On Tuesday, July 18, 2017 at 9:50:42 AM UTC-4, Stormin' Norman wrote:
On Tue, 18 Jul 2017 08:00:20 -0400, Bob wrote:

Hello,

Let me try to ask this in an understandable way.

Been many, many years since I wired any outlets, switches, etc.,
so possibly the building codes have changed ? (live in Mass.)

Previously, when you installed or replaced a switch, outlets, or even a
GFCI, it was "required" that you run a green grounding wire from the
back of the metal box where you would have a screw grounding together
the box, and All the green wires from the outlets, etc grounds
to the switch or outlet grounding screw.

It was not allowed, I think, to just have the mounting tabs
do the grounding thru the box shell, although the mounting tabs
were (usually) common with the outlet or switch grounding screw.

I now see that Leviton implies for their their GFCI devices
that you can simply use the mounting tabs, and that a separate ground
wire to the box grounding screw is not required.

Do I have this right ?
Has the code changed.

Just use the GFCI mounting tabs, and don't run a separate ground wire ?

Or,...?

Thanks,
Bob

Bob, if you are positive the box is grounded, then run a pigtail from
a ground screw in the box to the GFCI. If there is a separate ground
wire in the circuit, connect that to the GFCI (and to the metal box).

Obtaining a ground through the tabs and mounting screws is possible,
but many times, in order to get the outlet to mate properly with the
wall cover plate, the outlets tabs are not always snug up against the
box. In that case, the electrical ground would be only through the
threads of the screws, which, IMHO, is less then desirable.

His question was if self-grounding is allowed. The answer is NEC allows
it, as long as the receptacle is listed for that purpose, which many are.