A neutral wire only carries the operational current. The PE (protective earth) carries only fault currents. The PEN conductor is a combination of the PE and the neutral, it carries operational current and in addition in case of a fault it would carry the fault current too. And in case of a broken PEN the same thing would happen as shown in the video with the broken neutral. But in addition metal housings of class 1 appliances would become live. That's the reason why PENs are only permitted if you use larger wires (at least 10mm² copper or 16mm² aluminium). Here in Germany the most common system is TN-C-S. You get three phases and a PEN from the supplier, the PEN is splitted into a separate neutral and PE inside of the service entrance box. In some older installations the PEN is splitted in the fuse box, and in installations made before 1973 the PEN was actually splitted on the outlet. The PEN was connected to the earth terminal, and from there a wire bridge was installed to the terminal for the neutral of the outlet. The N is actually an operational earthing, the PE is a protective earthing. You can actually calculate the voltage between the line conductors if you know the voltage between one line and the neutral. You multiply the voltage with sqrt of 3 (~1,73): 230 V * 1,73 = 398 V 240 V * 1,73 = 415 V In Germany kitchen cookers are connected to three phases, two heating plates on one line and the third one for the oven. The circuit is fused with three B16A MCBs: 400V * 16A * 1,73 = ~11kW If your neutral breaks in a three-phase system this will cause some major issues. For example imagine you've got a 20W soldering iron connected to L1 and a 3680W electric heater connected to L2 and the neutral breaks inside of your fuse box then this would happen: You'll get a voltage divider, the soldering iron would "see" 397.8V and the heater will "see" 2.2V.

Thats a good point. Ignoring any resistance issues with the ground rod, the ground rod impedance is something to think about. Since power stations almost always run as a wye configuration (from the station transformer at least) with a neutral conductor to handle unbalanced loads and provide a common return, the earth is connected to the neutral conductor at the power station. The earth being a rather good conductor as far as organic material goes, means when you put a ground rod into the ground from your house (this depends on the setup in your country as some will use the neutral from the pole) if it has to handle a fault, it will have to travel all the way through the earth possibly hundreds of miles to find the nearest transformer ground to complete the circuit, this results in high loop impedance, with can be almost as deadly as not having a ground at all. I'm interested in the different systems in use around the world. Some run separate ground and neutral from the transformer, some run combined ground/neutral from the transformer, some have no ground or neutral. In modern US installations (extreme rural installs excluded) we run the two lives from the split phase, and a combined neutral/ground that is grounded at the pole, then once it reaches the house another ground spike is used and the neutral and grounds are separate from there on.

Transformer station is 100m (~300 ft) from my home. And there's another one nearby for another grid segment. These transformer stations are small, they're only 15 to 20m² (150-160ft²) and are inside of a pre-manufactured concrete housing: www.hildesheimer-allgemeine.de/typo3temp/_processed_/4/b/csm_ecad01a400-70a35c98-4b90-11e7-aba0-377d83391380-710f3470-4b88-11e7-aba0-377d83391380_9c87ee5356.jpg The cables are laying below the sidewalk. In most cities and towns here overhead wiring was replaced by this system. The cables are laying inside of conduits, so they can be replaced easily. And here in Germany houses have an additional grounding system, even if the utility company provides a TN-system. The ground rod is implemented in the concrete foundation of the house. In older houses, built before the 1970s, the incoming water pipe was used. That was the reason they made these pipes of thick cast iron. In Europe these systems are common: -TN-S: The utility supplies you with the lines, a neutral and a ground wire. -TN-C: The utility supplies you with the lines and a PEN. The PEN is a combinated neutral and ground wire. In most cases this wire is splitted into two wires, a separate neutral and the ground inside of the house. This is changing the TN-C into a TN-C-S grid. -TT: The utility supplies you with the lines and a neutral. Ground must be provided locally by a ground rod. In addition to achieve the cut-off time in case of a short-circuit RCDs (residual current device, in america called GFCI) must be installed. The cut-off time in case of a short-circuit must be less than 0.4s for a circuit which is fused with less than 32A. In a TT grid you can only reach this time if you use RCDs/GFCIs, as you already mentioned the resistance is too high. Especially when the ground is dry. With the RCD you can achieve a cut-off time of less than 0.2s. In most cases we're talking about 0.02s. en.wikipedia.org/wiki/Earthing_system#Low-voltage_systems That's the reason why we have RCDs which are completely separate, not integrated into an outlet or a circuit breaker. But you can also get them integrated into these devices. When it's integrated into a circuit breaker it's called RCBO (residual current circuit breaker with overcurrent protection). There are RCDs available where you can install a single one to cover the whole house. They are rated for 3x40 or 3x63A. But that's no longer state of the art to use a single RCD for a whole house, because if a problem occurs the whole house is without power. And in addition every class 1 appliance produces a small leakage current, and these sum up.

Marcel, You live in Germany? I learned a little while back that many residences in germany have an incoming 3phase supply instead of a single phase supply as we get here in the US. How does that work for you guys? I imagine it makes high power appliances like stoves and large motors easy to install and handle with small amounts of copper. But is there ever a concern with having two outlets on different phases and having equipment connected between them? We have enough problems with that on our split phase in America when residential AV equipment is hooked up, say a TV or projector on the wall on one phase and a home theater or computer or similar device on a separate phase connected by cables which join the chassis grounds. It manifests here with a 60hz hum between devices and on some with particularly high leakage, small tingles from electric shock between the two phases (240V between the two). More modern electronics for this reason have gone to double insulated with only live and neutral with no ground connection, but many devices simply must have a ground because of exposed metalwork for the AV connections. Does that cause problems with high leakage devices between your 400V legs in a 3 phase system?

Yes, I live in Germany. Three-phase supply is common here in Germany. The connection is comparable to the split-phase system you use in the US, but instead of two-pole breakers we use three-pole breakers for three-phase appliances. All the other appliances are connected single phase, but you must take care that you distribute them evenly on all three phases. And I suppose AV-equipment is double insulated everywhere, the reason for this is that you can otherwise create a ground-loop which makes humming noises. The shielding of antenna cables is always grounded, that would be the first grounding point. The second one would be the grounding of a housing of a class 1(grounded) appliance. That's the reason why these appliances are all class 2 (double insulated). In most cases the hum would be 50, or in your case 60Hz. Sometimes it can be double the mains frequency, coming from the rectifier (pulsating current before it is smoothed with capacitors). AFAIK there are no problems if the system is according to the regulations and fully ok. In case of a damage of the neutral wire inside of the panel it can become ugly....the appliances connected there would be roasted propably. But in most cases one room is only connected to one phase. Kitchen cookers and stoves are connected three-phase, but they are 230V appliances in most cases so you need the neutral. The four plates are divided onto the two phases inside of the cooker, always one large and a small plate on one phase. The third phase L3 is for the baking oven. Actually this wiring is inside of the appliance, you just need to put the five wires (L1, L2, L3, N and ground) into the correct terminals. The stoves are always hardwired here. And you could wire them for single phase use, then you must insert bridges between the correct terminals. In this case here the terminal of a cooking field, the oven is a separate appliance: www.elektrikforen.de/attachments/img_3514-jpg.13051/ It's connected two-phase, the oven as a separate appliance would be connected to L3 directly in the box were the transition is from the installation of the house to the appliance cable. Cover removed: www.xavax.eu/bilder/00110/awx/00110828awx2.jpg brown is L1, black L2, grey L3, blue is neutral and green/yellow is the ground. The strain relief is for the cable to the stove. But you can also connect the stoves single phase. The manufacturers deliver bridges with the stove which then must be implemented: forum.teamhack.de/attachment/4898-anschluss-jpg/ 1, 2 and 3 are for the line conductors, next to it are the two neutrals (oven and cooking fields). Don't ask me why someone made a connection between the neutrals and the ground. That's not compliant to the regulations.

Here in the UK one often sees single phase 11kv circuits

@@greenpedal370 Gawd, shut ye gob!

@@kimballscarr OK Mr External Plant man But it took you 3 years to come up with that. Good work.

@@greenpedal370 That would be a rare example of an ultra relativistic correction... at low velocity

In Europe single phase systems are uncommon. The system that is used in most cases is three-phase. Even if you don't have a three-phase system in your house, there are always three phases below the street and the houses are equally distributed to the houses. Meaning first house is on L1, the next one on L2, the next one on L3, the next one on L1 again and so on.

Marcel Germann For most applications this is true. But some industrial systems do use three-phase to single-phase transformers. For example, where a limited supply is required, or as the mains supply element that is backed up by a standby emergency generator.

All industries that I know use the three-phase system here in Germany, because that's the standard here. And even if you don't need the three phases, you can always pick one of the three phases and a neutral and you've got 230V. Three-phase is common even in residentials. And there are three-phase generators available which generate 3x230/400 VAC. In Germany the kitchen cookers are connected to all three phases. The heating plates use L1 and L2, the baking oven is connected to L3. That requires a 5x2.5mm² cable (L1, L2, L3, N and PE) and it's fused with 3xB16A MCBs. That are round about 11 kW, but in most cases you could upgrade to 3x20A (~14 kW, depending on the length of the cable and heat dissipation) if that's not sufficient. In single phase systems the kitchen cooker is fused with 25 or 30A in most cases and the wiring is 4 or 6mm².

biggest lesson I learned in the caribbean, is that all the supplementary grounding, for extra ground rods, generators, solar panels, even cb and ham radios, needs pulled back to your main ground point with at least a 10 mm but preferably a 16 mm wire, to make them all one grounding point... otherwise, the lightning strikes can actually do more damage to them.I think the new 2017 International wiring codes addressed this as well. Thus, if you are running a line out to an outbuilding, or a generator, or a shed, and you are planning a ground spike there, you still want to find a way of connecting that ground spike back to the first ground spike or ground position in your home. I believe there is an excellent video showing this under the 2017 NEC videos.

If you draw a symetric load from all three phases there's no current flowing on the neutral. And in case of an unbalanced load only the difference between the load of all three phases will flow on the neutral. For example: L1: 15A, L2: 15A and L3: 16A would mean that there's only 1A flowing through the neutral. Your situation is purely theoretical, because you always have an imbalance in such a system. There are only a few appliances which don't require a neutral. In residentials a type of typical appliances which don't require a neutral are flow-type water heaters. They only require a cable with 4 wires, the three phases and the protective earth. If the neutral is connected you can touch it, even if you have an unbalanced load between the three phases. But the system would loose it's zero point or better you would have a floating zero if you disconnect the neutral, for example in your fusebox. That means all connected loads in these fusebox would act as a voltage divider. As a simple example you got a 20W soldering iron (~2645 Ohms) connected between a circuit connected to L1 and the neutral. On a different circuit, connected between L2 and neutral, you have an electric heater with a demand of 3680W (~14.4 Ohms). If you would disconnect the neutral in the fusebox the soldering iron will get a voltage of 398.8V and the heater will get 2.2V. Meaning your soldering iron would be roasted. And in case of a PEN wire in a TN-C or TN-C-S system you would loose your protective earth. This would, in addition to what I already said, cause that the housings of class 1 appliances would become live. Quite undesirable....

Jonathan Cook Building site 110V supplies are fed from isolating transformers. The secondary (output) windings are two identical windings with the ends joined, at this "mid-point" or join, a connection is made to earth. Another way of describing the winding, is a centre tapped secondary. Hence you will see the term CTE for Centre Tapped Earth. The reason for this arrangement is if either conductor in the cable, or tool, or whatever becomes exposed, the voltage to earth will only be about 55V. So the risk to a human is considerably less compared to normal 230V system. And on a building site, there is a far greater risk of damage to the cables, tools etc. compared to day, a home or office environment.

kzfaq.info/get/bejne/nLiYosmUst-lqZ8.html

Thanks Mark, I do understand this, but Im sure there is more to learn.

The neutral basically carries current that allows the voltages to be balanced. (That is, the neutral to phase voltage.) It's worth noting that with harmonic currents, the neutral current can be many times higher the current on any one phase at a given time. If not kept it check, it can cause electrical system failure. (Burnt wires, connections, arc flashes, etc...)

Yes, the statutory voltage envelope in the UK for low voltage supplies (230V single-phase, 400V three-phase) is -6% to +10%.

robbie77300 Hmm, except it does not really work like that. It only takes a relatively small current to give you an electric shock, and such leakage currents have a way of finding a route from the line (live) conductor to ground/earth via you, and then back to the supply. And yes, it has happened to me, while dry, and stood in a dry room.

Yes, 30ma for example, the threshold imbalance of tripping an RCD, gives quite a nasty shock. However, the impedance for 30ma to flow is around 7600 ohms. Standing in your living room with shoes on will be a far higher resistance/impedance than that. It wont just find a way if there is none. Anyone getting a shock from 230v in such circumstances will be almost certainly in contact with another flow route, not just a phase and nothing else. Enough current to give a shock, does not automatically happen unless there is a path capable of conducting such current available. Most assume contact with a phase means a shock occurs. This is not always true. Stand knee deep in wet cement, and it is going to be nasty. Stand in dry shoes in your living room, or even out on the path outside, and there will not be low enough impedance/resistance to the ground for perceivable current to flow if that route is the only path. Anyway, a demo, which shows it does indeed work that way....... kzfaq.info/get/bejne/rsCpeLtjs6uXfJc.html

In the US you would need a system bonding jumper to bond the secondary neutral to the equipment grounding conductor of the primary system.

Current doesn't magically disappear into the earth. The only way current would leak to ground is if it's able to use the ground as a path back to the source (the star-point of the transformer secondary, where the neutral wire is connected). A great video to watch is this by Mike Holt, it will explain everything about earthing, a must watch in my opinion: kzfaq.info/get/bejne/o9aXdLl2mbvbdqs.html

The neutral at the other end of the break would still be on earth.

If you lowered the resistance of the equipment you would blow the fuse or trip the circuit breaker but theoretically greatest loss of voltage happens where the greatest resistance is.

The same - 3 phase delta. 400kV and 275kV for the larger ones,

+Brendan Randle Yes you are describing "IT" electrical system (isolated from ground), as opposed to TN or TT supplies. Specialist-only (e.g. operating theatres) and, as you say, not normally used. Johns' video also explains why Isolation not normally used for everything in:- kzfaq.info/get/bejne/jd6PqZReuZfLdWg.html

AC means the line conductor moves between +230V and -230V relative to the neutral. The neutral is connected to the mass of Earth at the transformer, so is always the same voltage as the neutral, so any measurement of voltage between the Earth and neutral will be zero. There is no 120V in the UK. In places such as North America, the two line conductors (hot conductors) are between +120V and -120V relative to the neutral and Earth (ground), and are at 240V relative to each other - when one of them is +120V, the other one is -120V. That gives 240V between them for higher powered appliances such as dryers, or 120V between one of them and the neutral for smaller items.

You only get 3 phases from 3 corners of a delta, no reference to have a neutral. With a star you always create 4 reference points, 3 of which we get our line conductors and the center reference we get a neutral conductor.

Because neutral is on one side of the coil and live wire is on the other side, so potential difference exist.

Also, in some situations there really exists no ground like in the arctic, shipboard, or aircraft. I have seen helicopters at sea and in arctic land and the grounding hook basically gets a lightening bolt as it gets close to the aircraft. Sometimes in the arctic you will see salted wells 200' - 300' or more deep in attempt to create a ground. So this makes things very interesting. Particularly with rotor wing aircraft flying in snow or rain, where static charge production builds up to immense proportion. Though you see few of these problems in houses... remember where the ground is frozen there exists no possible ground.

Those voltages suggest the neutral connection at the transformer is missing or damaged.

@@jwflame Thanks... that never occurred to me, brilliant! If I may borrow my god-daughter's favored exclamation. The building was constructed in 1950 by a famous engineer, inventor, and industrialist credited with the first step to the automatic car... it had well over a million lavished on it in that days money 9000 sq.ft./900sq.m.. Electrically it is perfect, even with todays standards... except for a couple installs in the last 20 years. One of those is a piston type compressor of 25 hp/19KW... which was installed without a neutral but with a substandard ground wire gauge. Installed 12 years ago, though the panel has a neutral connection from the time of the buildings construction. The closing coil went out in the motor controller with very dodgy wiring job too. No control secondary power source, meaning it being hot wired without fuse protection, off the main; no interrupter of the supply, and; everything else never seen print in a standards book, So I undertook repair... my partner thought I was crazy to do it. The town has had for as long, as long I remember a phase problem, due to a transformer issue, and that I am not knowledgeable about. I thought they may have had a bad winding or phase connection, and bypassed that. But it just never occurred it could be a neutral though that makes absolute sense... but remembering most are Delta - Wye connected, brilliant! Am afraid it is my defective French education in physics, and EE, now nearing 50 years ago. Great explanations and help in educating those modern education has passed over. Of course, my Université Pierre-et-Marie-Curie-Paris, and you know the French they had all the great discoveries in the Age of Electrification. Don't remember Faraday even mentioned, but do François Arajo, Léon Foucault, and André-Marie Ampère, supposing; Arajo's story was more interesting; it's those Pirates... putain de merde! Of course, the French do not have any profanities existing.

@@jwflame I must admit your understanding of electricity and concepts is top notch.

With a high resistance path and a low resistance path most of the current flows in the low resistance path, but some still flows in the high resistance one. It's not one or the other, but sharing the current between them. It only takes a few mA (0.001 amps) to feel an electric shock, 10-20mA will cause muscle contractions, and above 30-40mA serious injury and death is increasingly likely. At 240 volts, 20mA is 12000 ohms, 40mA is 6000 ohms. The human body is not a fixed resistance , and with higher voltages the current flow will damage the skin very quickly, reducing the resistance and increasing the current.

@@jwflame Thank you

Isolated is safer, but it is impossible to ensure it stays that way - any inadvertent connection to ground anywhere would make it ground referenced, but with no control over which conductor was grounded. It's safer to make it ground referenced by design, so that fuses/circuit breakers are always in the correct conductor,.

+Tangobaldy Go watch/subscribe to Beno's channel:- kzfaq.infovideos

+Tangobaldy Go watch 'beno lifts' channel instead =). kzfaq.info

Wrong channel. You want mrmattandmrchay

Or will he smile for once and stop looking so serious

That’s North American. He’s in the UK. There are many videos on the North American system.

You won't get a shock from the neutral in normal operation (although touching one isn't recommended as a fault could result in dangerous voltages appearing). Neutral is always at 0V because it's connected to ground, and current cannot flow between ground and N because there is no voltage difference. Line is either +230V or -230V relative to ground. AC is not swapping L&N - it's just having L being positive or negative relative to N.

@@jwflame Many thanks John for the explaination. Very helpful.

@@jwflame In case of an isolated AC transfomer, without any earth connection, is it correct to say that there is voltage swapping between one conductor to the other? (Non of the conductors are connected to ground)

@@jwflame This is confusing "AC is not swapping L&N - it's just having L being positive or negative relative to N"

Output voltage would be the output voltage the transformer says it will be. Grounding does not change the output voltage.

John O Leary Answered in an earlier comment 😉

Mark 1024MAK is it got to do with balancing the loading across the 3 phases so the least amount of current should flow in the single neutral.

The three phase currents are at 0v after going across their loads at that point we can put them on the same conductor (neutral).

If everything worked perfectly this would be true, and then instead of Live (L) and Neutral (N) we would have two lines out of the transformer. L1 and L2. In a single fault condition there would be no earth path, so no fuse would trip and the frame of your toaster would sit there "Live" this would not be an issue if you touched it as there is no earth path. However if your faulty toaster had a fault from L1 to the frame and another appliance had a L2 fault then you would have the full 230V between them. In reality maintaining full isolation across a network is very hard, and bits of metal, pipes etc would end up being live to one line or another. Much easier to earth one line and call it a neutral. It works best when there are multiple earths on that neutral, otherwise known as the MEN system, or multiple earth neutral

John Simpson Thanks for the answer.

John Simpson Also, 3 phase system, if isolated system was used, and one phase has a fault to ground, it will go unnoticed because of the isolated setup. But now there is a potential 400v from the other phases to ground. Where as with neutral connected to earth, there is reference which means phase to earth faults should show, or operate tripping devices.

+James Searle John did a video on EXACTLY this -- kzfaq.info/get/bejne/jd6PqZReuZfLdWg.html

John Simpson In North America, 240 volt circuits have no neutral; both conductors are active. The line to neutral voltage is 120 volts,,and there are 2 active lines, 180 degrees out of phase.

The current in the neutral of a single phase circuit is identical to the current in the line (unless there is a fault).

Unless its 3 phase! under certain circumstances (Computers, Inverters etc) the neutral current can be HIGHER than and individual phase current (search for "3rd harmonic" for more information)

Concept: 2 wire circuits never can have a neutral. If one of the conductors is grounded then it’s a return wire. 3 wire single phase circuits center tap is a neutral, this is a neutral because it’s neutral to the phases on each side of it. In this set up it will carry the imbalance of the two phases. 4 wire wye, the conductor attached to the point where all 3 windings connect to each other is a neutral and it will carry the imbalance of the 3 line conductors.

230V, +10% / -6%., or anything between 216V and 253V. It is usually about 240V, as it was previously 240V +/- 6% and although the definition changed, reality did not.

Since 2009 the tolerance is +/- 10%. The +6 and -10% percent was during a transition period so the appliances in countries which had 220V before wouldn't get roasted.

You're talking about the electric strength of capacitors and other parts because in most cases this value for this rating is for a DC voltage. But the peak voltage in an AC-system is ~1.4 times (precisely it's the sqrt of 2) higher than the nominal 230V. Mains voltage in Europe is 230V, and the permitted tolerance is +/- 10%. Meaning the voltage can be between 207 and 253V. If you live next to a feeding point the voltage is always higher. Here in Germany we've switched from 220 to 230 for the harmonisation in 1986. Before this some had already 230V, now they have almost 240V. Near the feeding point the voltage is always higher, so the last one gets a deicent voltage (voltage drop in the cables is the cue).

The load isn't connected to ground, it's only connected with the two wires.

I understand the concept of a floating neutral, but why does current flow through the load during the negative half of the AC cycle when it reverses direction given that the neutral is bonded to a literal stake in the garden? During the negative half of the cycle (coming out of the bottom of your diagram) it has a parallel path to ground before the load. Would this not provide a lower impedance path than back through the load?

@@djr3485 Neutral is neutral. The voltage whether positive or negative is in the line. Many seems to think that the negative voltage comes from the neutral. This is false.

I see now how everything around you potentially can turn into one of the phases if there is a fault and that will dramatically increase your chances of completing the circuit with your body.

On a 3 phase transformer, if neutral is disconnected and the loads are equally balanced, then nothing changes. If loads are not balanced between the phases (most likely), then some will get a much higher voltage and others much lower, resulting in equipment damage and fires.

@@jwflame then why some phase has lover voltage even tho the neutral line is connected. In my area, one particular phase has much lover voltage (190v) compared to the other two (220v) resulting in unstable computer and dimm lights when using that particular line. That makes me think that neutral line won't guarantee stable voltage across phases.

@@dputra If the voltage is low all the time, then it's one or more of: cables that are too long, cables too small or the system is overloaded.

@@jwflame thanks for the answers! 👍👍👍

Yes, the current changes direction and flows in the opposite direction. it's either L to N, or N to L. Current will not flow between neutral and ground in either case, as both are at the same potential / voltage.

Thank you. But current still flows to ground (or whatever you want to call it) and not to the load because its much easier to do that than to overcome the load resistance? The question was not whether current flows between neutral and ground (it doesn't because they are wired together) but does it flow directly to ground/earth from the transformer the way your diagram depicts? Please explain

@@georgerocks5191 Current does not flow to ground. Current always returns to the source. If a circuit is defective current may flow through ground but only to reach the source. As for current always flowing out of the top terminal, instructors tend to treat simple AC circuits as if they are a strange form of DC. Don't care what the voltage polarity is. Don't care which way the current is flowing. It just doesn't matter. Instructors rarely tell you that. Bill

bill- if ground has lower resistance than the source, how can current return to the source? preferable path is to ground

@@georgerocks5191 A battery can be a source. The secondary of a transformer can be a source. All sources have one requirement. Every electron that leaves a source must be replaced by an electron that enters the other source terminal. This accounting is very strict. The only reason current flows at all is to balance the books in the source. Bill

kzfaq.info/get/bejne/d81zjMKVnp6sdmw.html

The coil of wire of which 230 volts is across is low in resistance and high in inductive reactance. Resistance and inductive reactance = impedance, long answer to affirm your correct thinking.

No, everything is 230V. Virtually all homes have a single phase supply which is neutral and 230V. Commercial and other large buildings have 3 phase and neutral, which is 230V from any one phase to neutral, and 400V between any 2 phases.