Vessel Electrical Systems Flashcards
7 cards from real SAMS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Vessel Electrical Systems flashcards as text
During a survey, you discover that a vessel's DC wiring uses automotive-grade wire throughout. The primary deficiency of automotive wire in the marine environment is:
Answer: Lack of tinned conductors, making it susceptible to corrosion in humid conditions
Marine-grade wire uses tinned copper conductors to resist corrosion from moisture and salt air; automotive wire uses bare copper that corrodes in the marine environment.
Stray current corrosion on a vessel is most effectively detected during a survey by:
Answer: Using a silver/silver-chloride reference electrode to measure hull potential in the water
A silver/silver-chloride reference electrode placed in the water adjacent to the vessel measures electrical potential and reveals stray current activity.
A vessel's battery bank shows a resting voltage of 12.0V after 24 hours off charge. This indicates the batteries are approximately:
Answer: At approximately 50% state of charge
A 12V lead-acid battery at 12.0V resting voltage is typically at approximately 50% state of charge, indicating significant depletion.
When evaluating a vessel's AC shore power system, a surveyor finds that the neutral and ground conductors are bonded together at the shore power inlet. This is:
Answer: A serious deficiency that can cause shock hazard and galvanic corrosion
Bonding neutral and ground at the shore power inlet on a vessel (rather than only at the source) creates a shock hazard and promotes galvanic corrosion through ground current flow.
A vessel is equipped with an isolation transformer for shore power. The primary benefit of this installation for the marine surveyor to note is:
Answer: It isolates the vessel's AC system from shore ground, eliminating a galvanic corrosion path
An isolation transformer breaks the galvanic connection between the vessel's underwater metals and shore ground, preventing galvanic corrosion through the shore power cable.
ABYC E-11 requires that all ungrounded conductors in a vessel's DC system be protected by an overcurrent device located within:
Answer: 72 inches of the power source or where the wire leaves a protected enclosure
ABYC E-11 requires overcurrent protection within 72 inches (7 feet) of the power source connection to limit the length of unprotected wiring.
During inspection, a surveyor finds multiple circuits connected to a single battery terminal stud with a 'ring terminal stack.' This installation raises concern because:
Answer: Stacked terminals can create high-resistance connections and make circuit isolation impossible
Stacking multiple ring terminals on a single stud creates resistance and makes it impossible to isolate individual circuits without disconnecting all circuits at that point.