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QuartermasterQuartermasterElectricity ElectiveElectricity Elective

Instructors: George Crowl

Course OutlineCourse Outline

b. Electricity:b. Electricity: i) Know and demonstrate the correct method of rescuing a person in i) Know and demonstrate the correct method of rescuing a person in

contact with a live wire.contact with a live wire. ii) Understand the construction of simple battery cells. Demonstrate the ii) Understand the construction of simple battery cells. Demonstrate the

proper care of storage batteries.proper care of storage batteries. iii) Explain the difference between direct current and alternating current iii) Explain the difference between direct current and alternating current

and the best uses for each.and the best uses for each. iv) Demonstrate that you know how to replace fuses, reset circuit iv) Demonstrate that you know how to replace fuses, reset circuit

breakers, and properly splice shipboard electric cable. breakers, and properly splice shipboard electric cable. v) Submit a diagram of the electrical system aboard the vessel used by v) Submit a diagram of the electrical system aboard the vessel used by

your ship.your ship. vi) Explain wire tables, the current-carrying capacity of circuits, and the vi) Explain wire tables, the current-carrying capacity of circuits, and the

hazards and prevention of electrical overloading.hazards and prevention of electrical overloading. vii) Explain electrolysis as applied to the deterioration of a boat’s vii) Explain electrolysis as applied to the deterioration of a boat’s

underwater fittings by galvanic action and its prevention.underwater fittings by galvanic action and its prevention.

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i) Know and demonstrate the correct i) Know and demonstrate the correct method of rescuing a person in contact method of rescuing a person in contact with a live wire.with a live wire.

Rescuing a PersonRescuing a Person

DO NOT TOUCH THEM!DO NOT TOUCH THEM!You will get the same shock they have, and be You will get the same shock they have, and be

disableddisabledCall 911. They will likely guide you.Call 911. They will likely guide you.Cut off the power at circuit breaker Cut off the power at circuit breaker If a line is down, DO NOT TOUCHIf a line is down, DO NOT TOUCHCall power company, ask them to cut powerCall power company, ask them to cut power

Still in Contact with Live WireStill in Contact with Live Wire

Stay 100 ft away from downed high wires! Do Stay 100 ft away from downed high wires! Do not attempt rescue.not attempt rescue.

Household current – Household current – Find wood or plastic pole (non-conducting)Find wood or plastic pole (non-conducting)Dry rope is also non-conductingDry rope is also non-conductingPull wire free of person, or Pull wire free of person, or

person from wireperson from wire

After Freed from ContactAfter Freed from Contact

Move away from dangerMove away from dangerCall 911 if not already doneCall 911 if not already doneLay person on backLay person on backCheck breathing and heartbeatCheck breathing and heartbeatStart rescue breathing or CPR Start rescue breathing or CPR

if neededif neededTreat for shock, cover above and belowTreat for shock, cover above and belowTreat burns with cold water, no oil / greaseTreat burns with cold water, no oil / greaseBad burns – cut away clothing, sterile dressingBad burns – cut away clothing, sterile dressing

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ii) Understand the construction of simple ii) Understand the construction of simple battery cells. Demonstrate the proper battery cells. Demonstrate the proper care of storage batteries.care of storage batteries.

Battery ConstructionBattery Construction

Lead-acid battery. Ea cell = 2V, need 6 for 12V.Lead-acid battery. Ea cell = 2V, need 6 for 12V.Dilute sulpheric acid conducts electricityDilute sulpheric acid conducts electricityPositive = lead dioxide, negative = pure leadPositive = lead dioxide, negative = pure leadPositive = Positive = +, red+, red; negative = ; negative = -, black-, black

Care of Storage BatteriesCare of Storage Batteries

Clean terminals regularly (baking soda)Clean terminals regularly (baking soda) Insure cells of conventional batteries are full Insure cells of conventional batteries are full

with distilled waterwith distilled waterPut a “boot” on the positive (red) terminalPut a “boot” on the positive (red) terminalLight dielectric grease on terminalsLight dielectric grease on terminals Insure tied down tightInsure tied down tightEliminate wing nuts, they come looseEliminate wing nuts, they come looseCharge fully, 13V or moreCharge fully, 13V or more

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iii) Explain the difference between direct iii) Explain the difference between direct current and alternating current and the current and alternating current and the best uses for each.best uses for each.

AC vs. DCAC vs. DC

Direct Current (DC) flows in one direction at a Direct Current (DC) flows in one direction at a level voltage (below left), usually from a batterylevel voltage (below left), usually from a battery

Alternating Current (AC) flows back and forth at Alternating Current (AC) flows back and forth at varying voltage (below right), usually from an varying voltage (below right), usually from an alternator or commerical power sourcealternator or commerical power source

AC vs. DC (2)AC vs. DC (2)

Shore power is AC, powers lights, TV, Shore power is AC, powers lights, TV, microwave, electrical sockets for tools, etc.microwave, electrical sockets for tools, etc.

Shore power is normally 110V, 60 cycleShore power is normally 110V, 60 cycleCommercial vessels may use self-generated AC Commercial vessels may use self-generated AC

at 240/480V to run motors, etc.at 240/480V to run motors, etc.Boat power is DC, powers nav lights, engine and Boat power is DC, powers nav lights, engine and

navigation instruments, cabin lights, etc.navigation instruments, cabin lights, etc.Boat power is 12V, does not cycle, generatorBoat power is 12V, does not cycle, generatorProvided by 1-4 batteries, controlled by battery Provided by 1-4 batteries, controlled by battery

switch. Special starting batteries sometimes.switch. Special starting batteries sometimes.

AC vs. DC (3)AC vs. DC (3)

AC is needed to transmit electricity a long way AC is needed to transmit electricity a long way over power lines.over power lines.

High voltage can be transformed down to house-High voltage can be transformed down to house-hold 110V by transformers relatively easilyhold 110V by transformers relatively easily

Universally used for household and Universally used for household and manufacturing purposesmanufacturing purposes

DC is best for many electronic applicationsDC is best for many electronic applicationsDC cannot travel far, so within a black box is OKDC cannot travel far, so within a black box is OK

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iv) Demonstrate that you know how to iv) Demonstrate that you know how to replace fuses, reset circuit breakers, replace fuses, reset circuit breakers, and properly splice shipboard electric and properly splice shipboard electric cable. cable.

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iv) Demonstrate that you know how to iv) Demonstrate that you know how to replace fuses, reset circuit breakers, replace fuses, reset circuit breakers, and properly splice shipboard electric and properly splice shipboard electric cable. cable.

Replace FusesReplace Fuses

Demonstrate, don't talkDemonstrate, don't talkFuses may actually be hard to find, check your Fuses may actually be hard to find, check your

car fuses if you don't have fuses on your boatcar fuses if you don't have fuses on your boatCheck fuse box list. If you don't have a list, Check fuse box list. If you don't have a list,

experiment (BUT start the list!)experiment (BUT start the list!)Turn off master switch if possibleTurn off master switch if possibleRemove fuse coverRemove fuse cover

Replace Fuses (2)Replace Fuses (2)

Remove (pull out or unscrew) fuseRemove (pull out or unscrew) fuse Inspect to see that it is blown (broken)Inspect to see that it is blown (broken)Confirm proper fuse rating (in amps)Confirm proper fuse rating (in amps) Install fuse of equal or lower rating, then coverInstall fuse of equal or lower rating, then cover Common ratings – 10A, 15A, 30ACommon ratings – 10A, 15A, 30A If fuse blows quickly, solve the underlying If fuse blows quickly, solve the underlying

problem first! Then reinstallproblem first! Then reinstallanother fuse.another fuse.

Overloaded circuits can Overloaded circuits can lead to fireslead to fires

Reset Circuit BreakersReset Circuit Breakers

Look like small light switchesLook like small light switchesButton forced out of alignmentButton forced out of alignmentRun your hand along to find Run your hand along to find

one “popped”one “popped”Push to “OFF”, then back “ON”Push to “OFF”, then back “ON” If it pops again, fix the problem,If it pops again, fix the problem,

don't keep resetting C/Bdon't keep resetting C/B

Shipboard Cable SplicingShipboard Cable Splicing

Meet ABYC standards (see NOTES for article)Meet ABYC standards (see NOTES for article)Use Use marinemarine racheting crimp connectors racheting crimp connectorsNylon-jacketed butt connectors (nylon tube)Nylon-jacketed butt connectors (nylon tube) If exposed to water, use and melt heat-sensitive If exposed to water, use and melt heat-sensitive

adhesive to waterproof the connectionadhesive to waterproof the connection

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v) Submit a diagram of the electrical v) Submit a diagram of the electrical system aboard the vessel used by your system aboard the vessel used by your ship. ship.

Electrical SystemElectrical System

Includes AC and DCIncludes AC and DCShows batteries, motor, instruments, etcShows batteries, motor, instruments, etcUses conventional electrical diagram symbolsUses conventional electrical diagram symbolsGood starting source should be the motor Good starting source should be the motor

electrical diagram for your engineelectrical diagram for your engineMost Sea Scout boats have been modified – Most Sea Scout boats have been modified –

show reality, not the way it was builtshow reality, not the way it was builtProbably will require you to use a circuit tester Probably will require you to use a circuit tester

to find out what reality isto find out what reality is

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vi) Explain wire tables, the current-vi) Explain wire tables, the current-carrying capacity of circuits, and the carrying capacity of circuits, and the hazards and prevention of electrical hazards and prevention of electrical overloading. overloading.

Wire TablesWire Tables

Two kinds – AWG and Metric (mostly AWG)Two kinds – AWG and Metric (mostly AWG)Standardizes wire selectionStandardizes wire selectionProvides conservative general guidance to the Provides conservative general guidance to the

public about how much current a wire can carrypublic about how much current a wire can carryDesign engineers will do a more precise jobDesign engineers will do a more precise jobSizes #0000 (0.46”) to #32 (0.008”), large to smallSizes #0000 (0.46”) to #32 (0.008”), large to smallFor solid wire, stranded wire is based on total For solid wire, stranded wire is based on total

cross-sectional area to carry same currentcross-sectional area to carry same current

Typical Wire TableTypical Wire Table

#16 wire#16 wireDiameter – 0.0508”Diameter – 0.0508”Diameter – 1.29032mmDiameter – 1.29032mmOhms/1000' – 4.016Ohms/1000' – 4.016Ohms/km – 13.17248Ohms/km – 13.17248Max amps for chassis wiring – 22Max amps for chassis wiring – 22Max amps for power xmsn – 3.7Max amps for power xmsn – 3.7Max freq – 11,000 HzMax freq – 11,000 HzBreaking strength – 75 poundsBreaking strength – 75 pounds

Current-Carrying CapacityCurrent-Carrying Capacity

Also Current Rating or AmpacityAlso Current Rating or AmpacityDepends on: insulation temperature rating, Depends on: insulation temperature rating,

conductor resistance, AC frequency, ambient conductor resistance, AC frequency, ambient temperature, heat dissipationtemperature, heat dissipation

Insulation is often the driving factorInsulation is often the driving factorCables (several wires) have lower capacity Cables (several wires) have lower capacity

because of heat buildup, or conduitbecause of heat buildup, or conduitFigures are for continuous current, short Figures are for continuous current, short

overloads will not usually affectoverloads will not usually affectCircuit breakers are sized to fit capacityCircuit breakers are sized to fit capacity

Electrical Overload HazardsElectrical Overload Hazards

Fire and electrical arcing are main issuesFire and electrical arcing are main issuesOverheated wire or arcing wire can start a fireOverheated wire or arcing wire can start a fireElectrical arc could set off gasoline explosionElectrical arc could set off gasoline explosion

Overload PreventionOverload Prevention

Size your circuit breakers and/or fuses to the Size your circuit breakers and/or fuses to the current capacitycurrent capacity

Loose or corroded wires increase resistance and Loose or corroded wires increase resistance and current. Means more current, possible arcing.current. Means more current, possible arcing.

Troubleshoot popped circuit breakersTroubleshoot popped circuit breakersUnplug high current appliances (microwave, Unplug high current appliances (microwave,

toaster, waffle iron, etc.)toaster, waffle iron, etc.)

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vii) Explain electrolysis as applied to the vii) Explain electrolysis as applied to the deterioration of a boat’s underwater deterioration of a boat’s underwater fittings by galvanic action and its fittings by galvanic action and its prevention. prevention.

Electrolysis, Galvanic ActionElectrolysis, Galvanic Action

Electrolysis – “Chemical decomposition Electrolysis – “Chemical decomposition produced by passing an electrict current produced by passing an electrict current through a liquid or solution containing ions.”through a liquid or solution containing ions.”

Galvanic corrosion – Two different metals will Galvanic corrosion – Two different metals will cause corrosion if in contact, or if in water that cause corrosion if in contact, or if in water that can pass ions from one metal to the othercan pass ions from one metal to the other

PreventionPrevention

Install one or more zinc sacrificial anodes on the Install one or more zinc sacrificial anodes on the prop shaft and/or other other equipmentprop shaft and/or other other equipment

Check your berth for stray electrical currentsCheck your berth for stray electrical currentsCheck your through-hulls at every quick haulCheck your through-hulls at every quick haul

Questions?Questions?