the black wire with the brown sheaf indicates perminant live, so if you are putting this into the switch live at the light fitting, the light will stay on perminantly, take the front off you switch and see what colour you common is and whichever one it is join the same colour at the light fitting with the black with brown sheaf (on a seperate terminal to your light switch wire). If you need more help visit my website at www.sparkyadvice.co.uk. I hope this helped
dale the electrician, April 2009