Electrical Systems & Wiring Flashcards
7 cards from real MTC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Electrical Systems & Wiring flashcards as text
A vessel's depth sounder display shows interference patterns when the VHF radio transmits. What is the most effective solution?
Answer: Route depth sounder and VHF cables separately and add ferrite chokes to the transducer cable
Separating power and signal cables and adding ferrite chokes suppresses RF interference conducted through wiring between the VHF transmitter and depth sounder.
What is the purpose of a battery combiner (automatic charging relay) in a dual-battery marine installation?
Answer: Connects battery banks in parallel during charging while isolating them during discharge
A battery combiner closes to join both banks in parallel when charging voltage is detected, then opens to isolate banks when voltage drops, protecting the start battery.
ABYC standards require that all marine electrical panel circuit labels be:
Answer: Permanently marked and legible under normal illumination conditions
ABYC E-11 requires that each overcurrent device be permanently labeled to identify the circuit it protects, ensuring safe operation and troubleshooting.
When testing the output of a marine alternator with a carbon pile load tester, the technician applies load until voltage drops to 13.0V and reads 85 amps. What does this confirm?
Answer: The alternator's output capacity under load at that voltage
A carbon pile test measures actual alternator output amperage at a specified voltage, confirming whether it meets the manufacturer's rated capacity.
What is the correct wire color for a DC negative (ground) conductor in a 12V marine electrical system per ABYC standards?
Answer: Black or yellow
ABYC E-11 specifies black or yellow as the standard color for DC negative conductors in marine systems to ensure consistent identification.
A technician discovers corroded connections at a vessel's DC distribution panel. What is the correct procedure for cleaning and protecting the connections?
Answer: Remove corrosion with a wire brush or contact cleaner, retorque to spec, and apply dielectric grease
Mechanical removal of corrosion, proper torquing to manufacturer specifications, and dielectric grease application restore conductivity and prevent future corrosion.
What is the minimum bend radius requirement for marine electrical cables to prevent insulation damage?
Answer: No less than three times the cable's outside diameter
ABYC E-11 requires that marine cables not be bent more sharply than three times the cable's outside diameter to prevent insulation cracking and conductor damage.