Home page Standards & Regulations Installation recommendation Installation recommendation GENERAL REQUIREMENTS Electrical installations for explosive atmosphere must comply with the requirements concerning installations in both non hazardous and hazardous locations: • national rules (Example NFC 15-100 + condition BE3 for France), • EN /IEC 60079-14, • IEC / EN 60079-17. EQUIPMENT SELECTION (EXCEPT CABLE ENTRIES) EXTERNAL INFLUENCES The material must be selected and installed so that it is protected against external, chemical, mechanical, thermal and electrical influences, vibrations, humidity, etc., which are likely to counteract the protection modes provided. PROTECTION AGAINST DANGEROUS SPARKS Limitation of earth fault currents. It is difficult to cover all systems, but the methods presented in EN / IEC 60079-14 represent general cases. These systems can be used in Zones 1 and 2 up to 1 000 V~/1 500 V. (Low voltage equipment). Nota: the equipment intended to be used in explosive atmosphere are not in the scope of LVD 2006/95/EC dated 12/12/2006. EQUALIZATION OF POTENTIALS All exposed conductive parts and all extraneous metallic parts must be connected to the equipotential connection system. The connection system may comprise protective conductors, metal pipes in metal cable ducts and metallic structural elements, but must not include the neutral conductor. It must be impossible for connections to come loose by themselves. CABLES Cables and accessories should be installed such that they are not exposed to mechanical damage, vibration and corrosive or chemical influences, for example due to solvents, and the effects of heat. When this type of exposure is inevitable, protective measures must be taken to install or to select appropriate cables (using reinforced cables with shielding inside a seamless aluminum conduit, cables with a mineral insulation casing, a semi-rigid metal casing …). CABLE JOINTING Whenever possible, complete cable lengths shall be installed in hazardous locations. Where this is impossible, a cable joint must be made to the mechanical, electrical or chemical constraints; it must also be enclosed in an enclosure in which the protection mode is appropriate for the Zone like junction boxes (AQR, EJB, GUB,…). ADDITIONAL REQUIREMENTS FOR TYPE OF PROTECTION ‘d’ – FLAMEPROOF ENCLOSURES Solid obstacles When installing equipment, care shall be exercised to prevent the flameproof flange joint approaching nearer than the distance specified in table below to any solid obstacle which is not part of the equipment, such as steelwork, walls, weather guards, mounting brackets, pipes or other electrical equipment. Protection of flameproof joints Flameproof joints shall be protected against corrosion. Flameproof joints shall not be painted. (WARNING: Painting of the enclosure after complete assembly is permitted. The application of grease to the flameproof joint faces will reduce, but not eliminate, the quantity of paint penetrating the gap (Silicone based greases are often suitable for this purpose) – see § ELECTRICAL INSTALLATIONS INSPECTION AND MAINTENANCE). Cable glands shall: • be appropriate to the type of cable employed, • maintain the type of protection, • be in accordance with § CABLE GLANDS. Thread engagement shall be at least five full threads (5 threads engaged for metric threaded, 3.5 threads engaged for NPT). Suitable grease may be used provided it is non setting, non-metallic and non-combustible and any earthing between the two is maintained. Where the threaded entry or hole size is different to that of the cable gland, a flameproof threaded adapter complying with IEC 60079-1 shall be fitted which complies with thread engagement requirements detailed above. Only one adapter is authorized. Unused cable entries shall be sealed with a flameproof blanking element complying with IEC 60079-1. Conduit systems Conduit sealing devices shall be provided, either as part of the flameproof enclosure or immediately or as close as practical to the entry to the flameproof enclosure using a minimum number of fittings. Conduit sealing devices, having parallel threads may be fitted with a sealing washer between the device and the flameproof enclosure providing that after the washer has been fitted, the applicable thread engagement is still achieved. Thread engagement shall be at least five full threads. (5 threads engaged for metric threaded, 3.5 threads engaged for NPT). Suitable grease may be used provided it is non-setting and any earthing between the two is maintained. ADDITIONAL REQUIREMENTS FOR TYPE OF PROTECTION ‘e’ – INCREASED SAFETY Enclosures containing bare live parts shall have a degree of ingress protection of at least IP54, whereas enclosures containing insulated parts shall only have a degree of ingress protection of at least IP44. The connection of cables to increased safety equipment shall be effected by means of cable glands appropriate to the type of cable used. Cable entries shall also respect « e » protection mode and must incorporate an appropriate sealing element in order to obtain a minimum degree of protection at least equal to IP54 at the enclosure connection. Some terminals (e.g. slot types) may permit the entry of more than one conductor. Where more than one conductor is connected to the same terminal, care shall be taken to ensure that each conductor is adequately clamped. Unless authorized by the documentation supplied with the equipment, two conductors with different diameters must not be connected to the same terminal, unless they have firstly been fixed by means of a single compression sleeve. To avoid the risk of short-circuits between adjacent conductors in terminal blocks, the insulation of each conductor shall be maintained up to the metal of the terminal. Combination of terminals and conductors in connection boxes and junction boxes: Care shall be taken to ensure that the heat dissipated within the enclosure does not result in temperatures in excess of the required equipment temperature class. This can be achieved by: • a) following the guidance technical note given relating to the permissible number of terminals, the conductor size and the maximum current, or • b) contacting us. ADDITIONAL REQUIREMENTS FOR TYPES OF PROTECTION ‘i’ – INTRINSIC SAFETY AND ‘nL’ TYPE OF PROTECTION – ENERGY-LIMITED CIRCUITS The aim of the installation rules for intrinsically safe circuits is to maintain separation from other circuits. Requirements of EPL ‘Gb’ or ‘Gc’ In installations to meet the requirements of EPL ‘Gb’, the intrinsically safe apparatus and the intrinsically safe parts of associated apparatus shall comply at least to level of protection ‘ib’. In installations to meet the requirements of EPL ‘Gc’, the intrinsically safe apparatus and the intrinsically safe parts of associated apparatus shall comply at least to level of protection ‘ic’. Simple apparatus need not be marked, but shall comply with the requirements of IEC 60079-0 and IEC 60079-11, in so far as intrinsic safety is dependent on them. No certification is required for a simple apparatus. Associated apparatus should preferably be located outside the hazardous area or, if installed inside a hazardous area, shall be provided with another appropriate type of protection in like inside a EJB enclosures. All apparatus forming part of an intrinsically safe system should, where reasonably practicable, be identifiable as being part of an intrinsically safe system. If sheaths or coverings are marked by a colour, the colour used for cables containing intrinsically safe circuits shall be light blue. Where intrinsically safe circuits have been identified by the use of light blue covered cable, then light blue covered cable shall not be used for other purposes in a manner or location which could lead to confusion or detract from the effectiveness of the identification of intrinsically safe circuits.If all intrinsically safe circuit cables or all cables of circuits which are not intrinsically safe are armoured, metal sheathed or screened, then marking of intrinsically safe circuit cables is not required. Alternative marking measures shall be taken inside control cabinets: • combining the cores in a common light blue harness, • labelling, • clear arrangement and spatial separation. The installation shall ensure that intrinsically safe circuit cables cannot be inadvertently connected to circuit cables which are not intrinsically safe. This may be achieved by: • a) separating the different types of circuit cables, or • b) placing the cables so as to protect against the risk of mechanical damage, or • c) using cables which are armoured, metal sheathed or screened for specific types of circuits (e.g. all circuits which are not intrinsically safe are run in armoured cable or all intrinsically safe circuits are armoured). Terminals for intrinsically safe circuits shall be separated from terminals of circuits which are not intrinsically safe: • a) When separation is accomplished by distance, then the clearance between terminals shall be at least 50 mm, • b) When separation is accomplished by use of an insulating partition or earthed metal partition, the partitions used shall extend to within 1,5 mm of the walls of the enclosure, or alternatively provide a minimum measurement of 50 mm between the terminals when taken in any direction around the partition. The minimum clearances between the bare conducting parts of external conductors connected to terminals and earthed metal or other conducting parts shall be 3 mm. The clearance between the bare conducting parts of field wiring terminals of separate intrinsically safe circuits shall be such that there is at least 6 mm between the bare conducting parts of connected external conductors. The terminals of the intrinsically safe circuits shall be marked as such. This marking may be by the use of colour, in which case it shall be light blue.