribution problem is what happens in a storm, if one phase drops to ground from a tree, storm damage etc, the other part of the wire downstream from the substation after the break will still have high voltage on it, backfeeding from all the other transformers that are connected to another phase to that broken wire. What they have been doing on the west coast lately and in other highly loaded rural areas, is changing the 7200 volt transformers out for single bushing 14.4kv and doubling the utility distribution voltage, or in some high growth areas, even going to 33.3 kv distribution voltage, and using 19.2 kv single bushing transformers (160:1 turns ratio). Higher voltage = less MGN current = less NEV voltage. The resistance stays the same, so the formula you gave for NEV of E = I x R, so it can be simplified to the lower the I value, the lower the E value, which makes everything safer, and avoiding the problem of Ferroresonance problems on a Delta wired MV distribution system.

[@flhusa1]

One more thing the power or utility company can climb the pole where your transformer supply is and check each 120v feed to see if the current is equal .

[@lewy1]

Some utilities don’t ground their guys on distribution. He is right though every riser pole and every transformer be it underground or overhead will have a down ground. If the pole had lightning arrestors the pole will have a down ground. Typically if it’s just a street light it’s not likely there is a down ground.

[@MikeHoltNEC]

I did not know that! Thanks and Merry Christmas

[@jongarrison8826]

cool video. very interesting. i have a question to which i cant find an answer. why do i have anywhere from 2 to 4 VAC when i put one lead into the soil of a house plant and the other lead into the ground of a wall socket? i did this on two different plants.

[@robertpeters9438]

The power of the load is carried through the wires. But, insulated wires on poles can develop substantial static voltage at surprising currents. These could kill you, so the locally isolated utility circuit must be grounded. Secondly, insulators leak current. So, the local circuit must be grounded or the neutral would rise close to line voltage from leakage. Thirdly, transmission lines induce voltages in soil and ungrounded wires. Thus, the need to keep the neutral of the local circuit loop grounded. Right?

[@germanarellano5119]

When you were talking about GEC. The correct word would be he is at the same potential because the grounds are in contact with the earth the person is standing on. Now like you said if he disconnected the cable to the ground rod and he grabbed each with one hand if there was enough current flowing back on that wire to the ground rod he could die☠ because he is in series.

[@dadebeb810]

The ansewer for number two, should be , for any current to flow through the body, there should be a potential difference ( some voltage) between the hand and the foot, but since the neutral is grounded, in to the earth by electrode, or pipe, or any means, your foot and the neutral would be at the same potential, so there will not be any shock, just an idea

[@MikeHoltNEC]

Nope, watch the video again. Grounding does not reduce NEV voltage.

[@tedlahm5740]

No neutral conductor on my neighborhood Pole mounted step down transformers. All of them are GROUNDED , yes at the end of the primary winding. But no such neutral conductor IS OBSERVED? Multi point grounding, yes because all pole mounted transformers are grounded. Please help as can not see this neutral conductor.

[@miguelac6872]

Mike, What is the behavior of subatomic particles when there is a voltage but no current? I fully understand that if there is no load there will be no current since there is no path for the circuit to close. When we use a phase tester and insert it into the phase receptacle of the electrical outlet, it turns on showing that there is electric potential at that specific point. What do you think that happens with the electrons? are the particles inside the atom polarized or charged with potential energy waiting for a path to flow? I hope you can get my point.

[@MikeHoltNEC]

Never thought of that, so I'm speachless...

[@mathman0101]

The answer relates to the physics around electromagnetic fields. You can watch Professor Walter Lewin’s (formerly at MIT) superb lectures on electricity and electromagnetic theory. The mathematics may be beyond 99 percent of licensed electricians math knowledge but if you persist you will get a lot out of it.

[@carultch]

It is arbitrary where we define voltage to equal zero, as what ultimately matters is the voltage difference between two points. In Physics, it is defined as zero, infinitely far away from the setup of charges in question, because that's what simplifies the math as much as possible. For an electrician's purpose, you define it equal to zero at ground. What voltage indicates is the energy per unit charge, that a particle has at any given point, relative to a reference location at which we define it to equal zero. It means there is a path along an electric field (due to a setup of other charges) from the point in question to the reference location, that would either on net give it energy or take energy from it, as it travels to the reference location. Whether the energy is given or taken depends on the product of the signs of the voltage and the charge travelling the path. Voltage is known as "electric potential" in physics, because it is the negative potential function of the electric field. Potential function is a term in vector calculus. You'll also see the term EMF (electromotive force) when magnetism gets involved, a nuance that accounts for the energy exchange no longer being path-independent.

[@Ormaaj]

The mobile charge carriers in a solid state conductor are described by the Fermi-Dirac distribution. Thinking about the particles is not a very useful level of abstraction for reasoning about the bulk properties of materials and low-frequency signals with very long wavelengths that electricians are mainly concerned with.

[@jimr164]

My home built in 50's only had water pipe bond? You do not mentioned that ,or did I miss it. I am in New jersey. Why not talk about water pipe gounding?

[@lit1electric]

Mike does service changes in his suit.🎉

[@MikeHoltNEC]

Let's make it clear, I hate wearing a suite... but I'm Mike Holt, and I'm told I have to...

[@tedlahm5740]

Philadelphia area. Multi point grounded system at every transformer pole. Yes, but can not OBSERVE a NEUTRAL conductor from pole to pole. Believe this is telling me the SUBSTATION is using a 3 phase 3 wire distribution system. thank you

[@defytyrantsofmississippi2198]

This is the capacitive effect of 2 conductors(the primary neutral and the earth) running parallel to each other and have opposing magnetic fields because the current is moving in opposite directions in them. The lower or closer you have the primary neutral conductor to the earth the greater the capacitive effect. The further away from the substation the greater the capacitive effect. The greater the capacitive effect for a given current the higher the neutral to ground voltage drop.

[@MikeHoltNEC]

You are 100% correct! Thank you.

[@fandulan]

thank you sir for a plesant lessons you have

[@hippo-potamus]

I wish you had explained the reason why those fatalities took place in relation to the video, gone over how 19v could be deadly, left off the multimeter mistake and what does an isolated screw driver jabbed into the ground have to do with your multimeter test? Was the screwdriver wire tied into your grounding system?

[@tonybrock5288]

Thanks for the info! Where do I find your video on measuring NEV and making those places safe?

[@MikeHoltNEC]

MikeHolt.com/nev

[@Blind_bag-R]

About the parallel ground wiring within premise, you explained what the code requires, but why it so requires?

[@flhusa1]

Please explain that a ground wire doesn't carry any voltage or current under normal circumstances.

[@MikeHoltNEC]

Current requires voltage, so no voltage, no current.

[@hinojosa552]

I think if you have any load running in your house , you will get shocked , now if you don't have any load running in your house , you can not get shocked , I think that was one of the questions someone asked, am I correct??

[@tedlahm5740]

The further you go away from the Sub Station you will INCREASE the resistance (in the conductor) and thereby REDUCE the current. The difference is you NEV (neutral to earth voltage DROP) Is this the correct concept?

[@tedlahm5740]

Correction: Now believe the CURRENT is independent of the of the conductor resistance. thank you

[@shadmtmtn1603]

The DC transmission lines are used for long distance (over 100km or 60miles) and high voltage (between 100kV and 800kV), all techs in this field are labelled HVDC, for High Voltage Direct Current. No lines to 1MV or over yet, but only a matter of time, in my humble electrician opinion ! The use of direct current (DC) for long lines is due to alternate current (AC) lines' capacitance, increasing with lenght, increasing the current in the line to deliver the same power to the user. The limitation to high voltage use in transmisson of electricity, above the Ohm's law, is the cost of high power conversion units at each level of the conversion in DC, while a 'simple' transformer is enough in AC, folding the price by 100 more or less ! Great video 👍🖖

[@dixondavies]

Not true. AC 3 phase high voltage transmission is the norm. Example 735kv from north Quebec to Montreal 2000 km. Rectification and invertion back to AC is inefficient. Virtually all generation and distribution is AC. DC is used when it is not possible to synchronise the sending snd recieving grids. Been in this business for 40 years.

[@randygomez952]

I'm so glad you made this video sir

[@flhusa1]

Remember electricity has to travel back to the source that created it . That being said electricity takes the path of least resistance . Think about that for a second it takes the path of LEAST RESISTANCE . It doesn't take the shortest path . If someone wires something incorrectly and that something has no wire to take voltage back to the utility and it enters the ground or earth no one knows which path it will take. If you get in between the path it is taking you will become a conductor . Think of a dog on a cable run. The dog can only travel along that cable . If the dog gets free from the cable it can travel anywhere . The dog loves to bite and if you get in its path you will get bitten. Please tell us where to get a stray voltage detector or how to use a multimeter to check for stray voltage especially in rural areas where no permits are required and people constantly wire things incorrectly .

[@MikeHoltNEC]

Not the path of least resistance, all paths back to the source.

[@98grand5point9]

Where I have worked the normal transmission voltage is 13.8 kv.

[@paulhoda133]

Greetings from Eastern Europe (Romania)! I'm struggling with this question for years: is there any way to reduce the NEV stray voltage on the consumer side? Like a super low resistance electrodes system(0.5 Ohm or so)? Or the equipotentialisation bonding is the only way to stay safe from risk of NEV electrocution in risky places

[@MikeHoltNEC]

Not much that can be done,; watch the video again, and watch MikeHolt.com/Pools.

[@paulhoda133]

Amazing! NEV is useful for measuring improper bonding. And even if NEV is elevated, a proper bonding prevents shocks due to stray voltages from NEV. Thank you!

[@ebaystars]

research making your own site safty grounds by making a UFER GROUNDING SYSTEM when building a new build using concrete and rebar

[@tedlahm5740]

The picture graphic you are using SHOWS the substation is using a 3 phase 4 wire Wye distribution system 7,200 volts each phase. comment please. If the substation was using a 3 phase 3 wire Delta system, then No neutral on the poles. comment please

[@amilcarcruz5757]

Great!!

[@dennyedwards4098]

is 2.4-3 NEV in the pool normal

[@larrylynn5047]

There also is what we call anufer ground another earth grounding system. And every utility pole is grounded, no matter how far apart..

[@Jnglfvr]

The explanation at 34:22 is wrong. If you have 10 amps between the rightmost and middle pole then that current bifurcates with some of that 10 amps going to ground and some being transferred on the neutral to the left hand pole. So there is LESS than 10 amps in current between the middle and right most pole. Similarly between the left hand pole and source. Assuming equal distances between poles and thus approximately equal wire resistance one one would expect that neutral current becomes smaller and thus neutral to earth voltage less as one gets closer to source which is what is observed.

[@ekawakakonahi1174]

So I’m welding in my garage on my small mig welder (120vac) and the utility neutral wire coming from my pole breaks and disconnects. Does my welder stop working? [I’m guessing it will still operate and hopefully my welder isn’t drawing well over the ampacity of my earthing conductor wire. ]

[@persona250]

I’m not familiar with how welders work but if the welder chassis is earthed it will rise in voltage potential with a lost incoming neutral probably leading to a shock outside .

[@will9751]

We transmit at 765kV maximum here in SA

[@mernokimuvek]

Solidly grounded medium voltage distribution was already outdated in Europe in the 1940s. North America should use Petersen coil grounding like Europe.

[@tedlahm5740]

Believe my power company substation is using a 3 phase 3 wire Delta distribution system. No neutral on the distribution poles. PS. If the substation used a 3 phase 4 wire distribution system , then the poles of the distribution system WOULD HAVE A PARALLEL grounding system. comment please.

[@josephballance2319]

Should the pool heater have a gfci breaker when heater and pool pump are on different branch circuits. Concern being if say electric heater has a low leak how will it be known

[@MikeHoltNEC]

Please post questions not related to the video at MikeHolt.com/Forum. Hint: There are no GFCI protection requirements for 'pool heaters.'

[@Keithf1]

Thank you.

[@johnbushur6080]

Where can I watch the next video?

[@MikeHoltNEC]

This was a live stream we did during 2020. Check out MikeHolt.TV for a more organized list of all our videos.

[@losttownstreet3409]

Not every country use the same system and it's not unsafe: in some countries you'll need multiple grounds at your residential home for safety but you also need a ground monitoring system which disconnects all 5 wires in case there is a problem with the ground. There is no true safe or unsafe as many regulations are best practice and can safely circumvent with other precautions (with much higher costs). You should follow the code to be safe at a reasonable price. (you don't want to measure the impedance of your ground roads in your multi grounded home ever 0.1 seconds) On the distribution side and industrial settings they have simply more money to make sure it's safe. But mistakes happens even there, there are many accidents at the distribution companies (even with PPE).

[@haroldbarber9828]

Dear Mike, I´m a sound engineer working in Venezuela, sometime ago i had problems due to the fact that there were 48 volts between neutral and earth (It was a shopping center being built, I suppose they left the electric system last). Since then I´ve been a maniac checking the voltages before connecting and searching for answers, that´s how I ended in your video. Somebody asked you the question I wanted to do: What is the maximum permissible NEV? Your answer was ambiguous "None... 5 volts is ok... but 19 volts might kill you" (By the way, 48 volts will burn your sound system) I think it was a bottom line question that deserved a better answer, what´s more, I would think there should be a legal limit.

[@MikeHoltNEC]

You are not measuring NEV! You have an open service neutral condition, in this case the voltage from metal parts to the earth can be close to 100V. Simply measure the L1-N and L1-n volts at the meter, disconnect, and panels from. When it changes from 120V to something else, then that means you lost the neutral just before that measuring point.

[@haroldbarber9828]

@@MikeHoltNEC That case was very special, it happened many years ago and have not repeated. But in "normal" conditions what would be the limit of acceptable NEV ?.

[@MikeHoltNEC]

@@haroldbarber9828 I give this information already in the video. Please watch it again.

[@TotalEMFSolutions]

Check out this doctor's advice. She is telling people to ground themselves in the city "Grounding In A City (Dr. Laura Koniver MD... The Intuition Physician)"

[@22jaybhall]

I had a customer call me because they were getting shocked touching light fixtures and brick wall ect. With no load there was 3 - 4 NEV with a load it got as high as 58 NEV. Still trying to figure this on out.

[@MikeHoltNEC]

You have an open service neutral; your 58V is NOT NEV.

[@bajothesparky2445]

I have a question.So since commed want neutral in the meter.Do I bond the neutral in the transformer to?Or the meter socket count as 1st point of bonded neutral since is screwed into the enclosure? THANKS MIKE FOR ALL YOUR DEDICATION FOR ALL OF US HERE.GOD BLESS YOU CHEERS FROM CHICAGO

[@MikeHoltNEC]

Don't worry about what the utility does with their grounding, just comply with 250.24 for electrical services.

[@tfun101]

20:25 I don’t know..California. That help? More than you know Mike..more than you know lol. 🤣

[@truckgotstuck]

Hi Mike! I am new to learning about this, but very interested. It took me a while to get it through my head the difference in the names of these types of grounds. I must have written notes 4 times before it stuck. And I think it stuck correctly finally. I am wondering if there is a reason why the EGC has to be grounded to the GEC? Should it not be sufficient that it's bonded to the neutral at main breaker panel? If there is a GEC at the transformer, then should the GEC for the house system and other remote buildings be located at the respective panels for each building to keep the NEV interference to a minimum? Buildings are 50m apart, but there is 1 building that is less than 5m from the Transformer. I was wondering if there is a way to isolate the EGC and the GEC to prevent the NEV from feeding back into the system? I would think they should be able to be isolated. Maybe I have missed something... ? Still learning! I am learning a lot form your videos and it is very much appreciated!

[@MikeHoltNEC]

NEV is 'normal' and you can't remove it without making the installation unbonded, which causes a safety hazard. Watch MikeHolt.com/Fundamentals for the answers to your other questions.

[@mikefixac]

I am not quite getting it. When I watch the video of Mike out in the field, I don’t see the hook up of the meter to the screwdriver. It looks like he’s just touching one lead to the neutral, and I don’t see the other lead hooked to the screwdriver.

[@mikefixac]

Also at the end of the video, Mike says to watch the next video on how to check NEV to make sure electrical systems are safe. I can’t find that video he’s talking about. Perhaps it’s because I’m watching from KZbin videos and not his website.

[@MikeHoltNEC]

No. 1 One lead is connected to earth (no shown and not needed to be shown) and the other lead is not touching the neutral, it's touching metal parts. Please watch the video again.

[@MikeHoltNEC]

I'll see if we can edit this out. If you want to see the other video, watch MikeHolt.com/Pools.

[@mikefixac]

@@MikeHoltNEC Thanks so much.

[@mikefixac]

@@MikeHoltNEC Not sure what you mean by "edit this out". If you'd like me to delete my comment, I have no problem with that. Thank you.

[@JodyBC1]

I had a issue in a dorm one time where the students were getting shocked in the shower on the bottom floor. The service to the Bld. was fed from over head lines to utility owned pad mount and then UG to the service equipment. This issue went on for years, Several contractors had looked at it, PCO kep telling coustomer to drive ground rods. I went and found that the ground from the pole (N-Earth ground wire) had a elevated votage (18V) to earth, at the pad mount it was the same. Asked the PCO to remake or jump the connection on the overhead line. They said it wasnt the problemb-refused. I said "ok Ill come back with the bucket truck when you leave and jump it" the then agreed to do it ----> this cleared the 18V back to 1.3V. Long story short College was happy and PCO looked liked IDIOTS. To this day I have been doing all their work - 15 years now. Great video.

[@danielsullivan9865]

This problem is much more common than utility companies would want you to know. I’ve had the very same problem in one of my buildings but fortunately I am an electrical inspector and I discovered it.

[@stargazer7644]

What does “jump it” mean? Bond across a bad connection?

[@JodyBC1]

@@stargazer7644 yes

[@donberg01]

This is not the same as measuring the soil resistance with 4 pole Fluke 1645 earth resistance meter?

[@MikeHoltNEC]

Using a volt meter gives you 'volts' using a 4-pole earth resistance meter give you earth's soil resistivity in ohms.

[@donberg01]

@@MikeHoltNEC Thanks, looks like two different tests, for different reasons, difference of potential (E)& fall of potencial (Ώ).

[@ohmware2020]

dear mike, please make a video on how to make an effective ground fault current path in a single phase 2 wire system line-ground/neutral system. thanks

[@MikeHoltNEC]

Watch "MikeHolt.com/Fundamentals" for your video!

[@ohmware2020]

@@MikeHoltNEC thanks mike

[@comingtofull-ageinchrist6736]

So, NEV isn't as important as making sure that the power is connected to an equipment grounding conductor to ensure that it has an effective ground fault current path to clear a fault! Because the only way to make it safe, as you have said in several of your videos with your panel of electricians, is to turn the power off, and the only way to do that is to make sure that a fault can clear by way of an effective ground fault current path.

[@MikeHoltNEC]

You got it Brother!

[@MrMaxyield]

How did this video JUST DROP yet the comments are months old...???🤔🤔🤔 Did you switch it from private to listed...???

[@MikeHoltNEC]

Somehow it was unlisted, so we made it public (again). Sorry.

[@MrMaxyield]

@@MikeHoltNEC thank you Mike. This is an important video that I'll be playing in my service van for my apprentice tomorrow... Thank you for what you do for our industry...

[@MikeHoltNEC]

@@MrMaxyield Excellent

[@amilmartinez9078]

Hi mike. Can you help me out understanding how to tell when a bank is delta or why and how the connections differ from each other Thanks so much

[@MikeHoltNEC]

Watch this video - kzbin.info/www/bejne/b4u9i4VugspnpKc

[@bowlampar]

Every time passed under these high voltage power line gave me a creep feeling, how many more time people need to get electrocuted before they want to locate these lines to sub ground tunnel for safety reason. 😬

[@tedlahm5740]

No neutral conductor at my neighborhood pole mounted step down transformers. 7,200 volt SINGLE BUSHING but NO SECOND conductor observed going back to the Sub Station, ONLY multiple point grounding at each transformer ABSOLUTELY YES, but no OBSERVED neutral conductor? thank you

[@matthewbrownell1741]

Should guy wires be isolated or grounded ? I say isolated .you keep saying they use guy wires as a path for ground??? This is not true.

[@germanarellano5119]

Mike I have been following you for years and there hasn't been a video that I would say to my self oh man now I understand the reason for that code and then you sometimes get more questions then answers. As a little insight. Transmission might vary by utility company but here it is 765kv,345kv,138kv and 69kv. Distribution starts at 34kv and goes to either 12kv or 4kv from transmission voltages and this is done using Ac voltage. Dc voltage doesn't travel as far. Which is something Edison tried but Tesla proved that Ac is more effective for long distance transmission of power.

[@MikeHoltNEC]

Please read up about DC transmission line, they are only used when great distances are required! So it's the opposite of what you thought! www.powermag.com/benefits-of-high-voltage-direct-current-transmission-systems/

[@marcemarce9821]

Well done sir, thank you

[@businessman5894]

These pictures are hard to understand

[@Ed-ym4tu]

If you have an outside panel next to the power companies meter and the neutral and ground are bonded in that location, can you use that ground bar on outside equipment like an HVAC inverter for ground or doe it need to be tied into the main panel inside the house?

[@garypoplin4599]

20:11 “That’s California.” ‘Nough said.

[@tedlahm5740]

All my observable step down transformers only have one conductor (single bushing) on the top of the can. 7,200 volts yes, NO NEUTRAL back to the distribution point. comment please

[@MikeHoltNEC]

Is this in the US? Where?

[@dylanoakes9557]

The Other end of the primary is connected to the tank internally, so that makes the case ground on the back of the tank double as the H2 connection

[@chrisbauer1925]

Yeah often times the utility not only bonds the primary and secondary neutrals, but actually uses one wire as both. Often this wire is the messenger wire for the triplex secondaries as well. So it's serving the purpose of primary neutral, secondary neutral, and messenger wire. So likely this is the case if you're in the US.

[@brnmcc01]

@@MikeHoltNEC Maybe he's in a very old rural area with a SEWR system, Single Wire Earth Return. But that is 1930's era stuff.

[@persona250]

I can’t see how this works other than single wire earth return .

[@cuidarmundo]

Soy electricista, y se ve que es buena información, lo malo es que no se ingles🥲

[@sammyjimsmith6100]

My wife won't watch this video for 2 mins but I will

[@MikeHoltNEC]

Lol... I understand why...

[@halledwardb]

​@@MikeHoltNECits part of my 12 and 16 yr daughters school work.

[@jasonparkinson7621]

Great explanation. Thanks.

[@llewen123]

It's guy wire rather then guide wire

[@realestateservicessaleshea99]

Thanks for the video. The screwdriver tip.👍🏻 I just jam the lead into the ground. 🍺🍺🍺🥃🥃🏌🏻‍♀️ Stay safe. Retired (werk'n)keyboard super tech. Wear your safety glasses.

[@claudearmstrong9232]

Am I naive to think my electrical ed. Makes this session look way more complex than actual? Just point to grounds v.s. resistance over distance and point emf is measured from ground anyplace in the system? Who cares about the components or no. Of phases. Or other components. It's only resistance from point of measure to ground. Now, if ground resistance isn't zero, then that is added to distance resistance. Why all the yap about irrelevant stuff?

[@MikeHoltNEC]

I have no clue what you said...

[@davenone7312]

@29:50 You did not know the proper use of your voltmeter? Not sure I would have told anyone that! Do you even work out in the field or just read code books all day?

[@MikeHoltNEC]

What is the point of your comment? What I said was that that the voltage selection was set to dc and not ac. This is called a mistake. If you want to know more about my qualifications, visit MikeHolt.com/Mike By the way, when I make a mistake, I am very confortable to be honest and not play like I'm perfect. Have a great life.

[@Ormaaj]

​@@MikeHoltNEC So you're measuring the AC RMS voltage of the neutral with respect to itself as attenuated through the impedance of the earth. That will be a roughly in-phase common mode signal, and the RMS or RMS + DC value won't be meaningful in that context. A scope with a differential probe would probably be the best way to measure whatever DC offset or phase shift may exist between neutral and earth, not a DMM. Even then, measuring the common-mode differential signal is probably not very useful because you don't have a stable reference to measure against. A better solution would be to separately capture the the neutral and earth signals using the zero-crossing, positive, and negative peaks of the line voltage as a stable DC reference (as obtained from a simple unregulated rectified DC power supply). You can then use your scope's math functions to subtract and compare against those signals.

[@MikeHoltNEC]

@@Ormaaj I'm just measuring the NEV of the utility neutral. For more information, see MikeHolt.com/NEV. Watch that, so you'll realize that nothing you wrote had anything to do with this topic.

[@Ormaaj]

Sure. I think the scope of what you're talking about here is just narrower than I was thinking.

[@MikeHoltNEC]

@@Ormaaj What were you thinking?