Doh ... good point.
Most things were off / unplugged ... but not the fridge/freezer. This turned out to be the culprit. There was no reading across the plug pins, so I tried it in the adjacent socket. It now seems okay in either socket, though the cable was trapped slightly when I went to...
I have a ring main that's protected by an MCB and an RCD. With the RCD set and the MCB off there's a very low resistance between phase and earth (around 10 ohms). Why might this be?
The reading was taken at the site of a socket on the main; and the socket was removed, so the ring was also...