I am replacing a couple of wall lights. With the mains power off, I get no resistance between the bear earth wire and the neutral wire at the wall; they seem to form a circuit. This strikes me as strange but the old lights worked well and had an earthing point. There is no resistance between the switch earth and the wall earth, as I would expect. With the switch on there is a high but measureable resistance between the earth and the live at the wall.
Is this normal. Any help appreciated.