does a middle-of-the-run switch always have to be grounded ? i have installed a couple without, i.e. the ground in is just spliced with the ground out w/out connecting the ground screw on the switch, and it works fine. however, the book shows to always do it.
Yes, you need to ground the switch if the switch has a ground terminal on it and the box has a ground wire in it.
There are a few exceptions.
If the switch is installed in a metal box, the box is adequately grounded, and the switch is a self grounding device, then you do not have to install a grounding pigtail to the device.
If the switch face plate is non-metallic and is secured to the switch using non-metallic screws, then you do not have to install a grounding pigtail to the device.
Your statement about the switches not having a ground connected and still working fine is true, but that is because the ground wire is not needed under "normal conditions". The ground wire is there for safety. It is intended to carry fault current under "emergency" conditions.
edit: I beleive Chris is correct and I am wrong about the faceplate exception, my apologies, I take it back.
Last edited by EBFD6; 10-19-2008 at 06:37 PM.
Reason: I was wrong