SAMS Vessel Electrical Systems 3

Question 1

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:

Accepted Answer

Lack of tinned conductors, making it susceptible to corrosion in humid conditions

Answer

Lower voltage rating than marine-grade wire

Answer

Inability to carry sufficient amperage for marine loads

Answer

Non-compliance with USCG color coding requirements

Question 2

Stray current corrosion on a vessel is most effectively detected during a survey by:

Accepted Answer

Using a silver/silver-chloride reference electrode to measure hull potential in the water

Answer

Measuring AC voltage between hull fittings with a multimeter

Answer

Checking battery terminal color changes

Answer

Inspecting the shore power cord for discoloration

Question 3

A vessel's battery bank shows a resting voltage of 12.0V after 24 hours off charge. This indicates the batteries are approximately:

Accepted Answer

At approximately 50% state of charge

Answer

Fully charged at 100%

Answer

Completely discharged and damaged

Answer

At approximately 75% state of charge

Question 4

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:

Accepted Answer

A serious deficiency that can cause shock hazard and galvanic corrosion

Answer

Correct and required by ABYC E-11 for proper grounding

Answer

Acceptable only on vessels under 26 feet

Answer

Required only when shore power exceeds 30 amps

Question 5

A vessel is equipped with an isolation transformer for shore power. The primary benefit of this installation for the marine surveyor to note is:

Accepted Answer

It isolates the vessel's AC system from shore ground, eliminating a galvanic corrosion path

Answer

It increases shore power voltage to 240V automatically

Answer

It provides backup power when shore power is unavailable

Answer

It reduces the shore power amperage draw by 50%

Question 6

ABYC E-11 requires that all ungrounded conductors in a vessel's DC system be protected by an overcurrent device located within:

Accepted Answer

72 inches of the power source or where the wire leaves a protected enclosure

Answer

7 inches of the power source

Answer

12 inches of any terminal connection

Answer

24 inches of the battery switch

Question 7

During inspection, a surveyor finds multiple circuits connected to a single battery terminal stud with a 'ring terminal stack.' This installation raises concern because:

Accepted Answer

Stacked terminals can create high-resistance connections and make circuit isolation impossible

Answer

Ring terminals are not approved for marine use by ABYC

Answer

Battery studs are rated for only one conductor under USCG regulations

Answer

This arrangement bypasses the battery switch