ColJack said:they quite often use 2 or 3 cables in large mains installs simply because they either don't do cable large enough, or that if they did it's not flexible enough to be bent to fit..
I always wondered why they don't do this anyway since 2 cables can take more current than the equivalent size can..
ie 10mm² can take 46A so that's 92A for double.. but 25mm² can only take 80A
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please excuse any typos, I'm typing with 2 plasters on my fingers..
Our factory kitchen has a paralleled supply 2 x 95mm²!!