Electrical Systems & Wiring Flashcards

What is the minimum wire gauge (AWG) required for a 30-amp marine circuit according to ABYC standards?

Answer: 10 AWG

ABYC standards require 10 AWG wire for a 30-amp circuit to prevent overheating and voltage drop.

Which type of marine wire insulation is specifically rated to resist fuel and oil exposure?

Answer: BC-5W2 rated wire

BC-5W2 rated wire meets ABYC and UL standards for fuel and oil resistance in marine environments.

A marine vessel's alternator is producing 14.8V at idle but drops to 12.9V under heavy load. What is the most likely cause?

Answer: Undersized alternator output capacity

Excessive voltage drop under load typically indicates the alternator lacks sufficient ampere output for the vessel's electrical demand.

When installing a marine VHF radio, which bonding requirement must be met for optimal antenna performance?

Answer: The radio chassis must be bonded to the vessel's DC negative bus

Bonding the VHF chassis to the DC negative bus creates a proper RF ground plane and minimizes interference.

What does a circuit breaker rating of 'trip-free' mean in a marine electrical panel?

Answer: The breaker will trip even if the handle is held in the ON position

A trip-free breaker will open the circuit during an overload regardless of whether the handle is held in the ON position, providing reliable overcurrent protection.

What is the purpose of a galvanic isolator installed in a shore power connection?

Answer: Blocks DC galvanic currents while allowing AC shore power to flow

A galvanic isolator uses capacitors or diodes to block low-voltage DC galvanic currents that cause underwater metal corrosion while passing 120V AC shore power.

When testing a marine battery with a digital multimeter, a resting voltage of 12.06V indicates what state of charge?

Answer: Approximately 25% charged

A resting voltage of 12.06V corresponds to approximately 25% state of charge for a 12V lead-acid battery.