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Bud--

wrote:
On Wed, 13 Oct 2010 14:29:30 -0500, wrote:

For example, they even put a green ground screw on switches
now. WHY? If the switch is in a metal box, it's grounded by the
screws, but even in a plastic box, that small piece of metal on the
front of the switch is covered by a plastic plate.

You are only properly grounded in a metal box if the device is listed
as self grounding (a spring or brass clip on the yoke)
In a plastic box, there is no guarantee the plate will be plastic and
you still have metal screws. Before the grounded switches, they only
allowed plastic screws on switch plates but that rule was not followed
much either.

Far as I know, a switch doesn't need to be "self grounding". The NEC
just requires metal screws and a grounded metal box. (Receptacles that
use the mounting screws must be "self grounding".)

If I remember right, the argument was that you might have a plastic
plate now, but someone could install a metal plate in the future.

--
bud--