Installation of Cables & Wiring systems in Hazardous Areas

Refrerence IEC Standrad : IEC 60079-14

The  essential guidelines for Cables and wiring systems installations in Hazardous Areas are given in IEC 60079-14

Standard Electrical Cables DO NOT REQUIRE Ex Certifications , neither as equipment nor as component . Cables are not covered by ATEX Directive for equipment (2014/34/EU) .

Cables are covered by strict Installation guidelines and as such are not considered a potential source of IGNITION .

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An exception may be the Trace Heating Cable , which form part of the commercially availablly Trace Heating systems and share the overall Trace Heating System Ex Certificate.

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The Proper and stringent guidelines are tabulated in IEC 60079-14 covering the selection , installation and termination of cables.

The parameters covered by IEC 60069-14 are :

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Cables with low tensile strength sheaths (commonly known as “easy tear” cables) shall not be  used in hazardous areas unless installed in conduit.

 Cables that have an outer sheath with an initial tensile strength of less than 7 N/mm2 according to the cable manufacturer’s documentation shall be installed with additional mechanical protection, for example installation in conduit.

The microscopic spaces between the conductors (strands) or in the existing within the bedding should not act as flame transmitters or gas migration paths . These spaces may exist within a poorly constructed cables .

The overall cable construction shall be either :

a) nominally circular and installed with a cable entry device properly selected in accordance with IEC 60079-14 

to maintain the Type of Protection of the Ex Equipment; or

b) non-circular (for example flat) cables selected together with the specific cable entry device to maintain the Type of Protection of the Ex Equipment.

For nominally circular cables, where there is an inner sheath provided in the cable on which a sealing ring is to be applied this shall be nominally circular to maintain the Type of Protection when fitted with a compatible cable entry device

Recalling baiscs of cables:

A Cable is a : Assembly of one or more conductors and/or optical fibres, with a protective covering and possibly filling, insulating and protective material.

Armour : Covering consisting of a metal tape(s) or wires, generally used to protect the cable from externalmechanical effects

Screen : Conducting layer or assembly of conducting layers having the function of control of the electric field within the insulation

Shield : Surrounding earthed metallic layer which serves to confine the electric field within the cable orto protect the cable from external electrical influence ( Metallic sheaths, foils, braids, armours and earthed concentric conductors may also serve as shields )

Braid :Covering formed from plaited metallic or non-metallic material ( Generally used to act as an electrical screen, and in some cases PE conductor, if cross section allows, but also have an additional function to provide mechanical strength, commonly referred to as braided armour.)

Protective Earthing Conductor : PE conductor : protective conductor provided for protective earthing

Inner Sheath : Non-metallic sheath generally applied under a metallic sheath, reinforcement or armour

Bedding : Cushioning layer or layers applied to a cable immediately beneath a metallic layer such as the
armour or the reinforcement