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High protective conductor currents - Deletion of 543.7.1.204

AJJewsbury

543.7.1.204 - the one about duplicate c.p.c.s needing to be 'terminated independently of each other' - has gone.

Does anyone understand the thinking behind this? It seems a bit odd to me.

Given that (in my experience) more problems occur at terminals rather than along cable runs, if we need the c.p.c.s to be duplicated, it seems like a bit of a flaw that one single loose connection can make them both useless simultaneously. I can see that in some instances (e.g. a terminal on a socket on a ring) that losing a single terminal carries a limited immediate risk (as the leakage current from a single socket should be small and all other sockets are still connected to a c.p.c.) but in other instances - say the connection of both c.p.c.s to the earth bar in a DB - that single fault could be very significant.

   - Andy.

Parents

  • Is there evidence for this? Are we seeing regular problems attributed to this?

    I've certainly found plenty of instances of 1.0/1.5/2.5 wires popping out of screw terminals when front plates are removed. Maybe the problem is more due to front-plate mounted terminals than the conductor size, with the wiring being stressed as the accessory is pushed home after wiring and any movement of the conductors being then invisible, and the majority of plate accessories using the smaller sizes. Maybe if we'd used more 4.0mm² on socket circuits we'd be less happy about that size not needing duplication.

       - Andy.

  • in reply to AJJewsbury
    AJJewsbury said:
    Maybe if we'd used more 4.0mm² on socket circuits we'd be less happy about that size not needing duplication.

    Single perhaps ... in T&E, 4.0 mm2 has 1.5 mm2 protective conductors !

Reply
  • in reply to AJJewsbury
    AJJewsbury said:
    Maybe if we'd used more 4.0mm² on socket circuits we'd be less happy about that size not needing duplication.

    Single perhaps ... in T&E, 4.0 mm2 has 1.5 mm2 protective conductors !

Children
  • in reply to gkenyon

    Indeed - we have very little experience of using ≥4mm² c.p.c.s with front-plate accessories...

       - Andy.

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