This is the Ofgem paper on their policy on the costs of upgrading distribution network uplifts.
https://www.ofgem.gov.uk/ofgem-publications/87259/gu...
Really good find.
That document tells us that 95% of new connections happen without requiring any "network reinforcement" ... which means that 5% of new connections do! The costs they trigger end up at £30m per year ... and the customers of the new lines ends up paying roughly two-thirds of that - £20m per year.
Elsewhere, I could find that in the 2010-11 period, there were roughly 300,000 new electricity connection requests in the year.
That means some 15,000 electricity connections end up paying that £20m - an average of £1,333 extra, on top of the £1,000 - £2,000 that is the standard charge for a new supply.
Openreach have installed roughly 75,000 cabinets since starting in 2010 - about 12,000 cabinets per year. If 5% of
intended cabinets turned out to need to pay extra supply charges, and were dropped by the project, there could be 600 cabs per year, 12 per week, being left out.