We know that all current flow in loops, i.e. if they start at a source they must come back to the source. So for transmission lines, does the current that flow through our appliances in our homes go back to the generating station? If yes, how?

  • 2
    \$\begingroup\$ Through the other lines. You might've noticed they come in groups. \$\endgroup\$
    – user253751
    Jan 16, 2020 at 11:00
  • \$\begingroup\$ Not only does it flow back but, it comes from the power station. \$\endgroup\$
    – Andy aka
    Jan 16, 2020 at 11:51

1 Answer 1


Transmission lines for our home appliances have multiple lines and the current return path is shared among these lines because in alternate current (AC) transmission, each line is a send and return path for current.

When it comes to transmission lines for trains, it is often seen that the ground send is one single line up in the air, while the return path is the train railway (and to some extent also the earth).

  • \$\begingroup\$ "Return path is the train railway"? So would someone get a shock if they were to touch the rails? \$\endgroup\$
    – penguin99
    Jan 16, 2020 at 11:33
  • \$\begingroup\$ "The electrified rail threatens electrocution of anyone wandering or falling onto the tracks." from Wikipedia en.wikipedia.org/wiki/Third_rail \$\endgroup\$
    – jonathanjo
    Jan 16, 2020 at 11:40
  • \$\begingroup\$ With the 25kV overhead electrification in the UK, current transformers are used to force the return current back along a dedicated conductor, rather than relying on the track. I believe this is to reduce EMI interference emissions. \$\endgroup\$
    – Neil_UK
    Jan 16, 2020 at 12:51
  • \$\begingroup\$ @noorav No one will get a shock, because there is (almost) no voltage and just a lot of current flowing through the rails. \$\endgroup\$ Jan 16, 2020 at 18:05

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