Section 1 General requirements

1.1 General

1.1.1 The requirements of this Chapter apply to all offshore units defined in Pt 1, Ch 2 Classification Regulations except where otherwise stated. Where applicable, the relevant requirements for electrical services necessary to maintain the unit in a normal sea-going, operational and habitable condition, for electrical services essential for safety and for the safety of crew and unit from electrical hazards as stated in Pt 6, Ch 2 Electrical Engineering of the Rules and Regulations for the Classification of Ships (hereinafter referred to as the Rules for Ships) are to be complied with.

1.1.2 Attention is also to be given to any relevant statutory regulation of the National Administration in the country in which the unit is to operate and/or be registered.

1.1.3 Where reference is made to the requirements of the Rules for Ships, references therein to ‘ship(s)’ are to be understood to refer to ‘unit(s)’.

1.2 Documentation required for design review

1.2.1 The documentation in Pt 6, Ch 2, 1.2 Documentation required for design review of the Rules for Ships is to be submitted for consideration. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

NOTE

Where reference is made in the Rules for Ships to explosive gas atmospheres and/or combustible dusts, or to the electrical equipment for use in those areas, see also Pt 7, Ch 2, 8 Electrical equipment for use in explosive gas atmospheres and Pt 7, Ch 2, 9 Additional requirements for electrical equipment on oil storage units for the storage of oil in bulk having a flash point not exceeding 60°C (closed-cup test).

1.2.2 Electrical system study and calculations are to be in accordance with the IEC 61892-2:2012, Mobile and fixed offshore units – Electrical installations – Part 2: System design, Section 9, or an alternative relevant International or National Standard.

1.2.3 The general arrangement of the unit, showing the hazardous zones and spaces, is to include details on the permitted temperature class and gas group of the electrical equipment. The temperature class and apparatus group of the electrical equipment are associated with the ignition temperature and energy required for ignition of the hazardous substances.

1.3 Documentation required for supporting evidence

1.3.1 The documentation and particulars in Pt 6, Ch 2, 1.3 Documentation required for supporting evidenceof the Rules for Ships are to be submitted as supporting evidence. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

1.3.2 A description of the philosophy of the systems of power generation and distribution, describing their modes of operation under normal and emergency conditions, is to be submitted.

1.3.3 Arrangement plans of main and emergency switchboards, section boards, and documentation that demonstrates that creepage and clearance distances are in accordance with Pt 6, Ch 2, 7.5 Creepage and clearance distances. The form factor of internal separation of low voltage switchgear and control gear assemblies is to be in accordance with IEC 61439-2, Low-voltage switchgear and control gear assemblies – Part 2: Power switchgear and control gear assemblies, or alternative relevant International or National Standards. The form factor is to be stated, and the arrangement plans are to show how the form factor has been achieved.

1.4 Surveys

1.4.1 The equipment required to be surveyed is given in Pt 6, Ch 2, 1.4 Surveys of the Rules for Ships, which are to be complied with.

1.5 Additions or alterations

1.5.1 The requirements for additions or alterations are given in Pt 6, Ch 2, 1.5 Additions or alterations of the Rules for Ships, which are to be complied with.

1.6 Definitions

1.6.1 Definitions are given in Pt 6, Ch 2, 1.6 Definitions of the Rules for Ships and in IEC 61892-1:2010, Mobile and fixed offshore units – Electrical installations – Part 1: General requirements and conditions, Section 3. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

1.6.2 Essential services are those necessary for the propulsion and safety of the unit, such as the following:

Items as given in Pt 6, Ch 2, 1.6 Definitions 1.6.1 of the Rules for Ships;
Thruster systems for positional mooring;
Abandonment systems dependent on electric power;
Ventilation systems for hazardous areas and those maintained at an overpressure to exclude the ingress of dangerous gases;
Wellhead control and disconnection systems dependent on electric power.

1.6.3 Services considered necessary for minimum comfortable conditions of habitability are given in Pt 6, Ch 2, 1.6 Definitions 1.6.2 of the Rules for Ships.

1.6.4 Services such as the following, which are additional to those in Pt 6, Ch 2, 1.6 Definitions 1.6.2 and Pt 6, Ch 2, 1.6 Definitions 1.6.3, are considered necessary to maintain the unit in a normal and sea-going operation and habitable condition:

Drilling plant equipment;
Processing and production equipment;
Hotel services, other than those required for habitable conditions;
Thrusters, other than those for essential services; and
Lifting appliances for the transfer of material, equipment or personnel.

1.7 Design and construction of equipment

1.7.1 The requirements for design and construction are given in Pt 6, Ch 2, 1.7 Design and construction of the Rules for Ships, which are to be complied with. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

1.7.2 Equipment or apparatus required to be suitable for use in an explosive gas atmosphere shall comply with the requirements of Pt 7, Ch 2 Hazardous Areas and Ventilation, Pt 6, Ch 2, 8 Protection from electric arc hazards within electrical equipment, Pt 6, Ch 2, 9 Rotating machines, Pt 6, Ch 2, 10 Converter equipment and Pt 6, Ch 2, 11 Electrical cables and busbar trunking systems (busways), IEC 60092-502, Electrical installations in ships – Part 502: Tankers – Special features, IEC 61892-7, Mobile and fixed offshore units – Electrical installations – Part 7: Hazardous areas or alternative relevant International or National Standard. Such equipment shall be constructed and tested in accordance with the requirements of the IEC 60079 series, Explosive atmospheres (or alternative relevant International or National Standard) and be fit for purpose for the actual ambient temperature and other environmental conditions.

1.8 Quality of power supplies

1.8.1 The requirements for quality of power supplies are given in Pt 6, Ch 2, 1.8 Quality of power supplies of the Rules for Ships and IEC 61892- 1:2010, Mobile and fixed offshore units – Electrical installations – Part 1: General requirements and conditions, Section 4.7, which are to be complied with.

1.9 Ambient reference and operating conditions

1.9.1 The requirements for ambient reference and operating conditions are given in Pt 6, Ch 2, 1.9 Ambient reference and operating conditions of the Rules for Ships, which are to be complied with where applicable. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

1.9.2 The rating for classification purposes of essential electrical equipment is to be based on the maximum ambient air and water temperatures expected at the location of the unit. In the absence of precise temperatures, the following temperatures are to be assumed:

For units intended to operate within the tropical belt (i.e. between latitudes 35°N and 20°S):
- Primary cooling water supply 32°C
- Cooling air temperature 45°C.
For units intended to operate in northern or southern waters outside the tropical belt:
- Primary cooling water supply 25°C
- Cooling air temperature 40°C.

1.9.3 The air temperature range considered with respect to the selection of equipment, the safe operation of which may be subject to limitations on ambient temperature (e.g. safe type electrical equipment), is to be that expected at the location of the equipment, taking into account local sources of heat and the range of ambient air temperature expected at the location of the unit. In the absence of precise information, the maximum air temperature is to be assumed to be that of the cooling air temperature given in Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2 or Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2, as appropriate, and the minimum is to be assumed to be minus 20°C, or as determined by reference to Annex B of IEC 61892-1, Mobile and fixed offshore units – Electrical installations – Part 1: General requirements and conditions.

1.9.4 Where electrical equipment is installed within environmentally controlled spaces, the ambient temperature for which the equipment is suitable for operation at its rated capacity may be reduced to a value not more than 10°C below that determined by reference to Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2 or Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.3, provided:

the equipment is not for use for emergency services and is located outside of machinery space(s);
temperature control is achieved by an independent and redundant cooling unit(s) so arranged that, in the event of loss of one cooling unit, for any reason, the remaining unit(s) will be capable of satisfactorily maintaining the design temperature;
the equipment is able to be initially set to work safely within the cooling temperature (see Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2 and Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2) until such a time that the lesser ambient temperature may be achieved; the cooling equipment is to be rated for an ambient temperature of not less than the cooling temperature (see Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2 and Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.2); and
alarms are provided, at a continuously attended control station, to indicate any malfunction of the cooling units. See also Pt 6, Ch 1, 1.3 Control, alarm and safety equipment 1.3.3.

1.9.5 Where equipment is to comply with Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.4, it is to be ensured that electrical cables for their entire length are adequately rated for the maximum ambient temperature to which they are exposed along their length.

1.9.6 Items of equipment used for cooling and maintaining the lesser ambient temperature in accordance with Pt 6, Ch 2, 1.9 Ambient reference and operating conditions 1.9.4 are considered essential services and are to satisfy the requirements of Pt 6, Ch 2, 5.2 Essential services.

1.10 Inclination of the unit

1.10.1 The requirements for inclination of the unit are given in Pt 6, Ch 2, 1.10 Inclination of ship of the Rules for Ships, which are to be complied with where applicable. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

1.10.2 Essential and emergency electrical equipment is to operate satisfactorily under the conditions as shown in Pt 6, Ch 2, 1.10 Inclination of the unit 1.10.2 for column-stabilised, tension-leg and self-elevating units. For buoy and deep draught caisson units, the angles of inclination will be specially considered in each case.

Table 2.1.1 Inclination of other units

Installations,components	Angle of inclination, degrees in any direction
	Column-stabilised units		Self-elevating units
	Static	Dynamic	Static	Dynamic
Essential electrical equipment	15	22,5	10	15
Electrical equipment for emergency services	25	25	15	15

1.11 Location and construction of equipment

1.11.1 The requirements for location and construction are given in IEC 61892-1:2010, Mobile and fixed offshore units – Electrical installations – Part 1: General requirements and conditions, Sections 4.15 to 4.20 and Pt 6, Ch 2, 1.11 Location and construction of the Rules for Ships, which are to be complied with. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

1.11.2 Electrical equipment, as far as is practicable, is to be located:

Such that it is accessible for the purpose of maintenance and survey;
Clear of flammable material;
In spaces adequately ventilated to remove the waste heat liberated by the equipment under full load conditions, at the ambient conditions specified in Pt 6, Ch 2, 1.9 Ambient reference and operating conditions;
Where flammable gases cannot accumulate. If this is not practicable, electrical equipment is to comply with the relevant requirements of Pt 7, Ch 2, 8 Electrical equipment for use in explosive gas atmospheres;
Where it is not exposed to the risk of mechanical injury or damage from water, steam or oil; and
Clear of areas at risk of cryogenic spills.

1.11.3 Equipment located in hazardous areas, or required to remain operational during catastrophic conditions, is to comply with the relevant requirements of Pt 7, Ch 2, 8 Electrical equipment for use in explosive gas atmospheres.

1.11.4 Where electrical power is used for propulsion, the equipment is to be so arranged that it will operate satisfactorily in the event of partial flooding by bilge water above the tank top up to the bottom floor plate level, under the normal angles of inclination given in Pt 6, Ch 2, 1.10 Inclination of the unit for essential electrical equipment, see also Pt 5, Ch 13 Bilge and Ballast Piping Systems.

1.12 Earthing of non-current-carrying parts

1.12.1 The requirements for earthing of non-current-carrying parts are given in Pt 6, Ch 2, 1.12 Earthing of non-current carrying parts of the Rules for Ships and IEC 61892-6:2007 Section 4 Mobile and fixed offshore units – Electrical installations – Part 6: Installation which are to be complied with. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

1.12.2 Where the current-carrying conductor exceeds 120 mm², a 70 mm² earthing conductor is permitted, provided that the circuit protection arrangements are such as will prevent an excessive temperature rise under fault conditions.

1.13 Bonding for the control of static electricity

1.13.1 The requirements for bonding for the control of static electricity are given in Pt 6, Ch 2, 1.13 Bonding for the control of static electricity of the Rules for Ships, IEC 60092-502:1999, Electrical installations in ships – Part 502: Tankers – Special features, Section 5.5 and IEC 61892-6:2007, Mobile and fixed offshore units – Electrical installations – Part 6: Installation, Section 4, which are to be complied with where applicable. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

1.13.2 Bonding straps for the control of static electricity are required for storage tanks, process plant and piping systems located in hazardous areas, or for flammable products and solids liable to release flammable gas and/or combustible dust, which are not permanently connected to the structure of the unit either directly or via their bolted or welded supports and where the resistance between them and the structure exceeds 1MΩ.

1.14 Alarms

1.14.1 The requirements for alarms are given in IEC 61892-2:2012, Mobile and fixed offshore units – Electrical installations – Part 2: System design, Section 12.12.2.4 and Pt 6, Ch 2, 1.14 Alarms of the Rules for Ships which are to be complied with. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

1.14.2 Cables for emergency alarms and their power sources are to be in accordance with Pt 6, Ch 2, 1.16 Operation under fire conditions.

1.14.3 Electrical equipment and cables for emergency alarms are to be so arranged that the loss of alarms in any one area due to localised fire, cryogenic spill, collision, flooding or similar damage is minimised, see Pt 6, Ch 2, 1.16 Operation under fire conditions, Pt 6, Ch 2, 1.17 Operation under flooding conditions and Pt 11, Ch 5, 7 Cryogenic releases, .

1.15 Labels, signs and notices

1.15.1 The requirements for labels, signs and notices are given in Pt 6, Ch 2, 1.15 Labels, signs and notices of the Rules for Ships, which are to be complied with.

1.16 Operation under fire conditions

1.16.1 The requirements for operation under fire conditions are given in Pt 6, Ch 2, 1.16 Operation under fire conditions of the Rules for Ships, which are to be complied with. Additions or amendments to these requirements are given in the following paragraph(s) of this sub-Section.

NOTE

For fire safety stops, see also Pt 7, Ch 1, 2.4 Fire safety stops.
For low location lighting, see also Pt 7, Ch 1, 3.5 Escape route or low location lighting (LLL).

1.16.2 The following emergency services and their emergency power supplies are also required to be capable of being operated under fire conditions:

Emergency Shut-down (ESD) systems, see Pt 7, Ch 1, 7 Emergency shutdown (ESD) systems.
Emergency Release Systems (ERS), see Pt 7, Ch 1, 8 Emergency release systems (ERS).

1.17 Operation under flooding conditions

1.17.1 The requirements for operation under flooding conditions are given in Pt 6, Ch 2, 1.17 Operation under flooding conditions of the Rules for Ships, which are to be complied with.

1.18 Protection of electrical equipment against the effects of lightning strikes

1.18.1 The requirements for protection of electrical equipment against the effects of lightning strikes are given in Pt 6, Ch 2, 1.18 Protection of electrical equipment against the effects of lightning strikes of the Rules for Ships, which are to be complied with.

1.19 Programmable electronic systems

1.19.1 The requirements for programmable electronic systems are given in Pt 6, Ch 2, 1.19 Programmable electronic systems of the Rules for Ships, which are to be complied with.