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I have heard that transformer connects to house only via phase(s) - neutral from house is actually grounded, as well as transformers and they connect via earth. Is this true? What is resistance of ground?

I understand this is made to save on wiring.

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    \$\begingroup\$ Are you talking "North American" continent kind of stuff? (Split-phase.) In the US, for example, it is usual to have a grounded neutral (middle leg of power transformer secondary) with L1 being one side and L2 being the other side of that secondary. In that case, the middle leg of the power transformer is grounded at the pole (or buried box) and also grounded at the home, as well. The resistance of the ground between the power transformer and the home varies. In a test I read in California, this would start out at just a few Ohms, but over a decade's time, would increase to a few tens of Ohms. \$\endgroup\$ Commented Sep 5, 2023 at 13:19
  • \$\begingroup\$ Certainly not true in the UK. Where did you hear this? \$\endgroup\$
    – Finbarr
    Commented Sep 5, 2023 at 13:20
  • \$\begingroup\$ Which wiring scheme do you refer to. There are plenty to choose from. \$\endgroup\$
    – Andy aka
    Commented Sep 5, 2023 at 13:20
  • \$\begingroup\$ This varies from country to country. Please check en.wikipedia.org/wiki/Earthing_system and see if you can narrow it down to a particular case. \$\endgroup\$
    – winny
    Commented Sep 5, 2023 at 13:26

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It is not true that utility power is fed to the consumer through live wires alone, with earth / ground serving as the neutral.

Here's a typical schematic for a three-phase system.

enter image description here

The neutral wire, which is connected to the earthed 'star point' of the secondary of the distribution transformer, is earthed at the sub-station as well as at every pole over which it is led.

Likewise, with the American split-phase system.

enter image description here

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It depends where you live and your electrical system. It is likely that you get a neutral so planet earth is not used as return conductor, that would not work very well (except for high-voltage long-haul DC connections maybe where it is actually used).

As it is possible to have three phase wiring with only three phases and no neutral or ground for distributing mains near houses. Then a local transformer must tap between two phases and on the secondary it can provide your house a single or split phase where the neutral/return wire is connected to earth potential at some place, depending on your electrical system, either at transformer, or at your house, both, etc, and you may also get a separate earth wire.

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