I dont get it ... twin & earth 2.5mm

[Cackles]

From what Ive read you always have a safety margin. 2.5mm t&e from what Ive seen has a rating of 24 amps. But in a ring mains using 2.5mm youve to use a 30A fuse? Any help appreciated.

[baldelectrician]

The point of a ring is just that (two cable supplying the one outlet)

When you plug something in to a ring circuit the current is supplied from both cables at the same time.

That is why it's important to check continuity and integrity of the ring when testing.