Not in Baileys of my vintage. You may recall I had problems with faulty switches on the control panel last September . They are single pole merely joining the 12v+ when switched on. The earth links are elsewhere . I need to check the actual lights themselves and establish if their switches are single or double pole. Ian seems to be on the case. I’ll look in more detail when I get home.Every electrical appliance/light will have its own "earth" connection (two wires) because the bodywork, not being ferrous metal, cannot be used for return purposes.