Why is the neutral called the grounded conductor? (2024)

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teufelhounden91

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Location
Austin, TX, USA
  • Oct 14, 2015
  • #1

I've recently watched Mike Holt's video on electrical fundamentals and common grounding myths. I talked to my Master Electrician about how Mike states current leaves source and returns to source and that current does not seek ground; it seeks a return path back to where it came from. Mike also talks about how putting a ground rod at a pole is pointless and serves no purpose. I brought these things up to my master electrician and he disagreed with both of them. He states that current is always going to travel from one side of an imbalance to another, and will find something at a lower potential to travel to – whatever that maybe. He also stated that the neutral conductor is grounded somewhere down the line from the utility so current through a neutral is still making it to ground somewhere. He said that a light pole that has anchors encased in concrete has a very high impedance path to ground so the purpose of the ground rod at a pole is to bond to the steel and give a lower impedance path to ground than the steel through the concrete. He feels that putting a ground rod at a pole can only improve the possibility of lightning making it to ground, rather than relying on the steel in the concrete. He believes the more grounds the better, which is another one of Mike Holt's myths. My question is maybe due to my misunderstanding of Mike Holt's theory, but isn't a neutral "created" (for lack of a better term) by the utility in the windings of their generator? The neutral is not a neutral because it is referencing earth correct? It is a neutral because it is tapped at a midpoint in a coil of wire. Or is it tapping the midpoint and bringing it to ground what makes the whole neutral concept to work in the first place?

charlie b

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Lockport, IL
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Retired Electrical Engineer
  • Oct 14, 2015
  • #3

My reply is going to require two posts. This is the first post.

Mike is right; your Master is wrong. The notion of current going from high potential to low potential is only part of the story. For a lightning strike, you have a one-time release of energy through the motion of electrons from one location to another. But for a continuous flow of current (which is what we deal with most of the time) you need a complete circuit, a complete path. That means from the positive pole of the battery, through the wire to one side of the light bulb, through the light bulb, through the other wire to the negative side of the battery, and finally through the battery itself to return to the point at which it all started. Substitute “generator” or “transformer” for “battery,” and the story remains true. Current flow begins at a source, and current will return to that source. If current did not have a way to get back to the source, there would not be a complete path, and current could not have started flowing in the first place. Current cannot make its way into planet Earth and disappear. It needs a complete path back to its source.

However, current certainly can use planet Earth as a conductive path, if by so doing it can find its way back to its source. Suppose you are holding a defective power tool in your hand. It still works, but a loose internal wire is energizing the case. There are two current paths available, and current will take any and all paths that it can find. For this discussion, let’s treat the panelboard as though it were the source. We know the real source is a generator or transformer further upstream. But for my present purposes, this will work well enough.

  • Path 1 starts at the panel. Current leaves the circuit breaker, travels along the wire to the receptacle outlet. From there, current travels along the tool’s power cord, through the tool (which, as I said, is still working), out the other wire within the tool’s power cord, and back to the receptacle outlet’s other side. From there, it travels back to the panel along the branch circuit wire, and hits the neutral bar. We will say that that completes the circuit.
  • Path 2 starts the same way, up until current has made its way into the tool. Some current will now travel to the metal case via the broken wire. From there, it travels to the hand of the person holding the tool, through that person’s body to the feet, shoes, and floor. It travels through the dirt (and when you have a whole planet full of dirt, you have a very good conductor of electricity) to the location of the ground rod. It goes up the ground rod, travels up the grounding electrode conductor, and lands on the panel’s neutral bus. This is the same point at which Path 1 terminated, and therefore we will say that the current following this path has returned to its source.

charlie b

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  • Oct 14, 2015
  • #4

This is the second post.

The neutral wire is called a “neutral” because it is equally separated (in terms of voltage) from each of the other wires.

  • In a single phase, 120/240V system, there is 120 volts between the neutral and Phase A, and there is 120 volts between the neutral and Phase B. In this case, due to the relative points in time at which Phase A voltage reaches its positive peak and at which Phase B reaches its positive peak, the voltage between Phase A and Phase B is 240 volts.
  • In a three phase, 120/208V system, there is 120 volts between the neutral and Phase A, there is 120 volts between the neutral and Phase B, and there is 120 volts between the neutral and Phase C. In this case, due to the relative points in time at which the three Phase voltages reach their positive peaks, the voltage between any two Phases is 208 volts.


The neutral is also called the “grounded” conductor because (for most of the systems we work with) we intentionally run a wire from the neutral bus to planet Earth. Why do we do that? This is a topic of much debate, and I can’t give a really satisfactory answer. One reason is said to do with creating a path for lightning to find its way into dirt. Another reason is said to do with making sure that the voltage between any of the phase wires and the ground upon which you are standing is pinned to a constant value (e.g., 120 volts). If the system had no connection to planet Earth, the voltage between any phase and the dirt would fluctuate moment-to-moment, and could reach some really undesirably high values.

But I will assert, with total confidence, that the reason we connect the neutral wire to ground has nothing to do with giving the current an easy path that it can follow into the dirt. Current has no interest in traveling into the dirt. As I said in the earlier post, it is willing to use dirt, if that allows it to make its way back to its source. But otherwise, it will not travel along the grounding electrode conductor, onto the ground rod, and into the dirt.

teufelhounden91

Senior Member
Location
Austin, TX, USA
  • Oct 14, 2015
  • #5

charlie b said:

This is the second post.

The neutral wire is called a “neutral” because it is equally separated (in terms of voltage) from each of the other wires.

  • In a single phase, 120/240V system, there is 120 volts between the neutral and Phase A, and there is 120 volts between the neutral and Phase B. In this case, due to the relative points in time at which Phase A voltage reaches its positive peak and at which Phase B reaches its positive peak, the voltage between Phase A and Phase B is 240 volts.
  • In a three phase, 120/208V system, there is 120 volts between the neutral and Phase A, there is 120 volts between the neutral and Phase B, and there is 120 volts between the neutral and Phase C. In this case, due to the relative points in time at which the three Phase voltages reach their positive peaks, the voltage between any two Phases is 208 volts.


The neutral is also called the “grounded” conductor because (for most of the systems we work with) we intentionally run a wire from the neutral bus to planet Earth. Why do we do that? This is a topic of much debate, and I can’t give a really satisfactory answer. One reason is said to do with creating a path for lightning to find its way into dirt. Another reason is said to do with making sure that the voltage between any of the phase wires and the ground upon which you are standing is pinned to a constant value (e.g., 120 volts). If the system had no connection to planet Earth, the voltage between any phase and the dirt would fluctuate moment-to-moment, and could reach some really undesirably high values.

But I will assert, with total confidence, that the reason we connect the neutral wire to ground has nothing to do with giving the current an easy path that it can follow into the dirt. Current has no interest in traveling into the dirt. As I said in the earlier post, it is willing to use dirt, if that allows it to make its way back to its source. But otherwise, it will not travel along the grounding electrode conductor, onto the ground rod, and into the dirt.

Thank you so much for taking the time to reassure me of what I understood Mike Saying. I agree 100% with everything you said. So if this is how we understand current flow is it true that if we had no GEC anywhere around bonded to a neutral bus and we drove a ground rod 20ft away from a panel and hooked it to a breaker, current would not flow period? Because it cannot find a path back to source. Earth is a great conductor but I doubt current would travel a mile away to a pole that has an XFMR on it and find source there. (Because the number of possible paths of resistance increase exponentially the further away you go). Mike Holt drove a ground rod and drew 4.8a on it (120v) from a breaker but I'm assuming the only way this was possible was because the panel had a GEC to get the current back to source.

On another note, what are your thoughts on driving ground rods at poles? Do you agree with Mike that they're unnecessary? If the pole has anchors and steel encased in concrete isn't this essentially a ufer ground with less surface area?

Thank you again, great answers!

ActionDave

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Location
Durango, CO, 10 h 20 min from the winged horses.
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Licensed Electrician
  • Oct 14, 2015
  • #6

teufelhounden91 said:

Thank you so much for taking the time to reassure me of what I understood Mike Saying. I agree 100% with everything you said. So if this is how we understand current flow is it true that if we had no GEC anywhere around bonded to a neutral bus and we drove a ground rod 20ft away from a panel and hooked it to a breaker, current would not flow period? Because it cannot find a path back to source. Earth is a great conductor but I doubt current would travel a mile away to a pole that has an XFMR on it and find source there. (Because the number of possible paths of resistance increase exponentially the further away you go). Mike Holt drove a ground rod and drew 4.8a on it (120v) from a breaker but I'm assuming the only way this was possible was because the panel had a GEC to get the current back to source.

On another note, what are your thoughts on driving ground rods at poles? Do you agree with Mike that they're unnecessary? If the pole has anchors and steel encased in concrete isn't this essentially a ufer ground with less surface area?

Thank you again, great answers!

Check out this past thread......

http://forums.mikeholt.com/showthread.php?t=116358

C

Carultch

Senior Member
Location
Massachusetts
  • Oct 15, 2015
  • #7

teufelhounden91 said:

I've recently watched Mike Holt's video on electrical fundamentals and common grounding myths. I talked to my Master Electrician about how Mike states current leaves source and returns to source and that current does not seek ground; it seeks a return path back to where it came from. Mike also talks about how putting a ground rod at a pole is pointless and serves no purpose. I brought these things up to my master electrician and he disagreed with both of them. He states that current is always going to travel from one side of an imbalance to another, and will find something at a lower potential to travel to – whatever that maybe. He also stated that the neutral conductor is grounded somewhere down the line from the utility so current through a neutral is still making it to ground somewhere. He said that a light pole that has anchors encased in concrete has a very high impedance path to ground so the purpose of the ground rod at a pole is to bond to the steel and give a lower impedance path to ground than the steel through the concrete. He feels that putting a ground rod at a pole can only improve the possibility of lightning making it to ground, rather than relying on the steel in the concrete. He believes the more grounds the better, which is another one of Mike Holt's myths. My question is maybe due to my misunderstanding of Mike Holt's theory, but isn't a neutral "created" (for lack of a better term) by the utility in the windings of their generator? The neutral is not a neutral because it is referencing earth correct? It is a neutral because it is tapped at a midpoint in a coil of wire. Or is it tapping the midpoint and bringing it to ground what makes the whole neutral concept to work in the first place?

I have a problem with the terms groundING conductor and groundED conductor being completely different concepts. The fact that they start with the same base word, and it is the conjugation ending only that makes the difference is a major source of confusion. Especially when working with non-native English speakers, who aren't accustomed to focusing on the little ending of a word. This is why you will often find me erroneously calling the groundED conductor, the neutral, even in applications where it is incorrect to call it the neutral. Sometimes I'll even default to calling the wires by their industry norm color code, instead.

The reason the neutral is the groundED conductor, is that it is bonded to the equipment grounding system/grounding electrode system at exclusively one point, where it gets a voltage reference to ground. Neutral carries the return current during normal operating conditions, and if you measure any point on neutral relative to ground, it will usually be within individual volts of ground. Just enough to apply ohm's law, and get the current through the wire back to the source where it is bonded to ground.

Last edited:

charlie b

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Location
Lockport, IL
Occupation
Retired Electrical Engineer
  • Oct 15, 2015
  • #8

teufelhounden91 said:

On another note, what are your thoughts on driving ground rods at poles? Do you agree with Mike that they're unnecessary? If the pole has anchors and steel encased in concrete isn't this essentially a ufer ground with less surface area?

I agree with Mike: the ground rod is worthless. The only thing that will protect a person against electrical shock would be the equipment grounding conductor. All the stories you might have heard about people or animals receiving a shock from touching a light pole are the result of an inadequate EGC.

G

GoldDigger

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Location
Placerville, CA, USA
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Retired PV System Designer
  • Oct 15, 2015
  • #9

Actually the shocks are the result of an inadequate EGC combined with a ground fault in equipment or wiring. Why is the neutral called the grounded conductor? (9)

S

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
  • Oct 15, 2015
  • #10

charlie b said:

I agree with Mike: the ground rod is worthless. The only thing that will protect a person against electrical shock would be the equipment grounding conductor. All the stories you might have heard about people or animals receiving a shock from touching a light pole are the result of an inadequate EGC.

Does Mike, and subsequently you mean useless in regards to the electrical distribution system, or useless in regards to that AND lightning? I don't have a deep knowledge of lightning protection theory, and I thought the ground rod offered some level of help in this way.

jumper

Senior Member
Location
3 Hr 2 Min from Winged Horses
  • Oct 15, 2015
  • #11

Strathead said:

I don't have a deep knowledge of lightning protection theory, and I thought the ground rod offered some level of help in this way.

The GES is supposed to help a little, but in truth-good insurance is better protection.

240.4(A)(1) Grounded Systems.
(1) Electrical System Grounding. Electrical systems that
are grounded shall be connected to earth in a manner that
will limit the voltage imposed by lightning, line surges, or
unintentional contact with higher-voltage lines and that will
stabilize the voltage to earth during normal operation.

mgookin

Senior Member
Location
Fort Myers, FL
  • Oct 15, 2015
  • #12

Strathead said:

Does Mike, and subsequently you mean useless in regards to the electrical distribution system, or useless in regards to that AND lightning? I don't have a deep knowledge of lightning protection theory, and I thought the ground rod offered some level of help in this way.

Isn't it true that the ground rod at your service is intended to form a path through the Earth to the ground rod at the pole such that when a primary crosses to a secondary it reverts energy back to the source instead of into the building?

teufelhounden91

Senior Member
Location
Austin, TX, USA
  • Oct 15, 2015
  • #13

ActionDave said:

Check out this past thread......http://forums.mikeholt.com/showthread.php?t=116358

Thank you, great info here

G

GoldDigger

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Location
Placerville, CA, USA
Occupation
Retired PV System Designer
  • Oct 15, 2015
  • #14

mgookin said:

Isn't it true that the ground rod at your service is intended to form a path through the Earth to the ground rod at the pole such that when a primary crosses to a secondary it reverts energy back to the source instead of into the building?

The current goes back to the source. The energy does not.
In the absence of both neutral and EGC as well as ground/earth paths there will be no current flowing and no energy dissipated. Just lethal voltages waiting for someone to complete the circuit.

teufelhounden91

Senior Member
Location
Austin, TX, USA
  • Oct 15, 2015
  • #15

OK boys I'm gonna dig this hole a little deeper. Suppose you have a panel and from a 20 amp breaker you bring a wire to a completely insulated bowl in the ground. Essentially a pool made out of rubber. If we filled this pool with water and ran our wire to the water and let it lay in there, there is no way current can get back to source so a person sitting in this rubber pool would not get shocked. Correct? If we ran another wire from the water to the earth and we have no GEC at our panel this would still not give current a path back to source right? Still safe to sit in. However if we have a GEC at the panel that is bonded to the neutral bus, then somebody sitting in the water would get the piss knocked out of them because now there is a path to source correct?

Another question...ow far away will a fault travel through planet earth to get back to source? Willy fall travel a mile away to get back to a transformer up on a pole? 5 miles?

I apologize for my daftness, just want to make sure that I understand this completely.

teufelhounden91

Senior Member
Location
Austin, TX, USA
  • Oct 15, 2015
  • #16

GoldDigger said:

The current goes back to the source. The energy does not.
In the absence of both neutral and EGC as well as ground/earth paths there will be no current flowing and no energy dissipated. Just lethal voltages waiting for someone to complete the circuit.

Thank you, this is how I understand it as well. The master electrician I work for says that I need to prove this to him before he will change his thinking. I think that every electrician needs to be on board with this as a basis for their understanding of electrical theory. This changes everything. There are so many experienced electricians who don't know this, and are teaching coming up electricians incorrect information.

teufelhounden91

Senior Member
Location
Austin, TX, USA
  • Oct 15, 2015
  • #17

I suppose I could not be lazy and just do a voltage drop calculation until my value reaches zero then I'll get my distance out of it.

G

GoldDigger

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Location
Placerville, CA, USA
Occupation
Retired PV System Designer
  • Oct 15, 2015
  • #18

teufelhounden91 said:

OK boys I'm gonna dig this hole a little deeper. Suppose you have a panel and from a 20 amp breaker you bring a wire to a completely insulated bowl in the ground. Essentially a pool made out of rubber. If we filled this pool with water and ran our wire to the water and let it lay in there, there is no way current can get back to source so a person sitting in this rubber pool would not get shocked. Correct? If we ran another wire from the water to the earth and we have no GEC at our panel this would still not give current a path back to source right? Still safe to sit in. However if we have a GEC at the panel that is bonded to the neutral bus, then somebody sitting in the water would get the piss knocked out of them because now there is a path to source correct?

Another question...ow far away will a fault travel through planet earth to get back to source? Willy fall travel a mile away to get back to a transformer up on a pole? 5 miles?

I apologize for my daftness, just want to make sure that I understand this completely.

1. There is a ground on the POCO neutral at the transformer secondary, so your ground electrode will probably not trip a breaker but it will sure mess up the guy in the pool. If there were no ground at the source either, then your analysis would be right.
2. That is the hard thing to accept. Once you get past the electrode resistance at each end, the resistance of the earth itself, whether 1 mile or 5000, is effectively zero. The (infinite) number of parallel paths decreases not increases the resistance.

teufelhounden91

Senior Member
Location
Austin, TX, USA
  • Oct 15, 2015
  • #19

how far will fault current travel to find the source?

how far will fault current travel to find the source?

GoldDigger said:

1. There is a ground on the POCO neutral at the transformer secondary, so your ground electrode will probably not trip a breaker but it will sure mess up the guy in the pool. If there were no ground at the source either, then your analysis would be right.
2. That is the hard thing to accept. Once you get past the electrode resistance at each end, the resistance of the earth itself, whether 1 mile or 5000, is effectively zero. The (infinite) number of parallel paths decreases not increases the resistance.

1) Yes I agree about the poco ground. I should've specified that as well. I see what you're saying about the earth's resistance decreasing as parallel paths increase. I believe I was thinking of that backwards but either way the earth's resistance is not a constant because of the changing density of the dirt, sand, rocks, moisture, etc as well as the fact that it is a 3 dimensional plane. Theoretically however if we are being told that earth's overall resistance is 0 ohms then I believe you would be correct.

2) If this is the case (zero earth resistance) then current will always find a path back to source no matter where you are right? If fault current experiences no resistance once it hits earth why would it not always keep going to find its path back to source somewhere. Nothing is resisting it. This is why I feel like Earth can't have an exact zero resistance.

I don't think that a fault will travel 5000 miles to find source. I don't know why I feel that way but it just doesn't seem right to me that at some point the current will not just lose its momentum or and not make it to source at a great enough distance. I admit I could be totally wrong.

G

GoldDigger

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Staff member

Location
Placerville, CA, USA
Occupation
Retired PV System Designer
  • Oct 15, 2015
  • #20

To be totally blunt, you are totally wrong. But you are in good company. Why is the neutral called the grounded conductor? (17)
The resistance of the earth is not exactly zero. But it is so low that for all practical purposes it is zero.
Individual electrons do make the whole trip. They just move a little more in that direction, as do gazillions of other electrons along the way. There is a very very small but finite voltage gradient that moves the all. The actual voltage gradient within the earth is a linear sum of all of the voltage gradients from all of the circuits that are completed through the earth.
But there are far higher voltages and currents within the core which are responsible for the Earth's magnetic field.

Finally, if there really is no earth path to the source the elections will not just wander around looking. Why is the neutral called the grounded conductor? (18)

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Why is the neutral called the grounded conductor? (2024)

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