So any light switch installed since your local ahj authority having jurisdiction or in other words the building department adopted the 1999 nec should be grounded. Sunday december 9 2018 light switches have been required to be grounded since the 1999 edition of the national electrical code.
How To Wire Cooper 277 Pilot Light Switch
New light switch has no ground screw. The code states that ungrounded systems can use grounded devices with out the use of a ground wire. Wrap the wire around the screw then cinch the nut down to hold it. Yes as long as the ground is bonded at the panel and spliced through at every junction along the way but the ground did not have a termination screw at the fixture box for the lamp holder and the ground wire at that point was just tucked into the junction box then the continuity of the ground will still be bonded all the way through. If the light box is not metal then the ground wire should be bonded to one of the fixture mounting screws. Last and least if theres no screw present in the box to connect a ground wire and no place to put a screw heres a workaround. Just install the new switches without a ground and tighten the green screw down so it is out of the way.
This just means the device is not grounded and neither is the. Remove one of the long screws that holds the fixture in place. A plastic box with no ground. As long as you are using nylon plastic switchplates you have nothing conductive that a. For a normal light switch the ground is a safety feature not necessary for operation. You can leave that screw unconnected if you dont have a ground wire or if you have the wire but no screw on the switch you can ground the switch another way.
Thread an 8 32 nut onto the screw. The purpose of a ground wire on a light switch. If the wiring to the new light does not have a ground wire then one should be provided from the power source using an approved cable. Yes it is fine and even by code.