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Chapter 13 - Electrical Systems.

1301. In submitting design data for approval, the designer shall include:-

1. Diagrams of all A.C. and D.C. power generation;
   
   
2. Diagrams of all A.C. and D.C. power distribution, and
   
   
3. An electrical load analysis.

Data should clearly indicate the electrical ratings of all components and equipment, and the specifications of all wiring.

1302. Except where necessary for performing it's normal duty, no electrical equipment shall be installed:-

1. Adjacent to any system piping or component containing flammable fluid;
   
   
2. In spaces provided for passenger accommodation;
   
   
3. Less than 10 cms. above the floating waterline at the maximum certified weight;
   
   
4. Within a Designated Fire Zone, or where flammable vapours may accumulate.

1303. Any electrical equipment installed in a Designated Fire Zone, a space where flammable fluids or vapours may accumulate, or directly adjacent to components containing flammable fluids shall be:-

1. Of a type certified safe for operation in the particular application, i.e., "explosion proof", "intrinsically safe", "increased safety";
   
   
2. Fire resistant; and
   
   
3. Installed and connected in such a manner that the fire integrity of Designated Fire Zone is not impaired.

1304. Power Generation. 

Electrical systems shall have at least two independent sources of power available for connection arranged such that, in the event of failure of power from one source, uninterrupted power is available to maintain services essential for the safe operation of the vehicle.

1305. The design of the electrical generator installation shall ensure that no generator will, under normal service load conditions, be connected to a load in excess of 80% of it's maximum rated capacity.

1306. Where storage batteries are used as a source of permanently installed power, arrangements shall be made for them to be charged from the vehicle power generating system and from an external source. Arrangements shall be made to prevent reversed polarity of charging circuits, and also to prevent battery discharge through the charging circuit should battery voltage exceed that of the charging source.

1307. The power generation system shall include adequate control of generators, with automatic voltage regulation and protection against overload in parallel operation of generators.

1308. Each generator shall, in addition to normal protection devices, be provided with means of isolation from the distribution system; this isolator shall be immediately accessible from the crew station from which the vehicle is normally manoeuvred.

1309. The power generation system shall be arranged such that no failure or malfunction of one power source shall impair the efficient supply of power from any other connected source.

1310. General service power generation shall not exceed 250 volts; exceptionally, where higher voltages may be required, additional safety requirements may need to be considered.

1311. Generator Prime Movers. 

Prime movers powering generating equipment shall be provided such that their continuous power rating is at least equivalent to the full rated load of the generator.

1312. Generator prime movers shall be provided with efficient automatic speed control such that, in the event of the full electrical load being removed, speed shall be limited to at least 5% less than the authorised overspeed trip setting.

1313. Controls and displays for starting, stopping and monitoring generator prime movers shall be provided in the compartment from which the vehicle is normally manoeuvred, and shall include an emergency stop control.

1314. Normal Power Distribution. 

Vehicle electrical services shall be provided through at least one normal bus-bar. Where more than one bus-bar and more than one generator are provided for normal distribution, control and protection devices shall be provided to prevent over-loading of bus-bars and generators. Wiring shall normally be two - or three - wire insulated systems (but see 1319). Bus-bars and their connections shall be copper, all connections being tinned or silver-surfaced to inhibit corrosion and reduce resistance; the use of aluminium bus-bars shall be specifically submitted for approval.

1315. All services shall be supplied through circuit protection devices; the current ratings shall be clearly shown on the device itself or immediately adjacent to it.

1316. Circuits associated with services essential for safe operation of the vehicle shall be protected with circuit-breakers readily available to a crew member at his normal duty station.

1317. All circuit protection devices associated with power distribution shall be readily accessible when the vehicle is in normal operation.

1318. Where circuit protection devices are connected in series, they shall be graded so that fault or overload conditions shall cause the device nearest the fault, and on the supply side, to operate first.

1319. Hull (ground) returns may be exceptionally approved for circuits operating at voltages not exceeding 55 volts where appropriate precautions are taken; these should include :-

1. Consideration of galvanic corrosion under normal operation;
   
   
2. Consideration of the ability of the grounding points to accept fault currents without danger to the hull, and without fire risk.
   
   Hull returns may be used for the starters of main engines and prime movers.

1320. All switches and circuit-breakers installed in circuits operating at 55 volts or more shall be double pole, both poles operating simultaneously.

1321. All circuits and sub-circuits shall be provided with means of connection and disconnection from the distribution system. For equipment required by section 1331 to be connected to an emergency source of power, direct connection to the emergency power source may be permitted.

1322. Means shall also be provided to ensure that all sources of installed electrical power may be disconnected from the distribution system(s), and such means shall be provided in the compartment from which the vehicle is normally manoeuvred.

1323. In marine sidewall vehicles, approved arrangements shall be made to provide electrical power for bilge pumping when electrical power is disconnected from the general distribution system(s).

1324. Where 3-phase supplies are used, an alarm shall be provided in the compartment from which the vehicle is normally manoeuvred to indicate in the event of failure of any one phase.

1325. Instrumentation and indication shall be provided in the compartment from which the vehicle is normally manoeuvred to at least inform crew members of the electrical load of each generator or power source, of any failure of primary power generation or distribution, and of the charge or discharge current of all installed batteries.

1326. In power distribution systems with no connection to ground or hull, provision shall be made to monitor insulation resistance.

1327. Attention is drawn to the requirement of Section 466.

Emergency Electrical Power. 

1330. All vehicles shall be provided with an emergency source of electrical power; the power source and it's distribution system shall be independent of, and physically separated from, the electrical power sources and distribution systems provided for normal operation to the maximum extent practicable. Provided that suitable measures are taken for safeguarding independent emergency operation under all circumstances, the emergency source of power may be used exceptionally and for short periods to supply non-emergency circuits.

1331. Power from the emergency source shall be capable of being connected, within not more than 20 seconds of failure of normal power supply, with sufficient capacity to supply simultaneously:-

1. Emergency lighting for 2 hours; (see 1332)
   
   
2. Main navigation lights for 2 hours;
   
   
3. Internal communication and public broadcast for 2 hours; (see 1333)
   
   
4. One radio receiver and transmitter for 4 hours; (see 1333)
   
   
5. Fire detection and fire extinguishing activation for 2 hours;
   
   
6. Essential instruments, equipment and controls for main propulsion and directional control for 4 hours;
   
   
7. Not Under Command lights for 12 hours; and
   
   
8. Any electrically powered whistle or bell, for 4 ´ hours.

1332. The emergency lighting requirements of Section 1331 shall provide adequate illumination of:-

1. Life-raft stowages;
   
   
2. All exits, evacuation paths, and life-raft embarkation points;
   
   
3. Passenger accommodation, and
   
   
4. Crew compartments, control stations and machinery spaces sufficient to permit operation and monitoring of all controls and displays essential for the safety and safe operation of the vehicle.

1333. In assessing the power requirements for communication prescribed in Section 1331, it should be assumed that the total accumulated usage of internal communication will not exceed 30 minutes, and that radio transmissions will not exceed a total accumulation of 30 minutes.

1334. With the exception of supplying essential power for equipment within Designated Fire Zones, all components and wiring of the emergency electrical power system shall be as remote as practicable from Designated Fire Zones.

1335. The source of emergency electrical power shall be located above the final floating waterline resulting from any damage considered in Chapter 3, and the emergency electrical system shall be capable of satisfactory functioning under such conditions.

1336. Where the source of emergency electrical power is a generator driven by an independent prime mover, any fuel required by that prime mover shall be supplied independently of the vehicle main fuel system, with storage to ensure continuous operation consistent with Section 1331.

1337. Where the source of emergency electrical power is a storage battery, it shall be of sufficient capacity to provide the emergency power required by Section 1331 without recharging, while maintaining the voltage to within 12% of nominal.

1338. Any emergency switchboard associated with distribution of power to emergency circuits should be installed in close proximity to the source of emergency power.

1339. Where the emergency circuit voltage and frequency is the same as that provided by the normal power source, the emergency switchboard should be supplied in normal operation from the main switchboard by a feeder protected with suitable overload and short-circuit devices; the emergency source of power should be connected automatically in the event of failure of normal power supply. Indication that electrical power is being supplied by the emergency power source shall be provided at a crew member's station in the compartment from which the vehicle is normally manoeuvred.

Electrical Equipment Installation. 

1340. All equipment associated with normal and emergency generation and distribution of power shall be capable of satisfactory operation under the acceleration loadings of Section 506.

1341. Equipment installations shall be designed paying due regard to the space required to ensure adequate ventilation, cooling, heat dissipation and servicing.

1342. All wiring and cables shall be supported and protected to eliminate chafing, vibration and undue strain on terminations and connections.

1343. Any live, rotating, or high temperature equipment shall be so installed or protected as to minimise the possibility of injury.

1344. Any exposed metal part of electrical equipment not intended to conduct current shall be effectively grounded; where necessary, the vehicle hull structure is to incorporate an adequate ground conductor.

1345. All ground connections shall be made using copper or corrosion resistant material; connections are to be made paying due regard for the need to avoid dissimilar metallic contact, and all ground connections shall be readily accessible for inspection.

1346. All connections and terminations shall be made paying due regard to the corrosive effects of the operating environment, and shall be positioned or protected to minimize the accumulation of moisture and dust, and to minimize the possibility of damage.

1347. All electrical equipment shall be installed and connected so as to minimize so far as is practicable, galvanic action arising from contact of dissimilar metals.

1348. All electrical equipment, cables and wiring, shall be installed, and where appropriate electrically protected, to minimize, so far as is practicable mutual electromagnetic or electrostatic interference between circuits or equipment.

1349. Where environmental conditions require the installation of equipment which is certified as safe in the particular atmosphere - e.g. "explosion-proof" - the integrity of the equipment shall be maintained by the use of seals or connections of equivalent rating.

1350. In vehicles incorporating distribution of electrical power of more than one voltage or frequency, outlets and plugs shall be provided to ensure that incorrect connection cannot be made; placards adjacent to outlets shall be provided indicating the voltage and frequency.

1351. Power outlets in toilets and washrooms shall only be provided with an A.C. supply, connected through an isolating transformer.

1352. Switches in toilets and washrooms shall be of watertight construction, or enclosed in a durable continuous insulation.

1353. Cargo and Motor Vehicle Spaces. 

Electrical equipment in spaces designed for the carriage of cargo or motor vehicles shall be certified as safe for operation in explosive vapour/air mixtures, and their installation and connection shall preserve that integrity. No electrical equipment shall be installed in such spaces less than 0.45 m. above the deck.

1354. Wires and Cables. 

All wires and cables shall be selected taking into consideration their permissible load and temperature ratings, and the service and environment to which they will be subjected.

1355. Any wires or cables passing through, or supplying equipment in, Designated Fire Zones, shall be covered with a covering which is incombustible as defined in section 1002(b). All other wiring shall have at least low flame-spread or fire-retardant covering.

1356. No wires or cables providing the services required by section 1231, other than those associated with fire detection and fire extinguishing, shall pass through, or be attached to the boundary of, a Designated Fire Zone.

1357. The covering of all wires and cables shall be impervious to moisture, and shall not be damaged by any fluid or temperature to which, by virtue of their installation, they may be subject.

1358. Lights. (See also Chapter 14)

All light bulbs and fluorescent tubes shall be mounted so as to minimize the effect of shock and vibration upon their effective operation, and should be suitable for "heavy duty".

1359. All external lights and lights in spaces subject to moisture shall be in effectively watertight closures provided with means of draining entrained moisture.

1360. All lights shall be positioned to permit adequate dissipation of heat, and to minimize the possibility of contact with flammable material.

1361. Batteries. 

All installed batteries shall be securely fastened in stowages constructed of, or treated with, material resistant to corrosion from battery electrolyte.

The fastening shall ensure that the danger of spilt electrolyte in the event of experiencing the accelerations quoted in Section 506 is minimized.

1362. Battery stowages shall be adequately vented to atmosphere, either naturally from the top of the stowage, or by forced ventilation; the vent opening shall be remote from any other hull openings.

1363. Batteries employing differing forms of construction or electrolyte shall be secured in separate stowages; all stowages shall be located where the batteries are not exposed to extremes of temperature or humidity.

1364. Batteries shall not be stowed in or adjacent to Designated Fire Zones, nor in spaces designed to be normally occupied by passengers or crew members.

1365. Consistent with 1364, any battery used for starting engines or prime movers shall be stowed as close as practicable to the starter motor in order to minimize voltage drop.

1366. Batteries connected to a charging circuit shall be provided with reverse current protection; if charged through rectifiers, the rectifiers shall also be protected against overloading.

1367. Where battery charging arrangements provide for alternate sources of charging power, protection against reverse current in each circuit shall be provided.

1368. Batteries which may experience thermal runaway during charging shall be equipped with temperature warning devices activating a distinctive warning in the compartment from which the vehicle is normally manoeuvred. Such batteries shall be connected with quick-release terminal connections, and their charging circuits shall incorporate an isolating switch or circuit breaker.

1369. No equipment which may constitute a potential source of ignition of flammable vapours shall be installed in a battery stowage.

1370. Where batteries are installed as the main source of electrical power, arrangements shall be made on board to fully charge them within 8 hours. Batteries installed as a main source of power shall be of sufficient capacity to at least provide the services required by section 1331, plus starting a main engine.

1371. Charging circuits shall be so arranged to permit a battery being charged to simultaneously provide power to the vehicle systems.

1372. Bonding. 

All metal sheaths of electrical conductors shall be electrically continuous and shall be grounded (earthed).

1373. All metal piping systems containing flowing fluids which could potentially generate static electricity shall be electrically continuous and grounded.

1374. Where hull return systems are used and approved, all metal parts of the vehicle structure shall form a continuous electrical path providing electrical contact when the vehicle alights.

1375. The design of all fuel replenishment points shall include bonding connections.

1376. Primary conductors designed for the discharge of lightning strikes shall have a current-carrying capacity at least equal to that of 6mm² of pure copper.

1377. External Power Supply. 

Any external power supply connection shall be certified waterproof, and shall be arranged such that the external power source may only be connected with polarity and phasing compatible with the vehicle systems.

1378. All external power supply connections shall be clearly identified with the voltage and type of power for which it is intended.

1379. External power connnections shall be arranged such that the external power source cannot be paralleled with any installed power source.

1380. Lighting Systems. 

All spaces provided for the accommodation or use of passengers, all crew compartments, and all spaces accessible which contain machinery or equipment requiring periodic attention or servicing, shall be provided with adequate lighting supplied by the normal power source.

1381. The lighting system provided to meet the requirement of section 1380 shall be arranged so that, in the event of fire or failure of the normal power source, the emergency lighting system will not be rendered inoperative.

1382. The system providing power for emergency lighting should become operative automatically upon failure of the normal lighting system power supply, or upon connection of the emergency source of electrical power to the distribution system.

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