I am just replacing some light switches from plastic to chrome. Most have metal back boxes and I can easily earth the switches. The light switches in the loft conversion have plastic back boxes. One of these is a two way gang switch which had a sleeved earth 'hanging' about when I removed the switch so I attached this directly to the earth terminal on the chrome switch. Have I done the right thing here? The light switch at the top of the stairs that links to this (also a plastic back box) has no available earth wire. What should I do here?