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?

"William Munny" wrote in message
...
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.

charlie wrote:
"William Munny" wrote in message
...
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.

And orange is isolated ground for computer equipment/instrumentation
that requires it.

--

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?



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

On 8/14/2009 10:29 AM William Munny spake thus:

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

"charlie" wrote:

What's that all about?

they are on a ups for safety critical use during blackouts.

Or they are on an isolated ground.

"William Munny" wrote in message
...
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?


Cool, thanks...

But, that's before the centrifuge, to settle out the heavy
electrons.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"David Nebenzahl" wrote in message
.com...
On 8/14/2009 10:29 AM William Munny spake thus:

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

In article , "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?

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" wrote in message
...
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?


How's the hired gun business working out?

On Sat, 15 Aug 2009 09:49:15 -0400, "Perry Aynum"
wrote:


"William Munny" wrote in message
...
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?


How's the hired gun business working out?

ORANGE receptacles are "isolated ground" (used to be - not necessarity
true any more) meaning the "U" ground was not connected to the
mounting tab.

On Sat, 15 Aug 2009 08:33:57 GMT, (Doug Miller)
wrote:

In article , "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?

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)


How is isolated ground different then "regular" ground?

On Aug 18, 9:43*pm, (Doug Miller) wrote:
In article , Ashton Crusher wrote:
On Sat, 15 Aug 2009 08:33:57 GMT, (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.

On Aug 14, 1:29*pm, "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?

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

On Aug 18, 8:31*am, stan wrote:
On Aug 18, 9:43*pm, (Doug Miller) wrote:

In article , Ashton Crusher wrote:
On Sat, 15 Aug 2009 08:33:57 GMT, (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.

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

On Aug 18, 10:12*am, wrote:
On Tue, 18 Aug 2009 07:07:06 -0700 (PDT), Chip C



wrote:
On Aug 18, 8:31*am, stan wrote:
On Aug 18, 9:43*pm, (Doug Miller) wrote:

In article , Ashton Crusher wrote:
On Sat, 15 Aug 2009 08:33:57 GMT, (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.

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

Isolation transformer is there for safety.

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

In article , wrote:
On Wed, 19 Aug 2009 03:48:21 GMT, (Doug Miller)
wrote:

In article
, Chip C
wrote:

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.

"proerly grounded" and EMT as ground is an oxymoron.

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.

On Aug 18, 1:12*pm, wrote:
On Tue, 18 Aug 2009 05:31:40 -0700 (PDT), stan

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?

IBM decided IG was snake oil on the late 70s and removed the
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

Chip C wrote:
On Aug 18, 10:12 am, wrote:
On Tue, 18 Aug 2009 07:07:06 -0700 (PDT), Chip C



wrote:
On Aug 18, 8:31 am, stan wrote:
On Aug 18, 9:43 pm, (Doug Miller) wrote:
In article , Ashton Crusher wrote:
On Sat, 15 Aug 2009 08:33:57 GMT, (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.
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

Isolation transformer is there for safety.

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.

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--

JIMMIE wrote:
On Aug 18, 1:12 pm, wrote:
On Tue, 18 Aug 2009 05:31:40 -0700 (PDT), stan

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?
IBM decided IG was snake oil on the late 70s and removed the
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

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--

In article , Ashton Crusher wrote:
On Sat, 15 Aug 2009 08:33:57 GMT, (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

wrote:
On Tue, 18 Aug 2009 05:31:40 -0700 (PDT), stan
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?


IBM decided IG was snake oil on the late 70s and removed the
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

On Tue, 18 Aug 2009 00:05:10 -0700, Ashton Crusher
wrote:

On Sat, 15 Aug 2009 08:33:57 GMT, (Doug Miller)
wrote:

In article , "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?

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)


How is isolated ground different then "regular" ground?
The "u" ground is not connected to the "frame" ground.

On Tue, 18 Aug 2009 10:30:21 -0400, wrote:

On Tue, 18 Aug 2009 07:22:52 -0700 (PDT), Chip C
wrote:

On Aug 18, 10:12Â*am, wrote:
On Tue, 18 Aug 2009 07:07:06 -0700 (PDT), Chip C



wrote:
On Aug 18, 8:31Â*am, stan wrote:
On Aug 18, 9:43Â*pm, (Doug Miller) wrote:

In article , Ashton Crusher wrote:
On Sat, 15 Aug 2009 08:33:57 GMT, (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.

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

Isolation transformer is there for safety.

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

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.

On Wed, 19 Aug 2009 03:48:21 GMT, (Doug Miller)
wrote:

In article , Chip C wrote:

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.

"proerly grounded" and EMT as ground is an oxymoron.

In article , Chip C wrote:

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.

In article ,
The Daring Dufas 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?")

On Tue, 18 Aug 2009 15:15:22 GMT, (Doug Miller)
wrote:

In article , wrote:
On Wed, 19 Aug 2009 03:48:21 GMT, (Doug Miller)
wrote:

In article
, Chip C
wrote:

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.

"proerly grounded" and EMT as ground is an oxymoron.

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.

A couple generations ago, colored outlets have to move to
the back of the hospital, please.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..

On 8/19/2009 8:47 PM spake thus:

On Tue, 18 Aug 2009 15:15:22 GMT, (Doug Miller)
wrote:

In article , wrote:

On Wed, 19 Aug 2009 03:48:21 GMT, (Doug Miller)
wrote:

In article
, Chip C
wrote:

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.

"proerly grounded" and EMT as ground is an oxymoron.

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.


--
Found--the gene that causes belief in genetic determinism

On 8/20/2009 11:05 AM spake thus:

On Thu, 20 Aug 2009 10:56:39 -0700, David Nebenzahl
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.


--
Found--the gene that causes belief in genetic determinism

On Thu, 20 Aug 2009 11:19:14 -0700, David Nebenzahl
wrote:

On 8/20/2009 11:05 AM spake thus:

On Thu, 20 Aug 2009 10:56:39 -0700, David Nebenzahl
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.


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.

David Nebenzahl wrote:
On 8/20/2009 11:05 AM spake thus:

On Thu, 20 Aug 2009 10:56:39 -0700, David Nebenzahl
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.


Chuckle. At work, on certain data circuits, they braze or epoxy the
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...

aemeijers wrote:
David Nebenzahl wrote:
On 8/20/2009 11:05 AM spake thus:

On Thu, 20 Aug 2009 10:56:39 -0700, David Nebenzahl
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.


Chuckle. At work, on certain data circuits, they braze or epoxy the
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...

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

Nate Nagel wrote:
aemeijers wrote:
David Nebenzahl wrote:
On 8/20/2009 11:05 AM spake thus:

On Thu, 20 Aug 2009 10:56:39 -0700, David Nebenzahl
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.


Chuckle. At work, on certain data circuits, they braze or epoxy the
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...

do they also happen to have walls covered with sheets of copper soldered
together? I've worked in some places like that...

nate

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.

--
aem sends...

aemeijers wrote:
Nate Nagel wrote:
aemeijers wrote:
David Nebenzahl wrote:
On 8/20/2009 11:05 AM spake thus:

On Thu, 20 Aug 2009 10:56:39 -0700, David Nebenzahl
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.


Chuckle. At work, on certain data circuits, they braze or epoxy the
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...

do they also happen to have walls covered with sheets of copper
soldered together? I've worked in some places like that...

nate

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.

--
aem sends...

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...

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Nate Nagel wrote:
aemeijers wrote:
Nate Nagel wrote:
aemeijers wrote:
David Nebenzahl wrote:
On 8/20/2009 11:05 AM spake thus:

On Thu, 20 Aug 2009 10:56:39 -0700, David Nebenzahl
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.


Chuckle. At work, on certain data circuits, they braze or epoxy the
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...

do they also happen to have walls covered with sheets of copper
soldered together? I've worked in some places like that...

nate

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.

--
aem sends...

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...

nate

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.

--
aem sends...

wrote:
On Thu, 20 Aug 2009 11:19:14 -0700, David Nebenzahl
wrote:

On 8/20/2009 11:05 AM spake thus:

On Thu, 20 Aug 2009 10:56:39 -0700, David Nebenzahl
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.


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.

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--

aemeijers | 2009-08-20 | 10:39:27 PM wrote:

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

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.

So long as there is any kind of "connection" a fault will start an arc that
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.