Phil Munro wrote:
Takoma Park Volunteer Fire Department Postmaster wrote:

blueman wrote:

When used with metal boxes, do the self-grounding outlets provide as
good a quality result as using a separate screwed-in grounding wire?



According to underwriters laboratories the answer is yes.
--
Tom H

It should be noted that the "screw ground" will not be a good one
unless the outlet is fastened to the box with metal washers for proper
spacing, and then screwed down tightly. I see lots of outlets that are
loosely screwed because the metal box is not flush with the finished
wall. The wall plate then holds the receptacle in place against pulling
against the screw to the box. --Phil

That simply is not true. If the receptacle is installed in accordance
with the manufacturers instructions no washers are required. Self
grounding receptacles are tested for grounding continuity using only the
mounting screw that is held captive by the spring on the yoke that
assures conductive contact between the yoke and the mounting screw.
--
Tom H