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 <[email protected]> Reply-To: <[email protected]> Date: Mon, 8 Jul 2019 12:48:24 -0700 To: <[email protected]> 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, [email protected] 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 <[email protected]> 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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> - ---------------------------------------------------------------- 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 <[email protected]> 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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
