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Bud--

On 10/11/2011 9:47 AM, wrote:
On Oct 10, 10:45 am, wrote:
On 10/8/2011 7:03 AM, wrote:

On Oct 5, 7:25 pm, wrote:
On Wed, 5 Oct 2011 12:30:40 -0700 (PDT), "

wrote:
When using a metal junction box, eg handybox for a switch,
is it acceptable code to:

A - Just ground the metal box and rely on the switch getting
grounded by being fastened to the box

B - Just ground the switch and rely on the box getting
grounded by being fastened to the switch

C - Both must be grounded using wire?

Thanks all.

With switches, the BOX must be grounded - the switch grounds to the
box.

OK, so now we have the switch grounding question
resolved. But there was mention of a difference for
receptacles? So, what is the rule for a receptacle
with a metal box?

1. Surface metal box (handybox, ...) with 2 screws securing the
receptacle strap to the box. Often the screws have a paper or similar
disc on the screws to keep them attached to the loose receptacle - at
least one disc has to be removed.

2- Receptacle attaches to metal cover on metal box - all I can think of
are for 4" square boxes. Receptacle has to attach to the cover with 2
screws (a few other requirements). Old covers have the receptacle
attached to the cover with one screw.

3. "Self grounding" receptacles with a clip from the yoke to the
screws, metal box.

4. In almost all other cases, a ground wire to the receptacle.

(406.11, 250.146)

And why would one be different
than the other?

Grounding of switches is to ground any metal plates. It should be quite
difficult to get high ground currents.

Grounding of receptacles is to make a good contact for ground return
currents from devices attached to the receptacle through the receptacle
ground pin.

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bud--- Hide quoted text -

- Show quoted text -

Thanks for the explanation Bud. But unless I'm missing
something, at the end of it, the rules for a switch or
a receptacle in a metal box seem the same. Meaning
the switch gets grounded to the metal box via the two
screws that hold it to the box or metal cover too right?

Yes on the switch. The requirements are much tighter for a receptacle.

The requirement for a switch was added fairly recently because with
plastic boxes the switch (and metal plates) are not grounded.
Receptacles in plastic boxes were always required to have a ground wire.

--
bud--