The main IEC Installation standards that are in use today for gas / vapour hazards and dust hazards are detailed below.
IEC 60079-14 : Electrical apparatus for explosive gas atmospheres – Part 14: Electrical installations in hazardous areas (other than mines)
IEC 61892-7 : Mobile and fixed offshore units - Electrical installations - Part 7: Hazardous areas
IEC 61241-14 : Electrical apparatus for use in the presence of combustible dust - Part 14: Selection and installation
Cable Gland Installation Guidelines
Installation should only be carried out by a competent person, skilled in the installation of cable glands. Care should be taken to avoid damage to entry threads when handling and installing cable glands.
Cable Glands should not be installed whilst circuits are live. Similarly, following energising of the electrical circuits, cable glands should not be dismantled or opened until the circuit has been safely de-energised.
Cable Gland components are not interchangeable with those of any other cable gland manufacturer. It is important to note that components from one manufacturer's product cannot be used in that of another, and that modification of a cable gland product will invalidate the hazardous area certification.
The cable gland is not a user serviceable product and spare parts are not permitted to be supplied under the certification.
Cable Gland seals are included within the cable gland when despatched from the factory. There should be no circumstances where seals need to be removed from the cable gland. Care should be taken to avoid exposure of cable gland seals to dirt, hostile substances, e.g. solvents, and other foreign bodies.
You can download all of CMP's Installation Instructions by clicking here.
Depending upon the specific form of protection of the main equipment it may be necessary to fit a sealing washer at the cable entry interface to maintain the appropriate Ingress Protection level of the enclosure. For Increased Safety (Ex e) equipment, or Increased Safety terminal chambers found on Ex de equipment, a sealing washer is recommended to maintain the minimum Ingress Protection rating, and should always be fitted. For other forms of protection, e.g. Flameproof Ex d apparatus, the inclusion of a sealing washer is optional.
It can be noted that IEC 60079-14, section 10.4.1 states that Flameproof (Ex d) cable entry devices may be fitted with a sealing washer between the entry device and flameproof enclosure providing that after the washer has been fitted, the applicable thread engagement is still achieved. For parallel threads, the thread engagement is normally five full threads or 8mm, whichever is the greater.
It can also be noted that IEC 60079-14, section 11.3 states that for Increased Safety Ex e enclosures, threaded cable entry devices connected 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, providing the axis of the cable entry device is perpendicular to the external surface of the cable entry plate or enclosure.
CMP Sealing Washers, which are installed at the cable entry interface, between the equipment enclosure and the cable entry device (cable gland) have been 3rd party tested in Ingress Protection tests to IEC 60529. CMP Products would recommend their use in most typical outdoor situations.
Always ensure that the correct fixing accessories provided by CMP Products are used, as appropriate to secure the cable glands into the mating equipment.
In addition to Sealing Washers, CMP Products are also able to provide Locknuts, Earth Tags, and Serrated Washers which should be used as appropriate to the equipment configuration. Usually for any equipment other than Ex d apparatus, it will be necessary to use as a minimum a Locknut, and also a Serrated Washer if the enclosure of the equipment or application requires it. The addition of an Earth Tag will depend upon the earth continuity provision of the enclosures installed.
Always use the correct tools, as incorrect tools will inevitably lead to mistakes, potential damage and/or personal injury. Gloves are recommended when handling and terminating cables and cable glands. Safety and personal protection should be given priority over all other considerations.
Dedicated CMP Cable Gland spanners for each cable gland size are available, these are recommended for correctly installing the product.
Adjustable spanners and wrenches are not recommended as there is a possibility of slippage that can lead to accidental injury or damage to surface finish.
Any sharp tools, instruments or knives used to cut or strip the cable sheath should be equipped with a safety blade or other safety feature consistent with the tool design and intended use.
Braid snips should be used to remove unwanted or excess cable braid. Ensure that braid snips are in good condition and effectively sharp enough to enable a first time clean cut of the cable braid without snagging.
A hacksaw, or other similar tool, should be used to cut armour wires. Hacksaw blades should be checked regularly and replaced when worn, or whenever evidence that a consistent first time clean cut is no longer possible. Note, when cutting armour wires, care should be taken to avoid cutting into the inner cable bedding or insulation beneath the armour wires.
Please refer to CMP Products in sourcing tools if required, who will be happy to assist.
There are no user serviceable parts contained within a hazardous area cable gland. As such there is very little opportunity to perform maintenance on installed cable glands.
Where cables are required to be clamped external to the equipment and separate from the cable gland, periodical checks to ensure that any cable clamps used adequately secure the cable.
It may be necessary under plant operators policy to carry out earth continuity tests to verify good earthing protection. Any external earth connections should be checked to ensure that fasteners are tight and free from corrosion.
Parts should not be substituted or replaced from one cable gland to another. Components from one manufacturer are not interchangeable with those supplied by another manufacturer.
Apart from cleaning or removal of surface dirt when required, the product is free of maintenance. It is not possible for users to repair or recondition hazardous area cable glands.
Any product found to be damaged or not in accordance with the original model certification should be removed from service and replaced.
For operations within the Oil & Gas industry, or any other area where potentially flammable atmospheres exist the prevailing local codes of practice or standards must be observed. For example the European Normative EN60079:17 or the IEC Standard 60079:17.
Under normal service conditions there are two types of inspection, Initial and Periodic. Initial inspection sets out to verify that the equipment installed is appropriate to it's hazardous area situation, and Periodic inspection is a routine used to monitor the effects of change or deterioration.
Three grades of inspection are adopted for electrical equipment and plant installed within potentially flammable atmospheres (hazardous areas). These are :-
Visual Inspection, Close Inspection and Detailed Inspection.
Visual and Close inspections can be carried out whilst the equipment or apparatus is still energised and do not require the enclosure to be opened. A Detailed inspection may be required as a result of the findings from a Visual or Close inspection.
Further details on the three grades of inspections can be found within tables 1 to 3 of EN60079:17, and it's relevance to the various forms of explosion protection.
Plant operators would usually initiate an inspection plan utilising either it's own inspection department, or alternatively an external inspection services company. Within the inspection plan, the parameters of the inspection will be clearly defined. It is not common under such terms of reference for cable glands to be routinely opened and examined internally, without due cause and this would normally be done only in the case where a problem has been identified with the cable termination.
Whilst cable gland products can be designed to provide ease of inspection and disconnectability, the reality of the situation is that cable glands are seldom dismantled for inspection, and wherever possible this is avoided. The level of inspection carried out on cable glands is fairly limited.
Whenever equipment is to be removed from service it is recommended that the cable and cable gland entry arrangement are closely examined and assessed by a competent technician before connecting up to a replacement piece of equipment.