Until fairly recently, underground 11 KV cables were invariably 3 core, paper insulated, lead covered, with an earthed steel wire armouring. Then came the more modern plastic insulated cables, with earthed armour and a red plastic over sheath to distinguish them from LV cables.
However the modern trend seems to be a bundle a 3 single core cables, each with an aluminium core, plastic insulation, copper wire armouring and a red plastic sheath.
Why is this used ? It seems to me that 3 single core cables would be more costly to manufacture, and more labour intensive to joint or terminate, than one 3 core cable.
I fail to see the advantage, but presume that there must be some advantage, or why make the change ?
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