8.1 General
8.1.1 Electrical arrangements for workboats certificated under this code should
comply with the requirements given below and be in compliance with international or
national standards for marine electrical installations or the standards published by the
UK authorised Classification Societies and appropriate for workboats <24M Load line
length.
8.1.2 The design and installation of electrical systems and equipment should be
appropriate for the vessel's particular duties and the environment in which it operates.
Electrical equipment should be suitable for use in a marine environment with due
consideration of humidity, temperature, degradation due to salt water and vibration.
Special consideration should be given to the choice and installation of electrical
equipment that could be subjected to large vibration and shock loadings e.g. Offshore
Service Vessels.
8.1.3 For general guidance, a number of the most common standards which are
appropriate to a small vessel are listed in the Appendix 13 (other standards which are
considered more appropriate and safe for a particular application may be used, provided
they are acceptable to the Certifying Authority). MGN 359footnote also refers.
8.2 Electrical Requirements
8.2.1 The electrical equipment and installations (including any electrical means
of propulsion) shall be such that the vessel and all persons on board are protected
against electrical hazards.
8.2.2 The electrical equipment and installations shall be maintained to ensure
that the vessel is in an operational and habitable condition.
8.2.3 Multihulls and vessels fitted with multiple engine rooms should refer to
Section 7.1.5.
8.3 Lighting
8.3.1 For lighting distribution in common accommodation areas, it is recommended
that the lighting is distributed on different final circuits to maintain a level of
lighting in case of failure of a single distribution circuit.
8.3.2 Consideration should be given to the design and placement of lighting in
order to preserve the night vision of Navigation Watchkeepers.
8.4 Batteries
8.4.1 Battery System Requirements
8.4.1.1 Batteries and battery systems should be provided to satisfy, as a minimum, the
back up requirements of sections 7, 16, 18 and 19 regarding propulsion machinery
starting systems, radio communication systems, electronic navigation and electronic
charts.
8.4.1.2 The battery terminals should be protected against accidental contact with
metallic objects.
8.4.1.3 Battery charging systems should be fitted with circuitry to prevent overcharging
and over-voltage, and should have a charge indicator.
8.4.1.4 A battery disconnect switch should be provided to simultaneously isolate all non
earthed poles.
8.4.2 Battery Stowage
8.4.2.1 All batteries should be secured firmly to avoid movement when the vessel is
subjected to sudden acceleration or deceleration, a large angle of heel or trim.
8.4.2.2 Ventilated batteries should be installed with drip trays to collect any
electrolyte spillage.
8.4.3 Ventilation
8.4.3.1 To ensure that any evolved hydrogen released by ventilated batteries under
normal operation or valve regulated batteries under charger fault condition is expelled,
battery compartments, lockers and containers should be supplied with air at a level
below the top of the batteries, and should be exhausted from the highest point of the
space directly to the open air with bends of no more than 45° to ensure no trapped
pockets of hydrogen.
8.4.3.2 Particular installation and ventilation arrangements should follow national
standards, and standards of a recognised Classification Society appropriate for battery
installations on small workboats and including any necessary provisions for electrical
apparatus in hazardous areas.
8.5 Cables
8.5.1 Electric cables should be constructed to a recognised standard (see 8.1 and
Appendix 13) for marine use in small vessels.
8.5.2 Note that when selecting cables, particular attention should be given to
environmental factors such as temperature and contact with damaging substances, e.g.
polystyrene, which degrades PVC insulation or for example the effect of salt laden
atmosphere on un-tinned exposed copper conductors.
8.5.3 Adequate provision should be made for securing electrical connections, e.g.
by use of locking washers.
8.5.4 Cables should be secured and protected against chafe. For example, where
they enter and exit cable pipes or bulkhead transits or battery boxes.
8.5.5 Cables for different applications should be installed to provide the
necessary separation and other safeguards to minimise electromagnetic interference
(EMI), as detailed in the referenced standards and guidance.
8.6 Hazardous Spaces
8.6.1 Where practicable, electrical equipment should not be installed in a space
where petroleum vapour or other hydrocarbon gas is likely to accumulate. When equipment
is installed in such a space it must comply with a recognised standard for prevention of
ignition of a flammable atmosphere.
8.6.2 Any compartment which contains a gas consuming appliance or any compartment
into which flammable gas may leak or accumulate, should be provided with a hydrocarbon
gas detector and alarm. The detector and alarm should be designed to comply with a
recognised standard relating to electrical equipment in hazardous areas.
8.6.3 Where explosion proof electrical equipment is fitted on board a vessel, it
must be maintained in accordance with the manufacturers’ requirements and serviced
appropriately to maintain its certified explosion proof characteristics.
8.6.4 Vessels in which the carriage of Dangerous Goods is intended, should comply
with the additional requirements indicated in Section 29.
8.7 Lightning Protection
8.7.1 Where a considerable risk of lightning strike is identified, it is
recommended that attention is paid to lightning strike protection. For information on
lightning protection, reference should be made to ISO 10134 “Small Vessels - Electrical
Devices - Lightning Protection Systems” and other guidance referenced in Appendix 13.
8.8 Emergency Supplies
8.8.1 Emergency Lighting
8.8.1.1 When general lighting within a vessel is provided by a centralised electrical
system, an alternative source of lighting (which may be a suitable portable battery
operated lamp(s) if practical, taking into consideration the size and complexity of the
vessel) should be provided. This alternative source of lighting should be sufficient
to:-
- .1 enable persons to make their way to the open deck;
- .2 illuminate survival craft launching and embarkation;
- .3 illuminate man-overboard rescue equipment and rescue areas;
- .4 permit work on essential machinery;
- .5 illuminate emergency control and communication centres.
8.8.1.2 This alternative source of lighting should be capable of operation for a period
of time sufficient to deal with emergency situations and to enable the safe mustering
and evacuation of all persons on board.
8.8.2 Emergency Radio
8.8.2.1 Emergency supplies to GMDSS radio equipment should be designed and installed to
supply the equipment for a minimum of 3 hours in the event of failure of the main
electrical supply.
8.8.3 Navigational Supplies
8.8.3.1 Emergency power should be readily available to supply navigation lights and
navigation equipment for a minimum of 3 hours. The navigation equipment to be supplied
by emergency power should include Global Navigation Satellite System (GNSS), echo
sounder and Automatic Identification System (AIS).
8.8.4 Emergency Batteries
8.8.4.1 Batteries supplying essential services (emergency lighting, steering systems,
navigation and communications equipment) should be located in a position not likely to
flood in normal operations or in the event of minor damage.
8.10 Earthing and Bonding
8.10.1 The purpose of earthing and bonding of non-current carrying parts of an
electrical system is to reduce the danger of shock to personnel and to minimise damage
to equipment and corrosion from the effects of earth currents. These can occur from
failures of insulation of live conductors, induced voltages and currents.
8.10.2 All exposed non-current carrying conductive parts of both fixed and portable
electrical machines or equipment which are liable under fault conditions to become live
and similar parts inside non-metallic enclosures are to be connected to earth unless the
machines or equipment are:
- a) supplied at a voltage not exceeding 50 V direct current or 50 V root
mean square between conductors, achieved without the use of auto-transformers, or;
- b) supplied at a voltage not exceeding 250 V by safety isolating transformers
supplying only one consuming device, or;
- c) constructed in accordance with the principle of double insulation (Class II) as
per IEC 61440 or equivalent insulation intended to prevent the appearance of
dangerous voltages on its accessible parts due to a fault in the basic insulation.