Cable flameproof

These are heat- and flameproof cables suitable for high fire risk zones. In severe fire conditions, when the outer protection and insulation have been destroyed, these cables would still maintain continuity of essential services. 

In a very general sense, terminal boxes, regardless of their type of protection (increased safety or flameproof), ensure an additional cooling surface and a greater distance between the thermic critical cable entries and the source of heat losses, compared with direct cable entries into the flameproof main compartment of the apparatus. 

In general, cable entries according to IEC 60079-1 and EN 50018 shall withstand the explosion pressure inside the enclosure and shall ensure the flameproofness by an adequate design and construction of all mechanical parts. In addition, the general requirements stated in IEC 60079-0 and EN 50014 shall be fulfilled. On the whole, to pass a flameproof enclosure with electrical power or electrical and optical signals four methods have been established (Figs 6.80 and 6.81) ... 

Figure 6.80 Techniques for cable entries into a flameproof enclosure (left to right) ...

Figure 6.81 Flameproof plug-and-socket connectors ( cable couplers ), fitted into a flameproof enclosure (EEx dl equipment for coal mines).

The cable for power or signal transmission passes the flameproof enclosure on the direct way via a cable entry complying with the d -standards. This technique has its origins in the United Kingdom and France (including their historical spheres of economical influence), and in the countries of the former Eastern bloc. Examples for direct cable entries are given in Fig. 6.82. 

Plug-and-socket connectors, cable couplers, see Fig. 6.81. These parts are inserted into an opening of the flameproof enclosure and act as a flameproof seal. This also applies to the unplugged state of plug and socket. Such means are favoured where apparatus is frequently removed, e.g. in coal mines (Group I application). 

Electrical and optical connections between two flameproof enclosures separated by a partition wall are made by the insertion of (multiple) cable bushings or fibre bushings in an opening or thread of the partition wall. This technique is identical with the means of connection between e - and d -compartments (see Section 6.7.2, Table 6.19, and Section 6.7.6, Fig. 6.70, and, in addition, Fig. 6.84). 

In this example, the flameproof enclosure is fitted with a terminal compartment in increased safety - e As an alternative, flameproof cable entries or conduits may be fitted. 

The mains line is fed via a flameproof cable connector to the high voltage unit. Figure 6.108(b) shows a high voltage unit, containing ... 

Figure 6.117 Flameproof vessel light fitting (cable entry via conduit).

These cable entries comply with the requirements given in General requirements and Flameproof enclosure - d e.g. EN 50014 and... 

The flameproof power cable - cable protection by rapid-acting switchgear... 

X Semiconductor alloy batteries antifriction compounds 23,3210,342, ammunition cable sheathing flameproofing compounds 3512, 3522, 361, ceramics glass pottery type castings for commercial 362, 372, 38, 932 printing solder alloys fireworks treatment of parasitic diseases pesticides... 

Mineral insulated cables terminated into accessories with approved flameproof glands. These have a longer gland thread than normal MICC glands of the type shown in Fig. 3.39. Where the cable is laid underground, it must be protected by a PVC sheath and laid at a depth of not less than 500mm. 

PVC armoured cables terminated into accessories with approved flameproof glands or any other wiring system which is approved by the British Standard. All certified flameproof enclosures will be marked Ex, indicating that they are suitable for potentially explosive situations, or EEx, where equipment is certified to the harmonized European Standard. All the equipment used in a flameproof installation must camy the appropriate markings, as shown in Fig. 3.72, if the integrity of the wiring system is to be maintained. 

Electricity is particularly dangerous because it cannot be seen only an electrician should ever interfere with any electrical device, starter motor, connection box, or cable. Water should be kept away from all electrical equipment and any damage to electrical equipment must be put right by a skilled electrician before it is used. Special flameproof electrical equipment is provided in areas where flammable solvents are handled. 

Route of pipelines must avoid electrical cables, heavy traffic, hot areas Detectors and warning devices for CO leak Flameproof fittings, photocell-actuated gas control valves Induced Draught (ID) fans and tail gas scrabbers (if the gases contain H2S or other sulphurous compounds)... 

Cable tray routes as per drawing Cable tray suppoits adequate and secure Cable tray assembled and secured correctly Cable ttay earthing as per specification Cable tray earth continuity checks satisfactory Earth cables/bonds securely terminated Cables securely banded/shrouded Correct cable glands fitted Junction boxes and covers securely fitted Flameproof equipment fitted as per specification Lighting fittings correctly erected and secure Distribution boards installed and connected as per drawings... 

Mineral insulated cables terminated into accessories with approved flameproof glands. These have a longer gland thread than normal MICC glands. Where... 

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