For all ev installs so far with additional consumer unit I have used 25mm tails.
I am now looking at a ip65 consumer unit next to a meter box and pondering various options for connection between the meter box and the new consumer unit. One suggestion on a facebook group was to run 10mm tails through 25mm flexicon, but are 10mm tails acceptable.
OSG 2.2.3.1 state that consumer tails should be 25mm but no regulation referenced and I cant find anything in BS7671, I have seen comments on other sites that some or most DNO's require 25mm tails. Looking at technical guidelines from DNO's in my area SSEN and GTC, both specify maximum length of tails but no mention of minimum size.
My thinking is that the run would be very short and the the 10mm tails would be protected by a 32A RCBO in the new consume unit, therefore very little risk.
I would like a second opinion from a group I am familiar with and based on what I have read over the last year feel I can trust.
