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BS7671 switched protective conductors

Former Community Member
Former Community Member
While referencing BS7671 relating to standby generator earthing I came across the clause below:

537.1.5 Where an installation is supplied from more than one source of energy, one of which requires a means of earthing independent of the means of earthing of other sources and it is necessary to ensure that not more than one means of earthing is applied at any time, a switch may be inserted in the connection between the neutral point and the means of earthing, provided that the switch is a linked switch arranged to disconnect and connect the earthing conductor for the appropriate source, at substantially the same time as the related live conductors.


The requirement for the Earth switch pole to close at substantially the same time, should this be early make - late break to ensure this system is earthed prior to live conductors being closed?


Bill
Parents
  • Former Community Member
    0 Former Community Member
    Hi Alasdair, not quite the situation I was considering, basically, I'd prefer to ensure that the earth and neutral connections are in place prior to closing the live condutor circuit. My assumption it that the switching would always pass through an "Off" state. the situation to be avoided being live pole(s) closing before the earth/neutral circuits are in place. The wording I quoted doesn't I feel make this a requirement.

    BTW I agree completely, we're meant to be engineers thinking about what we're doing no just blindly following the text.

    Bill
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  • Former Community Member
    0 Former Community Member
    Hi Alasdair, not quite the situation I was considering, basically, I'd prefer to ensure that the earth and neutral connections are in place prior to closing the live condutor circuit. My assumption it that the switching would always pass through an "Off" state. the situation to be avoided being live pole(s) closing before the earth/neutral circuits are in place. The wording I quoted doesn't I feel make this a requirement.

    BTW I agree completely, we're meant to be engineers thinking about what we're doing no just blindly following the text.

    Bill
Children
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