On Sep 15, 10:34 pm, mm wrote:
On Fri, 14 Sep 2007 11:15:46 -0700, Joe wrote:
On Sep 14, 9:20 am, N8N wrote:

snip

instead of using the clamp screw just drill and tap the
back of the box for a standard ground screw, then you don't have to
bust up the plaster to get at the clamp screw

Better and quicker, use a grounding clip on the side of the metal box.

Quicker yes, but why would a clip be better than a screw, that can be
tightened?

The clip actually puts as much (and maybe a bit more) bare wire in
contact with a metal box as a screw does. Since grounds don't (or
shouldn't) carry current either a screw or clip will be just fine.
Cranking down on a screw only deforms the copper and adds precious
little to the conductivity of the junction. Makes sense, then, to save
some time on the project by using clips. HTH

Joe