Ron D. wrote:
David:

You have an old box. Note the bare copper wires under the strain
reliefs. You need to dig them out.

These
http://www.zoro.com/i/G3705676/?utm_...Zo7 AodHwgAKQ
ground clips are eused in that situation.

They are a bit difficult to attach, but The secure a solid pigtail to
the side of the box. e.g. the edge that's exposed.

What I use in this case is an ground Ideal Term-a-nut. See
http://www.grainger.com/product/IDEA...ctor-Nut-4YD75

So, you can dig out the bare ground. Install the term-a-nut and a
solid pigtail. The solid pigtail goes to the ground clip and the
free end of the term-a-nut (fork terminal goes to the green screw on
the outlet),

With multiple GFCI's you would want to not series the GFCI. e.g. One
GFCI protects the outlets down stream.

What can cause nuisance tripping is shared neutrals. The term is
shared, but think of it as neutrals attached as "T-splices"

GFCI's do not need a ground, but if they don;t have one, they must be
labeled that there is no ground.

You are not supposed to rely on the screw connection from the box to
to the outlet, although some outlets are designed so it's OK.

Your house looks like it had original had two prong outlets and the
upgrade wasn't done correctly. The conversion can be a pain, but the
term-a-nuts make the job much easier.

When there is a threaded hole in the box that can accept a ground
screw, then other ways are possible.

So far, I've never tapped a ground hole.

Hi Ron,

I put a screw into the box and ran a wire from the screw to the GFCI's
ground. But first I checked the line voltage with the neutral wire on the
neutral side of the plug with a hair dryer running. Then I exchanged the
neutral wire with the new ground wire and checked the voltage again with the
hair dryer running. The voltages were exactly the same. That proved to me
that the ground wire is making a good connection back to the service panel.
Do you see an alternate explanation that would disprove my conclusion?

Thanks for your reply.
--
David Farber
Los Osos, CA