ABYC SYSTEMS RECENT TIPS QUESTIONS AND
ANSWERS SURE A+
✔✔True - ✔✔T of F: pre-wired battery chargers with isolated outputs may have both
positive and negative outputs which require overcurrent protection on both legs.
✔✔Overcurrent protection installed at the shunt based on the size of the conductors
supplying the remote ammeter. - ✔✔What type of overcurrent protection is required for
the wires leading from an ammeter shunt in a positive DC conductor to a remote meter?
✔✔False - ✔✔T of F: Most GFCI's are inherently ignition protected
✔✔True - ✔✔T or F: Harmonic distortion of the AC output waveform from some
inverters may interfere with proper GFCI operation.
✔✔Only when the inverter/charger is an AC power source (i.e. when inverting, not when
operating as a charger or pass-thru for shore power) - ✔✔When should an
inverter/charger output neutral be grounded at the inverter/charger?
✔✔Break-before-make + Overcurrent Protected - ✔✔What are two special features
required for an AC power transfer switch (i.e., switches between multiple AC sources to
a branch circuit, device or recepticle)?
,✔✔Must be wire reinforced to prevent collapse due to suction - ✔✔What feature must
be incorporated for all raw water intake hosing?
✔✔Barbed Hose Adapter - ✔✔Which of the following would be most suitable method for
a water hose attachment: Threaded Nipple, Barbed Hose Adapter, Smooth Pipe, Pipe
Coupling?
✔✔As motor winding heat up, resistance increases and current goes down, perhaps
below the level that would trip OC. - ✔✔Why is motor "locked rotor" condition a difficult
issue for overcurrent protection?
✔✔Gasoline engine rooms, LPG storage areas, Gasoline fuel storage areas - ✔✔What
are three areas on a boat in which electrical devices must be "ignition protected".
✔✔Inverters - ✔✔Of the following items, which is most likely to not be ignition protected:
Fuses, Battery Chargers, Inverters, Alternators, Blowers, Starter Motors, Circuit
Breakers, Bilge Pumps?
✔✔7" if unsheathed, 72" if sheathed and connected to battery terminal, 40" if sheathed
and connected to power source other than battery terminal. - ✔✔Describe the "7-40-72"
rule for DC overcurrent protection
✔✔Starter Motors - ✔✔What class of devices are excluded from OC protection?
✔✔7" - unsheathed, 40" - sheathed (there is no 72" rule for AC sources) - ✔✔What two
distances are allowable for AC power source OC protection?
✔✔True - ✔✔If power is drawn from the output of a battery switch or the positive
terminal on a starter motor, this is a situation that is considered by ABYC to be a
"source of power" and as such must have independent overcurrent protection. T or F?
✔✔16 AWG - ✔✔What is the smallest wire guage allowed by ABYC (if not sheathed or
inside an equipment housing)?
✔✔True - ✔✔T or F: AC wire sizes are generally determined by ampacity, not voltage
drop.
✔✔False - use 3% drop - ✔✔T or F: according to ABYC, Bilge Blower motors can
tolerate 10% voltage drop when sizing DC cables.
✔✔1. Used inside or outside of engine room? 2. Required Insulation Temperature
Rating? 3. How many current carrying conductors will be bundled together? - ✔✔What
three factors must be known to size AC wiring?
, ✔✔True. (provided there is no damage to the conductor and it meets the pull-test
requirements) - ✔✔T or F: Although only 4 electrical terminal connections are allowed
per stud, it is permissible to have more than one wire per terminal connector.
✔✔6 lbs - ✔✔How many pounds must a friction type electrical connected withstand (on
the first pull)?
✔✔36" - ✔✔What is the max unsupported length of cable allowed for connection to
batteries?
✔✔One size smaller than the DC output conductor. To carry an inadvertent DC short to
the chassis back to the source (battery) long enough to trip overcurrent without
conductor or damage (because the AC grounding conductor is usually too small to
accomplish this!) - ✔✔What is the minimum guage required for connecting battery
charger and inverter cases back to the engine negative terminal or bus? What is the
purpose of this conductor?
✔✔Ampere Interrupting Capacity (AIC) of at least the battery manufacturer's short-
circuit rating or 100X nominal AH rating. - ✔✔What OC protection is required for battery
banks with > 2200 CCA or 500 AH ratings?
✔✔10' - ✔✔What is the maximum distance allowed between the main shore power
disconnect circuit breaker and the shore power inlet before requiring additional OC
protection?
✔✔It must not blow before the main shore power circuit breaker nor be rated greater
than 125% of the main shore power circuit breaker. - ✔✔If additional OC protection is
required (within 10' of shore power inlet) and a fuse is used, what are the limits on the
rage of allowable AIC for this fuse?
✔✔Always, unless an isolation transformer is installed within 10' of shore power
connection. - ✔✔When must an ELCI or RCD be installed?
✔✔30 mA, 100 ms maximum - ✔✔What are the trip level and trip time maximums for
ELCIs & RCDs?
✔✔True - ✔✔T of F: Inverters with integral AC outlets must have an embedded GFCI
✔✔Not quite... Propane is LPG but not all LPG is propane.
LPG - Liquefied Petroleum Gas - is flammable hydrocarbon gas liquefied through
pressurisation.
ANSWERS SURE A+
✔✔True - ✔✔T of F: pre-wired battery chargers with isolated outputs may have both
positive and negative outputs which require overcurrent protection on both legs.
✔✔Overcurrent protection installed at the shunt based on the size of the conductors
supplying the remote ammeter. - ✔✔What type of overcurrent protection is required for
the wires leading from an ammeter shunt in a positive DC conductor to a remote meter?
✔✔False - ✔✔T of F: Most GFCI's are inherently ignition protected
✔✔True - ✔✔T or F: Harmonic distortion of the AC output waveform from some
inverters may interfere with proper GFCI operation.
✔✔Only when the inverter/charger is an AC power source (i.e. when inverting, not when
operating as a charger or pass-thru for shore power) - ✔✔When should an
inverter/charger output neutral be grounded at the inverter/charger?
✔✔Break-before-make + Overcurrent Protected - ✔✔What are two special features
required for an AC power transfer switch (i.e., switches between multiple AC sources to
a branch circuit, device or recepticle)?
,✔✔Must be wire reinforced to prevent collapse due to suction - ✔✔What feature must
be incorporated for all raw water intake hosing?
✔✔Barbed Hose Adapter - ✔✔Which of the following would be most suitable method for
a water hose attachment: Threaded Nipple, Barbed Hose Adapter, Smooth Pipe, Pipe
Coupling?
✔✔As motor winding heat up, resistance increases and current goes down, perhaps
below the level that would trip OC. - ✔✔Why is motor "locked rotor" condition a difficult
issue for overcurrent protection?
✔✔Gasoline engine rooms, LPG storage areas, Gasoline fuel storage areas - ✔✔What
are three areas on a boat in which electrical devices must be "ignition protected".
✔✔Inverters - ✔✔Of the following items, which is most likely to not be ignition protected:
Fuses, Battery Chargers, Inverters, Alternators, Blowers, Starter Motors, Circuit
Breakers, Bilge Pumps?
✔✔7" if unsheathed, 72" if sheathed and connected to battery terminal, 40" if sheathed
and connected to power source other than battery terminal. - ✔✔Describe the "7-40-72"
rule for DC overcurrent protection
✔✔Starter Motors - ✔✔What class of devices are excluded from OC protection?
✔✔7" - unsheathed, 40" - sheathed (there is no 72" rule for AC sources) - ✔✔What two
distances are allowable for AC power source OC protection?
✔✔True - ✔✔If power is drawn from the output of a battery switch or the positive
terminal on a starter motor, this is a situation that is considered by ABYC to be a
"source of power" and as such must have independent overcurrent protection. T or F?
✔✔16 AWG - ✔✔What is the smallest wire guage allowed by ABYC (if not sheathed or
inside an equipment housing)?
✔✔True - ✔✔T or F: AC wire sizes are generally determined by ampacity, not voltage
drop.
✔✔False - use 3% drop - ✔✔T or F: according to ABYC, Bilge Blower motors can
tolerate 10% voltage drop when sizing DC cables.
✔✔1. Used inside or outside of engine room? 2. Required Insulation Temperature
Rating? 3. How many current carrying conductors will be bundled together? - ✔✔What
three factors must be known to size AC wiring?
, ✔✔True. (provided there is no damage to the conductor and it meets the pull-test
requirements) - ✔✔T or F: Although only 4 electrical terminal connections are allowed
per stud, it is permissible to have more than one wire per terminal connector.
✔✔6 lbs - ✔✔How many pounds must a friction type electrical connected withstand (on
the first pull)?
✔✔36" - ✔✔What is the max unsupported length of cable allowed for connection to
batteries?
✔✔One size smaller than the DC output conductor. To carry an inadvertent DC short to
the chassis back to the source (battery) long enough to trip overcurrent without
conductor or damage (because the AC grounding conductor is usually too small to
accomplish this!) - ✔✔What is the minimum guage required for connecting battery
charger and inverter cases back to the engine negative terminal or bus? What is the
purpose of this conductor?
✔✔Ampere Interrupting Capacity (AIC) of at least the battery manufacturer's short-
circuit rating or 100X nominal AH rating. - ✔✔What OC protection is required for battery
banks with > 2200 CCA or 500 AH ratings?
✔✔10' - ✔✔What is the maximum distance allowed between the main shore power
disconnect circuit breaker and the shore power inlet before requiring additional OC
protection?
✔✔It must not blow before the main shore power circuit breaker nor be rated greater
than 125% of the main shore power circuit breaker. - ✔✔If additional OC protection is
required (within 10' of shore power inlet) and a fuse is used, what are the limits on the
rage of allowable AIC for this fuse?
✔✔Always, unless an isolation transformer is installed within 10' of shore power
connection. - ✔✔When must an ELCI or RCD be installed?
✔✔30 mA, 100 ms maximum - ✔✔What are the trip level and trip time maximums for
ELCIs & RCDs?
✔✔True - ✔✔T of F: Inverters with integral AC outlets must have an embedded GFCI
✔✔Not quite... Propane is LPG but not all LPG is propane.
LPG - Liquefied Petroleum Gas - is flammable hydrocarbon gas liquefied through
pressurisation.
