Having bought a DiLOG electrical multifunction tester I thought I'd better give our house installation a quick check over and knock me down wiv a feavver if the RCD test warns '>50V' (do not pass go, do not collect ...).
Checked at different sockets, and did Z1+Z2 type tests L-PE (PFC) and L-N (PSC) and they're sensible values, and checked continuity between N and PE at outlet I'm testing and earth at CU and company head, and it all seems nice and tight so I don't think I really do have an earthing problem. So what could be causing the tester to complain? (Apart from the tester itself being NBG, which I hope is not the case.)