I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?

Ralph Mowery wrote:
I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?


That is hot side. (Black wire goes there) Ground is green, Neutral is
white. Nothing new.

On Wed, 25 Nov 2015 10:30:48 -0500, "Ralph Mowery"
wrote:

I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?


That is a "self grounding" receptacle and could legally be installed
in a grounded metal box without using the ground wire terminal on the
device. It is still a good idea to use the wire tho.
These are handy if you are retrofitting a 3 prong receptacle in a box
that was grounded but still only had the 2 prong devices installed.
(somewhat common for a while in the 50s)

"Tony Hwang" wrote in message
...
Ralph Mowery wrote:
I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with
it
on one end.

What is the reson for that ?


That is hot side. (Black wire goes there) Ground is green, Neutral is
white. Nothing new.

I may not have made it clear. I know about the screws where the 3 wires go.
It is the screws that mount the receptical to the box I have the question
about.

I have not bought any in many years and just noticed a week or so ago they
started putting some brass or copper keepers on only one end to hold the
mounting screws to the end of the receptical. The other end is still plastic
or paper. They may have started doing that 10 years or so ago, I don't
know when it started.

On Wednesday, November 25, 2015 at 10:27:28 AM UTC-6, Ralph Mowery wrote:

I may not have made it clear. I know about the screws where the 3 wires go.
It is the screws that mount the receptical to the box I have the question
about.

I have not bought any in many years and just noticed a week or so ago they
started putting some brass or copper keepers on only one end to hold the
mounting screws to the end of the receptical. The other end is still plastic
or paper. They may have started doing that 10 years or so ago, I don't
know when it started.

Yes, they have been doing this for many yrs...it's for a more positive connection to ground (if you're using a metal box).

On Wed, 25 Nov 2015 11:11:12 -0500, wrote:

On Wed, 25 Nov 2015 10:30:48 -0500, "Ralph Mowery"
wrote:

I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?


That is a "self grounding" receptacle and could legally be installed
in a grounded metal box without using the ground wire terminal on the
device. It is still a good idea to use the wire tho.
These are handy if you are retrofitting a 3 prong receptacle in a box
that was grounded but still only had the 2 prong devices installed.
(somewhat common for a while in the 50s)

Yes, this is the correct answer. The "self grounding" outlets cost a few
cents more. They are a good idea, but I agree to still use the ground
wire where possible. Personally, I'd just make all of them with the self
grounding device and eliminate more clutter on the store shelves. For
the manufacturer, the cost to add this, cant amount to much of anything.
Of course if there's plastic or bakelite boxes, this does nothing.

"bob_villain" wrote in message
...
.

I have not bought any in many years and just noticed a week or so ago
they
started putting some brass or copper keepers on only one end to hold the
mounting screws to the end of the receptical. The other end is still
plastic
or paper. They may have started doing that 10 years or so ago, I don't
know when it started.

Yes, they have been doing this for many yrs...it's for a more positive
connection to ground (if you're using a metal box).

I did dig out some recepticals and a light switch that I have had for many
years and they had the special keeper on one end. Also had some that just
had the plastic keepers on both ends. Guess that I never noticed that.
before. All I could recall just had the plastic on both ends. I can see
where the plastic could sort of insulate the frame/ground connection.

Most of my work was in electronics and 3 phase wiring. Never did very much
with the 120/240 circuits other than just enough to know which wire to hook
where to keep the neutral and hot on the correct side. Did not have to know
the code for most things.

On 11/25/2015 8:30 AM, Ralph Mowery wrote:
I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?

It's not really a "keeper" but, rather, serves to ensure electrical
contact from the *metal* frame of the switch/outlet *through* the
screw and into a (metal) Jbox.

Some idiot replaced a "three-way" switch in the garage with a regular
light switch. Seeing three terminals on the switch (the third being
the safety ground!), he assumed the third wire ("traveler") should be
connected to that screw! Had me puzzled wondering why I caught
a shock "only sometimes" when TOUCHING the switch/plate!

Had the house been wired with metal Jboxes instead of plastic, this
wouldn't have happened (a breaker would have blown whenever that
traveler ended up with line potential!)

On Wed, 25 Nov 2015 11:58:50 -0700, Don Y
wrote:

On 11/25/2015 8:30 AM, Ralph Mowery wrote:
I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?

It's not really a "keeper" but, rather, serves to ensure electrical
contact from the *metal* frame of the switch/outlet *through* the
screw and into a (metal) Jbox.

Some idiot replaced a "three-way" switch in the garage with a regular
light switch. Seeing three terminals on the switch (the third being
the safety ground!), he assumed the third wire ("traveler") should be
connected to that screw! Had me puzzled wondering why I caught
a shock "only sometimes" when TOUCHING the switch/plate!

Had the house been wired with metal Jboxes instead of plastic, this
wouldn't have happened (a breaker would have blown whenever that
traveler ended up with line potential!)

A good reason why people who lack the knowledge should NOT be allowed to
touch electrical wiring!!!

Also one of the reasons why I use ONLY metal boxes. I will admit that I
used metal boxes all my life, so it's probably an "old age" thing, but I
feel that metal boxes are safer as far as grounding, and also a little
safer if something in the box overheats, since plastic burns whereas
metal dont. Not to mention that the screw holes in plastic boxes tend to
strip out, and once that happens the box has to be replaced, which
likely means ripping walls apart. Whereas, if the threads strip in a
metal box, one can just rethread it for a thicker bolt or use a sheet
metal screw.

"Don Y" wrote in message
...
It's not really a "keeper" but, rather, serves to ensure electrical
contact from the *metal* frame of the switch/outlet *through* the
screw and into a (metal) Jbox.

Some idiot replaced a "three-way" switch in the garage with a regular
light switch. Seeing three terminals on the switch (the third being
the safety ground!), he assumed the third wire ("traveler") should be
connected to that screw! Had me puzzled wondering why I caught
a shock "only sometimes" when TOUCHING the switch/plate!

Had the house been wired with metal Jboxes instead of plastic, this
wouldn't have happened (a breaker would have blown whenever that
traveler ended up with line potential!)


It never fails to amaze me what some can do.

At work a receptical on a ground fault breaker would trip with any load.
Some other workers had tried replacing the breaker and it still tripped with
any load.

To make a long story short, the wires went from the breaker box to another
box with terminal strips in it. Some one had used the wrong neutral going
to the receptical. One of the workers (he did have a state license) would
just pick up any neutral when doing the wiring.
If I could help it, I would not let him change a battery in a one cell
flashlight from some of the things he did at work.

On 11/25/2015 12:25 PM, Ralph Mowery wrote:
"Don Y" wrote in message
...
It's not really a "keeper" but, rather, serves to ensure electrical
contact from the *metal* frame of the switch/outlet *through* the
screw and into a (metal) Jbox.

Some idiot replaced a "three-way" switch in the garage with a regular
light switch. Seeing three terminals on the switch (the third being
the safety ground!), he assumed the third wire ("traveler") should be
connected to that screw! Had me puzzled wondering why I caught
a shock "only sometimes" when TOUCHING the switch/plate!

Had the house been wired with metal Jboxes instead of plastic, this
wouldn't have happened (a breaker would have blown whenever that
traveler ended up with line potential!)

It never fails to amaze me what some can do.

At work a receptical on a ground fault breaker would trip with any load.
Some other workers had tried replacing the breaker and it still tripped with
any load.

To make a long story short, the wires went from the breaker box to another
box with terminal strips in it. Some one had used the wrong neutral going
to the receptical. One of the workers (he did have a state license) would
just pick up any neutral when doing the wiring.
If I could help it, I would not let him change a battery in a one cell
flashlight from some of the things he did at work.

I consider "basic electricity" (not to be confused with detailed Code
requirements) to be a "no brainer". But, apparently, there are lots
of DIY'ers who *have* no brains! Too many people who *think* they
know what they are doing...

On Wednesday, November 25, 2015 at 12:42:34 PM UTC-6, Ralph Mowery wrote:
"bob_villain" wrote in message
...
.

I have not bought any in many years and just noticed a week or so ago
they
started putting some brass or copper keepers on only one end to hold the
mounting screws to the end of the receptical. The other end is still
plastic
or paper. They may have started doing that 10 years or so ago, I don't
know when it started.

Yes, they have been doing this for many yrs...it's for a more positive
connection to ground (if you're using a metal box).

I did dig out some recepticals and a light switch that I have had for many
years and they had the special keeper on one end. Also had some that just
had the plastic keepers on both ends. Guess that I never noticed that.
before. All I could recall just had the plastic on both ends. I can see
where the plastic could sort of insulate the frame/ground connection.

Most of my work was in electronics and 3 phase wiring. Never did very much
with the 120/240 circuits other than just enough to know which wire to hook
where to keep the neutral and hot on the correct side. Did not have to know
the code for most things.

As you say, with your experience you may have used specs for isolated-ground applications. Then, the mounting tabs are insulated and there's only a dedicated ground on the receptacle.

Ralph Mowery posted for all of us...



I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?

They are listed as self grounding outlets. No need to run a jumper to a
metal box.

--
Tekkie

On Wed, 25 Nov 2015 10:30:48 -0500, "Ralph Mowery"
wrote:

I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?

That is a sgety fround connection - grounds the receptacle body to the
metal box (if you are using a metal box) making the bare or green
ground wire redundant.

On Wed, 25 Nov 2015 09:09:49 -0700, Tony Hwang
wrote:

Ralph Mowery wrote:
I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?


That is hot side. (Black wire goes there) Ground is green, Neutral is
white. Nothing new.
No, he is talking about the screws that hold the receptacle onto the
box. The terminal screws have never had "paper" to "retain" them.. Ya
gotta read the whole post!!!

On Wed, 25 Nov 2015 09:01:17 -0800 (PST), bob_villain
wrote:

On Wednesday, November 25, 2015 at 10:27:28 AM UTC-6, Ralph Mowery wrote:

I may not have made it clear. I know about the screws where the 3 wires go.
It is the screws that mount the receptical to the box I have the question
about.

I have not bought any in many years and just noticed a week or so ago they
started putting some brass or copper keepers on only one end to hold the
mounting screws to the end of the receptical. The other end is still plastic
or paper. They may have started doing that 10 years or so ago, I don't
know when it started.

Yes, they have been doing this for many yrs...it's for a more positive connection to ground (if you're using a metal box).
And it is mainly on "spec grade" receptacles - not so often on the
"cheapies"

On Wed, 25 Nov 2015 11:33:15 -0500, "Ralph Mowery"
wrote:


"Tony Hwang" wrote in message
...
Ralph Mowery wrote:
I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with
it
on one end.

What is the reson for that ?


That is hot side. (Black wire goes there) Ground is green, Neutral is
white. Nothing new.

I may not have made it clear. I know about the screws where the 3 wires go.
It is the screws that mount the receptical to the box I have the question
about.

I have not bought any in many years and just noticed a week or so ago they
started putting some brass or copper keepers on only one end to hold the
mounting screws to the end of the receptical. The other end is still plastic
or paper. They may have started doing that 10 years or so ago, I don't
know when it started.

That is strange. Maybe if you floated it in a bowl of water, you could
tell which way was north. That's all I can think of.

On Wed, 25 Nov 2015 16:18:37 -0500, Tekkie®
wrote:

Ralph Mowery posted for all of us...



I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?

They are listed as self grounding outlets. No need to run a jumper to a
metal box.

Haven't all the outlets been self-grounding for decades, even the ones
with paper keepers on the screws? I figured one should remove the
paper to get a better ground (if the ground through the bottom of the
screw head to the screw to the box isn't enough.)

On Wed, 25 Nov 2015 12:15:14 -0800 (PST), bob_villain
wrote:

As you say, with your experience you may have used specs for isolated-ground applications. Then, the mounting tabs are insulated and there's only a dedicated ground on the receptacle.

IG is mostly snake oil. IBM dropped the requirement in the Carter
administration.

On Wed, 25 Nov 2015 17:52:38 -0500, Micky
wrote:

On Wed, 25 Nov 2015 16:18:37 -0500, Tekkie®
wrote:

Ralph Mowery posted for all of us...



I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?

They are listed as self grounding outlets. No need to run a jumper to a
metal box.

Haven't all the outlets been self-grounding for decades, even the ones
with paper keepers on the screws? I figured one should remove the
paper to get a better ground (if the ground through the bottom of the
screw head to the screw to the box isn't enough.)

You can only do that when the device is mounted tight to the box. If
it is out there hanging on the drywall ears, the connection is not
good enough to reliably operate the O/C device.

On Wednesday, November 25, 2015 at 7:09:04 PM UTC-6, wrote:
On Wed, 25 Nov 2015 12:15:14 -0800 (PST), bob_villain
wrote:

As you say, with your experience you may have used specs for isolated-ground applications. Then, the mounting tabs are insulated and there's only a dedicated ground on the receptacle.

IG is mostly snake oil. IBM dropped the requirement in the Carter
administration.

The electrical inspection department around here still requires it for data processing equipment or any computer, medical or electronic gear. ^_^

[8~{} Uncle DATA Monster

On Wed, 25 Nov 2015 18:21:11 -0800 (PST), Uncle Monster
wrote:

On Wednesday, November 25, 2015 at 7:09:04 PM UTC-6, wrote:
On Wed, 25 Nov 2015 12:15:14 -0800 (PST), bob_villain
wrote:

As you say, with your experience you may have used specs for isolated-ground applications. Then, the mounting tabs are insulated and there's only a dedicated ground on the receptacle.

IG is mostly snake oil. IBM dropped the requirement in the Carter
administration.

The electrical inspection department around here still requires it for data processing equipment or any computer, medical or electronic gear. ^_^


You can't be talking about the code inspector so I am guessing someone
in your IT department still has a leisure suit in the closet.
It was determined decades ago that IG did nothing to make computers
work better and compromised surge protection.
You want as much bonded together as you can get with as short a path
as you can get. The IG made the ground too far away to do much in a
serious transient event like a nearby lightning strike.

On Wednesday, November 25, 2015 at 8:50:55 PM UTC-6, wrote:
On Wed, 25 Nov 2015 18:21:11 -0800 (PST), Uncle Monster
wrote:

On Wednesday, November 25, 2015 at 7:09:04 PM UTC-6, wrote:
On Wed, 25 Nov 2015 12:15:14 -0800 (PST), bob_villain
wrote:

As you say, with your experience you may have used specs for isolated-ground applications. Then, the mounting tabs are insulated and there's only a dedicated ground on the receptacle.

IG is mostly snake oil. IBM dropped the requirement in the Carter
administration.

The electrical inspection department around here still requires it for data processing equipment or any computer, medical or electronic gear. ^_^


You can't be talking about the code inspector so I am guessing someone
in your IT department still has a leisure suit in the closet.
It was determined decades ago that IG did nothing to make computers
work better and compromised surge protection.
You want as much bonded together as you can get with as short a path
as you can get. The IG made the ground too far away to do much in a
serious transient event like a nearby lightning strike.

It may have changed in the last few years but the inspection department here didn't necessarily follow the NEC word for word. They had things that they required that weren't required by the NEC. It was my understanding that the isolated grounds were to help cut down on electrical noise getting into electronic equipment. Back in the 1980's when I did electrical wiring for a mission control center that contained a super computer, atomic clock and all sorts of other electronics, the crew installed ground rods all over the damn place. I even drilled through the concrete slab under the raised flooring in at least a dozen places, installed ground rods then bonded the rods to the system ground and raised flooring. The crew installed ground rods every 10 feet around the outside walls and all the grounds were bonded. I always did what the electrical inspectors or The Core Of Engineers demanded. O_o

[8~{} Uncle Code Monster

On Wed, 25 Nov 2015 20:13:50 -0500, wrote:

On Wed, 25 Nov 2015 17:52:38 -0500, Micky
wrote:

On Wed, 25 Nov 2015 16:18:37 -0500, Tekkie®
wrote:

Ralph Mowery posted for all of us...



I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?

They are listed as self grounding outlets. No need to run a jumper to a
metal box.

Haven't all the outlets been self-grounding for decades, even the ones
with paper keepers on the screws? I figured one should remove the
paper to get a better ground (if the ground through the bottom of the
screw head to the screw to the box isn't enough.)

You can only do that when the device is mounted tight to the box. If
it is out there hanging on the drywall ears, the connection is not
good enough to reliably operate the O/C device.

Good point. Of course that woudl be true whether the "keeper" is
paper, plastic, or metal.

On Wed, 25 Nov 2015 19:18:07 -0800 (PST), Uncle Monster
wrote:

On Wednesday, November 25, 2015 at 8:50:55 PM UTC-6, wrote:
On Wed, 25 Nov 2015 18:21:11 -0800 (PST), Uncle Monster
wrote:

On Wednesday, November 25, 2015 at 7:09:04 PM UTC-6, wrote:
On Wed, 25 Nov 2015 12:15:14 -0800 (PST), bob_villain
wrote:

As you say, with your experience you may have used specs for isolated-ground applications. Then, the mounting tabs are insulated and there's only a dedicated ground on the receptacle.

IG is mostly snake oil. IBM dropped the requirement in the Carter
administration.

The electrical inspection department around here still requires it for data processing equipment or any computer, medical or electronic gear. ^_^


You can't be talking about the code inspector so I am guessing someone
in your IT department still has a leisure suit in the closet.
It was determined decades ago that IG did nothing to make computers
work better and compromised surge protection.
You want as much bonded together as you can get with as short a path
as you can get. The IG made the ground too far away to do much in a
serious transient event like a nearby lightning strike.

It may have changed in the last few years but the inspection department here didn't necessarily follow the NEC word for word. They had things that they required that weren't required by the NEC. It was my understanding that the isolated grounds were to help cut down on electrical noise getting into electronic equipment. Back in the 1980's when I did electrical wiring for a mission control center that contained a super computer, atomic clock and all sorts of other electronics, the crew installed ground rods all over the damn place. I even drilled through the concrete slab under the raised flooring in at least a dozen places, installed ground rods then bonded the rods to the system ground and raised flooring. The crew installed ground rods every 10 feet around the outside walls and all the grounds were bonded. I always did what the electrical inspectors or The Core Of Engineers demanded. O_o


I was around for that, we were using braided ground straps on every
floor post and ferrites on anything that wasn't grounded. The thought
was very short ground paths and ferrites to slow down the signal long
enough to slow down the transient in the signal lines until it was
shunted out ... or some such thing. Whatever it did work for esd and
common mode transients.
When we finally analysed the "noise" we identified the enemy and it
was us!
The noise was not external at all, it was coming from 100-200a switch
mode power supplies in the mainframes.
The next generation of machines (30xx and 43xx) had quieter power
supplies and all of that stuff went away (circa 1980 or so).

A few years later we took that "short ground path" stuff out of the
glass house and into the hinterlands to protect all of those little
machines you see in "retail" from lightning (banks, hotels,
restaurants and stores)

We had people plugging their terminals in regular outlets and using
the IG for the operator's space heater.
We were telling people

On Wed, 25 Nov 2015 22:32:36 -0500, Micky
wrote:

On Wed, 25 Nov 2015 20:13:50 -0500, wrote:

On Wed, 25 Nov 2015 17:52:38 -0500, Micky
wrote:

On Wed, 25 Nov 2015 16:18:37 -0500, Tekkie®
wrote:

Ralph Mowery posted for all of us...



I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?

They are listed as self grounding outlets. No need to run a jumper to a
metal box.

Haven't all the outlets been self-grounding for decades, even the ones
with paper keepers on the screws? I figured one should remove the
paper to get a better ground (if the ground through the bottom of the
screw head to the screw to the box isn't enough.)

You can only do that when the device is mounted tight to the box. If
it is out there hanging on the drywall ears, the connection is not
good enough to reliably operate the O/C device.

Good point. Of course that woudl be true whether the "keeper" is
paper, plastic, or metal.

The clip bonds the screw to the device yoke and the threads bond it to
the box ... or so they say.

On Wed, 25 Nov 2015 23:15:16 -0500, wrote:

On Wed, 25 Nov 2015 22:32:36 -0500, Micky
wrote:

On Wed, 25 Nov 2015 20:13:50 -0500, wrote:

On Wed, 25 Nov 2015 17:52:38 -0500, Micky
wrote:

On Wed, 25 Nov 2015 16:18:37 -0500, Tekkie®
wrote:

Ralph Mowery posted for all of us...



I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?

They are listed as self grounding outlets. No need to run a jumper to a
metal box.

Haven't all the outlets been self-grounding for decades, even the ones
with paper keepers on the screws? I figured one should remove the
paper to get a better ground (if the ground through the bottom of the
screw head to the screw to the box isn't enough.)

You can only do that when the device is mounted tight to the box. If
it is out there hanging on the drywall ears, the connection is not
good enough to reliably operate the O/C device.

Good point. Of course that woudl be true whether the "keeper" is
paper, plastic, or metal.

The clip bonds the screw to the device yoke and the threads bond it to
the box ... or so they say.

I"ll pay attention next time i'm at th estore or in the wall.

On Wednesday, November 25, 2015 at 10:14:12 PM UTC-6, wrote:
On Wed, 25 Nov 2015 19:18:07 -0800 (PST), Uncle Monster
wrote:

On Wednesday, November 25, 2015 at 8:50:55 PM UTC-6, wrote:
On Wed, 25 Nov 2015 18:21:11 -0800 (PST), Uncle Monster
wrote:

On Wednesday, November 25, 2015 at 7:09:04 PM UTC-6, wrote:
On Wed, 25 Nov 2015 12:15:14 -0800 (PST), bob_villain
wrote:

As you say, with your experience you may have used specs for isolated-ground applications. Then, the mounting tabs are insulated and there's only a dedicated ground on the receptacle.

IG is mostly snake oil. IBM dropped the requirement in the Carter
administration.

The electrical inspection department around here still requires it for data processing equipment or any computer, medical or electronic gear. ^_^


You can't be talking about the code inspector so I am guessing someone
in your IT department still has a leisure suit in the closet.
It was determined decades ago that IG did nothing to make computers
work better and compromised surge protection.
You want as much bonded together as you can get with as short a path
as you can get. The IG made the ground too far away to do much in a
serious transient event like a nearby lightning strike.

It may have changed in the last few years but the inspection department here didn't necessarily follow the NEC word for word. They had things that they required that weren't required by the NEC. It was my understanding that the isolated grounds were to help cut down on electrical noise getting into electronic equipment. Back in the 1980's when I did electrical wiring for a mission control center that contained a super computer, atomic clock and all sorts of other electronics, the crew installed ground rods all over the damn place. I even drilled through the concrete slab under the raised flooring in at least a dozen places, installed ground rods then bonded the rods to the system ground and raised flooring. The crew installed ground rods every 10 feet around the outside walls and all the grounds were bonded. I always did what the electrical inspectors or The Core Of Engineers demanded.. O_o


I was around for that, we were using braided ground straps on every
floor post and ferrites on anything that wasn't grounded. The thought
was very short ground paths and ferrites to slow down the signal long
enough to slow down the transient in the signal lines until it was
shunted out ... or some such thing. Whatever it did work for esd and
common mode transients.
When we finally analysed the "noise" we identified the enemy and it
was us!
The noise was not external at all, it was coming from 100-200a switch
mode power supplies in the mainframes.
The next generation of machines (30xx and 43xx) had quieter power
supplies and all of that stuff went away (circa 1980 or so).

A few years later we took that "short ground path" stuff out of the
glass house and into the hinterlands to protect all of those little
machines you see in "retail" from lightning (banks, hotels,
restaurants and stores)

We had people plugging their terminals in regular outlets and using
the IG for the operator's space heater.
We were telling people

I repaired or replaced a lot of small UPS units that secretaries plugged in one of those small electric heaters they brought from home. ^_^

As I recall, weren't the building transformers derated due to the prevalence of switching power supplies in computer and office equipment which were putting (I can't remember the term,"asymmetrical?") loads on the transformers? I seem to remember that switching power supplies have a lot of filtering on the incoming power, not necessarily to keep electrical noise from getting in but to keep it from getting out. o_O

[8~{} Uncle Switching Monster

On Wed, 25 Nov 2015 23:16:19 -0800 (PST), Uncle Monster
wrote:



As I recall, weren't the building transformers derated due to the prevalence of switching power supplies in computer and office equipment which were putting (I can't remember the term,"asymmetrical?") loads on the transformers? I seem to remember that switching power supplies have a lot of filtering on the incoming power, not necessarily to keep electrical noise from getting in but to keep it from getting out. o_O

[8~{} Uncle Switching Monster

That is true on both counts.

"Ralph Mowery" writes:
I noticed that instead of the old paper or plastic keepers on the duplex
recepticals now one end has a brass or copper item to keep the screw with it
on one end.

What is the reson for that ?


It ensures continuity for the grounding system
when installed in a metal handy box.