let me tell you how a lighting circuit is wired,
we do it two ways,either loop in loop out to the ceiling rose,or to the switch,that is a live and a neutral to the rose or to the switch,these come from the db,ok?then you have a switch wire,this runs to the switch from the rose,it may be coloured red and black,or,blue and brown,depends how old your house is,
if its red and black,then you connect the red wire to the loop in live in the rose,and the black wire to your lamp connection,at the switch,you connect the red to L1,and the black to L2,so when you turn the switch on,it puts power from the live loop in to the lamp.simple:-)
mm, January 2011