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Non armoured underground 3 phase cable

mapj1

Those who know me will know I am prone to go and stick my nose in whenever something interesting is happening, and a few days ago I had the chance to be a nuisance to some chaps installing a cluster of car chargers in a car park.
Ignoring their use of twin wall duct at a depth under kerbside turf of about  8 inches in places, I felt their choice of cables was interesting - from the origin of the supply to the breaker cabinet was as I would have specified in their boots, namely  4 core plus earthed armour SWA. (95mm2 of it so no slouching here.) But the cable in the thinner ducting from the cabinet to the individual chargers was 5 core NYYJ - single solid 10mm2 copper cores in Bn/Bk/Gy/Bl/GnYw and no armour, just the 5 circular cores in a bedding that looked not unlike white bathroom mastic. Having pinched an offcut it seems about as flexible as the average poker, i.e not really, and so I imagine it is no fun at all to install, and without armour, I struggle to see how penetration would be sure to operate ADS in the traditional way, but perhaps they rely on RCD operation.

Now it is really nothing to do with me, and it is now all lit up and working fine, and I'm sure will now work for many years, and in any case I'm sure the cable is pre-chosen by someone back at head office,  but would many of us here be happy with such a cable choice?  After all the single phase near-equivalent of burying arctic flex or twin and earth in a duct would be looked on as inadequate I think.
Mike.

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  • if ever there was a hole in the ground ide have to look in it

    I'm glad it's not just me then! Indeed looking into a few holes in France when I was there, their norm seems to be double plastic sheathed cables (HiTuff like) in twinwall duct. I guess their preference for not supplying a PE terminal to customers and long tradition of treating N as a live conductor means they don't have a handy conductor to earth any armour to. Still the overall safety effect must be similar to what we do - although that might be partly due to other things - e.g. perhaps better record keeping of cable locations and/or permit to dig or just being happier to hand dig.

    BS 7671 wise,  it's only acceptable if you can show it's just as safe as an earthed armour.... which might be tricky if it shallow and not in an environment where future excavation can be reliably controlled.

       - Andy.

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  • if ever there was a hole in the ground ide have to look in it

    I'm glad it's not just me then! Indeed looking into a few holes in France when I was there, their norm seems to be double plastic sheathed cables (HiTuff like) in twinwall duct. I guess their preference for not supplying a PE terminal to customers and long tradition of treating N as a live conductor means they don't have a handy conductor to earth any armour to. Still the overall safety effect must be similar to what we do - although that might be partly due to other things - e.g. perhaps better record keeping of cable locations and/or permit to dig or just being happier to hand dig.

    BS 7671 wise,  it's only acceptable if you can show it's just as safe as an earthed armour.... which might be tricky if it shallow and not in an environment where future excavation can be reliably controlled.

       - Andy.

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