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Earth is used as return path for any current. Someone described it as an endless source/sink for electrons. I don’t have any delta loads in my house, but I cou

Earth is used as return path for any current. Someone described it as an endless source/sink for electrons. I don’t have any delta loads in my house, but I could of course if I needed to.

mindslight 4y ago
That's odd, and I can only think you must live in an area where the earth is conductive enough to carry significant current (or are the cables coming from the transformer inside a metal conduit?) The earth is nothing like "an endless source/sink for electrons". Rather, electricity always flows in a complete loop (circuit), and the current flow is somehow getting back to the transformer to complete that circuit.
- derefr 4y ago
  All you need to conduct long distances through the earth is a big buried plate to spread the current across. See e.g. https://en.m.wikipedia.org/wiki/Earth-return_telegraph https://en.m.wikipedia.org/wiki/Earth-return_telegraph. > The earth is nothing like "an endless source/sink for electrons" It’s a bounded sink for electrons, though — i.e. it has capacitance — insofar as a positive ionization required for a static discharge (lightning) built up in the earth can be “spent” by grounding voltage into it. You can think of the earth as a constantly-recharging (but sometimes rapidly discharged) anti-supercapacitor. Just like the atmosphere is a constantly recharging (but sometimes rapidly discharged) regular supercapacitor. Ignoring that, though, what people usually mean by this is that the combined neutrals of the entire power grid are on the other end of any dumping of current you’re doing into ground. It’s not just your local neighbourhood transformer; if your transformer’s resistivity increased too much due to the added ground-return current, then the rest of the current could find another path to some other, further-afield transformer, or multiple such. Or maybe even the local power plant. Or some unrelated grid-connected power plant. Or—dangerously—a power plant connected to a physically proximate but electrically disconnected grid… which is in part what makes power-factor wobble around so much in black-start grid power stations.
  - mindslight 4y ago
    Sure, the earth in bulk is essentially a conductor and it's possible to transmit electricity through the ground (eg single wire earth return). I would just think it impractical for last hop residential distribution (eg the effect in the original post), as getting a good connection is hard and the distance is short. > the combined neutrals of the entire power grid are on the other end of any dumping of current you’re doing into ground This only makes sense if the primary side of the transformers have a grounded conductor ("neutral"), and it's bonded to the grounded conductor on the secondary side. I don't know much about common power distribution topologies, but this would seem less safe as it would increase the possibility of the high distribution voltage trying to find its way back to the plant/grid/ground through end-user services.
  - jcalvinowens 4y ago
    > It’s a bounded sink for electrons, though — i.e. it has capacitance — insofar as a positive ionization required for a static discharge (lightning) built up in the earth can be “spent” by grounding voltage into it. The Earth has no special ability to absorb electrons beyond what a jar of dirt does. In a lightning discharge, the earth and the thundercloud act as opposite plates of a capacitor with an air dielectric. As a thought experiment: if I built a hypothetically perfect giant metal shield covering the entire planet 100ft above ground, and perfectly insulated it from earth, lightning would discharge to the shield, and there would be zero potential from the shield to the actual Earth either before or after the discharge. There is nothing electrically special about the physical Earth, it's just a conductor. > Ignoring that, though, what people usually mean by this is that the combined neutrals of the entire power grid are on the other end of any dumping of current you’re doing into ground. What you're describing only happens during fault conditions. Except in extremely unusual circumstances like [1], the Earth is not used as a normal return path for utility neutral current. The return current flows on dedicated neutral conductors. Actually, in am ideally balanced Wye, there isn't any real neutral current at all. [1] https://en.m.wikipedia.org/wiki/Single-wire_earth_return https://en.m.wikipedia.org/wiki/Single-wire_earth_return
    - deleted 4y ago
      [deleted]
jcalvinowens 4y ago
I would be happy to be proven wrong... but I bet your transformer has a grounded neutral point with a dedicated conductor to your service panel, even if all your loads are phase to phase. It could be corner grounded... but my understanding is that is very uncommon. EDIT: I read your post again and I think "three phase" means "three wires": a 240V hot, a 0V neutral, and an earth wire?
- renewedrebecca 4y ago
  "three phase" generally means 3 hots, each 120 degrees out of phase with each other. You may or may not have a neutral with a 3 phase system.
  - jcalvinowens 4y ago
    Yeah. I thought maybe the author of that post was confusing "three wires" with "three phases". I don't know about the EU, but in the US there's almost always a grounded neutral point on three phase systems, even if the loads are all phase to phase. All the literature I've ever found says corner grounded deltas are "not to be used in new installations", and ungrounded deltas are similarly discouraged.
    - renewedrebecca 4y ago
      Ah, ok, that makes sense.

Earth is used as return path for any current. Someone described it as an endless source/sink for electrons. I don’t have any delta loads in my house, but I could of course if I needed to.

mindslight 4y ago

That's odd, and I can only think you must live in an area where the earth is conductive enough to carry significant current (or are the cables coming from the transformer inside a metal conduit?) The earth is nothing like "an endless source/sink for electrons". Rather, electricity always flows in a complete loop (circuit), and the current flow is somehow getting back to the transformer to complete that circuit.

derefr 4y ago
All you need to conduct long distances through the earth is a big buried plate to spread the current across. See e.g. https://en.m.wikipedia.org/wiki/Earth-return_telegraph https://en.m.wikipedia.org/wiki/Earth-return_telegraph. > The earth is nothing like "an endless source/sink for electrons" It’s a bounded sink for electrons, though — i.e. it has capacitance — insofar as a positive ionization required for a static discharge (lightning) built up in the earth can be “spent” by grounding voltage into it. You can think of the earth as a constantly-recharging (but sometimes rapidly discharged) anti-supercapacitor. Just like the atmosphere is a constantly recharging (but sometimes rapidly discharged) regular supercapacitor. Ignoring that, though, what people usually mean by this is that the combined neutrals of the entire power grid are on the other end of any dumping of current you’re doing into ground. It’s not just your local neighbourhood transformer; if your transformer’s resistivity increased too much due to the added ground-return current, then the rest of the current could find another path to some other, further-afield transformer, or multiple such. Or maybe even the local power plant. Or some unrelated grid-connected power plant. Or—dangerously—a power plant connected to a physically proximate but electrically disconnected grid… which is in part what makes power-factor wobble around so much in black-start grid power stations.
- mindslight 4y ago
  Sure, the earth in bulk is essentially a conductor and it's possible to transmit electricity through the ground (eg single wire earth return). I would just think it impractical for last hop residential distribution (eg the effect in the original post), as getting a good connection is hard and the distance is short. > the combined neutrals of the entire power grid are on the other end of any dumping of current you’re doing into ground This only makes sense if the primary side of the transformers have a grounded conductor ("neutral"), and it's bonded to the grounded conductor on the secondary side. I don't know much about common power distribution topologies, but this would seem less safe as it would increase the possibility of the high distribution voltage trying to find its way back to the plant/grid/ground through end-user services.
- jcalvinowens 4y ago
  > It’s a bounded sink for electrons, though — i.e. it has capacitance — insofar as a positive ionization required for a static discharge (lightning) built up in the earth can be “spent” by grounding voltage into it. The Earth has no special ability to absorb electrons beyond what a jar of dirt does. In a lightning discharge, the earth and the thundercloud act as opposite plates of a capacitor with an air dielectric. As a thought experiment: if I built a hypothetically perfect giant metal shield covering the entire planet 100ft above ground, and perfectly insulated it from earth, lightning would discharge to the shield, and there would be zero potential from the shield to the actual Earth either before or after the discharge. There is nothing electrically special about the physical Earth, it's just a conductor. > Ignoring that, though, what people usually mean by this is that the combined neutrals of the entire power grid are on the other end of any dumping of current you’re doing into ground. What you're describing only happens during fault conditions. Except in extremely unusual circumstances like [1], the Earth is not used as a normal return path for utility neutral current. The return current flows on dedicated neutral conductors. Actually, in am ideally balanced Wye, there isn't any real neutral current at all. [1] https://en.m.wikipedia.org/wiki/Single-wire_earth_return https://en.m.wikipedia.org/wiki/Single-wire_earth_return
  - deleted 4y ago
    [deleted]

jcalvinowens 4y ago

I would be happy to be proven wrong... but I bet your transformer has a grounded neutral point with a dedicated conductor to your service panel, even if all your loads are phase to phase. It could be corner grounded... but my understanding is that is very uncommon. EDIT: I read your post again and I think "three phase" means "three wires": a 240V hot, a 0V neutral, and an earth wire?

renewedrebecca 4y ago
"three phase" generally means 3 hots, each 120 degrees out of phase with each other. You may or may not have a neutral with a 3 phase system.
- jcalvinowens 4y ago
  Yeah. I thought maybe the author of that post was confusing "three wires" with "three phases". I don't know about the EU, but in the US there's almost always a grounded neutral point on three phase systems, even if the loads are all phase to phase. All the literature I've ever found says corner grounded deltas are "not to be used in new installations", and ungrounded deltas are similarly discouraged.
  - renewedrebecca 4y ago
    Ah, ok, that makes sense.