Re: [PSES] Ground on ship

[Ken Javor]

At least on US Navy surface ships, power is not referenced to structure.
Green wires connect to structure but a single phase can short to ground and
not cause a problem.

Ken Javor
Phone: (256) 650-5261



From: Richard Nute 
Reply-To: 
Date: Sun, 14 Jul 2019 14:27:31 -0700
To: 
Subject: Re: [PSES] Ground on ship

   
 For us safety nerds, grounding provides an equipotential environment, which
means no current through the body.  And, the grounding circuit provides a
return path for fault current.  We don't pay attention to Gnd0, Gnd1, Gnd2,
Gnd-Iso, etc.; for safety purposes, they are all at the same potential --
ground.  While Gnd-Iso may not be at ground potential, current from Gnd-Iso
to ground should be inconsequential.  So, for us safety nerds, "ground" is
our (lazy) way of referring to an equipotential environment. 
 
 Best regards,
 Rich  
  

 
 
 
 
On 7/13/2019 2:31 PM, Doug Powell wrote:
 
 
> 
>  
>  
>  
>  
>  This is purely speculation on my part but it seems to me that the single
> syllable "ground" is a lazy way of referring to anything that is a common
> return line, whether bonded to earth or not. I've seen circuits with
> references to Gnd0, Gnd1, Gnd2, Gnd-Iso, etc.  
>  
> 
>  
>  
> Of course, this shorthand way of referring to circuits does cause a lot of
> confusion. And, I personally classify this as falling into the same category
> as when people with an inexperienced eye say this bit of failed electronics
> "must have a short somewhere" .
>  
> 
>  
>  
> Doug
>  
> 
>  
>  
> --
>  
> Douglas E Powell
>  
> doug...@gmail.com
>  
> https://www.linkedin.com/in/dougp01 
>  
>  
>  
 
 -


This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at
http://product-compliance.oc.ieee.org/ can be used for graphics (in
well-used formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to
unsubscribe) <http://www.ieee-pses.org/list.html>
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher  
David Heald 



-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

Re: [PSES] Ground on ship

[Richard Nute]

For us safety nerds, grounding provides an equipotential environment, 
which means no current through the body.  And, the grounding circuit 
provides a return path for fault current.  We don't pay attention to 
Gnd0, Gnd1, Gnd2, Gnd-Iso, etc.; for safety purposes, they are all at 
the same potential -- ground.  While Gnd-Iso may not be at ground 
potential, current from Gnd-Iso to ground should be inconsequential.  
So, for us safety nerds, "ground" is our (lazy) way of referring to an 
equipotential environment.


Best regards,
Rich



On 7/13/2019 2:31 PM, Doug Powell wrote:


This is purely speculation on my part but it seems to me that the 
single syllable "ground" is a lazy way of referring to anything that 
is a common return line, whether bonded to earth or not. I've seen 
circuits with references to Gnd0, Gnd1, Gnd2, Gnd-Iso, etc.


Of course, this shorthand way of referring to circuits does cause a 
lot of confusion. And, I personally classify this as falling into the 
same category as when people with an inexperienced eye say this bit of 
failed electronics "/must have a short somewhere/" .


Doug

--
Douglas E Powell
doug...@gmail.com
https://www.linkedin.com/in/dougp01




-

This message is from the IEEE Product Safety Engineering Society emc-pstc discussion 
list. To post a message to the list, send your e-mail to 

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

Re: [PSES] Ground on ship

[Doug Powell]

 This is purely speculation on my part but it seems to me that the single syllable "ground" is a lazy way of referring to anything that is a common return line, whether bonded to earth or not. I've seen circuits with references to Gnd0, Gnd1, Gnd2, Gnd-Iso, etc.  Of course, this shorthand way of referring to circuits does cause a lot of confusion. And, I personally classify this as falling into the same category as when people with an inexperienced eye say this bit of failed electronics "must have a short somewhere" .Doug--Douglas E Powelldoug...@gmail.comhttps://www.linkedin.com/in/dougp01   Currently out of the office and working from my Android phone   From: ri...@ieee.orgSent: July 13, 2019 1:26 PMTo: EMC-PSTC@LISTSERV.IEEE.ORGReply-to: ri...@ieee.orgSubject: Re: [PSES] Ground on ship  Hi Bill:
On 7/13/2019 10:42 AM, Bill Owsley
  wrote:
They
  started out, and still in some rural areas, use earth as the
  "ground" for the return of the AC power being provided to users. 

  The descriptive term is "SWER,"  Single Wire Earth Return.
https://en.wikipedia.org/wiki/Single-wire_earth_return
https://www.esdnews.com.au/swer-still-going-strong/
  
  A brief history and acknowledgement of the SWER inventor:
https://www.engineeringnz.org/our-work/heritage/heritage-records/single-wire-earth-return-swer/
  
  And, a more scholarly report:
https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=6061=masters_theses
  
  Best regards,
  Rich
  

-

This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org>

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc.


Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas <sdoug...@ieee.org>
Mike Cantwell <mcantw...@ieee.org>

For policy questions, send mail to:
Jim Bacher  <j.bac...@ieee.org>
David Heald <dhe...@gmail.com>


-

This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc.


Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas sdoug...@ieee.org
Mike Cantwell mcantw...@ieee.org

For policy questions, send mail to:
Jim Bacher  j.bac...@ieee.org
David Heald dhe...@gmail.com

Re: [PSES] Ground on ship

[Richard Nute]

Hi Bill:

On 7/13/2019 10:42 AM, Bill Owsley wrote:
They started out, and still in some rural areas, use earth as the 
"ground" for the return of the AC power being provided to users.


The descriptive term is "SWER,"  Single Wire Earth Return.

https://en.wikipedia.org/wiki/Single-wire_earth_return

https://www.esdnews.com.au/swer-still-going-strong/

A brief history and acknowledgement of the SWER inventor:

https://www.engineeringnz.org/our-work/heritage/heritage-records/single-wire-earth-return-swer/

And, a more scholarly report:

https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=6061=masters_theses

Best regards,
Rich




-

This message is from the IEEE Product Safety Engineering Society emc-pstc discussion 
list. To post a message to the list, send your e-mail to 

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

Re: [PSES] Ground on ship

[Bill Owsley]

 "ground" terminology from what I have seen, it a power company concept, (you 
know, the 50/60 hertz AC power distributed all over).  They started out, and 
still in some rural areas, use earth as the "ground" for the return of the AC 
power being provided to users.  I can right now today in 2019, take a short 
drive out to the rural regions and look at the power poles at the farm where my 
horses are boarded and wonder how the current loop is completed.  One hot wire 
along the road of poles to a transformer that obviously is connected to real 
earth.  A copper wire along the side of the pole that is wrapped around the 
bottom of that pole when installed into the ground.  It also serves as a path 
for lightning.
The slightly more modern road poles will have a "ground" wire routed above the 
insulated mounted hot wire.  A close look will reveal that the non-insulated 
wire is also connected to another wire, usually on each pole, that goes down to 
the bottom of the pole for ground contact.  It catches lightning, and serves as 
a known and controlled return for the AC power, since earth as a "return" is 
somewhat variable.
Since all of our electrical and electronics have evolved from this origin, 
"ground" has become the catch all for any and all returns for power and signals 
going out.
I like to point out that the vast majority of schematics use a variety of 
"ground" symbols to indicate some sort of universal return path that is not 
defined, and maybe it means the return path in the schematic is on the back 
side of the paper.  
Oh that is blank !!  
And so our EMC industry is created.

As our electronics migrated to cars, then portables, then aircraft, then space 
ships, cell phones, etc.
The concept of "ground" got rather messy since it lost the "earth" connection.
Our continued employment is dependent on those that still trying using "earth" 
(or ocean) as "ground" to drain away EMI and solve all the EMI problems.  
ps. And I love those that still chop up the return paths into all sorts of 
named "grounds" !
The highly imaginative tales of why it is necessary to divide the returns into 
various names is always entertaining.  Do tell me more !!  
Return path impedance's are key to our trade !
Review the classic "field and waves" class in college.
Also AC circuits, Kirchhoff current law in particular with respect to fields 
and waves.

I work today designing ~15 kW inductive transmitters that also receive 
nano-watt return signals on the same circuit, and I do not get to use any 
shielding chassis, etc.  It is all pcb's and plastic only.I have not done any 
radar, but that is what I imagine the environment is about.












On Monday, July 8, 2019, 4:50:09 PM EDT, Ken Javor 
 wrote:  
 
 On US military surface ships, power is ungrounded.  Green wires do connect to 
structure, so in the case of a fault the equipment enclosure is at ground 
potential, but it isn’t going to trigger a protection device that way.

The whole discussion about sea water conductivity is moot.  You could ask the 
same question about an airplane: it’s ungrounded in flight; metal structure 
works just fine as John Woodgate says.

Where sea water is useful is transmitting hf.  As Rich notes, the large surface 
area of the ship’s hull in contact with conductive sea water allows the surface 
of the sea to act as an extended counterpoise for hf masts operating against 
the ship as a counterpoise. At frequencies where the ship is electrically 
short, sea water makes these masts much more efficient than they would be if 
only the ship structure acted as counterpoise.

Ken Javor
Phone: (256) 650-5261


From: Richard Nute 
Reply-To: 
Date: Mon, 8 Jul 2019 12:48:24 -0700
To: 
Subject: Re: [PSES] Ground on ship

   
 Hi Peter:
 
 Sea water is a very good conductor, better than soil.  Fresh water is an okay 
conductor.  Pure water is a poor conductor.
 
 The hull of a steel ship is well grounded in the ocean, and reasonably well 
grounded in fresh water due to the large contact area with the water. 
 
 If the hull is not steel, there usually are enough fittings that the ship is 
reasonably well-connected to the water.  The propeller and drive shaft also 
provide a connection to the water.
 
 I've heard of ship-board hams who will tow a large brass plate for a good 
ground for their transmitter.
 
 Commercial AM transmitters try to locate their antennas near a body of salt 
water like San Francisco Bay or the Great Salt Lake.
 
 I would guess that a ground pin of a shipboard outlet would be connected to 
the hull metal.  This gives the same protection from electric shock as 
land-based outlets.
 
 See also:
 
 
http://electrotechnical-officer.com/primary-methods-of-grounding-and-bonding-on-ship/
 
 
 Best regards,
 Rich
 
 
On 7/8/2019 11:19 AM, 06cee064502d-dmarc-requ...@ieee.org wrote:
 
 

  
 
 
 
Hello gr

Re: [PSES] Ground on ship

[Ted Eckert]

I agree with Mr. Woodgate.

The issue is whether there is a risk of a voltage between the conductive 
enclosure of a device and exposed conductive materials in the environment. The 
“ground” system only needs to ensure that there won’t be a voltage difference 
between a device’s exposed parts and anything the user can touch in the 
environment. If the metal structure of the ship is used as the “ground” and the 
ground pin of outlets is connected to the metal structure of the ship, and the 
ship’s generator uses the metal structure as a grounding reference, the system 
should function similarly to the grounding system of a properly wired structure 
on solid land.

Ted Eckert
Microsoft Corporation

The opinions experessed are my own and do not necessarily reflect those of my 
employer.

From: John Woodgate 
Sent: Monday, July 8, 2019 11:39 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Ground on ship


'Ground' only means 'the places which we agree have zero volts on them', 
nothing more. So wherever that is, on a ship or an aircraft (or inside an 
appliance with a  2-core power cable), that is 'ground'.

Best wishes

John Woodgate OOO-Own Opinions Only

J M Woodgate and Associates 
www.woodjohn.uk<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.woodjohn.uk=02%7C01%7Cted.eckert%40microsoft.com%7Cfd6c2919eaa44b74be3a08d703d64243%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636982091089615454=ZULc%2BjK2cbzgfl3w9igbG2dWt5vkg6qJPpuMhOWr6mQ%3D=0>

Rayleigh, Essex UK
On 2019-07-08 19:19, 
06cee064502d-dmarc-requ...@ieee.org<mailto:06cee064502d-dmarc-requ...@ieee.org>
 wrote:
Hello group,

Is there a real ground in a ship?  i.e if a Class I product is used on the 
board of a ship, does the ground pin actually doing anything? The ship is 
floating in the ocean and I cannot understand if there is a real ground there 
or not? Can you guys educate me please?

Thank you
Peter
-


This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
mailto:emc-p...@ieee.org>>

All emc-pstc postings are archived and searchable on the web at: 
http://www.ieee-pses.org/emc-pstc.html<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Femc-pstc.html=02%7C01%7Cted.eckert%40microsoft.com%7Cfd6c2919eaa44b74be3a08d703d64243%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636982091089615454=lMLSDvk%2Fb%2B%2BBBuHBDN9z%2FCBnq9Oe22h7v0oC1%2Fuw6%2Fk%3D=0>

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fproduct-compliance.oc.ieee.org%2F=02%7C01%7Cted.eckert%40microsoft.com%7Cfd6c2919eaa44b74be3a08d703d64243%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636982091089625444=xTdcVAZsNL6wo99zDliuOoTdDnYeBjOIChnQTcDY3jw%3D=0>
 can be used for graphics (in well-used formats), large files, etc.

Website: 
http://www.ieee-pses.org/<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2F=02%7C01%7Cted.eckert%40microsoft.com%7Cfd6c2919eaa44b74be3a08d703d64243%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636982091089625444=CJ6OxDHBkWZ%2Fuo%2BIkwvUBg40PeysYbVprQtFG%2BnWKFY%3D=0>
Instructions: http://www.ieee-pses.org/list.html (including how to 
unsubscribe)<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Flist.html=02%7C01%7Cted.eckert%40microsoft.com%7Cfd6c2919eaa44b74be3a08d703d64243%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636982091089635444=77yfJfjWUS4Lu2S1oiOlQ%2BpyQASJd4vtgG2w24W3PfA%3D=0>
List rules: 
http://www.ieee-pses.org/listrules.html<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Flistrules.html=02%7C01%7Cted.eckert%40microsoft.com%7Cfd6c2919eaa44b74be3a08d703d64243%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636982091089635444=QaYs3LgNCrr%2B4oIupa3GkqLIzkmKq56MnvjVdMZrQUc%3D=0>

For help, send mail to the list administrators:
Scott Douglas mailto:sdoug...@ieee.org>>
Mike Cantwell mailto:mcantw...@ieee.org>>

For policy questions, send mail to:
Jim Bacher mailto:j.bac...@ieee.org>>
David Heald mailto:dhe...@gmail.com>>
-


This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
mailto:emc-p...@ieee.org>>

All emc-pstc postings are archived and searchable on the web at: 
http://www.ieee-pses.org/emc-pstc.html<https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.ieee-pses.org%2Femc-pstc.html=02%7C01%7Cted.eckert%40microsoft.com%7Cfd6c2919eaa44b74be3a08d703d64243%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636982091089635444=x94VoSnb32FOabTdHlfHExJO

Re: [PSES] Ground on ship

[Ken Javor]

On US military surface ships, power is ungrounded.  Green wires do connect
to structure, so in the case of a fault the equipment enclosure is at ground
potential, but it isn¹t going to trigger a protection device that way.

The whole discussion about sea water conductivity is moot.  You could ask
the same question about an airplane: it¹s ungrounded in flight; metal
structure works just fine as John Woodgate says.

Where sea water is useful is transmitting hf.  As Rich notes, the large
surface area of the ship¹s hull in contact with conductive sea water allows
the surface of the sea to act as an extended counterpoise for hf masts
operating against the ship as a counterpoise. At frequencies where the ship
is electrically short, sea water makes these masts much more efficient than
they would be if only the ship structure acted as counterpoise.

Ken Javor
Phone: (256) 650-5261



From: Richard Nute 
Reply-To: 
Date: Mon, 8 Jul 2019 12:48:24 -0700
To: 
Subject: Re: [PSES] Ground on ship

   
 Hi Peter:
 
 Sea water is a very good conductor, better than soil.  Fresh water is an
okay conductor.  Pure water is a poor conductor.
 
 The hull of a steel ship is well grounded in the ocean, and reasonably well
grounded in fresh water due to the large contact area with the water.
 
 If the hull is not steel, there usually are enough fittings that the ship
is reasonably well-connected to the water.  The propeller and drive shaft
also provide a connection to the water.
 
 I've heard of ship-board hams who will tow a large brass plate for a good
ground for their transmitter.
 
 Commercial AM transmitters try to locate their antennas near a body of salt
water like San Francisco Bay or the Great Salt Lake.
 
 I would guess that a ground pin of a shipboard outlet would be connected to
the hull metal.  This gives the same protection from electric shock as
land-based outlets.
 
 See also:
 
 http://electrotechnical-officer.com/primary-methods-of-grounding-and-bondin
g-on-ship/
 
 
 Best regards,
 Rich
 
 
On 7/8/2019 11:19 AM, 06cee064502d-dmarc-requ...@ieee.org wrote:
 
 
>   
>  
>  
>  
> Hello group,
>  
> 
>  
>  
> Is there a real ground in a ship?  i.e if a Class I product is used on the
> board of a ship, does the ground pin actually doing anything? The ship is
> floating in the ocean and I cannot understand if there is a real ground there
> or not? Can you guys educate me please?
>  
> 
>  
>  
> Thank you
>  
> Peter
>  
>  
>  
>  
>  
 
 -


This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at
http://product-compliance.oc.ieee.org/ can be used for graphics (in
well-used formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to
unsubscribe) <http://www.ieee-pses.org/list.html>
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher  
David Heald 



-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

Re: [PSES] Ground on ship

[Gert Gremmen]

Ground is only called ground because it was usage to use the real ground 
as safety potential.


Why ? Because we humans historically  tend to connect with our feet to 
the soil, and  if any touchable conductor has the same potential


as the soil, there is no hazard. This works only in reasonably wet areas.

Grounding Safety is about the voltage_difference_ we can reach as humans 
using hand and legs to bridge distances.


In the northern countries, and in the mountains the soil is mainly rock, 
and does not conduct electricity well enough


to function as a safety "ground" (actually "safety rock"). The utility 
their relies on other mechanisms for safety then soil ground.


The soil is connected to the surface of our globe. If we could reach the 
moon with our hand, there would probably


a huge discharge current between the two bodies, because the moon is not 
grounded.


Ground is relative. Inside a metallic volume, ground has no meaning 
anymore, because you need to touch


the metal wall before you can touch ground. Inside such a volume the 
'ground" is the metal wall.


All conductive items need to be connected to the volume (=ship) wall to 
remain safe.


It makes no sense seeking for our globes soil potential (ground) inside 
a metallic volume.


Gert Gremmen








On 8-7-2019 20:19, 06cee064502d-dmarc-requ...@ieee.org wrote:

Hello group,

Is there a real ground in a ship?  i.e if a Class I product is used on 
the board of a ship, does the ground pin actually doing anything? The 
ship is floating in the ocean and I cannot understand if there is a 
real ground there or not? Can you guys educate me please?


Thank you
Peter
-


This message is from the IEEE Product Safety Engineering Society 
emc-pstc discussion list. To post a message to the list, send your 
e-mail to mailto:emc-p...@ieee.org>>


All emc-pstc postings are archived and searchable on the web at: 
http://www.ieee-pses.org/emc-pstc.html


Attachments are not permitted but the IEEE PSES Online Communities 
site at http://product-compliance.oc.ieee.org/ can be used for 
graphics (in well-used formats), large files, etc.


Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to 
unsubscribe)

List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas mailto:sdoug...@ieee.org>>
Mike Cantwell mailto:mcantw...@ieee.org>>

For policy questions, send mail to:
Jim Bacher mailto:j.bac...@ieee.org>>
David Heald mailto:dhe...@gmail.com>>


--
Independent Expert on CE marking
Harmonised Standards (HAS-) Consultant @ European Commission for RED and EMC
EMC Consultant
Electrical Safety Consultant


-

This message is from the IEEE Product Safety Engineering Society emc-pstc discussion 
list. To post a message to the list, send your e-mail to 

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 
<>

Re: [PSES] Ground on ship

[Doug Powell]

In actuality the ship's hull is not that well connected to the water. There
are a number of issues such as the paint used on the hull to prevent
corrosion in salt water and the fact that the ship's screws are generally
made of brass and galvanic corrosion is a problem. Which is why US Navy
ships have large sacrificial anode of lead on the bottom of the hull. Ships
can also become magnetized and often must pass through a degaussing range
on return to port. As for RF ground with respect to sea water, one might
argue that the paint is so thin that is the effective capacitance negates
any insulating value at frequency. However naval radio and radar systems
are very high powered and I don't believe they rely on that alone.

Best, Doug



On Mon, Jul 8, 2019 at 1:48 PM Richard Nute  wrote:

>
> Hi Peter:
>
> Sea water is a very good conductor, better than soil.  Fresh water is an
> okay conductor.  Pure water is a poor conductor.
>
> The hull of a steel ship is well grounded in the ocean, and reasonably
> well grounded in fresh water due to the large contact area with the water.
>
> If the hull is not steel, there usually are enough fittings that the ship
> is reasonably well-connected to the water.  The propeller and drive shaft
> also provide a connection to the water.
>
> I've heard of ship-board hams who will tow a large brass plate for a good
> ground for their transmitter.
>
> Commercial AM transmitters try to locate their antennas near a body of
> salt water like San Francisco Bay or the Great Salt Lake.
>
> I would guess that a ground pin of a shipboard outlet would be connected
> to the hull metal.  This gives the same protection from electric shock as
> land-based outlets.
>
> See also:
>
>
> http://electrotechnical-officer.com/primary-methods-of-grounding-and-bonding-on-ship/
>
>
> Best regards,
> Rich
>
> On 7/8/2019 11:19 AM, 06cee064502d-dmarc-requ...@ieee.org wrote:
>
> Hello group,
>
> Is there a real ground in a ship?  i.e if a Class I product is used on the
> board of a ship, does the ground pin actually doing anything? The ship is
> floating in the ocean and I cannot understand if there is a real ground
> there or not? Can you guys educate me please?
>
> Thank you
> Peter
>
>
> -
> 
>
> This message is from the IEEE Product Safety Engineering Society emc-pstc
> discussion list. To post a message to the list, send your e-mail to 
> emc-p...@ieee.org
>
> All emc-pstc postings are archived and searchable on the web at:
> http://www.ieee-pses.org/emc-pstc.html
>
> Attachments are not permitted but the IEEE PSES Online Communities site at
> http://product-compliance.oc.ieee.org/ can be used for graphics (in
> well-used formats), large files, etc.
>
> Website: http://www.ieee-pses.org/
> Instructions: http://www.ieee-pses.org/list.html (including how to
> unsubscribe) 
> List rules: http://www.ieee-pses.org/listrules.html
>
> For help, send mail to the list administrators:
> Scott Douglas sdoug...@ieee.org
> Mike Cantwell mcantw...@ieee.org
>
> For policy questions, send mail to:
> Jim Bacher j.bac...@ieee.org
> David Heald dhe...@gmail.com
>


-- 

Douglas E Powell

doug...@gmail.com
http://www.linkedin.com/in/dougp01

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

Re: [PSES] Ground on ship

[John Woodgate]

Hi, Rich. All what you say is true. Now extend it to a fibreglass rowing 
boat! The connection of the hull with sea water is of no significance at 
all, as I'm sure you know. The pernicious idea that you can dump 
unwanted electricity into the planet, dry(ish) or wet, is responsible 
for more EMC failures than you can shake a mainmast at!


This confusion stems from radio transmission at low radio-frequencies. 
At VHF and above, the transmitter's output is connected to the two arms 
of a dipole (or other mechanical device that has effectively the same 
electrical function). At lower frequencies, such a structure would be 
too big, so one arm is simulated by an array of wires buried in the 
earth. This acts as a mirror, so eliminating the problem of sinking a 
300 foot mast into bedrock.  There must be a continuous circuit, 
otherwise no current could flow from the transmitter. The fact that we 
can't see the energy flowing out as an electromagnetic wave is just due 
to our limited visual bandwidth (just one octave out of at least 21 
octaves in the electromagnetic spectrum).


The same thing applies at the receiver; for VHF and above we hoist a 
dipole (maybe with extra elements to make a Yagi), which has two 
conductors leading from it, but at lower frequencies we have to put up a 
long wire antenna, connected to one side of the receiver input circuit 
and connect the other end of the receiver input circuit to a buried 
metal rod, thus setting up the continuous circuit.  This has nothing to 
do with some concept of a 'ground', with mysterious powers to absorb 
however much unwanted electrical energy we throw at it.


Ground is whatever you decide has zero volts on it, so all other 
voltages are measured with respect to it. In a digital wristwatch, it's 
about a square millimetre of PCB foil.



Best wishes
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK

On 2019-07-08 20:48, Richard Nute wrote:


Hi Peter:

Sea water is a very good conductor, better than soil.  Fresh water is 
an okay conductor.  Pure water is a poor conductor.


The hull of a steel ship is well grounded in the ocean, and reasonably 
well grounded in fresh water due to the large contact area with the 
water.


If the hull is not steel, there usually are enough fittings that the 
ship is reasonably well-connected to the water.  The propeller and 
drive shaft also provide a connection to the water.


I've heard of ship-board hams who will tow a large brass plate for a 
good ground for their transmitter.


Commercial AM transmitters try to locate their antennas near a body of 
salt water like San Francisco Bay or the Great Salt Lake.


I would guess that a ground pin of a shipboard outlet would be 
connected to the hull metal.  This gives the same protection from 
electric shock as land-based outlets.


See also:

http://electrotechnical-officer.com/primary-methods-of-grounding-and-bonding-on-ship/


Best regards,
Rich

On 7/8/2019 11:19 AM, 06cee064502d-dmarc-requ...@ieee.org wrote:

Hello group,

Is there a real ground in a ship?  i.e if a Class I product is used 
on the board of a ship, does the ground pin actually doing anything? 
The ship is floating in the ocean and I cannot understand if there is 
a real ground there or not? Can you guys educate me please?


Thank you
Peter



-


This message is from the IEEE Product Safety Engineering Society 
emc-pstc discussion list. To post a message to the list, send your 
e-mail to mailto:emc-p...@ieee.org>>


All emc-pstc postings are archived and searchable on the web at: 
http://www.ieee-pses.org/emc-pstc.html


Attachments are not permitted but the IEEE PSES Online Communities 
site at http://product-compliance.oc.ieee.org/ can be used for 
graphics (in well-used formats), large files, etc.


Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to 
unsubscribe)

List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas mailto:sdoug...@ieee.org>>
Mike Cantwell mailto:mcantw...@ieee.org>>

For policy questions, send mail to:
Jim Bacher mailto:j.bac...@ieee.org>>
David Heald mailto:dhe...@gmail.com>>



-

This message is from the IEEE Product Safety Engineering Society emc-pstc discussion 
list. To post a message to the list, send your e-mail to 

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, 

Re: [PSES] Ground on ship

[IBM Ken]

Ultimately if the on-board AC power generation is connected to the metal
structure of the ship, then I'd think it is the same as on land, except the
ship hull superstructure is the 'ground'.

In fact, you might have a 'better' ground on a ship since the metal
structure of the ship is exposed in more situations ('ground' is all around
on a ship, as compared to the paths to earth ground on land; cold water
pipes, ground rods, green/yellow wires, conduit, RF grounds, etc), so
there's more opportunities for a fault to 'ground out' and trip an upstream
overcurrent protection device.

I'm thinking mostly of large military ships - if you're talking about
fiberglass (or wooden!) pleasure craft then the story is less clear, but I
believe they often have a common grounding point too; it's just much
smaller.


-Ken A

On Mon, Jul 8, 2019 at 2:19 PM <06cee064502d-dmarc-requ...@ieee.org>
wrote:

> Hello group,
>
> Is there a real ground in a ship?  i.e if a Class I product is used on the
> board of a ship, does the ground pin actually doing anything? The ship is
> floating in the ocean and I cannot understand if there is a real ground
> there or not? Can you guys educate me please?
>
> Thank you
> Peter
> -
> 
>
> This message is from the IEEE Product Safety Engineering Society emc-pstc
> discussion list. To post a message to the list, send your e-mail to 
> emc-p...@ieee.org
>
> All emc-pstc postings are archived and searchable on the web at:
> http://www.ieee-pses.org/emc-pstc.html
>
> Attachments are not permitted but the IEEE PSES Online Communities site at
> http://product-compliance.oc.ieee.org/ can be used for graphics (in
> well-used formats), large files, etc.
>
> Website: http://www.ieee-pses.org/
> Instructions: http://www.ieee-pses.org/list.html (including how to
> unsubscribe) 
> List rules: http://www.ieee-pses.org/listrules.html
>
> For help, send mail to the list administrators:
> Scott Douglas sdoug...@ieee.org
> Mike Cantwell mcantw...@ieee.org
>
> For policy questions, send mail to:
> Jim Bacher j.bac...@ieee.org
> David Heald dhe...@gmail.com
>

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

Re: [PSES] Ground on ship

[ebj]

Good resources are MIL-STD-1310H and MIL-STD-1399-300B, I believe... Elyaנשלח 
מסמארטפון ה-Samsung Galaxy שלי.
 הודעה מקורית מאת: Richard Nute  תאריך: 
8.7.2019  15:48  (GMT-05:00) אל: EMC-PSTC@LISTSERV.IEEE.ORG נושא: Re: [PSES] 
Ground on ship 

Hi Peter:
  
  Sea water is a very good conductor, better than soil.  Fresh water
  is an okay conductor.  Pure water is a poor conductor.
  
  The hull of a steel ship is well grounded in the ocean, and
  reasonably well grounded in fresh water due to the large contact
  area with the water. 
  
  If the hull is not steel, there usually are enough fittings that
  the ship is reasonably well-connected to the water.  The propeller
  and drive shaft also provide a connection to the water.
  
  I've heard of ship-board hams who will tow a large brass plate for
  a good ground for their transmitter.
  
  Commercial AM transmitters try to locate their antennas near a
  body of salt water like San Francisco Bay or the Great Salt Lake.
  
  I would guess that a ground pin of a shipboard outlet would be
  connected to the hull metal.  This gives the same protection from
  electric shock as land-based outlets.
  
  See also:


http://electrotechnical-officer.com/primary-methods-of-grounding-and-bonding-on-ship/
  
  
  Best regards,
  Rich

On 7/8/2019 11:19 AM,
  06cee064502d-dmarc-requ...@ieee.org wrote:


  
  

  
Hello group,


Is there a real ground in a ship?  i.e if a Class I
  product is used on the board of a ship, does the ground
  pin actually doing anything? The ship is floating in the
  ocean and I cannot understand if there is a real ground
  there or not? Can you guys educate me please?


Thank you
Peter
  

#yiv5252605836 #yiv5252605836 --_filtered #yiv5252605836 
{panose-1:2 4 5 3 5 4 6 3 2 4;}  _filtered #yiv5252605836 
{font-family:Calibri;panose-1:2 15 5 2 2 2 4 3 2 4;} #yiv5252605836   
#yiv5252605836 p.yiv5252605836MsoNormal, #yiv5252605836 
li.yiv5252605836MsoNormal, #yiv5252605836 div.yiv5252605836MsoNormal  
{margin:0cm;margin-bottom:.0001pt;font-size:11.0pt;font-family:sans-serif;} 
#yiv5252605836 a:link, #yiv5252605836 span.yiv5252605836MsoHyperlink  
{color:#0563C1;text-decoration:underline;} #yiv5252605836 a:visited, 
#yiv5252605836 span.yiv5252605836MsoHyperlinkFollowed  
{color:#954F72;text-decoration:underline;} #yiv5252605836 
span.yiv5252605836EpostStil17  {font-family:sans-serif;color:windowtext;} 
#yiv5252605836 .yiv5252605836MsoChpDefault  {font-family:sans-serif;}  
_filtered #yiv5252605836 {margin:70.85pt 70.85pt 70.85pt 70.85pt;} 
#yiv5252605836 div.yiv5252605836WordSection1  {} #yiv5252605836 
  


  

-

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 


All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

Re: [PSES] Ground on ship

[Richard Nute]

Hi Peter:

Sea water is a very good conductor, better than soil.  Fresh water is an 
okay conductor.  Pure water is a poor conductor.


The hull of a steel ship is well grounded in the ocean, and reasonably 
well grounded in fresh water due to the large contact area with the water.


If the hull is not steel, there usually are enough fittings that the 
ship is reasonably well-connected to the water.  The propeller and drive 
shaft also provide a connection to the water.


I've heard of ship-board hams who will tow a large brass plate for a 
good ground for their transmitter.


Commercial AM transmitters try to locate their antennas near a body of 
salt water like San Francisco Bay or the Great Salt Lake.


I would guess that a ground pin of a shipboard outlet would be connected 
to the hull metal.  This gives the same protection from electric shock 
as land-based outlets.


See also:

http://electrotechnical-officer.com/primary-methods-of-grounding-and-bonding-on-ship/


Best regards,
Rich

On 7/8/2019 11:19 AM, 06cee064502d-dmarc-requ...@ieee.org wrote:

Hello group,

Is there a real ground in a ship?  i.e if a Class I product is used on 
the board of a ship, does the ground pin actually doing anything? The 
ship is floating in the ocean and I cannot understand if there is a 
real ground there or not? Can you guys educate me please?


Thank you
Peter




-

This message is from the IEEE Product Safety Engineering Society emc-pstc discussion 
list. To post a message to the list, send your e-mail to 

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: 

Re: [PSES] Ground on ship

[John Woodgate]

'Ground' only means 'the places which we agree have zero volts on them', 
nothing more. So wherever that is, on a ship or an aircraft (or inside 
an appliance with a  2-core power cable), that is 'ground'.


Best wishes
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK

On 2019-07-08 19:19, 06cee064502d-dmarc-requ...@ieee.org wrote:

Hello group,

Is there a real ground in a ship?  i.e if a Class I product is used on 
the board of a ship, does the ground pin actually doing anything? The 
ship is floating in the ocean and I cannot understand if there is a 
real ground there or not? Can you guys educate me please?


Thank you
Peter
-


This message is from the IEEE Product Safety Engineering Society 
emc-pstc discussion list. To post a message to the list, send your 
e-mail to mailto:emc-p...@ieee.org>>


All emc-pstc postings are archived and searchable on the web at: 
http://www.ieee-pses.org/emc-pstc.html


Attachments are not permitted but the IEEE PSES Online Communities 
site at http://product-compliance.oc.ieee.org/ can be used for 
graphics (in well-used formats), large files, etc.


Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to 
unsubscribe)

List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas mailto:sdoug...@ieee.org>>
Mike Cantwell mailto:mcantw...@ieee.org>>

For policy questions, send mail to:
Jim Bacher mailto:j.bac...@ieee.org>>
David Heald mailto:dhe...@gmail.com>>



-

This message is from the IEEE Product Safety Engineering Society emc-pstc discussion 
list. To post a message to the list, send your e-mail to 

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
Scott Douglas 
Mike Cantwell 

For policy questions, send mail to:
Jim Bacher:  
David Heald: