Section 2 Electrical Installations

201. Main source of electrical power

1. Every unit should be provided with a main source of electrical power which is to include at least two generating sets.

2. The power of these sets is to be such that it is still possible to ensure the functioning of the serv- ices referred to in 102.1 and listed in (1) to (8) below, except for power servicing drilling oper- ations, in the event of any one of these generating sets being stopped.

(1) Ventilation of hazardous areas and those areas maintained at an overpressure to exclude the in- gress of dangerous gases.

(2) Navigation, signal and special purpose lights.

(3) Lights for all machinery spaces, control stations, alleyways, stairway and exits.

(4) Fire pumps.

(5) Propulsion equipment.

(6) Bilge pumps.

(7) Ballast pumps for column-stabilized units.

(8) Radio equipment.

3. For restricted service units, one set of the main sources of electrical power may be acceptable.

Where, however, the lighting systems of these units listed in above 2 (2) are solely operated by

electric power, the units are to be provided with an independent electric power source capable of operating these lightings in the event of failure of the main source of electrical power.

4. Where a.c. generators are used as a main source of electrical power, they are to have sufficient ca-

pacity to permit the starting stall or any other devices to

of the largest motor in the units without causing any other motors to fail due to excessive voltage drop on the system.

5. The requirements in above Par 1 to electric power is supplied from other

Par 4 do not apply to the units which are so designed that units or from the shore. However, the units having the light-

ing systems listed in above 2 (2) are to be so designed as to be capable of operating these light-

ing systems without supplying electric power from other units or from the shore except that two or more sets of electric power sources are provided at these suppliers.

6. For restricted service units, where generators used mainly for operating purpose are provided in ad- dition to the main source of electric power except the independent electrical power source required by above Par 3, these generators and their driving engine are to be regarded as machinery used solely for operating purpose.

7. Where transformers or converters constitute an essential part of the supply system, the system is to be so arranged as to ensure the same continuity of the supply as stated in Par 2.

8. A main electrical lighting system which is to provide illumination throughout those parts of the unit normally accessible to and used by personnel is to be supplied from the main source of power.

9. The arrangement of the main lighting system should be such that a fire or other casualty in the space or spaces containing the main source of power, including transformers or converters, if any, will not render the emergency lighting system under 202. inoperative.

10. The arrangement of the emergency lighting system is to be such that a fire or other casualty in the space or spaces containing the emergency source of power, including transformers or converters, if any, will not render the main lighting system required by this Article inoperative.

11. The main source of electrical power is to comply with the following:

(1) Where the electrical power can normally be supplied by one generator, suitable load shedding arrangements are to be provided to ensure the integrity of supplies to services required for pro- pulsion and steering as well as the safety of the unit. In the case of loss of the generator in operation, adequate provision is to be made for automatic starting and connecting to the main switchboard of a standby generator of sufficient capacity to ensure safe navigation when under- way and to ensure the safety of the unit with automatic restarting of the essential auxiliaries in- cluding, where necessary, sequential operations. The Society may dispense with these provisions where the power necessary to ensure the functioning of the service referred to in 102. 1, ex-

cept for power servicing drilling operations,

(2) If the electrical power is normally supplied

is 250 kW or less.

by more than one generator simultaneously in paral-

lel operation, provision should be made, for instance, by load shedding to ensure that, in case of loss of one of these generating sets, the remaining ones are kept in operation without over-

load to ensure safe navigation when underway and to ensure the safety of the unit.

(3) Where the main source of electrical power is necessary for propulsion of the unit, the main

busbar should be subdivided into at least two parts which should normally be connected by cir- cuit breakers or other approved means. The connection of generating sets and other duplicated equipment are, so far as is practicable, to be equally divided between the parts.

202. Emergency source of electrical power

1. Every unit is to be provided with a self-contained emergency source of electrical power.

2. The emergency source of power, the transitional source of emergency power and the emergency switchboard are to be located above the worst damage waterline and in a space not within the as- sumed extent of damage referred to in Ch 4, and be readily accessible. They should not be for- ward of the collision bulkhead, if any.

3. The location of the emergency source of power, the transitional source of emergency power and emergency switchboard in relation to the main source of electrical power are be such as to ensure that a fire or other casualty in the space containing the main source of electrical power or in any machinery space of category A will not interfere with the supply or distribution of emergency power. As far as practical, the space containing the emergency source of power, the transitional source of emergency power and the emergency switchboard are not to be contiguous to boundaries of machinery spaces of category A or of those spaces containing the main source of electrical power. Where the emergency source of power, the transitional source of emergency power, and the emergency switchboard are contiguous to the boundaries of machinery spaces of category A or to those spaces containing the main source of electrical power, or to spaces of Zone 1 or Zone 2, the contiguous boundaries should be in compliance with Ch 10, 201.

4. Provided that suitable measures are taken for safeguarding independent emergency operation under all circumstances, the emergency switchboard may be used to supply non-emergency circuits, and the emergency generator may be used exceptionally and for short periods to supply non-emergency circuits.

5. For units where the main source of electrical power is located in two or more spaces which have their own systems, including power distribution and control systems, completely independent of the

systems in the other spaces and such that a fire or other casualty in any one

of the spaces will

not affect the power distribution from the others, or to the services under Par 6, the provisions of above Par 1 may be considered satisfied without an additional emergency source of electrical pow-

er, provided that the Society is satisfied that:

(1) there are at least two generating sets, meeting the provisions of 103. and each of sufficient ca- pacity to meet the provisions of Par 6, in each of at least two spaces;

(2) the arrangements under above Subparagraph (1) in each such space are equivalent to those un- der Par 8, and Par 11 to Par 14, and 204. so that a source of electrical power is available at

all times to the services under Par 6;

(3) the location of each of the spaces referred to in above Subparagraph (1) is in compliance with

Par 2 and the boundaries meet the provisions of Par 3 except that contiguous boundaries

should consist of an "A-60" bulkhead and a cofferdam, or a steel bulkhead insulated to class "A-60" on both sides.

6. The power available is to be sufficient to supply all those services that are essential for safety in

an emergency, due regard being

paid to such services as may have to be operated simultaneously.

The emergency source of power should be capable, having regard to starting currents and the tran-

sitory nature of certain loads, of

supplying simultaneously at least the following services for the pe-

riods specified hereinafter, if they depend upon an electrical source for their operation:

(1) For a period of 18 h, emergency lighting:

(A) at every embarkation station on deck and over sides;

(B) in all service and accommodation alleyways, stairways and exits, personnel lift cars, and personnel lift trunks;

(C) in the machinery spaces and main generating stations including their control positions;

(D) in all control stations and in all machinery control rooms;

(E) in all spaces from which control of the drilling process is performed and where controls of

machinery essential for the performance of this process, or devices for emergency switch- ing-off of the power plant are located;

(F) at the stowage position or positions for fire-fighters’ outfits;

(G) at the sprinkler pump, if any, at the fire pump referred to in Subparagraph (5) at the emer- gency bilge pump, if any, and at their starting positions;

(H) on helidecks, to include perimeter and helideck status lights, wind direction indicator illumi- nation, and related obstruction lights, if any;

(2) For a period of 18 h, the navigation lights, other lights and sound signals, required by the International Regulations for the Prevention of Collisions at Sea, in force;

(3) For a period of four days signalling lights and sound signals required for marking of offshore structures;

(4) For a period of 18 h:

(A) all internal communication equipment that is required in an emergency;

(B) fire and gas detection and their alarm systems;

(C) intermittent operation of the manual fire alarms and all internal signals that are required in an emergency;and

(D) the capability of closing the blowout preventer and of disconnecting the unit from the well- head arrangement, if electrically controlled;

unless they have an independent supply from an accumulator battery suitably located for use in an emergency and sufficient for the period of 18 h;

(5) For a period of 18 h, one of the fire pumps, if dependent upon the emergency generator for its source of power;

(6) For a period of at least 18 h, permanently installed diving equipment, if dependent upon the unit’s electrical power;w

(7) On column-stabilized units, for a period of 18 h:

(A) ballast control and indicating systems under Ch 5, 203. 6 (11) and

(B) any of the ballast pumps under Ch 5, 203. 6 (3); only one of the connected pumps need

be considered to be in operation at any time;

(8) For a period of half an hour:

(A) power to operate the watertight doors as provided under Ch 4, 602. 2 (3) (A), but not necessarily all of them simultaneously, unless an independent temporary source of stored en-

ergy is provided;and

(B) power to operate the controls and indicators provided under Ch 4, 602. 2 (3) (A).

The emergency source of power may be either a generator or an accumulator battery.

Where the emergency source of power is a generator it is to be:

7. (1) driven by a suitable prime mover with an independent supply of fuel, having a flashpoint

8. (closed cup test) of not less than 43°C ;

(2) started automatically upon failure of the main source of electrical power supply unless a transi-

tional source of emergency electrical power in accordance with Subparagraph (3) is provided; where the emergency generator is automatically started, it is to be automatically connected to the emergency switchboard; those services referred to the requirements in Par 10 are then to be connected automatically to the emergency generator ;

(3) provided with a transitional source of emergency power, as specified in Par 10, unless the emergency generator is capable of supplying the services mentioned in Par 10 and of being au-

tomatically started and supplying the required load as quickly as is safe and practicable but in not more than 45 seconds.

Where the emergency source of power is an accumulator battery it is to be capable of:

(1) carrying the emergency electrical load without recharging while maintaining the voltage of the

9. battery throughout the discharge period within 12 above or below its nominal voltage ;

(2) automatically connecting to the emergency switchboard in the event of failure of the main source of electrical power ; and

(3) immediately supplying at least those services specified in Par 10.

10. The transitional source of emergency electrical power where required by 8 (3) is to consist of an accumulator battery suitably located for use in an emergency which is to :

(1) operate without recharging whilst maintaining the voltage of the battery throughout the discharge

period within plus or minus 12% of its nominal voltage,

(2) be of sufficient capacity and be so arranged as to supply automatically in the event of failure of either the main or the emergency source of electrical power for half an hour at least the fol- lowing services if they depend upon an electrical source for their operation :

(A) The lighting required by 6 (1) and (2). For this transitional phase, the required emergency electric lighting, in respect of the machinery space and accommodation and service spaces may be provided by permanently fixed, individual, automatically charged, relay operated ac- cumulator lamps ; and

(B) All essential internal communication equipment required by 6 (4) (A) and (B) ;and

(C) Intermittent operation of the services referred to in 6 (4) (C) and (D), unless, in the case of

(B) and (C), they have an independent supply from an accumulator battery suitably located for use in an emergency and sufficient for the period specified.

11. The emergency switchboard is to be installed as near as is practicable to the emergency source of power and, where the emergency source of power is a generator, the emergency switchboard is to be located in the same space unless the operation of the emergency switchboard would thereby be impaired.

12. No accumulator battery fitted to meet the provisions for emergency or transitional power supply should be installed in the same space as the emergency switchboard, unless appropriate measures to the satisfaction of the Society are taken to extract the gases discharged from the said batteries. An indicator is to be mounted in a suitable place on the main switchboard or in the machinery control room to indicate when the batteries constituting either the emergency source of electrical power or the transitional source of electrical power are being discharged.

13. The emergency switchboard is to be supplied during normal operation from the main switchboard by an interconnector feeder which is to be adequately protected at the main switchboard against overload and short circuit and which is to be disconnected automatically at the emergency switch- board upon failure of the main source of electrical power. Where the system is arranged for feed- back operation the interconnector feeder is also to be protected at the emergency switch board at least against short circuit.

14. In order to ensure ready availability of the emergency source of electrical power, arrangements are to be made where necessary to disconnect automatically non-emergency circuits from the emergency switchboard to ensure that electrical power is to be available automatically to the emergency circuits.

15. Condition of inclinations for emergency generator operation are to be in accordance with 103.

16. Provision is to be made for the periodic testing of the complete emergency system. This is to in- clude the testing of transitional sources and automatic starting arrangements.

203. Starting arrangements for emergency generators

1. Emergency generating sets are to be capable of being readily started in their cold condition at a temperature of 0 . If this is impracticable, or if lower temperatures are likely to be encountered, provision acceptable to the Society is to be made for maintenance of heating arrangements, to en- sure ready starting of the generating sets.

2. Each emergency generating set arranged to be automatically started is to be equipped with approved starting devices approved by the Society with a storage energy capability of at least three consec- utive starts. The source of stored energy is to be protected to preclude critical depletion by the au- tomatic starting system, unless a second independent means of starting is provided. In addition, a second source of energy is to be provided for an additional three starts within 30 minutes unless manual starting can be demonstrated to be effective.

3. The stored energy is to be maintained at all times, as follows :

(1) Electrical and hydraulic starting systems are to be maintained from the emergency switchboard.

(2) Compressed air starting systems may be maintained by the main or auxiliary compressed air re- ceivers through a suitable non-return valve or by an emergency air compressor which, if electri- cally driven, is supplied from the emergency switchboard.

(3) All of these starting, charging and energy storing devices are to be located in the emergency generator space. These devices are not to be used for any purpose other than the operation of

the emergency generator set. This does not preclude the supply to the air receiver of the emer- gency generator set from the main or auxiliary compressed air system through a non-return valve fitted in the emergency generator room.

4. Where automatic starting is not required, manual starting is permissible, such as manual cranking inertia starters, manually charged hydraulic accumulators, or power charge cartridges, where they can be demonstrated as being effective.

5. When manual starting is not practicable, the requirements of Par 2 and Par 3 are to be complied with except that starting may be manually initiated.

204. Precautions against shock, fire and other hazards of electrical origin

1. Exposed metal parts of electrical machines or equipment which are not intended to be live but which are liable under fault conditions to become live are to be earthed unless the machines or equipment are:

(1) supplied at a voltage not exceeding 50 V d.c. or 50 V a.c., root mean square between con- ductors; auto-transformers are not to be used for the purpose of achieving this voltage; or

(2) supplied at a voltage not exceeding 250 V by safety isolating transformers supplying only one

consuming device; or

(3) constructed in accordance with the principle of double insulation.

2. Additional safety means are to be provided for portable electrical apparatus for use in confined or exceptionally damp spaces where particular risks due to conductivity exist.

3. All electrical apparatus should be so constructed and so installed that it does not cause injury when handled or touched in the normal manner.

4. Where not obtained through normal construction, arrangements should be provided to effectively

earth all permanently installed machinery, metal structures of derricks, masts and helicopter

Details of impressed-current cathodic protection systems, including installation and locations, be submitted when such systems are installed.

5. Switchboards are to be so arranged as to give easy access, where needed, to apparatus and

decks. are to

equip-

ment, in order to minimize danger to personnel. The sides and backs and, where necessary, the

fronts of switchboards should be suitably guarded. Exposed live parts having voltages to earth ex- ceeding a voltage to be specified by the Society are not to be installed on the front of such switchboards. There are to be nonconducting mats or gratings at the front and rear, where necessary.

6. Distribution systems with hull return are not to be installed, but this does not preclude, under con- ditions approved by the Society, the installation of:

(1) impressed current cathodic protective systems;

(2) limited and locally earthed systems (e.g., engine starting systems);

(3) limited and locally earthed welding systems;where the Society is satisfied that the equipotential

of the structure is assured in a satisfactory manner, welding systems with hull return may be installed without this restriction;and

(4) insulation level monitoring devices provided the circulation current does not exceed 30 mA un- der the most unfavourable conditions.

7. When a distribution system, whether primary or secondary, for power, heating or lighting, with no connection to earth is used, a device capable of continuously monitoring the insulation level to earth and of giving an audible or visual indication of abnormally low insulation values is to be

provided.

8. All metal sheaths and armour of cables are to be electrically continuous and are to be earthed.

9. All electric cables and wiring external to equipment should be at least of a flame-retardant type and should be so installed as not to impair their original flame-retarding properties. Where neces-

sary for particular applications, the Society may permit the use of special types of cables such as radio frequency cables, which do not comply with the foregoing.

10. Cables and wiring serving essential or emergency power, lighting, internal communications or sig-

nals are to be so far as A and their casings and

practicable other high

routed clear of galleys, laundries, machinery spaces of category fire risk areas. Cables connecting fire pumps to the emergency

switchboard are to be of a fire resistant type where they pass through high fire risk areas. Where practicable all such cables are to be run in such a manner as to preclude their being rendered un- serviceable by heating of the bulkheads that may be caused by a fire in an adjacent space.

11. Cables and wiring are to be installed and supported in such a manner as to avoid chafing or oth- er damage.

12. Terminations and joints in all conductors are to be so made that they retain the original electrical, mechanical, flame-retarding and, where necessary, fire-resisting properties of the cable.

13. Each separate circuit should be protected against short circuit and against overload, except as per- mitted in Ch 8, 506., or where the Society may exceptionally otherwise permit.

14. The rating or appropriate setting of the overload protection device for each circuit are to be per- manently indicated at the location of the protection device.

15. Lighting fittings are to be so arranged as to prevent temperature rises which could damage the cables and wiring, and to prevent surrounding material from becoming excessively hot.

16. Accumulator batteries are to be suitably housed, and compartments used primarily for their accom- modation are to be properly constructed and efficiently ventilated.

17. Electrical or other equipment which may constitute a source of ignition of flammable vapours are to not be permitted in these compartments except as permitted in Par 19.

18. Accumulator batteries, except for batteries of self-contained battery-operated lights, are not to be located in sleeping quarters. The Society may grant exemptions from or equivalencies to this provi- sion where hermetically sealed batteries are installed.

19. In paint lockers, acetylene stores, and similar spaces where flammable mixtures are liable to col- lect as well as any compartment assigned principally to accumulator batteries, no electrical equip- ment is to be installed unless the society is satisfied that such equipment is:

(1) essential for operational purposes;

(2) of a type which will not ignite the mixture concerned;

(3) appropriate to the space concerned;and

(4) appropriately certified for safe usage in the vapours or gases likely to be encountered.

20. Electrical apparatus and cables are to, where practicable, be excluded from any compartment in which explosives are stored. Where lighting is required, the light is to come from outside, through the boundaries of the compartment. If electrical equipment cannot be excluded from such a com- partment, it is to be so designed and used as to minimize the risk of fire or explosion.

21. Where spilling or impingement of liquids could occur upon any electrical control or alarm con- sole, or similar electrical enclosure essential to the safety of the unit, such equipment is to have suitable protection against the ingress of liquids referring to KS C IEC 60529.

205. Final sub-circuits

1. In general, each motor for the systems or equipment essential for the safety of the units is to be connected to a separate final sub-circuit.

2. Lighting circuits are to be supplied by final sub-circuit separate from those for heating and motor.

This requirement does not apply to cabin fans and electrical appliances for domestic use.

3. Each heater is to be connected to a separate final sub-circuit except that small heaters may be con- nected to a single final sub-circuit of aggregate current rating not exceeding 15A.

4. Each insulated pole of final sub-circuit is to be protected by a fuse or a circuit -breaker.

206.

High voltage electrical installations

1. Where the high voltage electrical systems or equipment exceeding the voltage of a.c. 1 kV is used for the systems or equipment essential for the safety of the units, the constructions and installations of these systems or equipment are to be in accordance with Pt 6, Ch 1, Sec 16 of Rules for the Classification of Steel Ships.

2. Other high voltage electrical equipment used solely for operating purpose may comply with National or International Standards recognized by the Society.

207. Earthing and cathodic protection

1. Where not obtained through normal construction, arrangements are to be provided to effectively earth all machinery, metal structures of drilling towers, masts and helicopter platforms.

2. Details of impressed-current cathodic protection systems, including installation and locations, are to be submitted when such systems are installed.