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Broken PEN

Kelly Marie Angel

I know this subject has been done to death but why are the neutral/PEN conductors more likely to go open circuit than any of the phases? It seems to me there is some basic problem the way they are installed are they not tightened to the same degree as the phases? I know being a black conductor they may seem less important than the red yellow and blue  but can the DNOs have a refresher course or similar to remind them the black wire is just as important as the others. I may be over simplifying this but to me it just seems odd that the one cable is more prone to coming loose than the others. Also I know I used the old proper colors  rather than the new ones but its late so indulge me a bit. I remember years ago the neutral link on a pole near my old house  burnt out when the DNO guy pulled and wiggled it there was a flash and a bang  he dropped the lead which was badly melted maybe this is part of the problem??

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    In places where it is four singles - like overhead, as noted it is not more prone to come undone - the problem is that is less likely to fail in a safe way and so less acceptable than 'a power cut' which is what happens when one phase drops - which is so common it is not counted as a significant event. lost PENs are supposed to be counted, at least recently.

    Actually on the overheads of most DNOs the neutrals are double crimped and have slack loops that the phases do not, so that usually the phase goes twang first.  This is very deliberate so that the line can be declared 'PME ready'

    The problem arises big time with the underground cables, which are more like 3 core coax, where the armour is the neutral - because when this gets wet (stones or roots damage the sheath, or at joints) the water soaks in from the outside first - then it is quite common the outer armour goes high resistance while the phase cores in their wax paper wrap have not yet rotted right through.. .

    Mike,.

    PS this doc describes the problem facing SSE https://ssenfuture.co.uk/wp-content/uploads/2021/12/311_SSEPD_NLR_LV_UG_CLEANFINAL_REDACTED.pdf

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  • 0

    In places where it is four singles - like overhead, as noted it is not more prone to come undone - the problem is that is less likely to fail in a safe way and so less acceptable than 'a power cut' which is what happens when one phase drops - which is so common it is not counted as a significant event. lost PENs are supposed to be counted, at least recently.

    Actually on the overheads of most DNOs the neutrals are double crimped and have slack loops that the phases do not, so that usually the phase goes twang first.  This is very deliberate so that the line can be declared 'PME ready'

    The problem arises big time with the underground cables, which are more like 3 core coax, where the armour is the neutral - because when this gets wet (stones or roots damage the sheath, or at joints) the water soaks in from the outside first - then it is quite common the outer armour goes high resistance while the phase cores in their wax paper wrap have not yet rotted right through.. .

    Mike,.

    PS this doc describes the problem facing SSE https://ssenfuture.co.uk/wp-content/uploads/2021/12/311_SSEPD_NLR_LV_UG_CLEANFINAL_REDACTED.pdf

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