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External lighting columns - earthing conductor (reg 714.411.203)

Apostolos

Good afternoon

Sorry for the back to back question about external lighting

Based on regulation 714.411.203:

'Where street furniture is connected directly to a distributor's PME network, the earthing conductor and any main protective bonding conductors to any extraneous-conductive parts shall have a minimum copper equivalent CSA of 6mm2 for PEN conductors of the supply with copper equivalent CSA up to 10mm2. For larger sized neutral conductors, the main bonding shall comply with Table 54.8.'

If I have lighting columns at the back of a building and I am feeding them from inside the building, and the building system is a PME system, does this apply?

Its wording confuses me really because it says about connection directly to a DNO PME network....

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    Similarly, 714.411.3.1.2 supports the concept "need not be

    That was written in the days when 411 required bonding of extraneous-conductive-parts in general - so a 714 regulation was needed to "modify" the general requirements. Section 700 is all about supplementing or modifying general requirements. Now the general requirements no longer contradict, there's no need for such a regulation at all - its very presence suggests a difference from general requirements - which isn't the case. To my mind 714.411.3.1.2 should disappear (or keep some of the reassuring words as a NOTE as best).

    714.411.203 says "any main protective bonding conductors" (doesn't say there has to be some, just any if you have them)

    Agreed, although if there are no bonded extraneous-conductive-parts, why does the Earthing conductor have to be sized for PME?

    Going off on a bit of a tangent, I still feel there's a bit of an elephant in the room with the change to 411 to only require bonding within buildings - as we've then lost the previous protection that c.p.c.s feeding Class 1 equipment that was in contact with extraneous-conductive-parts outdoors from being forced to carry potentially large diverted N currents (or other large currents, from faults or imported from outside the installation), that previously main bonding conductors would provided a low impedance by-pass for).

       - Andy.

  • 0 in reply to AJJewsbury
    AJJewsbury said:
    Agreed, although if there are no bonded extraneous-conductive-parts, why does the Earthing conductor have to be sized for PME?

    The installation needs to be future-proofed, but isn't it size of main earthing conductor a condition of supply anyway with most DNOs?

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