Colored Electrical Outlets
William Munny
are red or orange (not the outlets cover plates, the outlet itself).
What's that all about?
charlie
"William Munny" <w...@jbigwhiskey.org> wrote in message
news:h646uo$42i$1...@news.albasani.net...
> In some hospitals and office buildings, I see some electrical outlets that
> are red or orange (not the outlets cover plates, the outlet itself).
>
> What's that all about?
they are on a ups for safety critical use during blackouts.
dpb
And orange is isolated ground for computer equipment/instrumentation
that requires it.
--
Mortimer Schnerd
If the power goes out, then emergency generators kick in. The red
paneled outlets can be energized by the emergency system as well as the
normal system; the white ones only work when normal power is running.
We would then plug only essentials into the red paneled outlets. During
the normal run of the day, it doesn't matter which outlet you use. The
"red only" will only apply when the generator's are supplying things.
In 17 years as a nurse, I've never had to use emergency power. But it's
there....
Mortimer Schnerd, RN
mschnerd at carolina.rr.com
David Nebenzahl
> In some hospitals and office buildings, I see some electrical outlets that
> are red or orange (not the outlets cover plates, the outlet itself).
>
> What's that all about?
Special sanitary electricity. They run it through an autoclave to
disinfect it.
--
Found--the gene that causes belief in genetic determinism
Robert Neville
>> What's that all about?
>
>they are on a ups for safety critical use during blackouts.
Or they are on an isolated ground.
Doug Miller
Red = connected to emergency power (nearly all hospitals, and many office
buildings, have backup generators in case utility power fails)
Orange = isolated ground (used for sensitive electronic equipment, usually
medical or laboratory instruments, or high-end computer gear)
William Munny
> are red or orange (not the outlets cover plates, the outlet itself).
>
> What's that all about?
>
Cool, thanks...
Stormin Mormon
electrons.
--
Christopher A. Young
Learn more about Jesus
www.lds.org
.
"David Nebenzahl" <nob...@but.us.chickens> wrote in message
news:4a85a4c0$0$7469$8226...@news.adtechcomputers.com...
Perry Aynum
> are red or orange (not the outlets cover plates, the outlet itself).
>
> What's that all about?
>
How's the hired gun business working out?
cl...@snyder.on.ca
wrote:
ORANGE receptacles are "isolated ground" (used to be - not necessarity
true any more) meaning the "U" ground was not connected to the
mounting tab.
Ashton Crusher
wrote:
How is isolated ground different then "regular" ground?
Doug Miller
>On Sat, 15 Aug 2009 08:33:57 GMT, spam...@milmac.com (Doug Miller)
>wrote:
>>
>>medical or laboratory instruments, or high-end computer gear)
>
>
>How is isolated ground different then "regular" ground?
stan
> In article <jkkk85lt63128hjduf2am1b28l117ni...@4ax.com>, Ashton Crusher <d...@moore.net> wrote:
> >On Sat, 15 Aug 2009 08:33:57 GMT, spamb...@milmac.com (Doug Miller)
> >wrote:
>
> >>Orange = isolated ground (used for sensitive electronic equipment, usually
> >>medical or laboratory instruments, or high-end computer gear)
>
> >How is isolated ground different then "regular" ground?
>
> http://tinyurl.com/n937l4
Thanks to all posters. Learned something. And made one think. Thank-
you.
Sounds like 'Isolated' Ground might also be called an 'Individual'
Ground!
In other words the grounding wire from this type of outlet (orange!)
is run individually to the grounding point; not using the ground used
for a 'run' or group of 'regular' outlets.
Have only used an orange outlet once, connected to the output of a UPS
located in our basement and wired up stairs to the room with the main
PC etc. AFIK took the ground back to the output of the UPS.
But as one poster pointed out if we have other computer type gear (say
printers or scanners etc. plugged into regular outlets) their grounds
may inadvertently be connected via the various cables connecting them
to the main computer with its isolated ground. Thus possibly defeating
the purpose of the individual ground?
The < http://tinyurl.com/n937l4 > was a useful explanatory.
JIMMIE
Many building have three types of circuits.
Commercial: Same old stuff you got at your house.
Essential: These are backed up by generator.
Critical: These are backed up by both a generator and an
Uninterruptable Power Supply similar to the battery backup you may
have for your PC.
The critical circuits are marked so people will not know not to plug
things into them they shouldn't like blow dryers, personal heaters,
and janitorial equipment. Also it lets them know you could plug in a
heart-lung machine there. There may also be rules about what you can
use on essential circuits so they may also be marked.
Jimmie
Chip C
That's a good article about the hoo-hah surrounding isolated ground.
I'm convinced that architects put them in out of rote habit. I've
personally never seen a computer with documentation that requires
them.
I believe that audio and signal processing equipment might benefit
from them, since in some places (at some time) I hear was ok to use
the metallic conduit as the circuit's ground, and not pull a bare or
green wire. The conduit picks up a lot of noise, so it causes problems
for equipment that uses the ground as a signal reference level. The
orange outlet at least guarantees you a real copper ground all the way
back to something earthed. As others have said, today's codes,
especially for hospitals, now guarantee this for all outlets.
I am also told that the orange outlets can indicate a circuit fed by a
(nearby) isolation transformer, on the output side of which the
neutral is re-referenced (ie, tied) to ground. This guarantees that at
the outlet, ground and neutral are close together in voltage.
Otherwise, in large commercial buildings, as you get further from the
point of grounding you can find that ground and neutral not only have
noise relative to each other but are far apart in DC levels.
As others have said, the read outlets are on circuits that can be fed
by the generators if the utility power cuts out. (And yes, the
breakers for these circuits are in bright read service panels.) But be
warned, a lot of places do generator and cutover tests at some regular
schedule, usually at some early morning hour, which cause outages of a
second or so. Much hospital equipment (fridges, lighting, elevators,
plus patient support equipment that has internal batteries) ride
through these fine, but computers don't. And of course, when a utility
outage happens, it takes time for the generators to ramp up (the
nominal standard is generally 15 seconds, in the real world can be
longer). Bottom line: don't plug a computer in to a hospital red
outlet without a UPS.
Chip C
Chip C
> On Tue, 18 Aug 2009 07:07:06 -0700 (PDT), Chip C
Yes, in cases where its output is not referenced to earth. The two-
prong shaver outlets that used to be in bathroom light fixtures were
like this. Also I hear that in the UK (and other 240V places??) they
use 120V isolated power on outdoor construction sites.
If the one of the transformer output legs is tied to earth, then I
don't see the safety benefit.
Chip C
Doug Miller
>I believe that audio and signal processing equipment might benefit
>from them, since in some places (at some time) I hear was ok to use
>the metallic conduit as the circuit's ground, and not pull a bare or
>green wire.
Not "in some places" -- anywhere that has adopted the U.S. National Electrical
Code.
Not "at some time" -- always.
Not "was ok" -- still is ok.
The NEC specifically permits the use of metal conduit of various types to be
used as the equipment grounding conductor. Bare or green wires are not
necessary.
> The conduit picks up a lot of noise, so it causes problems
>for equipment that uses the ground as a signal reference level.
Not if it's properly grounded, it doesn't.
JIMMIE
> On Tue, 18 Aug 2009 05:31:40 -0700 (PDT), stan
>
> <tsanf...@nf.sympatico.ca> wrote:
> >But as one poster pointed out if we have other computer type gear (say
> >printers or scanners etc. plugged into regular outlets) their grounds
> >may inadvertently be connected via the various cables connecting them
> >to the main computer with its isolated ground. Thus possibly defeating
> >the purpose of the individual ground?
>
> recommendation from the Physical Planning Manual. You are right, as
> soon as you connect equipment on different circuits together IG is
> meaningless, or worse a source of additional problems. Your bonding
> path becomes longer than the signal path so the line driver/receiver
> becomes your surge protection. We went the other way and added
> additional bonding, connecting machine frames directly together.
I used to work on a mainframe computer system that was updated to
isolated grounding. There were a few pieces of hardware on which it
was impossible to isolate the grounds but the engineers decided this
was OK. I have never seen so much blue smoke in my life as when they
applied power. This happened nearly 20 years ago and the essence of
ohms still lingers in the air. A few years ago all the equipment wa
upgraded and it was all designed for IG and the appropriate IG system
was installed. A few months ago the equipment was expanded and it was
decide that IG was not needed so now we have bare ground wires laying
in bare metal cable trays attached to IG ground points, cable trays
are fastened to earth ground.
Jimmie
bud--
The UK transformer has a centertap that is earthed. The hot wires are
60V from earth potential.
>
> If the one of the transformer output legs is tied to earth, then I
> don't see the safety benefit.
>
It keeps the hot wires from being at 2000V with respect to earth. Or
with 120V primary and secondary one secondary wire could be at 240V with
respect to the earth. When servicing electronic equipment an isolation
transformer with a completely floating secondary may be used. There can
be significant hazards working on equipment with the DC power system
tied to the neutral.
Almost all systems are earthed.
--
bud--
bud--
IMHO IG circuits were largely black magic.
There were a few manufacturers that wanted the isolated ground to be
tied *only* to a local ground rod (no connection to the electrical
system). It was a major code violation and safety hazard.
--
bud--
The Daring Dufas
>
>> But as one poster pointed out if we have other computer type gear (say
>> printers or scanners etc. plugged into regular outlets) their grounds
>> may inadvertently be connected via the various cables connecting them
>> to the main computer with its isolated ground. Thus possibly defeating
>> the purpose of the individual ground?
>
>
> recommendation from the Physical Planning Manual. You are right, as
> soon as you connect equipment on different circuits together IG is
> meaningless, or worse a source of additional problems. Your bonding
> path becomes longer than the signal path so the line driver/receiver
> becomes your surge protection. We went the other way and added
> additional bonding, connecting machine frames directly together.
I was an electrician working on the mission control center for
the star wars program 20 years ago and we put ground rods under
the raised flooring, around the perimeter of the building, then
built a grounding grid under the flooring of the whole place. I
guess they didn't want any stray electric currents affecting the
multi million dollar Cray Super Computer.
TDD
cl...@snyder.on.ca
wrote:
The "u" ground is not connected to the "frame" ground.
cl...@snyder.on.ca
>Isolation transformer is for human safety.
A NON GROUNDED isolation transformer is for safety. A grounded
isolation transformer is for"noise" reduction on the line and
elimination of ground loop currents and floating grounds.
cl...@snyder.on.ca
wrote:
>In article <2193c58f-08dc-48e1...@w41g2000yqb.googlegroups.com>, Chip C <chipc...@yahoo.com> wrote:
"proerly grounded" and EMT as ground is an oxymoron.
Doug Miller
Not according to publishers of the NEC, it isn't.
"The equipment grounding conductor ... shall be one or more ... of the
following: ... Electrical metallic tubing...." [2008 NEC, Article 250.118]
I imagine they know a little more about it than you do.
Smitty Two
The Daring Dufas <the-dari...@stinky.net> wrote:
> I
> guess they didn't want any stray electric currents affecting the
> multi million dollar Cray Super Computer.
>
> TDD
Free association, probably my favorite quote of all time: "I used a #2
pencil and a quadrille pad."
(Seymour Cray's response to "What kind of computer did you use to design
the Cray supercomputer?")
cl...@snyder.on.ca
wrote:
EMT in a dry location - OK. But with humidity, and particularly
humidty and vibration, the integrity of the ground suffers in a short
time. I would never depend on the EMT for a safety ground.
Stormin Mormon
the back of the hospital, please.
David Nebenzahl
This seems to be analogous to backstabbed connections vs. screw-terminal
connections: allowed by the NEC, but not as good a technique.
Think about it: with EMT, all it takes is one loose screw somewhere in
the line to sever, or at least seriously degrade, the ground connection.
David Nebenzahl
> On Thu, 20 Aug 2009 10:56:39 -0700, David Nebenzahl
> <nob...@but.us.chickens> wrote:
>
>>>>Not according to publishers of the NEC, it isn't.
>>>>
>>>> "The equipment grounding conductor ... shall be one or more ... of
>>>> the following: ... Electrical metallic tubing...." [2008 NEC,
>>>> Article 250.118]
>>>>
>>>>I imagine they know a little more about it than you do.
>> >
>>> EMT in a dry location - OK. But with humidity, and particularly
>>> humidty and vibration, the integrity of the ground suffers in a short
>>> time. I would never depend on the EMT for a safety ground.
>>
>>This seems to be analogous to backstabbed connections vs. screw-terminal
>>connections: allowed by the NEC, but not as good a technique.
>>
>>Think about it: with EMT, all it takes is one loose screw somewhere in
>>the line to sever, or at least seriously degrade, the ground connection.
>
> That is true if you use a green wire ground too. Workmanship is the
> key to any installation. Most of the industrial jobs I inspected
> specified compression connectors wrench tight. That is a pretty solid
> ground path. They still pulled a green wire most of the time.
Yes. I forgot to mention that when I run conduit, I much prefer the
compression connectors to the "make-a-dimple-in-the-tubing-with-a-screw"
ones, which always seem a bit on the cheesy side to me.
cl...@snyder.on.ca
<nob...@but.us.chickens> wrote:
The problem is, the NEC allows either one to be used as a ground - and
the "dimple" is NOT a safe ground. The compression connector, wrench
tite - perhaps.
aemeijers
joints on the conduit, done with compression fittings. Before they pull
the copper or fiber, of course. Of course, a ground path isn't what they
are after.
--
aem sends...
Nate Nagel
do they also happen to have walls covered with sheets of copper soldered
together? I've worked in some places like that...
nate
--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel
aemeijers
rooms in the dungeon, now used for other things, that are covered with
expanded metal mesh over the concrete block, and in the plastered
ceiling. There is one room that I suspect has the sort of wallpaper you
describe, but thankfully I'm not allowed in there. The paperwork to be
allowed in the room in front of that room, and use the hardware there,
was bad enough.
--
aem sends...
Nate Nagel
y'know, now that I think about it, once upon a time expanded metal mesh
was used for lath for plasterwork. I know my high school was
constructed that way; not sure why they spec'd plaster and not drywall
as it was built in 1972 or 1973 I believe. Wouldn't that play holy hell
with radio reception? Obviously people weren't trying to listen to the
radio or watch TV inside a high school, but I'm sure quite a few homes
were built like this as well...
aemeijers
where there used to be a mesh door to complete the cage. I guess they
figured floor didn't need shielding, since that part of building was
well below grade, with no sewers and such below it.
--
aem sends...
bud--
I'm sure the code making panel will be interested - submit a code change
proposal. Be sure to include pictures of the dead bodies - it is very
effective. On the other hand, the code panels are not likely to make
changes based only on opinion.
"Dimple" is not a good description, as there were also fittings that
used a compression tool to create a "dimple". (They still allowed?)
In addition to using compression fittings you can use non-diecast
fittings (not sure what they are called). They are a lot better
connection on set-screw fittings. Or compression non-diecast fittings.
--
bud--
SteveBell
>>>>do they also happen to have walls covered with sheets of copper
>>>>soldered together? I've worked in some places like that...
>>>>
>>>Nah, the hardware itself is shielded now. But there are some
>>>storage rooms in the dungeon, now used for other things, that
>>>are covered with expanded metal mesh over the concrete block,
>>>and in the plastered ceiling. There is one room that I suspect
>>>has the sort of wallpaper you describe, but thankfully I'm not
>>>allowed in there. The paperwork to be allowed in the room in
>>>front of that room, and use the hardware there, was bad enough.
>>
>>y'know, now that I think about it, once upon a time expanded metal
>>mesh was used for lath for plasterwork. I know my high school was
>>constructed that way; not sure why they spec'd plaster and not
>>drywall as it was built in 1972 or 1973 I believe. Wouldn't that
>>play holy hell with radio reception? Obviously people weren't
>>trying to listen to the radio or watch TV inside a high school,
>>but I'm sure quite a few homes were built like this as well...
>>
>No, the wall mesh in these rooms was obvious RF sheilding. You could
>see where there used to be a mesh door to complete the cage. I guess
>they figured floor didn't need shielding, since that part of building
>was well below grade, with no sewers and such below it.
I once watched the construction of a Tempest-class area:
* Commercial metal studs
* One layer of metal-coated 5/8" wallboard on each side, metal out
* Tape seams with metal tape
* Another layer of metal-coated wallboard, seams shifted four feet
* Tape seams with metal tape
* One layer of regular wallboard for the finish surface
* Speakers to play music inside the walls
* Motion detectors to detect motion inside the walls
They did the ceiling after the walls closed in, so I didn't get to see
what happened there, but I'm sure it was equally impressive.
--
Steve Bell
New Life Home Improvement
Arlington, TX USA
John Gilmer
>
> Think about it: with EMT, all it takes is one loose screw somewhere in the
> line to sever, or at least seriously degrade, the ground connection.
>
will "trip" the CB.
I was installing some foil insulation on a wall with a outlet box. The
foil just brushed against the hot wire and FLASH, POP the breaker tripped.
I guess the foil had been grounded by another outlet's plaster ears.
elecwired
http://www.homeownershub.com/maintenance/Colored-Electrical-Outlets-389158-.htm
elecwired wrote:
William Munny wrote:
> In some hospitals and office buildings, I see some electrical outlets
> that
> are red or orange (not the outlets cover plates, the outlet itself).
> What\'s that all about?
-------------------------------------
The color is the grade type (heavy duty, ect)
aemeijers
red or orange indicates that the outlet is on the UPS system (aka
back-up battery/generator system), so it will still keep working when
the lights go out. So that is where you want to plug the ventilator and
such into.
The shape of the slots indicates the 'heavy duty' outlets. The little
side leg on one slot means 30amp, IIRC, but it goes both ways, and
normal stuff can also be plugged into there. Numerous web sites have
diagrams, if you are curious enough to Google them.
--
aem sends...
--
aem sends...
RBM
"aemeijers" <aeme...@att.net> wrote in message
news:xJGdnVA_Tfx-SAXR...@giganews.com...
outlet's electrical charicteristics, like voltage, amperage, phase. There
are numerous types and shapes of 30 amp outlets, as well as outlets of every
other amperage
Robert Neville
>The shape of the slots does not indicate "heavy duty", it indicates the
>outlet's electrical charicteristics, like voltage, amperage, phase. There
>are numerous types and shapes of 30 amp outlets, as well as outlets of every
>other amperage
Furthermore, color of the outlet in computer centers and other locations can
indicate isolated ground - a design the reduces surge impact on sensitive
devices.
cl...@snyder.on.ca
Orange indicates an "isolated ground" receptacle.. The ground pin is a
separate insulated ground that goes directly to the panel instead of
being grounded to all the other grounds and metal boxes and conduit
along the way like the normal ground. Causes less electric "noise" in
that particular ground for some electronics that might be sensitive to
it.
Red IS emergency backup power (UPS connected)
Keith S.
> Red IS emergency backup power (UPS connected)
>
Yellow is corrosion resistance contacts.
Green dot on the face is Hospital Grade.
Smitty Two
elecwired_at...@foo.com (elecwired) wrote:
Another fake fucking post from the bullshit homeowner website.
"Referenced article does not exist." Posted by the site's owner to drum
up more publicity, and all you idiots are playing along.
aemeijers
Per the wikipedia article (FWIW, of course):
Color code
The color of a device does not identify the voltage class or power
system for the device. Since the colors are not regulated by national
standards, the purpose of color-coding a receptacle is set by the
building owner. Brown, ivory, white, almond, grey, and black receptacles
in the 5–15 configuration are selected to blend with the decor of a room.
* Blue receptacles may indicate built-in surge suppressors.
* A red receptacle may indicate a special-service outlet such as
one connected to an emergency standby power source.
* At least one manufacturer makes a yellow receptacle which
identifies it as corrosion-resistant.
* A receptacle with a green dot is a so-called “hospital grade”
device; such devices are tested to survive harder use than wiring
devices intended for residential or commercial purposes. The NEMA
standard does not define green as a color for wiring devices.
A receptacle with an orange triangle is an isolated ground device, where
the grounding pin of the receptacle is connected to ground independently
of the frame of the receptacle and wiring outlet box. The receptacle
itself may be any color, but contrary to popular belief, a receptacle is
no longer an isolated ground device because the receptacle itself is
orange, although this was formerly the case in the United States.[14]
--
aem sends...
Stormin Mormon
The Stucco site is not a help forum, it's an
*advertising* forum that invades real forums
(like "alt.home.repair", part of "usenet")
parasitically in order to generate free
advertising for itself, which continually
advances its search engine placement, thereby
increasing its own revenue through its click-
through advertising commissions.
So the first thing you should do is write them
an email and tell them to quit spamming.
Then try to find your way here through proper
channels. Please do a google search on "Usenet"
and post the regular way.
--
Christopher A. Young
Learn more about Jesus
www.lds.org
.
"elecwired" <elecwired_at...@foo.com> wrote in message
news:45969$4c98d0c8$45499b77$18...@news.flashnewsgroups.com...
responding to
http://www.homeownershub.com/maintenance/Colored-Electrical-Outlets-389158-.htm
The Daring Dufas
The orange outlets indicate that they are isolated ground, the ground
circuit is not bonded to the mounting ears. They are specified for
data processing equipment to keep from sharing the ground circuit
with possible sources of electrical noise. Red outlets typically
indicate that they're hooked to an emergency power source that will
continue if the main power goes out. You usually see red outlets in
hospital rooms and this is what things like respirators/ventilators
will be plugged into.
TDD
The Daring Dufas
> On Wed, 22 Sep 2010 23:21:08 -0500, The Daring Dufas
> <the-dari...@stinky.net> wrote:
>
>> The orange outlets indicate that they are isolated ground, the ground
>> circuit is not bonded to the mounting ears. They are specified for
>> data processing equipment to keep from sharing the ground circuit
>> with possible sources of electrical noise.
>
> was snake oil and they stopped including IG in the specs for their
> equipment. There are some self proclaimed "experts" who still cling to
> this fantasy but it is finally dying the death it deserves.
A lot of older equipment was susceptible to electrical line noise. Heck,
the first personal computers I worked on back in the late 70's and early
80's would conk out due to the static electric charge from you
touching the case after you walked on carpet. I'll use the isolated
ground receptacles in commercial situations where there a lot of motors
and refrigeration/AC compressors on the same power system.
TDD
cl...@snyder.on.ca
>On Thu, 23 Sep 2010 05:11:26 -0500, The Daring Dufas
>IG will do nothing to stop an ESD hit through the case.
>The real "PCs were very noise tolerant and by the time IBM came out
>with the PS/2 they were using a multi layer board that didn't even
>need external shielding. I made several of them with wooden cases
>
>http://gfretwell.com/electrical/woody.jpg
The wooden case will work - but will NOT pass DOC specs - it will
radiate RF all across the spectrum.
Computers using the old linear power supplies were VERY sensitive to
line noise - which made isolated ground power circuits almost a
requirement in many applications.
Switch mode power supplies of today are extremely noise tollerant -
but a very large majority of them are also extremely noizy - with
little or no EMI filtering to stop the hash from the chopper circuit
from radiating back into the power supply, along with the associated
harmonics.
The Daring Dufas
> On Thu, 23 Sep 2010 05:11:26 -0500, The Daring Dufas
> The real "PCs were very noise tolerant and by the time IBM came out
> with the PS/2 they were using a multi layer board that didn't even
> need external shielding. I made several of them with wooden cases
>
> http://gfretwell.com/electrical/woody.jpg
OH MY GOD! That computer is soooooo old! 8-)
TDD
The Daring Dufas
The problem with switchers is what happens when you have a lot of them
on a power system. Building transformers, especially those for office
buildings have been redesigned over the years to cope with the
asymmetrical loads from switching power supplies. Heck, these days
noise tolerance is designed into the darned integrated circuits
themselves.
TDD
The Daring Dufas
> On Sep 22, 11:43 pm, gfretw...@aol.com wrote:
>> On Wed, 22 Sep 2010 23:21:08 -0500, The Daring Dufas
>>
>>> The orange outlets indicate that they are isolated ground, the ground
>>> circuit is not bonded to the mounting ears. They are specified for
>>> data processing equipment to keep from sharing the ground circuit
>>> with possible sources of electrical noise.
>>
>> was snake oil and they stopped including IG in the specs for their
>> equipment. There are some self proclaimed "experts" who still cling to
>> this fantasy but it is finally dying the death it deserves.
>
> wouldn't be coupled back into the mains (also on separate circuits so
> the cleaning servies wouldn't trip anything important).
Wasn't it at a hospital in someplace like Bulgaria where the cleaning
lady was unplugging ventilators in patient rooms to run her vacuum cleaner?
TDD
keith
> On Thu, 23 Sep 2010 11:10:56 -0400, gfretw...@aol.com wrote:
> >On Thu, 23 Sep 2010 05:11:26 -0500, The Daring Dufas
>
> >>On 9/22/2010 11:43 PM, gfretw...@aol.com wrote:
> >>> On Wed, 22 Sep 2010 23:21:08 -0500, The Daring Dufas
>
> >>>> The orange outlets indicate that they are isolated ground, the ground
> >>>> circuit is not bonded to the mounting ears. They are specified for
> >>>> data processing equipment to keep from sharing the ground circuit
> >>>> with possible sources of electrical noise.
>
> >>> IBM figured out in the early 80s that this isolated ground boondoggle
> >>> was snake oil and they stopped including IG in the specs for their
> >>> equipment. There are some self proclaimed "experts" who still cling to
> >>> this fantasy but it is finally dying the death it deserves.
>
> >>A lot of older equipment was susceptible to electrical line noise. Heck,
> >>the first personal computers I worked on back in the late 70's and early
> >>80's would conk out due to the static electric charge from you
> >>touching the case after you walked on carpet. I'll use the isolated
> >>ground receptacles in commercial situations where there a lot of motors
> >>and refrigeration/AC compressors on the same power system.
>
> >>TDD
>
> >IG will do nothing to stop an ESD hit through the case.
> >The real "PCs were very noise tolerant and by the time IBM came out
> >with the PS/2 they were using a multi layer board that didn't even
> >need external shielding. I made several of them with wooden cases
>
> >http://gfretwell.com/electrical/woody.jpg
>
> The wooden case will work - but will NOT pass DOC specs - it will
> radiate RF all across the spectrum.
Not necessarily. Boards today aren't as ugly RF wise as they once
were. Boards sold to the public (outside systems) must pass an FCC
compliance test that only allows 6dB for the case. Even at the worst
case, 6dB above the limits, it's hardly "radiating RF all across the
spectrum".
> Computers using the old linear power supplies were VERY sensitive to
> line noise - which made isolated ground power circuits almost a
> requirement in many applications.
T-R packs, yes. Linear supplies, not as much.
> Switch mode power supplies of today are extremely noise tollerant -
> but a very large majority of them are also extremely noizy - with
> little or no EMI filtering to stop the hash from the chopper circuit
> from radiating back into the power supply, along with the associated
> harmonics.
Poorly designed ones, yes. Ones that haven't passed conducted
emissions tests, perhaps. There are specs for these things too.
keith
> On Thu, 23 Sep 2010 21:34:40 -0400, cl...@snyder.on.ca wrote:
> >>IG will do nothing to stop an ESD hit through the case.
> >>The real "PCs were very noise tolerant and by the time IBM came out
> >>with the PS/2 they were using a multi layer board that didn't even
> >>need external shielding. I made several of them with wooden cases
>
> >>http://gfretwell.com/electrical/woody.jpg
> > The wooden case will work - but will NOT pass DOC specs - it will
> >radiate RF all across the spectrum.
>
> field strength meter and this was not noisy at all. It was certainly
> meet FCC class A spec.
Not surprising, since the class-A spec is 10dB below class-B. If they
passed class-B as an indivicual board (with the 6dB allowance for the
case), they'll pass class-A without a case with at least a 4dB margin.
> >Computers using the old linear power supplies were VERY sensitive to
> >line noise - which made isolated ground power circuits almost a
> >requirement in many applications.
>
> What PC used a linear supply? The first PC-1 5150 used a switcher
> supply and every one after that did too,
> Virtually every linear supply I ever saw at IMB was ferro resonant and
> very noise tolerant.
Computers (before PCs) once did use a lot of linear supplies and T-R
packs.
> >Switch mode power supplies of today are extremely noise tollerant -
> >but a very large majority of them are also extremely noizy - with
> >little or no EMI filtering to stop the hash from the chopper circuit
> >from radiating back into the power supply, along with the associated
> >harmonics.
>
> They are all required to have a line filter to keep this out of the
> power cord. None of this has anything to do with IG. IG is intended to
> keep noise off the EGC
keith
> On Thu, 23 Sep 2010 14:18:34 -0700 (PDT), keith <keith...@gmail.com>
> wrote:
>
>
>
> >On Sep 22, 11:43 pm, gfretw...@aol.com wrote:
> >> On Wed, 22 Sep 2010 23:21:08 -0500, The Daring Dufas
>
> >> <the-daring-du...@stinky.net> wrote:
> >> >circuit is not bonded to the mounting ears. They are specified for
> >> >data processing equipment to keep from sharing the ground circuit
> >> >with possible sources of electrical noise.
>
> >> was snake oil and they stopped including IG in the specs for their
> >> equipment. There are some self proclaimed "experts" who still cling to
> >> this fantasy but it is finally dying the death it deserves.
>
> >wouldn't be coupled back into the mains (also on separate circuits so
> >the cleaning servies wouldn't trip anything important).
>
> been a few people who installed them but they were not using the IBM
> Physical Planning manual.
They were in every building I worked in. They were up and down the
halls, even. Cleaning crews were instructed to use them exclusively.
cl...@snyder.on.ca
>On Thu, 23 Sep 2010 21:34:40 -0400, cl...@snyder.on.ca wrote:
>
>>>IG will do nothing to stop an ESD hit through the case.
>>>The real "PCs were very noise tolerant and by the time IBM came out
>>>with the PS/2 they were using a multi layer board that didn't even
>>>need external shielding. I made several of them with wooden cases
>>>
>>>http://gfretwell.com/electrical/woody.jpg
>> The wooden case will work - but will NOT pass DOC specs - it will
>>radiate RF all across the spectrum.
>>
>
>That was what I was told but we did do some rudimentary testing with a
>field strength meter and this was not noisy at all. It was certainly
>meet FCC class A spec.
I can categorically deny that as being even remotely possible, having
been in the computer manufacturung business for 5 years, and having
had numerous designs tested for FCC and DOT compliance.
A full foil lining on the wood case, at a very minimum, would be
required to pass.
>
>>Computers using the old linear power supplies were VERY sensitive to
>>line noise - which made isolated ground power circuits almost a
>>requirement in many applications.
>>
>
>What PC used a linear supply? The first PC-1 5150 used a switcher
>supply and every one after that did too,
>Virtually every linear supply I ever saw at IMB was ferro resonant and
>very noise tolerant.
I didn't say PC. I said computer.
I've got several linear computer power supplies stashed away in the
"way back" box., as well as 2 operating 6809 boxes with linear power
supplies.
>
>>Switch mode power supplies of today are extremely noise tollerant -
>>but a very large majority of them are also extremely noizy - with
>>little or no EMI filtering to stop the hash from the chopper circuit
>>from radiating back into the power supply, along with the associated
>>harmonics.
>
>They are all required to have a line filter to keep this out of the
>power cord. None of this has anything to do with IG. IG is intended to
>keep noise off the EGC
"Required" and "have" are at least 3 different things it appears.
A very LARGE percentage of low end PC power supplies have NO EMI
filtering on the line input.
Noise in the power cord WILL end up on the ground, to one extent or
another - and an IG keeps it more or less localized to that circuit.
cl...@snyder.on.ca
wrote:
Specs yes, but virtually no compliance enforcement.
Loads and loads of noncompliant crap come into the country every day -
with compliance stickers prominently displayed.
Like I said - I spent 5 years in the computer manufacturing business,
and what DID NOT comply was a whole lot more common than what did,
component wise.
To make a SYSTEM compliant with non-compliand components is possible,
but quite difficult.
We used 4 layer boards even back then - with built-in ground planes in
the critical areas - and often the difference between a system that
passed and one that didn't was as simple as different PLASTIC on the
case front - or changing suppliers of the video card - which had the
same part number, and supposedly the same design.
One plastic has RFI coating on the inside, while the other didn't. One
vieo card supplier had left off the "non-critical" despiking capacitor
or other EMR suppression device - and "might" pass with a well
sheilded and ferrited cord to the monitor, while the other, slightly
more costly, fully populated board would pass, hands down.
When the accountants started running the company instead of the
engineers, all hell broke loose when it came to certifying new models.
cl...@snyder.on.ca
>On Fri, 24 Sep 2010 13:12:02 -0400, cl...@snyder.on.ca wrote:
>
>>having
>>been in the computer manufacturung business for 5 years
>
>I started in the computer biz in 1966
Yes, and my stint in the computer manufacturing business goes WAY
back too. Not quite as far as you though!!!!
I got out of the manufacturing business many years ago - just before
the manufacturer went "T.U."
k...@att.bizzzzzzzzzzzz
>On Fri, 24 Sep 2010 01:13:25 -0400, gfre...@aol.com wrote:
>
>>On Thu, 23 Sep 2010 21:34:40 -0400, cl...@snyder.on.ca wrote:
>>
>>>>IG will do nothing to stop an ESD hit through the case.
>>>>The real "PCs were very noise tolerant and by the time IBM came out
>>>>with the PS/2 they were using a multi layer board that didn't even
>>>>need external shielding. I made several of them with wooden cases
>>>>
>>>>http://gfretwell.com/electrical/woody.jpg
>>> The wooden case will work - but will NOT pass DOC specs - it will
>>>radiate RF all across the spectrum.
>>>
>>
>>That was what I was told but we did do some rudimentary testing with a
>>field strength meter and this was not noisy at all. It was certainly
>>meet FCC class A spec.
>
>I can categorically deny that as being even remotely possible, having
>been in the computer manufacturung business for 5 years, and having
>had numerous designs tested for FCC and DOT compliance.
QRZ, I suppose, too.
>A full foil lining on the wood case, at a very minimum, would be
>required to pass.
You're *clearly* wrong. Computer components must pass *without* a case (with
a 6dB exemption). A component designed for class-B will *easily* pass class-A
limits without a problem.
>>>Computers using the old linear power supplies were VERY sensitive to
>>>line noise - which made isolated ground power circuits almost a
>>>requirement in many applications.
>>>
>>
>>What PC used a linear supply? The first PC-1 5150 used a switcher
>>supply and every one after that did too,
>>Virtually every linear supply I ever saw at IMB was ferro resonant and
>>very noise tolerant.
>
>I didn't say PC. I said computer.
>I've got several linear computer power supplies stashed away in the
>"way back" box., as well as 2 operating 6809 boxes with linear power
>supplies.
>>
>>>Switch mode power supplies of today are extremely noise tollerant -
>>>but a very large majority of them are also extremely noizy - with
>>>little or no EMI filtering to stop the hash from the chopper circuit
>>>from radiating back into the power supply, along with the associated
>>>harmonics.
>>
>>They are all required to have a line filter to keep this out of the
>>power cord. None of this has anything to do with IG. IG is intended to
>>keep noise off the EGC
No, they're required to pass the test. That's made a lot easier with the line
filter, but the filter is not a requirement.
k...@att.bizzzzzzzzzzzz
Not unless someone complains (usually a competitor).
>Loads and loads of noncompliant crap come into the country every day -
>with compliance stickers prominently displayed.
Sure, but irrelevant.
>Like I said - I spent 5 years in the computer manufacturing business,
>and what DID NOT comply was a whole lot more common than what did,
>component wise.
I've spent >35 years, most of which was spent designing this stuff.
>To make a SYSTEM compliant with non-compliand components is possible,
>but quite difficult.
Wrong! You clearly don't know what you're talking about. PCs have special
dispensation. As long as the components are listed (at the 6dB tightened
spec) the computer doesn't even need to be tested. Many DO NOT have any
shielding at all; all perfectly legal.
>We used 4 layer boards even back then - with built-in ground planes in
>the critical areas - and often the difference between a system that
>passed and one that didn't was as simple as different PLASTIC on the
>case front - or changing suppliers of the video card - which had the
>same part number, and supposedly the same design.
It *very* few exceptions, ground planes go EVERYWHERE, not just in "critical
areas". Power planes, too. Eight layers (4S4P) was our standard card 35
years ago, motherboards had even more signal layers.
>One plastic has RFI coating on the inside, while the other didn't. One
>vieo card supplier had left off the "non-critical" despiking capacitor
>or other EMR suppression device - and "might" pass with a well
>sheilded and ferrited cord to the monitor, while the other, slightly
>more costly, fully populated board would pass, hands down.
Sure, the PS/2s had a conductive coating on the inside (for ESD as much as for
RFI). There is no need for much of that anymore.
>When the accountants started running the company instead of the
>engineers, all hell broke loose when it came to certifying new models.
That's somehow supposed to be surprising?
k...@att.bizzzzzzzzzzzz
>On Fri, 24 Sep 2010 06:40:41 -0700 (PDT), keith <keit...@gmail.com>
>wrote:
>
>>> >Funny. IBM uses these outlets in their facilities so the noise
>>> >wouldn't be coupled back into the mains (also on separate circuits so
>>> >the cleaning servies wouldn't trip anything important).
>>>
>>> Not any one I worked at and I was all over the country. There may have
>>> been a few people who installed them but they were not using the IBM
>>> Physical Planning manual.
>>
>>They were in every building I worked in. They were up and down the
>>halls, even. Cleaning crews were instructed to use them exclusively.
>
>Old legends die hard. I was an Installation Planning Rep in the 90s
>and I still ran into people who swore IG was necessary but they were
>not in the IBM Physical Planning community and it certainly was not in
>our specs.
Like I said, this was in the lab buildings.
bremar
dear Mortimer, The red outlets are always hot ( always powered ). Use the red
outlets anytime, during regular power corp supply
or power outage (hospital backup UPS). Although, your hospital may have a
different electrical control scheme.
--
for full context, visit https://www.homeownershub.com/maintenance/colored-electrical-outlets-389158-.htm
Poochie the power guy
--
For full context, visit https://www.homeownershub.com/maintenance/colored-electrical-outlets-389158-.htm