neutral to earth voltage

Discussion in 'General Electronics Chat' started by shahnawaz, Jan 13, 2009.

  1. shahnawaz

    shahnawaz Thread Starter Active Member

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    islamabad, pakistan
    hi dear all
    can any one recommend me how much voltage should be enough between neutral to earth(ground) bars for a smooth running of a system.

    and one more thing is what the standered of world for the voltage between earth(ground) to nutral. and how much resistance is acceptable for the earth grounding. thanks for a quick reply.
  2. Bill_Marsden

    Bill_Marsden Moderator Staff Member

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    This is a tricky subject, in more than one way. Here is the problem.

    If you have a leg with 10 amps running through it, and the length of wire is dropping 3 volts, then there will be 3 volts between earth and neutral at the socket where power is tapped. Where the two connect (usually the line pole) there is no difference. So even though they are the same wire there can be a voltage differential, because the wire is also a resistor.

    There is no standard for this voltage as far as I know, just whether the wire itself is safe to carry the full current load. If it meets the criteria then the voltage difference between earth and ground doesn't matter.

    As to the second part of your question I don't know the definitive answer. As far as I know it is a 6 foot spike into the ground for ground.
  3. thingmaker3

    thingmaker3 Retired Moderator

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    The NEC, article 250.56, specifies no more than 25 Ohms to Earth ground. Voltage would, per this code article and Ohm's Law, be current times 25.

    If the NEC does not apply in your area, I suggest contacting your local authority for requirements. If the NED does apply in your area, I suggest contacting your local authority for any local variances or exceptions.
  4. italo

    italo New Member

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    Lets see ground wet ground or sand ground. Both are not exactly equal.
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