This is one of those cases where the UK and US usage is very different. In the UK, the thing a bulb goes into is a 'lampholder' (maybe a 'bulbholder', although that's normally for smaller bulbs). A 'Socket' is a female conneotor, a thing a plug goes into. Note that the correct useage is the socket is the frmale part, the plug is the male part, no matter wether it's mounted on a panel/chassis or fitted to the end of a cable. The term 'Jack' does not mean a socket (as it seems to in the States), it is a particualr type of connector, basically the ones yoy call 'phone plugs'. Think of the connector on the end of stereo headphones. Over here that's called a 'jack plug'. And of course what it plugs into is a 'jack socket' The term 'recepticle' might be used for a socket (but it wouldn't be common). More often it means the female part of a 'faston' connector (to cause more confusion, often called a 'Lucar spade' over here), the male part being called a 'blade' -tony