ABYC Marine Electrical Certification Exam Review Questions With Correct Answers!!

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 cable connection) - ANSWER False. Shore power neutral is tied to ground on the shore side. Tech A says that voltage supplied to the rotor controls the alternator output voltage. Tech B says that the alternator output is proportional to the rotor voltage. Which is correct, A, B, Both or Neither? - ANSWER Both. Tech A says that AC and DC are able to run together down the same conductor. Tech B says this is technically impossible. Which is correct, A, B, neither or both? - ANSWER Tech A According to ABYC, what is the maximum distance allowed between a boat's shore power connection and the main overcurrent protection device? - ANSWER 10' What is an ELCI and where is it required to be installed? - ANSWER Equipment Leakage Current Interrupter - within 10 feet of shore power connection unless an isolation transformer is located within 10' of shore power connection. T or F: When more than one option for shore power inlet is installed on a boat, the shore power neutrals shall be tied together on the boat. - ANSWER False, they must be isolated to prevent shock hazard at the unutilizd shore power connector pins. What ampacity is required for wire and terminals connecting a galvanic islolator? - ANSWER At least 135% of isloator's nominal rating. (A-28.11.1) What is the general rule for use of friction connectors? - ANSWER Ampacity 20 Amps, voltage drop across terminals 50 mV @ 20 A flow, no separation with a one-minute pull of 6 lb force. When measuring temperature to determine potential electrical issues involving excessive connector resistance, what is the threshold for concern? - ANSWER 25 degrees above ambient According to the ABYC, the shore-power grounded conductor should: A. Be connected to the AC neutral B. Not be grounded on the boat C. Be connected to the engine common positive terminal or its bus D. Be tied to the battery isolator - ANSWER B. Not be grounded on the boat If a customer complains about receiving shocks from her boat when shore power is active, the technican should first test: A. Polarity check of shore cord B. Polarity check of the battery system C. Current Leakage Test D. Converter voltage check - ANSWER A. Polarity check of shore cord A customer is complaining about low-voltage at the AC panel. What should you do first? A. Re-calibrate the panel meter B. Check the voltage at the dock pedestal C. Check the polarity indicator D. Replace the overcurrent device - ANSWER B. Check the voltage at the dock pedestal A customer notes a reverse-polarity problem. All of the following are likely causes, except: A. Improperly wired shore power cord B. Improperly wired shore power inlet receptacle C. An open neutral D. Reversal of the hot and neutral conductors in the AC panel feeder cable - ANSWER C. An open neutral What is a likely cause of non-functioning galvanic isolator? A. a shorted isolator diode B. Improper current rating of the isolator diode C. An on-board neutral-to-ground connection D. All of the above are possible - ANSWER D. All of the above are possible An "open Neutral" conductor in a 240V/120V shore power system will most likely show up as: A. Nuisance tripping of the AC main breaker B. Nuisance tripping of an appliance branch circuit breaker C. A loud humming noise emitted from the TV D. Burned out 120V appliance - ANSWER D. Burned out 120V appliance T or F: Generators that are "self-limiting" do not require overcurrent protection if the conductors used are of sufficient ampacity and sized for maximum current available. - ANSWER True (provided the generator's self-limiting current, AKA "overload current", does not exceed 120% of it's rated current output) What tool is used to test the insulation integrity of a generator windings and what is the generally accepted Mimimal measurement? - ANSWER Mega ohm meter (AKA "merger"), 1 M Ohm A customer complains that her generator will start from the local control panel at the generator, but not from the remo