Self-grounding outlets vs. grounding wire
 

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

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

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

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?

Much better. No one forgets to connect the self grounding outlets, but
many times they don't bother with the wire.

--
Joseph Meehan

26 + 6 = 1 It's Irish Math

No matter how approved it is, if the grounding connection
can be moved or compromised by normal mechanical vibration
(even kids running down the hall cause such vibrations), then
the ground is not sufficient. Approved ground make it
virtually impossible for the ground to be compromised by
vibration or receptacle movement when the power cord is
attached.

Not only do you want 'their' approval. The receptacle must
meet 'your' approval. Safety ground must remain fully
connected at all times - which is why the #10 screw that hold
receptacle to box, alone, is not sufficient as a safety
ground.

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?

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

--
Phil Munro Dept of Electrical & Computer Engin
Youngstown State University
Youngstown, Ohio 44555

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

Takoma Park Volunteer Fire Department Postmaster wrote:

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 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

Hmmm. Yes, I have seen that spring clip on some new receptacles in
the stores. But I have a lot of slightly older receptacles, and see a
lot of older ones installed, that do NOT have that clip. And they
cannot be screwed tightly against the metal box unless the box is in
just the right flush position with respect to the wall surface.
This also has a lot to do with the size of the wall hole around the
box. Again, construction practice seems (from my limited observations)
to get away with holes that are only just barely covered with the
plate, and in this case the receptacle tabs may not allow for much
tightening of the screw. Of course the clip helps solve the electrical
continuity problem. --Phil

--
Phil Munro Dept of Electrical & Computer Engin
Youngstown State University
Youngstown, Ohio 44555

blueman posted for all of us....

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

hey hows it going there? I am glad you changed your name to agree with your
mental state. You are making progress.

Oh, you want a real answer? Do the research Jeffy. But a big clue here is
do you think they would be listed by approval agencies if they didn't work?
(sorta like your brain)
--
Tekkie

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?

Assuming the box is grounded, yes. Obviously a plastic box wouldn't
work, but even metal boxes may not be grounded properly, so check.

Jeff

\|||/
(o o)
,----ooO--(_)-------.
| Please |
| don't feed the |
| TROLL's ! |
'--------------Ooo--'
|__|__|
|| ||
ooO Ooo

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

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 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


Hmmm. Yes, I have seen that spring clip on some new receptacles in
the stores. But I have a lot of slightly older receptacles, and see a
lot of older ones installed, that do NOT have that clip. And they
cannot be screwed tightly against the metal box unless the box is in
just the right flush position with respect to the wall surface.
This also has a lot to do with the size of the wall hole around the
box. Again, construction practice seems (from my limited observations)
to get away with holes that are only just barely covered with the
plate, and in this case the receptacle tabs may not allow for much
tightening of the screw. Of course the clip helps solve the electrical
continuity problem. --Phil

Phil
Without that spring the receptacle cannot be listed as self grounding.
If you thought I was advocating relying on the mounting screws of
ordinary receptacles as the grounding pathway think again. I am only
talking about the receptacles that have been tested by an electrical
testing laboratory and listed as self grounding.
--
Tom H