General About Marine Grounding - KVH Industries TracPhone F55 Installation Manual

Appendix G: Grounding and RF protection
G.3 General about marine grounding
G.3.1 Ground terms
Great confusion exists about the different ground terms used when dealing
with marine electrical installations. A distinction between the various terms is
listed below for reference.
G.3.2 DC Negative
Actually not a ground but a current carrying conductor which carries the same
current that flows in the positive conductor. The DC Negative may be
electrically connected to seawater (at one point only, via the engine negative
terminal though the shaft and the propeller) or left completely floating.
G.3.3 Lightning Ground
Ground potential immersed in seawater. Provides a path to ground lightning
strike energy. Please note that this is not a functional part of any other
electrical system.
G.3.4 Corrosion System Ground
Bonding arrangement that ensures equal electrical potential for all dissimilar
underwater metal parts and provides galvanic protection by means of
sacrificial anodes.
G.3.5 AC Ground (Protective Earth)
Ground potential immersed in seawater (typically the hull for steel and
aluminum vessels). Serves as safety ground (protective earth) thus preventing
shocks or electrocution in the event of a fault situation.
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General about marine grounding