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Discuss How is a generator earthed and given neutral? in the Electrical Forum area at ElectrciansForums.co.uk.

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  1. assegayer
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    assegayer Regular EF Member

    Location:
    London
    Hi

    I have a question i cant seem to get an answer too.

    If you have a portable generator and you plug for instance a fridge or any appliance directly into it, how is the neutral/earthing provided??

    I know already that normally you can connect the neutral and earth from an existing installation

    But what if you are for example somwhere random and i plug a fridge into a generator where is the neutral coming from? Surely it cannot be from the casing as if someone was to lift the generator up they would get a belt from the supposed to be neutral return path?

    Thanks in advance
     
  2. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    53A1B686-F7ED-4DF5-AD9E-B4E44ABE2FAE.png
     
  3. assegayer
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    assegayer Regular EF Member

    Location:
    London
    Thanks for the reply but what i still dont understand is where is the neutral in the generator getting its ground from? At the end of the day neutral is ground
     
  4. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    The neutral is not referenced to earth in a portable generator the generator supply is unearthed
    a protective conductor must connect the exposed conductive- parts of the generator frame (and its enclosure) to the exposed conductive parts of the equipment being supplied. No exposed conductive part of the separated circuit is to be connected to any protective conductor or exposed conductive parts of other circuits or to Earth otherwise the protective measure of electrical separation fails
     
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  5. assegayer
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    assegayer Regular EF Member

    Location:
    London
    This is what i am struggling to understand. Then how does the circuit work! Where is the neutral connected in the generator?!

    When normal electric is generated you have a star point and that is grounded thus u get your neutral off that point you dont just get a neitral from anywhere its earthed???
     
  6. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    The neutral in normal cases gets its 0v potential from being earthed at the star point which in this case is pointless as you are relying on Electrical separation as your protection against electric shock a ‘floating earth’
     
  7. assegayer
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    assegayer Regular EF Member

    Location:
    London
    What is a floating earth?
     
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  8. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    The generator supply is unearthed.
    The appliance and generator case are earthed.
    If you have an earth fault you can’t receive an electric shock as there is no earth return path to the origin ie the generator windings so no electric shock.
    The means of Electrical separation is only allowed on one item of equipment
     
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  9. assegayer
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    assegayer Regular EF Member

    Location:
    London
    Okay that is fair enough but

    Where is the neutral connected in the generator?
     
  10. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    The windings see the above illustration.
     
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  11. assegayer
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    assegayer Regular EF Member

    Location:
    London
    Sorry if it sounds like its a wind up it honestly isnt..

    But wouldnt that cause a short circuit having neutral and live on the same winding?
     
  12. HandySparks
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    HandySparks Trusted Advisor

    Location:
    Hampshire
    Business Name:
    Neish Electrical Services
    Think of the generator winding in the same way as the output winding of your local DNO transformer. They're both just a coil of wire sitting in a magnetic field, with neutral at one end and line at the other.
     
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  13. kingeri
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    kingeri Trusted Advisor

    Location:
    Yorkshire
    Think about the negative terminal on a battery as well, the circuit works but it ain't earthed!
     
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    • Agree Agree x 1
  14. Davisonp
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    Davisonp Regular EF Member

    Location:
    Amersham
    Business Name:
    Absolutely All Electrical LTD
    Does this help?
     

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  15. spinlondon
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    spinlondon Trusted Advisor

    Location:
    Harlow Essex
    Basically, an unearthed single phase generator has no neutral. It has two lives and together they add up to 230V.
    If you then Earth one of the lives, that will become the Neutral.
     
    • Agree Agree x 1
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