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
A vessel's lightning protection system should include a ground plate with a minimum underwater surface area of:
Answer: 1 square foot
ABYC E-4 requires a minimum of 1 square foot of underwater bonded metal surface area for an effective lightning ground plate.
During a survey, the inspector finds that a vessel's AC panel has Ground Fault Circuit Interrupter (GFCI) protection on all AC outlets in the head compartment. This installation is:
Answer: Correct and required by ABYC A-31 for protection in wet locations
ABYC A-31 requires GFCI protection for AC outlets in heads, galleys, machinery spaces, and other wet areas to protect against electric shock drowning and shock hazard.
Electric Shock Drowning (ESD) risk near docked vessels is primarily associated with:
Answer: AC current leaking into the water from a vessel's shore power system creating a voltage gradient
ESD occurs when AC current leaks into surrounding water from faulty shore power connections, creating a voltage gradient that can paralyze or kill swimmers.
A surveyor observes that a vessel uses wire nuts to splice conductors in the bilge area. This is deficient because:
Answer: Wire nuts are not approved for marine use and can loosen or corrode; marine-grade terminals or solder with heat shrink are required
Wire nuts are not approved for marine use as they can loosen with vibration and corrode in the wet environment; ABYC requires properly crimped marine-grade terminals or soldered connections.
A vessel equipped with a diesel generator must have the generator's neutral conductor:
Answer: Isolated from the vessel's bonding/grounding system to prevent shock hazard
ABYC standards require that the generator neutral be isolated from the vessel's grounding/bonding system to prevent the same ESD and galvanic corrosion issues as shore power neutral-ground bonds aboard.
When evaluating wire sizing for a DC circuit on a vessel, the surveyor must consider:
Answer: Both the ampacity for conductor protection and voltage drop for acceptable circuit performance
Proper marine DC wire sizing requires checking both ampacity (to prevent overheating) and voltage drop (to ensure adequate performance at the load end).
A surveyor finds that a vessel's battery cables are routed through the bilge without any chafe protection where they pass through a bulkhead. The primary risk this presents is:
Answer: Insulation chafe creating a short circuit capable of starting a fire
Unprotected battery cables chafing against a bulkhead opening can wear through insulation and create a high-current short circuit, which is a significant fire hazard.