IEC 60092-506-2003 pdf – Electrical installations in ships – Part 506: Special features – Ships carrying specific dangerous goods and materials hazardous only in bulk.
5 Electrical equipment in hazardous areas and areas where explosives are stored 5.1 General Electrical equipment and wiring shall not be fitted in hazardous areas and in areas where explosives are stored unless it is essential for the safety and operation of the ship. The electrical equipment installed and employed shall be suitable for the dangerous goods to be carried with due consideration of the following criteria: − for explosive dust concentration and in areas where explosives are stored • degree of protection IPXX (see IEC 60529); • surface temperature; − for explosive gas atmosphere • temperature class (IEC 60079 and IEC 60092-1 01 , Clause 1 2); • apparatus group (see IEC 60079 and IEC 60092-1 01 , Clause 1 2). 5.2 Risk due to explosive dust only from solid bulk cargoes The electrical equipment shall comply with the following minimum requirements, unless otherwise specified (see also 5.3 and Annex A): − degree of protection IP5X and surface temperature maximum 200 °C, or − certified safe type equipment of temperature class T3 having a degree of protection IP5X. If cargoes are to be carried which require a lower surface temperature, this shall be taken into consideration. NOTE Certain cargoes in class 5.1 and 9 require that the electrical equipment is disconnected. 5.3 Risk due to explosive gas atmosphere only Unless otherwise specified, the minimum requirements are (see also 5.4 and Annex A): − temperature class T3; − apparatus group IIB. If dangerous cargoes are to be carried which require equipment of a higher grading (for example, temperature class T4, T5 or T6, or apparatus group IIC), this shall be taken into consideration.
5.6 For dangerous goods class 1 as defined in 1 .2a) the electrical equipment shall meet the following requirements (see note 1 ): − degree of protection IP6X − surface temperature maximum 1 00 °C NOTE 1 Where dangerous goods of class I division 1 .4, compatibility group S, only are to be carried, special precautions for the construction installation and use of electrical equipment are not required. NOTE 2 Equipment other than of a certified-safe type may be used when safe operation is secured and it is acceptable to the appropriate authority. 5.7 Electrical equipment in the extended hazardous areas defined in 4.3.2e) and f) and 4.3.3e) and f) and as indicated in Annex B, items D, F or G shall at least be suitable for zone 2 shall be either: a) appropriate for use in the adjacent space in accordance with 5.1 to 5.6, or b) of type of protection “n” and of appropriate temperature class, apparatus group and degree of protection in accordance with 5.1 to 5.6, or c) of a type which ensures absence of sparks or arcs and hot spots during normal operation and which is approved by the appropriate authority. 6 Installation of electrical equipment in hazardous areas 6.1 In areas which are classified as hazardous when dangerous goods are carried, electrical equipment which is not essential for the safety and operation of the ship and which is not of a type approved for use in the hazardous areas specified in Clause 5, shall be − completely disconnected, and − protected against unauthorized re-connection. Disconnection shall be made outside the hazardous areas and be effected with isolating links or lockable switches. 6.2 All cables and electrical equipment shall be protected against mechanical damage.
7.1 .2 During initial start-up or after shut-down, it is necessary, before energizing any electrical apparatus within the space which is not suitably protected for the classification of the space in the absence of pressurization, to a) either ensure that the internal atmosphere is non-hazardous, or proceed with prior purging of sufficient duration that the internal atmosphere may be considered as non-hazardous, and b) pressurize the space. NOTE The atmosphere is considered non-hazardous when, at all points in the space, the equipment enclosures and any associated ducts, the concentration of explosive gases or vapours is below 30 % of the lower explosive limit. The place of measurement should be judiciously chosen to determine the highest concentration of gas. 7.1 .3 Monitoring shall be provided to ensure the satisfactory functioning of pressurization of spaces having an opening into a more hazardous zone. 7.1 .4 Where a flow monitoring device is used to indicate failure of pressurization, it should be verified that either the pressurization level required by 6.1 .1 is maintained with any door or other opening open, or an alarm is given if any door or opening is not closed.