As per EN 60079-14 : 2014-04;
9.3.2 Cables for fixed installations
Cables used for fixed installations in hazardous areas shall be appropriate for the ambient conditions in service. Cables shall be:
a) sheathed with thermoplastic, thermosetting, or elastomeric material. They shall be circular and compact. Any bedding or sheath shall be extruded. Fillers, if any, shall be nonhygroscopic; or
b) mineral insulated metal sheathed; or
c) special, e.g. flat cables with appropriate cable glands. They shall be compact and any bedding or sheath shall be extruded. Fillers, if any, shall be non-hygroscopic.
Where there is a likelihood that gas or vapour migration may occur through the interstices between individual cores of a cable, and the cable leads to a non-hazardous area or between different zones, then the construction and application of the cable shall be taken into account. Appropriate control measures to mitigate this condition shall be considered (see Annex E). Where there is a likelihood that propagation of flames may occur through the interstices between individual cores of a cable, this shall also be considered.
Mineral insulated cables shall be sealed.
10.2 Selection of cable glands
The cable gland shall be selected to match the cable diameter. The use of sealing tape, heat shrink tube or other materials is not permitted to make the cable fit to the cable gland.
Cable glands and/or cables shall be selected to reduce the effects of “coldflow characteristics” of the cable.
NOTE 1 Cables employ materials which could exhibit “coldflow” characteristics. Coldflow in cables can be described as the movement of the cable sheath under the compressive forces created by the displacement of seals in cable glands where the compressive force applied by the seal is greater than the resistance of the cable sheath to deformation. Coldflow could give rise to a reduction in the insulation resistance of the cable. Low smoke and/or fire resistant cables usually exhibit significant cold flow characteristics.
Cable glands shall be in accordance with IEC 60079-0 and shall be selected to maintain the requirements of the protection technique according to Table 10.
To meet the ingress protection requirement it may also be necessary to seal between cable glands, adapters and blanking elements and the enclosure (for example by means of a sealing washer or thread sealant).
NOTE 2 In order to meet the minimum requirement of IP54, threaded cable entry devices into threaded cable entry plates or enclosures of 6 mm or greater thickness need no additional sealing between the cable entry device and the entry plate or enclosure provided the axis of the cable entry device is perpendicular to the external surface of the cable entry plate or enclosure.
Where mineral-insulated metal sheathed cables are used, the requirement to achieve creepage distances shall be maintained by using a certified mineral insulated cable sealing device.
Cable Gland Selection Chart
1) Internal sources of ignition include sparks or equipment temperatures occurring in normal operation which can cause ignition. An enclosure containing terminals only or an indirect entry enclosure is considered not to constitute an internal source of ignition.
2) The term ‚volume‘ is defined in IEC 60079-1
e)Flameproof cable gland specified in the equipment documentation or complying with IEC 60079-1. Incorporating compound filled seals or elastometric seals that seal around the individual cores or other equivalent sealing arrangements.
d)Flameproof sealing device (for example a sealing chamber) specified in the equipment documentation or complying with IEC 60079-1and employing a cable gland appropriate to the cables used. The sealing device shall incorporate compound or other appropriate seals which permit stopping around individual cores. The sealing device shall be fitted at the point of entry of cables to the equipment.