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Waveform neutral

lyledunn

Two relatively long 300mm2 3-core Waveform  cables in ducts below ground supplying an industrial building. Currently the cables belong to the DNO but the contractor has permission to adopt them into a new proposed 1MVA PV/battery arrangement if he so wishes. The conductors are configured as three lines in parallel, outer copper wire screen in one cable as neutral and earth in the other. 

Its not a good start with the reduced neutral and plenty of machine control in the plant but no issues apparent. Parameters for normal design procedure are not yet clarified as everything is at an early stage but I was just wondering about the BS7671 perspective. I have never used the cable as it is generally for DNO application. The cable cannot be touched at any point other than at both ends.

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  • 0

    Split con would have been better. I'm not sure that wavecon is really suited to use the 's' part of a TNC-s installation - being firmly aimed at the 'C' part,  and this proposal has my 'here be dragons' antennea twitching.

    When you say " The conductors are configured as three lines in parallel" are these 3 cores lashed as single phase ? If so I'd re-jig to L-L N and use the armour as E..

    Or is it 3 phases, each phase 2 cores in parallel - which is very awkward as the N current will not be in the right place to ensure a good share.

    How close to the knuckle is the new proposed load, and how easy is it or not to get another line in the duct.

    No chance to 'TT' at the load end I suppose or to run a supplemental earth ?

    It may be that the best re-purpose of the DNO cable is as draw line for something with the right no of cores.

    Mike.

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  • 0

    Split con would have been better. I'm not sure that wavecon is really suited to use the 's' part of a TNC-s installation - being firmly aimed at the 'C' part,  and this proposal has my 'here be dragons' antennea twitching.

    When you say " The conductors are configured as three lines in parallel" are these 3 cores lashed as single phase ? If so I'd re-jig to L-L N and use the armour as E..

    Or is it 3 phases, each phase 2 cores in parallel - which is very awkward as the N current will not be in the right place to ensure a good share.

    How close to the knuckle is the new proposed load, and how easy is it or not to get another line in the duct.

    No chance to 'TT' at the load end I suppose or to run a supplemental earth ?

    It may be that the best re-purpose of the DNO cable is as draw line for something with the right no of cores.

    Mike.

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  • 0 in reply to mapj1

    Mapj; "Or is it 3 phases, each phase 2 cores in parallel - which is very awkward as the N current will not be in the right place to ensure a good share"

    Correct, Mike. It is a TPN, TN-S. I cannot blame the contractor for wanting to use the DNO cables when they become redundant. they are 300mm2 x 2 and about 70m long so a few quids worth to replace!

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