My DNO is about to upgrade my overhead supply from the existing transformer from 230V Single Phase (2 wire) TC-N-S (PME) to 230V / 460V split phase to accomodate a 20kW wind turbine. This means a 3 wire incomer. I have some issues over the positioning of the additional meter required but that's for another question. The supply will be provided by the same but now center tapped transformer with one "phase" going to the domestic CU and the other "phase" going to the G59 turbine enclosure and inverter bank. I will (and am obliged to) fit a lockable isolation switch - RECS2 say - to each live and neutral pair. However, the two neutrals have a common connection at the DNO junction box. Has anyone experienced or heard of a fault in the neutral connection that could result in 460V between either of the live feeds and the common earth ?? I have not come across any modern switch that differentially opens or closes to ensure that the live supply isolates first and powers on last i.e before and after neutral disconnect...............or am I worrying needlessly ??