BS EN ISO 10133:2017 ISO 10133:2012(E)


3.15 self-limiting device whose maximum output is restricted to a specified value by its magnetic or electrical characteristics


3.16 two-wire d.c. system with negative ground (earth) system in which the d.c. negative is connected to the ground through a metallic hull, the propulsion system or other means


4 General requirements


4.1 The system type shall be either a fully insulated two-wire d.c. system or a two-wire d.c. system with negative ground. Engine-mounted wiring systems can use the engine block as the grounded conductor.


For d.c. systems with a negative ground, the main grounding/earthing point shall be either: a)


the engine negative terminal; or b) a main grounding bus of sufficient current-carrying capacity.


The hull shall not be used as a current-carrying conductor. Systems with multiple battery banks shall have a common negative connection. Exceptions to this are for dedicated electrical systems isolated from a boat system, e.g. electric propulsion systems that are clearly identified as part of the isolated system.


4.2 An equipotential bonding conductor, if fitted, shall be connected to the craft’s main grounding/earthing point. 4.3


4.4


All manually operated switches and controls shall be marked to indicate their use, unless the purpose of the switch is obvious and mistaken operation of it will not cause a hazardous condition.


Protective devices such as trip-free circuit breakers or fuses shall be provided at the source of power,


e.g. the panel board (switchboard), to interrupt any overload current in the circuit conductors before heat can damage conductor insulation, connections or wiring system terminals.


4.5 The selection, arrangement and performance characteristics shall be such that: a)


there is a maximum continuity of service to healthy circuits where fault conditions exist in other circuits through selective operation of the various protective devices; and


b) electrical equipment and circuits are protected from damage due to overcurrents by coordination of the electrical characteristics of the circuit or apparatus and the tripping characteristics of the protective devices.


All d.c. equipment shall be capable of function within a voltage range of 75 % to 133% of nominal voltage at the battery terminals, e.g.:


4.6


— for a 12 V system: 9 V to 16 V; — for a 24 V system: 18 V to 32 V; — for a 48 V system: 36 V to 64 V.


EXCEPTION Where the circuit includes equipment requiring a higherminimumvoltage, the specified minimum voltage shall be used in the calculation of the conductor size. See Annex A.


4.7 The length and cross-sectional area of conductors in each circuit shall be such that the calculated voltage drop does not exceed 10 % of the nominal voltage. © ISO 2012 – All rights reserved


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