ABYC MARINE ELECTRICAL CERTIFICATION 2024
NEWEST EXAM 270 QUESTIONS WITH DETAILED
VERIFIED ANSWERS (100% CORRECT ANSWERS) /A+
GRADE ASSURED
How often (in inches) shall wire bundles be supported? - ANSWER: Every 18 inches.
What type of clamps are to be used for supporting wire bundles when routed over
engines and machinery? - ANSWER: Insulated Metallic Hanger Clamps
What tensile force must a 10 Gauge crimp connector withstand for one minute? -
ANSWER: 40 lbs (E-11 Table XV)
What is the max allowed unsupported cable length for battery cables? - ANSWER: 36
inches
T or F: Running AC and DC conductors together is allowed so long as the AC
conductors are sheathed. - ANSWER: True
The most common electrical circuit problem in marine applications is:
A. Short circuits
B. Too much continuity
C. Unwanted open
D. Inter circuit Short - ANSWER: C. Unwanted open
The primary by-product of excessive electrical resistance is:
A. Increased Amperage
B. Increased Voltage
C. Reduced Ambient Temperature
D. Heat - ANSWER: D. Heat
One HP = how many watts? - ANSWER: 1 HP = 746 Watts
What is the preferred tool for tracing shorted and open circuits?
A. Ohm meter
B. Amp clamp
C. Volt meter
D. TDR (time-domain reflectometer) - ANSWER: D. TDR (time-domain reflectometer)
A technician is installing a cable run from the batteries to the main DC panel board
on a boat as part of a refit. The boat has a 12-volt system and the distance form the
panel to the batteries is 15 ft. The maximum current draw from the panel is
calculated at 90 amps. What guage cable should be used (minimum)? - ANSWER: 0
AWG
,DC grounded conductors on new boats that are also equipped with AC systems
should use what color insulated wire? - ANSWER: Yellow
What is the smallest guage wire allowed for unsheathed wire runs through the boat?
- ANSWER: 16 AWG
T or F: Compared to deep cycle (house) batteries, cranking batteries will have thicker
lead plates to facilitate the higher, short-duration current draws. - ANSWER: False.
Start batteries have a greater number of thinner plates within each cell.
Which type of battery generally recharges faster? Deep cycle or cranking? - ANSWER:
Cranking
What tool and common household staple are used to clean battery terminals? -
ANSWER: Wire brush and backing soda.
Why might a fully-discharged wet-cell type battery freeze? - ANSWER: Most of the
sulfuric acid has been absorbed into the lead plates, leaving mostly water in the
electrolyte.
Batteries must be secured to prevent movement of more than ______ inches in any
direction when a pulling force of _____ or _____, whichever is less, is applied
through the center of gravity of the battery for how long? - ANSWER: 1 inch, 90 lbs
or 2x the battery weight, for 1 minute in each direction.
T or F: it is ok to install batteries directly below an uninterrupted fuel line? -
ANSWER: True
What provision must be in place on any fuel line located within 12 inches of a battery
terminals? - ANSWER: Must be protected with dielectric insulating material
Define: Battery reserve capacity = the number of minutes that a new, fully charged
battery at ______ degrees F can be continuously discharged at ______ amps while
maintaining _____ volts (for a 12 v battery) - ANSWER: 80 F, 25 Amps, 10.5 Volts
According to ABYC, what is the minimum battery reserve capacity? - ANSWER: 90
minutes
Define: Marine Cranking Amps = the discharge load, in amperes, that a new, fully-
charged battery at _____ degrees F can deliver for ______ seconds while maintaining
a voltage of _____ volts (for a 12 v battery). - ANSWER: 32 degrees F, 30 seconds,
7.2V
Define: Cold Cranking Amps = the discharge load, in amperes, that a new, fully-
charged battery at _____ degrees F can deliver for ______ seconds while maintaining
a voltage of _____ volts (for a 12 v battery). - ANSWER: 0 degrees F, 30 seconds, 7.2V
,What is the largest guage wire that may be connected to a bettery with wing-nuts? -
ANSWER: 8 AWG
Per ABYC E-10, a battery switch must be installed in the positive conductor from
each battery bank with a CCA rating greater than ____ (or greater than _____ Ah if
CCA rating not available). - ANSWER: 800 CCA or 100 Ahr (exceptions: electronic
equipment with battery backed memories; safety equipment such as bilge pumps,
alarms, CO detectors, bilge blowers; battery chargers; I'm pressed current systems.
What is the minimum ampere interrupting capacity (AIC) for main overcurrent
protection on a battery bank rated at 12 V, 1500 CCA? - ANSWER: AIC = 5000 Amps
(E-11 table IV-A)
What is the minimum ampere interrupting capacity (AIC) for main overcurrent
protection on a battery bank rated at more than 2200 CCA or more than 500 Ahr? -
ANSWER: AIC = 2X mnfg's short-circuit rating or 100X nominal Ahr rating.
T or F: it is ok to mount a battery switch inside an engine room, because ABYC startes
that it must be located as close to the batteries as practical. - ANSWER: False.
"Readily accessible" defines entry into the engine room in an emergency as
dangerous - use a remote battery switch.
Explain the "7-40-72" rule - ANSWER: Overcurrent protection must be located
withing 7 inches of the power source unless contained within a sheath, in which case
it may be up to 40 inches away. If the power source is a battery and the conductors
are sheathed, OC may be up to 72 inches away.
What does "trip free" breaker mean? - ANSWER: Resetting mechanism cannot
overrid over current interrupting mechanism. (Note: some residential breakers are
not trip free)
The maximum sustained charging voltage acceptable to some gell cell battery
manufacturers is:
A. 13.8 V
B. 14.5 V
C. 14.1 V
D. 13.2 Vll - ANSWER: C. 14.1 V
When testing a wet-cell battery with a hydrometer, what threshold is used to
determine a bad cell? - ANSWER: 0.050 points of specific gravity below other cells =
bad cell.
When testing a wet-cell battery with a hydrometer, what reading indicates a fully
charged battery? - ANSWER: 1.260 - 1.285 (temperature dependent)
When testing a fully charged start battery for capacity with a load tester, what % of
CCA rating should be induced by the load to test resulting voltage? - ANSWER: 50%
, Most engine-driven alternators are optimally spun at what percentage of engine
RPMs?
A. Between 10% and 50%
B. Less than 10%
C. Between 150% and 200%
D. Greater than 200% - ANSWER: C. Between 150% and 200%
T or F: A battery charger case shall be tied to the DC negative output terminal at the
battery charger. - ANSWER: False. the battery charger case shall be tied to the engine
negative terminal/bus, along with the negative output terminal of the battery
charger, not at the battery charger case itself.,
Why do battery chargers require a separate case connection to main AC grounding
bus and Engine negative / DC grounding bus? - ANSWER: In case of an internal short
to the case, the AC grounding wire would not carry enough current.
What is the minimal wire size required for a battery charger case connection to DC
ground/engine negative? - ANSWER: No smaller than 1 size below the DC current
carrying conductors between the charger and batteries - provided OC protection on
positive DC output is no greater than 135% of DC grounding cable ampacity and
conductor is no smaller than 16 AWG.
What device is typically found to satisfy the required OC protection between a
battery charger and the batteries? - ANSWER: Class T fuse rated for appropriate AIC
What may happen to a solar array or wind generator used to charge batteries
without a blocking diode? - ANSWER: Batteries will feed back into solar array or wind
generator coil and discharge (possibly damage). Note: many voltage regulators have
integral blocking diodes.
How far above bilge water level must a battery charger be mounted? - ANSWER: 24
inches or more (unless waterproof!)
How far away from a gasoline tank must a pre-wired battery charger's AC connection
plug be located? - ANSWER: At least 24 inches
T or F: All marine inverters shall utilize an internal or external GFCI on their AC
outlets. - ANSWER: False. (only when installed in location that required GFCI per
ABYC E-11)
T or F: most GFCI outlets can be used in a gasoline engine room - ANSWER: False.
Most are not ignition protected.
T or F: Because the shore power connection is a power source, the neutral conductor
should be tied to ground at the point where it comes in to the boat (shore power
NEWEST EXAM 270 QUESTIONS WITH DETAILED
VERIFIED ANSWERS (100% CORRECT ANSWERS) /A+
GRADE ASSURED
How often (in inches) shall wire bundles be supported? - ANSWER: Every 18 inches.
What type of clamps are to be used for supporting wire bundles when routed over
engines and machinery? - ANSWER: Insulated Metallic Hanger Clamps
What tensile force must a 10 Gauge crimp connector withstand for one minute? -
ANSWER: 40 lbs (E-11 Table XV)
What is the max allowed unsupported cable length for battery cables? - ANSWER: 36
inches
T or F: Running AC and DC conductors together is allowed so long as the AC
conductors are sheathed. - ANSWER: True
The most common electrical circuit problem in marine applications is:
A. Short circuits
B. Too much continuity
C. Unwanted open
D. Inter circuit Short - ANSWER: C. Unwanted open
The primary by-product of excessive electrical resistance is:
A. Increased Amperage
B. Increased Voltage
C. Reduced Ambient Temperature
D. Heat - ANSWER: D. Heat
One HP = how many watts? - ANSWER: 1 HP = 746 Watts
What is the preferred tool for tracing shorted and open circuits?
A. Ohm meter
B. Amp clamp
C. Volt meter
D. TDR (time-domain reflectometer) - ANSWER: D. TDR (time-domain reflectometer)
A technician is installing a cable run from the batteries to the main DC panel board
on a boat as part of a refit. The boat has a 12-volt system and the distance form the
panel to the batteries is 15 ft. The maximum current draw from the panel is
calculated at 90 amps. What guage cable should be used (minimum)? - ANSWER: 0
AWG
,DC grounded conductors on new boats that are also equipped with AC systems
should use what color insulated wire? - ANSWER: Yellow
What is the smallest guage wire allowed for unsheathed wire runs through the boat?
- ANSWER: 16 AWG
T or F: Compared to deep cycle (house) batteries, cranking batteries will have thicker
lead plates to facilitate the higher, short-duration current draws. - ANSWER: False.
Start batteries have a greater number of thinner plates within each cell.
Which type of battery generally recharges faster? Deep cycle or cranking? - ANSWER:
Cranking
What tool and common household staple are used to clean battery terminals? -
ANSWER: Wire brush and backing soda.
Why might a fully-discharged wet-cell type battery freeze? - ANSWER: Most of the
sulfuric acid has been absorbed into the lead plates, leaving mostly water in the
electrolyte.
Batteries must be secured to prevent movement of more than ______ inches in any
direction when a pulling force of _____ or _____, whichever is less, is applied
through the center of gravity of the battery for how long? - ANSWER: 1 inch, 90 lbs
or 2x the battery weight, for 1 minute in each direction.
T or F: it is ok to install batteries directly below an uninterrupted fuel line? -
ANSWER: True
What provision must be in place on any fuel line located within 12 inches of a battery
terminals? - ANSWER: Must be protected with dielectric insulating material
Define: Battery reserve capacity = the number of minutes that a new, fully charged
battery at ______ degrees F can be continuously discharged at ______ amps while
maintaining _____ volts (for a 12 v battery) - ANSWER: 80 F, 25 Amps, 10.5 Volts
According to ABYC, what is the minimum battery reserve capacity? - ANSWER: 90
minutes
Define: Marine Cranking Amps = the discharge load, in amperes, that a new, fully-
charged battery at _____ degrees F can deliver for ______ seconds while maintaining
a voltage of _____ volts (for a 12 v battery). - ANSWER: 32 degrees F, 30 seconds,
7.2V
Define: Cold Cranking Amps = the discharge load, in amperes, that a new, fully-
charged battery at _____ degrees F can deliver for ______ seconds while maintaining
a voltage of _____ volts (for a 12 v battery). - ANSWER: 0 degrees F, 30 seconds, 7.2V
,What is the largest guage wire that may be connected to a bettery with wing-nuts? -
ANSWER: 8 AWG
Per ABYC E-10, a battery switch must be installed in the positive conductor from
each battery bank with a CCA rating greater than ____ (or greater than _____ Ah if
CCA rating not available). - ANSWER: 800 CCA or 100 Ahr (exceptions: electronic
equipment with battery backed memories; safety equipment such as bilge pumps,
alarms, CO detectors, bilge blowers; battery chargers; I'm pressed current systems.
What is the minimum ampere interrupting capacity (AIC) for main overcurrent
protection on a battery bank rated at 12 V, 1500 CCA? - ANSWER: AIC = 5000 Amps
(E-11 table IV-A)
What is the minimum ampere interrupting capacity (AIC) for main overcurrent
protection on a battery bank rated at more than 2200 CCA or more than 500 Ahr? -
ANSWER: AIC = 2X mnfg's short-circuit rating or 100X nominal Ahr rating.
T or F: it is ok to mount a battery switch inside an engine room, because ABYC startes
that it must be located as close to the batteries as practical. - ANSWER: False.
"Readily accessible" defines entry into the engine room in an emergency as
dangerous - use a remote battery switch.
Explain the "7-40-72" rule - ANSWER: Overcurrent protection must be located
withing 7 inches of the power source unless contained within a sheath, in which case
it may be up to 40 inches away. If the power source is a battery and the conductors
are sheathed, OC may be up to 72 inches away.
What does "trip free" breaker mean? - ANSWER: Resetting mechanism cannot
overrid over current interrupting mechanism. (Note: some residential breakers are
not trip free)
The maximum sustained charging voltage acceptable to some gell cell battery
manufacturers is:
A. 13.8 V
B. 14.5 V
C. 14.1 V
D. 13.2 Vll - ANSWER: C. 14.1 V
When testing a wet-cell battery with a hydrometer, what threshold is used to
determine a bad cell? - ANSWER: 0.050 points of specific gravity below other cells =
bad cell.
When testing a wet-cell battery with a hydrometer, what reading indicates a fully
charged battery? - ANSWER: 1.260 - 1.285 (temperature dependent)
When testing a fully charged start battery for capacity with a load tester, what % of
CCA rating should be induced by the load to test resulting voltage? - ANSWER: 50%
, Most engine-driven alternators are optimally spun at what percentage of engine
RPMs?
A. Between 10% and 50%
B. Less than 10%
C. Between 150% and 200%
D. Greater than 200% - ANSWER: C. Between 150% and 200%
T or F: A battery charger case shall be tied to the DC negative output terminal at the
battery charger. - ANSWER: False. the battery charger case shall be tied to the engine
negative terminal/bus, along with the negative output terminal of the battery
charger, not at the battery charger case itself.,
Why do battery chargers require a separate case connection to main AC grounding
bus and Engine negative / DC grounding bus? - ANSWER: In case of an internal short
to the case, the AC grounding wire would not carry enough current.
What is the minimal wire size required for a battery charger case connection to DC
ground/engine negative? - ANSWER: No smaller than 1 size below the DC current
carrying conductors between the charger and batteries - provided OC protection on
positive DC output is no greater than 135% of DC grounding cable ampacity and
conductor is no smaller than 16 AWG.
What device is typically found to satisfy the required OC protection between a
battery charger and the batteries? - ANSWER: Class T fuse rated for appropriate AIC
What may happen to a solar array or wind generator used to charge batteries
without a blocking diode? - ANSWER: Batteries will feed back into solar array or wind
generator coil and discharge (possibly damage). Note: many voltage regulators have
integral blocking diodes.
How far above bilge water level must a battery charger be mounted? - ANSWER: 24
inches or more (unless waterproof!)
How far away from a gasoline tank must a pre-wired battery charger's AC connection
plug be located? - ANSWER: At least 24 inches
T or F: All marine inverters shall utilize an internal or external GFCI on their AC
outlets. - ANSWER: False. (only when installed in location that required GFCI per
ABYC E-11)
T or F: most GFCI outlets can be used in a gasoline engine room - ANSWER: False.
Most are not ignition protected.
T or F: Because the shore power connection is a power source, the neutral conductor
should be tied to ground at the point where it comes in to the boat (shore power
