Interesting project, thanks for pointing me to it Alex. I have a good relationship with Canterbury Windings so I may give them a shout to see what sort of price might be involved.
I'm not familiar with CY cables, do you mean single core version of these?
https://lapplimited.lappgroup.com/pr...ic-100-cy.html
or
https://lapplimited.lappgroup.com/pr...cy-cables.html
I read quite an interesting piece on balanced mains here:
http://vertexaq.com/about-the-aletheia-psus/
It seems to agree with what you say about keeping the source and amps on separate 'circuits'. However, I have also read elsewhere about it being best to run amps on unbalanced mains. Something to test I guess.
I also have the decision to make about MCBs, RCBOs and the other sorts of switches to use in the new CU. I've been in touch with RKR who has been amazing but I'm interested in all feedback. I will probably start a new thread!