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A/C, are the british different?

  1. Nov 5, 2007 #1
    I'm abit confused, i've been dealing with electricity for ages and ive always understood alternating current to have 2 altenating live wires and a third neutral/ground wire.
    Now im in the british education system and they are teaching us that alternating current only has one live wire and two neutral wires, only one of which is grounded (this makes no sense to me)

    when i look at the basic diagram of a generator i see no way how either of the usual 2 live wires could possibly be neutral unless they ground one of the two, in which case i dont see the use of another neutral/ground wire.
  2. jcsd
  3. Nov 5, 2007 #2


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    Well yes you are right.
    That is exactly what they do, reference one of the output lines to ground. As a matter of history, untill recently they used only the two wires. The "live" wire and "neutral" referenced to ground.
    The third wire "ground" is a recent addition as a matter of safety and does not carry and should not carry any current except when something goes wrong.
  4. Nov 6, 2007 #3


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    "...ive always understood alternating current to have 2 altenating live wires and a third neutral/ground wire."

    Don't get confused about the 230VAC that is coming into you home here in the US. It's single phase but you get two 115V legs and a ground (three wires). At the pole the transformer has a 230volt secondary that is center-taped to ground. Now at the breaker panel, each leg will have a neutral(return for leg) and ground(safety;just in case return) associated with it.
  5. Nov 6, 2007 #4
    ok, well id like to figure out what we are on here in singapore, ill go grab a multimeter and figure it out...

    if one of the outputs has been grounded so as to act as a neutral then either that or the ground wire should be interchangeable by right but i do see the purpose of having both now(incase one fails) so basically what i understand about the british mains so far is that there are 2 ground wires, one is a fail-safe. correct?

    i must say though, the 2 legs seem to make alot more sense to me... the british way seems to just waste more wire...
  6. Nov 6, 2007 #5
    wasting wire connecting one secondary output to the ground that is...
  7. Feb 25, 2008 #6
    The way streets are wired is that 3 phases go along the street and each house is supplied from one phase. Phase to neutral voltage is nominally 230V (used to be 240V).

    The distribution transformer is a Y with the neutral grounded at the transformer.

    The ground at the house may be at a different potential to the neutral wire depending on how well the load is balanced.
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