On Tue, 30 Nov 2004 13:30:05 GMT, 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?

In My Humble Option:

According to US NEC 250.148(A) the metal box must be connected to the
equipment grounding conductor via a grounding screw or listed
grounding device.

As for the receptical, after looking, 250.146(B) says you can use the
yoke to metal box as a grounding path if designed so.

I'm sure the electrical experts will have comments about this, but I
would not want to have to 'settle' ever for an 'implied' ground. I
want to see everything connected. Plus, if the receptacle has a
grounding screw installed, then 110.3(b) must be followed. Simply put,
read the receptacle's manufactures instructions. So use the ground
screw.

hth,

tom @ www.URLBee.com