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where does the current go

Discussion in 'Automotive Electronics' started by elecLear78, Jun 11, 2015.

  1. elecLear78

    elecLear78 Member

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    Generally in house hold the return current goes to earth, In vehicles where does the return current go?
     
  2. alec_t

    alec_t Well-Known Member Most Helpful Member

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    In a house sytem the return current should be to Neutral. Current to earth should trip an earth fault interrupter.
    In a vehicle the return current is via the vehicle bodywork.
     
  3. MaxHeadRoom78

    MaxHeadRoom78 Active Member

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    Only in the event of a equipment fault.
    Max.
     
  4. dave

    Dave New Member

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  5. elecLear78

    elecLear78 Member

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    sorry my mistake so in case of fault in vehicles how it is handled since return path to earth is not available?
     
  6. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    However it gets there, it goes to the negative pole of the battery. Less so if the engine is running, because then some of it goes to the (engine-block-grounded) alternator frame.
     
  7. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    If a "fault" occurs (wire insulation rubs through to the chassis or "ground"), the fault current flows into the chassis, which is in turn connected as in my previous post #5 on this topic. The difference between the fault current and the normal operating current for a given appliance (headlamp, etc) is only one of magnitude (That's why branch circuits are fused).

    Cars do not have an independent, safety ground like houses.
     
  8. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Technically "Neutral" is connected to "Earth" at your junction box.
     
  9. MaxHeadRoom78

    MaxHeadRoom78 Active Member

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    Earth ground in a service supply is required for safety, in an automobile at 12vdc this is not a consideration.
    Also it would be very hard to reference a moving object with rubber tyres to earth.:p
    Max.
     
  10. mvs sarma

    mvs sarma Well-Known Member

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    any current that starts at positive of the supply should , after load go to negative of the source.
    In case of automobiles, there are two sources.
    1. an alternator that works and supplies during vehicle in motion with one side connected to chassis for return patch, and
    2. battery with its negative connected to vehicle chassis that is generally called ground return.

    In either case the current would return to the source supplying the load.
     
  11. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hello,

    In the basement box the neutral is connected to earth, but no current flows unless there is fault. The main current flows in the wires. So it would be like taking a wire and connecting the negative terminal of the car battery to a copper stake pounded into the ground with the wire. No current flows to ground unless something goes wrong.
     
  12. Ian Rogers

    Ian Rogers Super Moderator Most Helpful Member

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    Yep!! I hate these topics.... All AC current goes to earth....

    Technically!! Neural isn't connected in your fuse / junction box ( or here in England it isn't ) ... The Electricity supply Co. has to deal with at the local sub station.... Originally a metal spike was driven into mother earth, this was your return... Now it is safer to let the leccy bods take care of it!!

    If there is current flowing from neutral to earth at the household, Something is amiss and you should stop playing!!
     
  13. MaxHeadRoom78

    MaxHeadRoom78 Active Member

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    I remember DC generators and +ve (Chassis) ground on auto's ;)

    In the UK the neutral is connected to earth ground at the 3ph star supply point and typically the service Co. do not supply a earth ground, and even when they did, it could not be used and the neutral is kept separate from earth at the service..
    Years ago the metallic water pipe was available for local grounding, with the advent of PVC etc, a ground rod had to be utilized together with a ELT.
    At least that is the way I remember it.;)
    M.
     

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