Ground is MORE IMPORTANT than you think! EB#57
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Date: 2023-11-27
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Comments and reviews: 20
Adrian's
Where I live in Portland Oregon the utility uses earth ground return for the high voltage distribution to residential neighborhoods. That means that on the top of the power pole there is only a single conductor coming from the utility that then feeds into a transformer. The other conductor that goes into the transformer makes its way down the pole and into the ground which completes the circuit with a similar conductor stuck into the ground back at the power distribution station. (Over a km away) I can only assume that back in the 1920s when they put the power in this neighborhood, this saved on copper. There are of course big warnings on this ground conductor that makes its way down the pole telling you not to cut it since if you did, that would then put that loose end attached to the transformer at some very high voltage.
It's pretty fascinating that they did it this way and I think it's somewhat unusual for inside a city. It also means if a single tree branch falls on the HV conductor nothing happens but if a tree falls on that's still attached to the ground, you get a short circuit. I have no idea if this ends up being more or less reliable in the long run.
On top of that, my house has earth ground with a rod driven into the ground. My earth grounding rod is probably only 25 m from the power pole which has the transformer on it with the earth ground return rod. It's all fascinating that it all just works and goes to show how amazing of a conductor the earth really is.
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Where I live in Portland Oregon the utility uses earth ground return for the high voltage distribution to residential neighborhoods. That means that on the top of the power pole there is only a single conductor coming from the utility that then feeds into a transformer. The other conductor that goes into the transformer makes its way down the pole and into the ground which completes the circuit with a similar conductor stuck into the ground back at the power distribution station. (Over a km away) I can only assume that back in the 1920s when they put the power in this neighborhood, this saved on copper. There are of course big warnings on this ground conductor that makes its way down the pole telling you not to cut it since if you did, that would then put that loose end attached to the transformer at some very high voltage.
It's pretty fascinating that they did it this way and I think it's somewhat unusual for inside a city. It also means if a single tree branch falls on the HV conductor nothing happens but if a tree falls on that's still attached to the ground, you get a short circuit. I have no idea if this ends up being more or less reliable in the long run.
On top of that, my house has earth ground with a rod driven into the ground. My earth grounding rod is probably only 25 m from the power pole which has the transformer on it with the earth ground return rod. It's all fascinating that it all just works and goes to show how amazing of a conductor the earth really is.
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The
Fantastic explanation video! Only thing you didn t explain is how you are still able to get a shock even when you aren t directly touching earth. The EEs in crowd know it s because the human body has natural parasitic capacitance with earth, but the less advanced people might not know that. I would really love to see a tour of all the cool modern home systems in your new place, the electrical system looks beautiful and very nice, it also looks like you have in floor heating. Something I d highly recommend, that I m not really sure why Marco reps doesn t do either is installing a step down transformer somewhere in your distribution box that s capable of 120 volts at a few hundred watts and run the output of that through an MCB to a few international standard outlets in your lab so you can run test equipment or other devices from the US without needing to use an additional external step down transformer for each device. Just make sure you label those outlets with 120V so that you or other people don t try to plug things not meant for that voltage in there. If you re adding that, another thing I highly recommend would be installing another step down transformer or regulated 12 volt DC power supply in the distribution board and run its output through your attic and crawl space so that you can easily tap off of it and power various IOT devices or other more permanent DIY projects like the door lock on your lab room without having to plug them into an outlet.
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Fantastic explanation video! Only thing you didn t explain is how you are still able to get a shock even when you aren t directly touching earth. The EEs in crowd know it s because the human body has natural parasitic capacitance with earth, but the less advanced people might not know that. I would really love to see a tour of all the cool modern home systems in your new place, the electrical system looks beautiful and very nice, it also looks like you have in floor heating. Something I d highly recommend, that I m not really sure why Marco reps doesn t do either is installing a step down transformer somewhere in your distribution box that s capable of 120 volts at a few hundred watts and run the output of that through an MCB to a few international standard outlets in your lab so you can run test equipment or other devices from the US without needing to use an additional external step down transformer for each device. Just make sure you label those outlets with 120V so that you or other people don t try to plug things not meant for that voltage in there. If you re adding that, another thing I highly recommend would be installing another step down transformer or regulated 12 volt DC power supply in the distribution board and run its output through your attic and crawl space so that you can easily tap off of it and power various IOT devices or other more permanent DIY projects like the door lock on your lab room without having to plug them into an outlet.
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Dr.
5: 35 The circuit breaker would have NOT saved your life on it's own. Only the RCD would save you. If you touched the live part, only very little current would flow, but still enough to hurt or injure you. It is very common in germany to have all circuits behind the RCD aka GFCI (ground fault circuit interrupter, but in America it is only bathroom outlets are required to have a GFCI installed (usually integrated into the outlet. I am from germany as well and our breaker panel looks very similar, but I know that thing from watching Electroboom.
The breaker only protects you when the live wire touches something, that is grounded. But with everything beeing behind the RCD, it will always react as well in that case (as you demonstrated with the ground wire. In german households the breaker is more to protect against overloading. In the US, without a RCD, they protect you from grounded conductive cases becoming live (By overloading the circuit, if the ground connection to neutral is good enough, but if earth on a device was not connected, nothing would save you, if the conductive case became live.
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5: 35 The circuit breaker would have NOT saved your life on it's own. Only the RCD would save you. If you touched the live part, only very little current would flow, but still enough to hurt or injure you. It is very common in germany to have all circuits behind the RCD aka GFCI (ground fault circuit interrupter, but in America it is only bathroom outlets are required to have a GFCI installed (usually integrated into the outlet. I am from germany as well and our breaker panel looks very similar, but I know that thing from watching Electroboom.
The breaker only protects you when the live wire touches something, that is grounded. But with everything beeing behind the RCD, it will always react as well in that case (as you demonstrated with the ground wire. In german households the breaker is more to protect against overloading. In the US, without a RCD, they protect you from grounded conductive cases becoming live (By overloading the circuit, if the ground connection to neutral is good enough, but if earth on a device was not connected, nothing would save you, if the conductive case became live.
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61Keys_To_Nirvana
Hello there, I have a query regarding my living situation in an apartment equipped with a three-phase 240-volt system. I've noticed that the ground wire displays some potential with reference to the actual ground, like my water drain faucet. Upon touching it, the voltage decreases, indicating a current limitation. It seems there might be a misconnection in the system. This becomes bothersome because whenever I wash my hands, I experience a slight shock. To resolve this, I have to unplug my geyser entirely, disconnecting the ground wire from the metal water faucets.
In India, most houses lack RCD or GFCI; instead, they use MCBs and fuses only.
Theoretically, the neutral and ground should mix somewhere in the system. Would it be advisable for me to disconnect the ground wire from the bus bar and connect it to the neutral in my distribution box before the breaker in the distribution box.
Additionally, I noticed the video didn't delve deeply into the concept of the neutral wire.
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Hello there, I have a query regarding my living situation in an apartment equipped with a three-phase 240-volt system. I've noticed that the ground wire displays some potential with reference to the actual ground, like my water drain faucet. Upon touching it, the voltage decreases, indicating a current limitation. It seems there might be a misconnection in the system. This becomes bothersome because whenever I wash my hands, I experience a slight shock. To resolve this, I have to unplug my geyser entirely, disconnecting the ground wire from the metal water faucets.
In India, most houses lack RCD or GFCI; instead, they use MCBs and fuses only.
Theoretically, the neutral and ground should mix somewhere in the system. Would it be advisable for me to disconnect the ground wire from the bus bar and connect it to the neutral in my distribution box before the breaker in the distribution box.
Additionally, I noticed the video didn't delve deeply into the concept of the neutral wire.
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Bjorn
4: 41 Germany uses the TN-C grid system (Earth and Neutral connected together in distributionpanel) but also the TT electric grid system (Earth and Neutral separated.
If you have a TT electric grid system, and the Neutral wire comes in contact with the PE wire (chassis home device etc) your RCD will also trip.
Here in Belgium we use the TT electric grid system, and depending on the load of the grid, and how far removed from the grid transformer, there can be a voltage between Neutral and PE between 0, 5V up to 5V.
The exact amount of current that is available i'm not sure off, but it is way above 100mA because i have seen RCD's of 100mA trip when the Neutral touched the PE wire.
Because the current in the PE wire is not monitored by the electricity company, this voltage / current between Neutral and PE is in fact free electricity if you stay below the tripping point of the RCD. Grtz
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4: 41 Germany uses the TN-C grid system (Earth and Neutral connected together in distributionpanel) but also the TT electric grid system (Earth and Neutral separated.
If you have a TT electric grid system, and the Neutral wire comes in contact with the PE wire (chassis home device etc) your RCD will also trip.
Here in Belgium we use the TT electric grid system, and depending on the load of the grid, and how far removed from the grid transformer, there can be a voltage between Neutral and PE between 0, 5V up to 5V.
The exact amount of current that is available i'm not sure off, but it is way above 100mA because i have seen RCD's of 100mA trip when the Neutral touched the PE wire.
Because the current in the PE wire is not monitored by the electricity company, this voltage / current between Neutral and PE is in fact free electricity if you stay below the tripping point of the RCD. Grtz
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Walter
I remember spending an entire month learning this entire concept just to find why LEDs plugged in and turned off with a switch keeps glowing in the dark faintly. always remember folks, ground with no RCCB is no better than having no ground.
To understand it easy for me, i like to think of earth as a high resistance path connected to Neutral like a resistor and one side is connected to your house(floor you are standing / appliances PE wire through earth rod) and the the other side is basically the electric pole / stepdown transformer that powers the entire neighborhood where the Neutral is also grounded through a rod there or before the RCCB in your main board.
When some problem occurs where the current flows somewhere else other than the neutral wire(through your body or protective earth, fault neutral line as i call it) it trips the RCCB protecting you or the device from catching fire.
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I remember spending an entire month learning this entire concept just to find why LEDs plugged in and turned off with a switch keeps glowing in the dark faintly. always remember folks, ground with no RCCB is no better than having no ground.
To understand it easy for me, i like to think of earth as a high resistance path connected to Neutral like a resistor and one side is connected to your house(floor you are standing / appliances PE wire through earth rod) and the the other side is basically the electric pole / stepdown transformer that powers the entire neighborhood where the Neutral is also grounded through a rod there or before the RCCB in your main board.
When some problem occurs where the current flows somewhere else other than the neutral wire(through your body or protective earth, fault neutral line as i call it) it trips the RCCB protecting you or the device from catching fire.
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ejonesss
why toasters may want to have a ground wire is for safety if the heating element should burn out the end of the heating element could come in contact with the metal parts including mostly the lifting platform and liven up the body of the toaster.
depending where the element breaks off it could send the full line voltage to the metal parts or a current limited line voltage.
in the second case the toaster may still work because the break happened near the neutral wire.
if the heating element breaks off at the live end
you get a bad shock if there was not a ground or since there is a ground a spark and blown fuse would be the result.
the ground of the device connects to earth ground that is why you cant easily series power supplies without floating the board from the case.
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why toasters may want to have a ground wire is for safety if the heating element should burn out the end of the heating element could come in contact with the metal parts including mostly the lifting platform and liven up the body of the toaster.
depending where the element breaks off it could send the full line voltage to the metal parts or a current limited line voltage.
in the second case the toaster may still work because the break happened near the neutral wire.
if the heating element breaks off at the live end
you get a bad shock if there was not a ground or since there is a ground a spark and blown fuse would be the result.
the ground of the device connects to earth ground that is why you cant easily series power supplies without floating the board from the case.
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gamingit
PEN is mix of neutral and ground (PE+N) and it comes in one wire in distribution and measuring cabinet. From there it gets divided into 2 wires (PE and N. Then PE goes to green-yellow bus bar in fuse box but N goes thru rcd and then connects to N bar. After that N goes to other devices and outlets and when N and PE come into short with live fuse and rcd react. One thing that i hate is doepke they have dumb design they made so when rcd reacts it sets lever to middle and you need to lower the lever down and lift it up again sometimes can happen that in middle position it lets power thru and its dangerous. Wore that comes from ground to bus bar has purpose and that is to send excess power to ground or that excess can damage metering device
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PEN is mix of neutral and ground (PE+N) and it comes in one wire in distribution and measuring cabinet. From there it gets divided into 2 wires (PE and N. Then PE goes to green-yellow bus bar in fuse box but N goes thru rcd and then connects to N bar. After that N goes to other devices and outlets and when N and PE come into short with live fuse and rcd react. One thing that i hate is doepke they have dumb design they made so when rcd reacts it sets lever to middle and you need to lower the lever down and lift it up again sometimes can happen that in middle position it lets power thru and its dangerous. Wore that comes from ground to bus bar has purpose and that is to send excess power to ground or that excess can damage metering device
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Malte
my dad was working for a broadcasting company in germany. they had 3 metel towers for sending programs in medium wave frequency. they highest was about 188m in lenght. the stabilisation of the tower was build with steel wires to the ground. the wires had isolators at the end with a cable bridge to secure the towers to ground (earth) from electrostatic charging. the mass of metal in the towers made the electrostatic athmosphere effect very dangerous. my dad demonstrated this to me on a sunny day, he got safety clothes on and attached the ground cable. an ca. 10 cm long electric flash appeared. later he told me, that on rainy days there can be one flash about 30 cm and there can be ca. 10000v and more in it and a lot of current strenght.
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my dad was working for a broadcasting company in germany. they had 3 metel towers for sending programs in medium wave frequency. they highest was about 188m in lenght. the stabilisation of the tower was build with steel wires to the ground. the wires had isolators at the end with a cable bridge to secure the towers to ground (earth) from electrostatic charging. the mass of metal in the towers made the electrostatic athmosphere effect very dangerous. my dad demonstrated this to me on a sunny day, he got safety clothes on and attached the ground cable. an ca. 10 cm long electric flash appeared. later he told me, that on rainy days there can be one flash about 30 cm and there can be ca. 10000v and more in it and a lot of current strenght.
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P ter
I think none of your protection would protected you, since they not ment to do that. The normal braker is to prevent overheating/fire/short circuit, the ground fault protection one is also ment to protect you in a way, if you have failed appliance(s, and they have massive leakage current. I had a neighbour, who was dumb, and after the electricians installed the ground fault protection, he touched it, because he tought, that this wil pop. and guess what: it never did. if your skin is not wet enaugh, you max remain way under 30mA, and you can still die, also this stuff only works if you have closed circuit with ground involved. if you touch the L and the N somehow, you'll also fry at the end of the cable. So everyone: BE CAREFUL!
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I think none of your protection would protected you, since they not ment to do that. The normal braker is to prevent overheating/fire/short circuit, the ground fault protection one is also ment to protect you in a way, if you have failed appliance(s, and they have massive leakage current. I had a neighbour, who was dumb, and after the electricians installed the ground fault protection, he touched it, because he tought, that this wil pop. and guess what: it never did. if your skin is not wet enaugh, you max remain way under 30mA, and you can still die, also this stuff only works if you have closed circuit with ground involved. if you touch the L and the N somehow, you'll also fry at the end of the cable. So everyone: BE CAREFUL!
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William
You drive ground rods, nine meters deep? Here, in the US, I ve rarely seen one over 8 feet (2. 5 m. I noticed that your soil was very loamy, meaning that it might not hold moisture well, which could be the reason that they get driven so low. Where I m at, we have about 4 - 6 inches of black dirt, and then thick clay and rock layer, which holds a lot of moisture. Some years ago, I bought a ground rod driver, for my SDS hammer drill, and even that s difficult. (Still better than pounding then in by hand, though) How do they drive the 9 meter rods?
6: 00 - That s exactly how I imagined a German electrical panel would look like. Clean and tidy! Nice!
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You drive ground rods, nine meters deep? Here, in the US, I ve rarely seen one over 8 feet (2. 5 m. I noticed that your soil was very loamy, meaning that it might not hold moisture well, which could be the reason that they get driven so low. Where I m at, we have about 4 - 6 inches of black dirt, and then thick clay and rock layer, which holds a lot of moisture. Some years ago, I bought a ground rod driver, for my SDS hammer drill, and even that s difficult. (Still better than pounding then in by hand, though) How do they drive the 9 meter rods?
6: 00 - That s exactly how I imagined a German electrical panel would look like. Clean and tidy! Nice!
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Ota
even in electronics, the ground should be connected to the ground, otherwise you can get some problems, for example in audio amplifier you can get sound distortion, hissing or popping sound.
this is because the dc generator only care about giving the two terminals a set difference of x Volts, but if your zero reference is at higher potential than ground, then the live will go even higher and sometimes this in electronics create some problems.
interesting fact, for properly measure earth impedance, you have to use the fall of potential method, an handheld meter will almost always give you a wrong measurement.
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even in electronics, the ground should be connected to the ground, otherwise you can get some problems, for example in audio amplifier you can get sound distortion, hissing or popping sound.
this is because the dc generator only care about giving the two terminals a set difference of x Volts, but if your zero reference is at higher potential than ground, then the live will go even higher and sometimes this in electronics create some problems.
interesting fact, for properly measure earth impedance, you have to use the fall of potential method, an handheld meter will almost always give you a wrong measurement.
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Sebastian
Also, you do NOT have a PEN or a TN-C system, but rather a TN-S system, because the PE and N is separated in a sealed cabinet (technically, before your meter, meaning that your utility company gives you a TN-S connection to grid, not a TN-C connection (since TN-C is split on THEIR side, inside their sealed cabinet. If you really want a TN-C system for some reason (might be good in future if you plan on installing a EV charger which expects a PEN) you can ask your utility company to not split the PE and N before meter, but after meter, which would mean PE and N is split in a cabinet you have access to.
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Also, you do NOT have a PEN or a TN-C system, but rather a TN-S system, because the PE and N is separated in a sealed cabinet (technically, before your meter, meaning that your utility company gives you a TN-S connection to grid, not a TN-C connection (since TN-C is split on THEIR side, inside their sealed cabinet. If you really want a TN-C system for some reason (might be good in future if you plan on installing a EV charger which expects a PEN) you can ask your utility company to not split the PE and N before meter, but after meter, which would mean PE and N is split in a cabinet you have access to.
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Stark
For those who do not know, actuall the cause of electrical shock from human touching Live wire (not talking about touching both L & N) is because the bonding of Earth and Neutral somewhere in Grid Transformer. Without any bonding to Earth from Neutral, it would not give shock, that is called Floating system and where L and N are both equally the same (both becomes Live but does not give shock if just one wire is touched. But because N and E are bonded, the Live will go through human body via Earth back to N. This is the precise explanation of electrical shock (or danger) that often people worry about.
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For those who do not know, actuall the cause of electrical shock from human touching Live wire (not talking about touching both L & N) is because the bonding of Earth and Neutral somewhere in Grid Transformer. Without any bonding to Earth from Neutral, it would not give shock, that is called Floating system and where L and N are both equally the same (both becomes Live but does not give shock if just one wire is touched. But because N and E are bonded, the Live will go through human body via Earth back to N. This is the precise explanation of electrical shock (or danger) that often people worry about.
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Fabian
without earth or ground aka an IT-System we would actually be safer (thats also why its mostly used in hospitals.
without any connection to earth the live wire can come loose and onto the housing or rather speaking you could touch one wire without anything happening.
if its an checked system (hospitals) electronic devices detect the problem and shutdown the connection or bring an alert if it cannot be turned of. (ie. if its someones life support or simmiliar)
if it is unchecked then nothing happens until an second problem occurs (ie. the neutral wire comes also loose or another phase.
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without earth or ground aka an IT-System we would actually be safer (thats also why its mostly used in hospitals.
without any connection to earth the live wire can come loose and onto the housing or rather speaking you could touch one wire without anything happening.
if its an checked system (hospitals) electronic devices detect the problem and shutdown the connection or bring an alert if it cannot be turned of. (ie. if its someones life support or simmiliar)
if it is unchecked then nothing happens until an second problem occurs (ie. the neutral wire comes also loose or another phase.
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TwistedShadowSAF
My understanding with ELCB is as you say, measures current in Vs current out, but it also helps diagnose causes of issues. so normal fuses and CB are protection for overload, so essentially too high current draw on a circuit or, there is a live touching neutral/Earth. an ELCB measures or identifies leaks on the neutral and earth lines since even if the live is off, a neutral touching earth will still cause it to trip. because there is still a potential between neutral and earth even when the live is disconnected from a circuit. when you're fault finding, that kinda detail helps a lot.
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My understanding with ELCB is as you say, measures current in Vs current out, but it also helps diagnose causes of issues. so normal fuses and CB are protection for overload, so essentially too high current draw on a circuit or, there is a live touching neutral/Earth. an ELCB measures or identifies leaks on the neutral and earth lines since even if the live is off, a neutral touching earth will still cause it to trip. because there is still a potential between neutral and earth even when the live is disconnected from a circuit. when you're fault finding, that kinda detail helps a lot.
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SWAPNIL
We get 220VAC from transformers which takes 11 - 13. 8kV as input. Transformers are just 2 coils with a couple cm gap between HT and LT. If somehow a phase from HT gets into contact with LT which isn't properly earthed, Nothing will blow up, everything will work properly between phase and neutral but the moment anyone gets close enough to electrical fittings, 6. 4KV will zap right through them.
Grounding also ensures every substation in an interconnected grid measures the same voltage in each phase wrt to earth, that's essential for fault finding.
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We get 220VAC from transformers which takes 11 - 13. 8kV as input. Transformers are just 2 coils with a couple cm gap between HT and LT. If somehow a phase from HT gets into contact with LT which isn't properly earthed, Nothing will blow up, everything will work properly between phase and neutral but the moment anyone gets close enough to electrical fittings, 6. 4KV will zap right through them.
Grounding also ensures every substation in an interconnected grid measures the same voltage in each phase wrt to earth, that's essential for fault finding.
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Kavinkumar
Is my understanding correct?
You got this big 3 phase AC generator in the power generation station. Let it be therma, nuclear or other sources. You got 3 phase voltage out of it. You send power through the 3 phase to long distance. Then you step down it to single phase in a transformer station. So, you get 1 high voltage terminal and a neutral point which is connected to ground at the station. These 2 lines will be sent to your home. So neutral is literally connected to earth but not in your home but in a step down station.
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Is my understanding correct?
You got this big 3 phase AC generator in the power generation station. Let it be therma, nuclear or other sources. You got 3 phase voltage out of it. You send power through the 3 phase to long distance. Then you step down it to single phase in a transformer station. So, you get 1 high voltage terminal and a neutral point which is connected to ground at the station. These 2 lines will be sent to your home. So neutral is literally connected to earth but not in your home but in a step down station.
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Krzychu1995
Very nice video. You mentioned point of separation of PE and N from PEN. This and types of electric grids would be a very interesting topic. I already approached that as I started to work for lighting equipment producer, but I'm interested in how would you explain this.
By the way in Poland we have the same system for electric distribution (colors of wires, breakers, etc. Only thing I would wish is to have more Shuko outlets, as they are much better than old style with PE as metal rod coming from socket.
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Very nice video. You mentioned point of separation of PE and N from PEN. This and types of electric grids would be a very interesting topic. I already approached that as I started to work for lighting equipment producer, but I'm interested in how would you explain this.
By the way in Poland we have the same system for electric distribution (colors of wires, breakers, etc. Only thing I would wish is to have more Shuko outlets, as they are much better than old style with PE as metal rod coming from socket.
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alx9r
In North America I often see common on schematics where it s not really an earth ground like, for example, on circuit boards and vehicles. I have been involved in many situations where that distinction indeed matters, and the more experienced the electrician or electrical engineer, the more they seem to care about the distinction in the documentation.
My circuit board designs often have had a different net for common and earth ground so that the coupling between the two can be managed.
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In North America I often see common on schematics where it s not really an earth ground like, for example, on circuit boards and vehicles. I have been involved in many situations where that distinction indeed matters, and the more experienced the electrician or electrical engineer, the more they seem to care about the distinction in the documentation.
My circuit board designs often have had a different net for common and earth ground so that the coupling between the two can be managed.
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