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Monthly Archives: January 2014

  • The Dangers of Using ‘Budget’ Cable Glands

    We have all become accustomed to the flood of supposedly ‘economy’ range of products from manufacturers in the electrical supply industry, which often come at a competitive price that seems good to be true. Unfortunately, this can often be the case and by using these products you may be taking serious risks with the integrity of your cable installation.

    The electrical contracting industry is more competitive than ever and efforts are always being made to improve margins and reduce costs, however many suppliers are providing cheap, sub-standard products in order to make themselves more competitive.

    As a supplier of cable glands from a number of reputable manufacturers such as: CMP, Hawke, and Prysmian – we have carried out research over the years to ensure that quality standards are adhered to, allowing us to provide products with extended warranties. This protects both our reputation as a supplier and hopefully yours as a contractor of quality installations.

    Our research has highlighted some of the following points worth bearing in mind:

    - Cable Glands are covered by European Legislation, supplying glands that do not comply with the standards is contravening legislation.
    - Many wholesalers and distributors are unaware of this, they may not realise what they are selling does not meet the relevant safety standards.

    What problems can occur with Cable Glands?

    There are three main factors affecting the safe performance of a cable gland, these include:

    - Integrity of mechanical design
    - Quality of materials used in manufacturing
    - Degradation of seals over time

    The tests contained within the current standard BS:EN50262 are designed to ensure that the product is of sufficient, robust mechanical design to enable it to withstand continuous shearing forces at the point of entry into the equipment and that the cable is adequately retained by the seals and/or armour clamp.

    Sealing materials also vary greatly in their ability to withstand attack from airborne pollutants and environmental elements. Reputable manufacturers test their seals to withstand prolonged exposure to these risks.

    Always check that your supplier can supply Third Party Test Reports that confirm these essential requirements, if they are unable to provide a test report, you should be aware that these products may not meet the required European legislation.

    Brass is Brass?

    A cheap inferior gland may, at first glance, look and feel very similar to a high-quality cable gland, but the quality of the brass used to make it can fluctuate greatly. Raw materials represent a significant cost in the cable gland manufacturing process, and due to the fact that extruded brass is a globally-traded commodity, the country of origin has a relatively small impact on the finished gland cost.

    Typically, poor quality glands are manufactured from “Honey” brass, which is melted down and recast scrap metal, full of impurities and air voids which undermine the strength and integrity of the finished product which, over time, could lead to threads shearing or glands literally falling apart.

    extruded brass bar Honey Brass
    Extruded Brass Bar Honey Brass


    In some cases, the gland may rust after only a few years of use, implying a high ferrous metal content within the brass used in their manufacturer.

    Actual case we have been called out to in the UK:

    budget cable gland failure

    Choosing a gland to give you piece of mind

    The first port of call should be checking if the product is CE marked. If it isn't, you should have serious concerns about the risks you may be taking by buying or using these products. Even if the product comes with a CE mark, be aware of rogue manufacturers as the presence of the CE mark does not always mean the product complies.

    If you have any concerns over the quality of the product you are buying, you should ask your supplier for the full CE Technical File, which will contain evidence of 3rd party testing and a detailed appraisal of the product compared to the prevailing standards.

    Don't damage your reputation

    Unfortunately, often it is not until cable glands have been installed that quality issues come to light. Then it can be too late to avoid the potentially incalculable cost to your long term reputation, not to mention the short term cost on the job.

    Should you require any further impartial advice on any of the above or if you would like to see further technical information, please do not hesitate to contact us.

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  • Q&A: How to Properly Remove A Bonded Screen With A Removal Tool?

    Question:

    I'm about to use a bonded screen removal tool for the first time, how do I make sure it works correctly and the screen is properly removed from the cable?

    Answer:
    When terminating or jointing MV cables with a bonded semi-conductive screen, this will have to be shaved from the cable primary insulation to the dimensions given within the accessory installation instructions. There are a variety of tools available that will perform this task, however when using a purpose-made screen removal tool the following points should be noted to ensure the cable is prepared correctly:

    Ensure the blade is set to the correct depth. Excessive removal of the cable insulation could increase the electrical stress at the point of removal, particularly with air-clearance terminations (Heatshrink and ColdShrink types). The best way to ensure the correct depth is to practice on a piece of unused cable first.

    Some tools require the application of silicone grease to the semi-conductive screen in order to lubricate and ease tool rotation. Fully familiarise yourself with the usage instructions supplied with the tool you are using and practice on a few lengths of unused cable to “get the feel” of the tool.

    Ensure the core is perfectly straight. Any bend in the cable can lead to the screen not being removed evenly around the circumference. This could happen to the underside of the cable and may not be immediately noticed, potentially causing partial-discharge issues.

    Using a specialist tool usually results in a perfectly prepared core, but if small amounts of bonded semi-conductive screen are left on the cable these can be removed with the use of a fine abrasive, non-linting cloth (120grit minimum). Care should be taken to only abraid cables circumferentially (NOT longitudinally) to avoid creating a partial-discharge path along the cable insulation.

    Once you have prepared your core(s), the primary insulation will require cleaning to ensure any loose particles are removed. Always clean polymeric insulation from the exposed conductor end, along and TOWARDS the semi-conductive layer in one direction, avoiding inadvertently contaminating the insulation with any semi-conductive compound residue.

    There are a number of different types of bonded screen used on cables. Although the aforementioned procedures are common to most polymeric semi-conductive compounds, it is important to confirm that your tool and cable/s are compatible before commencing work.

    ETS Cable Components offer a variety of quality-manufactured cable preparation tools from GBZ-Mannheim and Nexans. Please contact our Sales Team for further information, prices and advice.

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  • Q&A: How Do I Use A Trefoil Cleat on Triplex Cables?

    Question:

    I need to secure a cable in triplex formation with the use of a trefoil cleat, how would I go about doing this?

    Answer:

    Triplex cables are formed by having their three cores twisted around each other, this causes an issue when trying to secure the cable with traditional trefoil cleats. As the relative position of the cable varies along the cable run, the three cores will be in a different 'twisted' position at each cleat interval.

    triplex cable

    The overcome this problem, a SFT triplex cable former is available. The inner liner is applied around the cable, giving it a uniform profile allowing it to be fixed within a two-bolt LSF, VRT Vulcan or single way ES Emperor cable cleat.

    The triplex liner is manufactured from LSF Zero Halogen (LSZH) materials and thus is suitable for applications where LSZH properties are required.

    nylon-two-bolt-cleat-triplex vulcan-cleat-triplex emperor-cleat-triplex
    2LSF Cleat with Triplex Liner Vulcan Cleat with Triplex Liner Emperor Cleat with Triplex Liner


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  • Cable Cleat Specification Guidelines – Choosing The Correct Cleats

    Why do we use cable cleats?

    Cleats are an often under estimated component of cable management systems, principle they exist to fix, retain and support cables. In addition, where short-circuit faults are anticipated, correct cleating will result in the containment of the cables during a fault and enable the circuit to continue operation with the minimum disruption.

    What type of cleat do I need to use?

    We currently offer over 25 different types of cleats to suit various installation requirements. These range from our single and two bolt LSF cleats, through to Emperor stainless steel cleats, designed for installation within extremely harsh environments throughout the world, e.g. off-shore petrochemical plants.

    In the UK, the majority of commercial and industrial contracts call for the use of LSF cleats, aluminium two-part single way and trefoil cleats, along with the increasing use of stainless steel cleats, particularly since the advent of Fire Performance cables for critical circuits.

    The following questions need to be answered to ascertain the relevant cleat for any given installation:

    - What is the conductor size?
    - What type of cable? i.e. single core, multi-core, XLPE, unarmoured, steel wire armoured, aluminium wire armoured etc.
    - What is the overall diameter of the cable?
    - Does the specification call for a specific type of cleat or type of material?
    - Does the specification call for any fault current requirements?

    Common issues and questions raised when ordering cleats:

    - Preference for using cables ties to save money, instead of cleats.
    - Spacing requirements, i.e. ladder-rack not being wide enough to accommodate the required number of cleats.
    - The short-circuit withstand required from a cleat when installing single core AWA cables.
    - Suitability of cleat to a particular cable, e.g. Fire Performance cleats to suit FP400 cables.
    - Other spacing issues, such as the recommended mounting distance between cleats when installing cables vertically being different from when the same cable is being installed horizontally.

    ETS Cable Components are the UK's leading stockists and distributors of cable cleats and cable management accessories. For more information on our range of cleats, visit our cable cleats page or contact our Sales Team.

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