Extract From EN 60079-14 : 1997 / IEC 60079-14 : 1996
Installations In Hazardous Areas
1.0 Connections
The connection of cables and conduits to the electrical apparatus shall be made in accordance with the requirements of the relevant type of protection.
Notes:
- Certain types of cable employ materials which can exhibit significant "cold flow" characteristics which could have adverse effects on the protection of the apparatus. Where such cable is to be used, a suitable cable entry device should be employed, for example cable entry devices not employing compression seals which act upon the part(s) of the cable having "cold flow" characteristics.
- "Cold flow" can be more fully described as "thermoplastic materials which flow when subjected to pressure of ambient temperature".
Figure 1 - Selection chart for cable entry devices into flameproof enclosures for cables complying with item b) of 2.2 Selection
It is important to read notes and 2.2 Selection before selecting appropriate cable gland for flameproof applications from Figure 1 below:
NOTE - 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 (see 2.1 General) is considered not to constitute an internal source of ignition.
Extract From EN 60079-14 : 1997 / IEC 60079-14 : 1996
2.0 Cable Entry Systems
2.1 General
It is essential that cable entry systems comply with all the requirements referred to in the appropriate apparatus standard, that the cable entry device is appropriate to the type of cable employed, maintains the respective method of protection and is in accordance with clause 9.
Where cables enter into flameproof apparatus via flameproof bushings through the wall of the enclosure which are part of the apparatus (indirect entry), the parts of the bushings outside the flameproof enclosure will be protected in accordance with one of the types of protection listed in IEC 79-0. Normally the exposed part of the bushings will be within a terminal compartment which will either be another flameproof enclosure or will be protected by protection type ‘e’. Where the terminal compartment is Ex‘d’, then the cable system shall comply with 2.2. Where the terminal compartment is Ex‘e’, then the cable system shall comply with 3.0
Where cables enter into flameproof apparatus directly, the cable system shall comply with 2.2
2.2 Selection
The cable entry system shall comply with one of the following:
a) cable entry device in compliance with IEC 79-1 and the particular type of cable intended for use with that device.
b) thermoplastic, thermosetting or elastomeric cable which is substantially compact and circular, has extruded bedding and the fillers, if any, are non-hygroscopic, may utilize flameproof cable entry devices, incorporating a sealing ring selected in accordance with figure 1;
c) mineral insulated cable with or without plastic outer covering with appropriate flameproof cable entry device;
d) flameproof sealing device (for example a stopper box or sealing chamber) specified in the apparatus documentation or having component approval and employing cable entry devices appropriate to the cables used. The sealing devices such as stopper boxes or sealing chambers shall incorporate compound or other appropriate seals which permit stopping around individual cores. Sealing devices shall be fitted at the point of entry of cables to the apparatus;
e) flameproof cable entry devices incorporating compound filled seals around the individual cores or other equivalent sealing arrangements;
f) other means which maintain the integrity of the flameproof enclosure.
NOTE - Where a factory-made termination of the encapsulated type is used, no attempt should be made to interfere with the connection to the apparatus or to replace the cable.
Extract From EN 60079-14 : 1997 / IEC 60079-14 : 1996
3.0 Wiring Systems
3.1 General
Cables and conduits shall be installed in accordance with clause 9 and the following additional requirements concerning cable entries and conductor termination's.
3.2 Cable Entry Devices
The connection of cables to increased safety apparatus shall be effected by means of cable entry devices appropriate to the type of cable used. They shall maintain protection type ‘e’ and shall incorporate a suitable sealing component to achieve IP54 degree of protection of the terminal enclosure.
NOTES
- 1 To meet IP 54 it may be necessary to seal between the cable and the enclosure (for example by means of a sealing washer or thread sealant.
- Threaded cable entry devices into threaded cable entry plates or enclosures of 6mm or greater thickness need no additional sealing between the cable entry device and the entry plate or enclosure providing the axis of the cable entry device is perpendicular to the external surface of the cable entry plate or enclosure.
ACKNOWLEDGEMENT
Extracts from BS EN 60079-14 : 1997 reproduced with the permission of BSI under licence no. PD/1998 1818 and 1920. Complete editions of the standards can be obtained by post from BSI Customer Services, 389 Chiswick high Road, London. W4 4AL
