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
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
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
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
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
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
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
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
'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
Colleagues,
I have a client who is in need of some assistance with South American product
safety requirements. If you are one, or if you know of someone reputable that I
could refer my client to, please get in touch.
The sector is industrial machinery, including laser etching/marking, x-ray
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
Job Opening at Thermo Fisher Scientific for Safety/ Compliance based in
Sunnyvale, CA, Check the following link for more info:
Senior Compliance Engineer
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The Senior Compliance Engineer will provide guidance regarding
First, if you haven't already, consult the manufacturer. Maybe the
contact material is not suitable for the voltage or the current in your
application. Microswitches now rarely fail due to contamination.
Best wishes
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates
A micro switch occasionally fails because it does not make contact during
activation, and this is probably due to the contact surfaces being damaged
or dust / debris on them.
Any suggestions on labs that may have this competence to do some work and
analyze on such an issue?
Thanks!
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