SAMS Vessel Electrical Systems 4

Question 1

A vessel has a 30-amp, 120V shore power system. What is the maximum continuous load that should be placed on this system according to NEC/ABYC principles?

Accepted Answer

24 amps

Answer

The standard continuous load derating factor limits loads to 80% of circuit capacity, making 24 amps the maximum for a 30-amp system.

Question 2

When a marine surveyor observes that a vessel's alternator output wire lacks an overcurrent device near the alternator, the primary risk is:

Accepted Answer

Fire from a short circuit in the unprotected alternator output lead

Answer

An unprotected alternator output lead can carry full alternator current to a fault point with no way to interrupt it, creating a significant fire risk.

Question 3

Sacrificial zinc anodes on a vessel are part of the:

Accepted Answer

Cathodic protection system

Answer

Zinc anodes are sacrificial metals used in cathodic protection systems to prevent galvanic corrosion of more noble underwater metals.

Question 4

A surveyor finds that a vessel's bilge blower does not run before engine start. Per USCG regulations, gasoline-powered vessels with enclosed engine spaces must run the blower for a minimum of:

Accepted Answer

4 minutes

Answer

USCG regulations require a minimum of 4 minutes of blower operation before starting to purge accumulated fuel vapors from enclosed engine spaces.

Question 5

During inspection of a vessel's electrical panel, a surveyor notes that circuit breakers are used in both the ungrounded (positive) and grounded (negative) conductors. For DC systems, ABYC E-11 requires overcurrent protection in:

Accepted Answer

Only the ungrounded (positive) conductor

Answer

ABYC E-11 requires overcurrent protection only in the ungrounded (positive) conductor of DC circuits; protecting the grounded conductor is not required and can create unsafe conditions.

(SAMS) Society of Accredited Marine Surveyors Certified Practice Test

(SAMS) Society of Accredited Marine Surveyors Certified Practice Test

SAMS Vessel Electrical Systems 4