There's a lot of talk about DNO requirements regarding tail sizes. I don't know about other people's experiences, but from my own DNOs rarely know what their supply to a house consists of. As an example, a recent customer asked the DNO about their supply (fuse size, earthing, etc) as they wanted a new meter along with a rewire. They didn't need a rewire, it turned out to be BS from a 'quote from the van' merchant. Anyway, the customer was told "there is no record of the earthing arrangements on the computer. Your electrician should be able to tell you." The fuse size was given as 60 amp.
So, long one short. The DNO gave an unacceptably long delay and high price to fit an isolator. As luck would have it, the fuse fell out due to a lack of seals on the morning of the CU change. In that condition it was easy to spot the text "100 amp" just under the "English Electric" name.
16mm original tails fitted with no sign of damage or deterioration. I replaced them with 25mm tails for several reasons, anyone without full knowledge of the checks/calcs involved would think it was compulsory to do so (and I'm too lazy/busy to argue the ----), new tails look better, the DNO will be changing the meter soon (good job too as the seals had fallen off of the tail connector cover too!) and the cost to me was small and thus is priced in with a CU change.
