Johno12345:
Lamp sockets come with a 'cardboard' sleeve here in US; sleeve promarily is the 'insulator' from the hot/neutral screw terminals on the side of the socket, to the metalic outer shell (sometimes brass finished) We also have other configarations. There is also a lot of 'junk' as Ann was leading to above.
The interior of the socket is wired screwshell is neutral, center tab is 'hot', secondary tab is for 3 level lamps. 1 'on' is low wattage; 2 'on' is med. wattage; 1 & 2 "on" is 'high' wattage.
