Cable runs in hazardous and potentially explosive locations need to be carefully planned, with every component chosen to meet strict performance and safety requirements. Lee Frizzell, CMP Products’ Technical Director, looks at their importance in these environments and how correct specification can be achieved every time.

The importance of cable glands simply can’t be underestimated – especially in hazardous and potentially explosive installation locations. Put simply, without the correct specification there’s the very real risk of gas migration and the increased danger that products aren’t able to prevent or contain an explosion.

Attention to detail

Of course, all aspects of cable runs in these kinds of installations demand exceptional attention to detail; with every component – from cables to junction boxes and everything in between – carefully specified to ensure they remain operational in times of system stress and prevent ignition of surrounding explosive atmospheres.

And while cable glands may seem a minor part of the specification challenge, it’s vital that they aren’t underestimated. They are, after all, the primary sealing point for cable entry and exit points and on top of that provide mechanical retention, environmental protection, earth continuity and, in explosive atmospheres, they help to prevent or contain an explosion.

Explosive atmosphere installations are classified into various types depending on the type of hazard; typically flammable gases, vapours or combustible dusts. In these situations, cable glands serve five essential functions:

• Explosion protection: Flameproof (Ex d) glands prevent flames produced by an explosion inside an enclosure from transmitting into the external atmosphere. While Increased Safety (Ex e) glands terminate and seal the cable into the enclosure, which itself contains certified components that cannot spark or reach temperatures high enough to ignite an explosive atmosphere.
• Gas migration prevention: Correctly specified or installed glands will prevent explosive gases travelling along cable runs into neighbouring equipment, causing explosion risks.
• Environmental sealing: Glands must block ingress of moisture, dust and corrosive elements. This is particularly important in offshore, marine or chemical processing plants.
• Mechanical stability: Pull-out resistance, or strain relief prevents cable damage and preserves safety over the equipment’s lifespan. 
• Earth continuity: Any armour or metallic screen in the cable is terminated and grounded inside the cable gland.

Safey first

If not correctly specified, then even a high quality cable installation and enclosure can become dangerously compromised. So, what steps need to be taken to ensure correct and safe specification?

There are several key steps that need to be taken; starting with understanding the environment in which the system will operate. This is classified by different zones – with Zones 0, 1 and 2 relating to explosive gas; and Zones 20, 21 and 22 concerning explosive dust.

These zones are then broken down to confirm the explosive atmosphere and subgroup and from there the type of enclosure protection concept needed can be identified. As mentioned, Ex d is flameproof, while Ex e is increased safety – no sparks or heat sources. There are also Ex i, Ex nR and Ex t options. The correct type of cable gland is then chosen to complement the enclosure. Problems arise if the wrong kind of gland is used – for example, fitting an Ex e gland on an Ex d enclosure is extremely dangerous.

The cable type then needs to be matched to the appropriate gland. For example, armoured cables require glands that can correctly terminate steel wire armour (SWA), steel tape armour (STA) or aluminium wire armour (AWA). The material of the cable gland itself, most commonly brass, nickel-plated brass, stainless steel or aluminium must also be selected appropriately.

Attention must also be paid to the cable’s inner bedding diameter, overall diameter, any armour or braid thickness and the applicable tolerances. Any uncertainty in selection risks compromising the cable or cable gland’s performance and overall system integrity.

The inner construction of the cable also needs careful consideration. For example, multicore cables increase the risk of gas migration and flame transmission through any gaps; to mitigate this risk and maintain Ex d integrity, a barrier type gland is required to seal directly around the cable inner cores. Barrier glands are mandatory for Ex d with unfilled multicore cables (per EN/IEC 60079‑14).

A correctly specified barrier gland will provide the peace of mind that gas will be prevented from travelling between the inner cores into neighbouring equipment or enclosures. This is essential in installations where explosive gases (e.g. hydrogen, acetylene, methane, ethylene) are present and pressure differentials exist.

Up to standard

As with every element of any cable installation, cable glands need to comply with industry wide standards. For projects following UKEX/ATEX or IECEx requirements, the key is the EN/IEC 60079 series and every explosive atmosphere cable gland we sell complies with the strict requirements of these internationally recognised standards.

On top of this, glands should carry certification markings that match the explosive atmosphere classification of the system; with temperature ratings that meet or exceed site requirements; gland materials match environmental and chemical exposure profiles; and Ingress Protection (IP) ratings align with enclosure and site specifications. Any deviation can make the entire installation non-compliant.

And the specification challenge doesn’t end there:

• Corrosion resistance requirements instruct the choice of product material and coating or plating
• Thread type mismatch is a frequent cause of installation error. Enclosure and gland entry threads need to match in type, length and taper. For Ex d, minimum thread engagement must also meet EN/IEC 60079-1

And, of course, and it should go without saying – the manufacturer’s installation instructions need to be followed precisely.

Structured approach

Cable glands may be small, but their importance in hazardous and explosive atmospheres is mighty. They protect personnel and infrastructure by maintaining the integrity of the system. Incorrect gland specification or installation increases the risk of a catastrophic explosion, gas migration, or moisture ingress.

By following a structured approach — beginning with proper explosive atmosphere classification and matching gland design to cable type, through to confirming certification, assessing environmental conditions and ensuring correct thread engagement — engineers and installers can achieve the right cable gland specification every time.

Additional information is available here

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Unicrimp, part of the Scolmore Group companies, has added new earthing plates to its comprehensive Q-Crimp accessories range.

Brass earthing plates are designed to provide a low-resistance path to the earth, allowing electrical current to be safely dissipated into the ground in the event of a fault or short circuit.

The new Q-Crimp single and double brass earthing plates are suitable for Unicrimp’s Q-Nect IP66 junction boxes and for earthing 20mm brass glands.

Unicrimp recently expanded its cable glands range which now includes armoured industrial brass cable glands and nylon cable glands that are offered in a variety of BW, CW & AE1W and they are all manufactured to the latest approvals and BS 6121 standard.

For more information, click here

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Traditional dome top cable glands are ideal for creating simple and secure entry points for bulkheads and enclosures. However, when access to the interior of the enclosure is restricted or space is tight, installation time can be greatly increased and it may even be necessary to adopt specialist tooling – or, if the panel is large, two installers may be required to assemble the glands into position.

Here, Michael Crowther, Product Development Director at Hylec-APL, outlines the advantages of its Kwik-Fix cable glands for electrical installers in these scenarios.

Control cabinets, plant switchgear and building services, including heating, ventilation and air conditioning (HVAC) systems, all require access for cabling. Electrical installers or building services engineers will usually be tasked with commissioning, installing and securing such access – ideally as quickly and cost effectively as possible. But there are plenty of situations where access to the inside of such enclosures is restricted, and space is often at a premium – making traditional solutions awkward to install – while the harsh environment they are usually situated in demands that such access must be weatherproof and not allow ingress of water, dust or dirt.

While traditional cable glands are ideal solutions for many electrical installations, each application has its own unique considerations – particularly where space is tight, or access is difficult. Rapid assembly cable glands offer a potential alternative to traditional dome top glands, which use a rear mounting lock nut to secure the cable gland in such scenarios. But plant and mechanical engineers often don’t put much faith in rapid assembly cable glands – and their reluctance is hardly surprising, as rapid assembly products typically require a special tool for assembly, are often unwieldy to install and form an unreliable seal.

Hylec-APL’s Kwik Fix cable glands represent a real advancement of rapid assembly cable gland design – and don’t require a special assembly tool either.

Kwik-Fix cable glands

Designed for use in applications where access to the interior of a bulkhead or enclosure is restricted, the patented Kwik Fix cable gland is installed from just one side of a panel, without any special tools, doesn’t require a rear mounted locknut and can still achieve IP68 sealing of a cable transit. The Kwik Fix can also reduce installation time, which will increase productivity and profitability, and is especially suitable for use with large switch cabinets, as well as cooling and heating systems.

The Kwik Fix cable gland is installed by placing the mounting foot of the gland through the entry hole. The mounting foot is designed with a lip that can be pulled tight against the inner wall; an external hexagonal locking nut is then turned anti-clockwise to hold the gland in place and form an IP68 seal. Once locked in place you can install the corresponding cable in the traditional manner, tightening the top dome nut in a clockwise direction.

This means that the gland can be easily mounted and dismounted from one side, making installation and maintenance far simpler. In addition, the gland takes up less internal space, leaving more space for internal wiring within the enclosure. The gland can be fitted onto entries where the wall thickness is between 1mm and 4mm and the waterproof solutions can operate safely in temperatures between -20°C and 100°C. It carries UL and VDE approval, boasts integrated strain relief and is available in all standard hole sizes, M16, M20, M25 and M32 (suitable for cable sizes from 5–17mm), in RAL 7001 (Silver Grey), RAL 7035 (Light Grey) and RAL 9005 (Jet Black).

Kwik Fix cable glands also offer advantages when connecting electric vehicle (EV) charging point enclosures. Where the incoming cable comes from behind the enclosure, through a wall, the Kwik-Fix gland can be fixed on the inside of the enclosure without the installer having to get behind the enclosure wall to tighten up a lock nut. This method can quickly and easily provide an IP68-rated connection to an EV charging point.

Summary

Previously, when faced with restricted interior or rear access, installers have been forced to use products that do not guarantee the seal. Also, they often required spanners or special tools. Kwik Fix cable glands are easily installed and removed from one side only, making installation and maintenance much simpler and reducing costs. Moreover, these glands take up less space, meaning a smaller enclosure could be used or leaving more room for wiring.

Figure 1. How the Kwik-Fix cable gland works

Kwik-Fix cable glands are the answer in a tight spot!
For a free sample of the Kwik-fix cable gland, email hylecuser@hylec-apl.com with “Free Kwik-Fix sample” as the subject and don’t forget to type the address you want the sample sent to.

For more information, click here or call 01933 234400.

The post Michael Crowther outlines the advantages of Kwik-Fix cable glands appeared first on Professional Electricians Wholesaler.

WIN A HYLEC PACK OF DEBOX ELECTRICAL JUNCTION BOXES, INCLUDING DEBOX 11 – THIS FANTASTIC BUNDLE WORTH over £125, COURTESY OF HYLEC 

Time saving IP66/IP67-rated, surface mounted interior and exterior electrical junction boxes 

With spring just around the corner, people will be giving their properties a refresh and many will be looking to include new lighting. Lighting installations can be very time consuming, but the amazing Debox range from Hylec has made life a lot easier for the electrical professional/competent DIY person. Since the launch of the first ever inline screwless junction box, Debox SL, this unique concept has evolved into a whole range of ingenious, time and money saving junction boxes that have sold multiple millions of units. 

The newest member of the family, Debox 11, is an IP66/IP67-rated, surface-mounted electrical junction box specifically designed for interior or exterior use on projects such as exterior lighting, outbuildings and anywhere exposed to water or dust ingress. 

Debox 11 has 10 cable entry points, two on each side and two in the base of the box. All have soft membrane covers, giving a quick puncture-entry self-sealing system rated to IP66. The eight side-entry points also have a M20 size threaded entry to allow for use with cable glands, with no requirement for an internal locknut, giving a higher protection rating of IP67. Wires are easily and quickly connected into the five x 3-lever screwless connectors which are supplied with Debox 11. This quick connection method offers the added benefit of a maintenance free design. Inside the box, the connectors are held securely by a moulded mounting location before fastening the lid with two included captive lid screws.

This versatile enclosure can also be used to house a printed circuit board (PCB) with four pillar screw fixing points in the corners, making it ideal to be designed for wireless monitoring or as a Node transmitter. It also offers external fixing with two unique fixing lugs located on the sides, which preclude the need for an external mounting fixture to allow the box to be easily mounted to walls. In black flame-retardant, impact-resistant polypropylene and rated for use between minus 30°C to +100°C., Debox 11 measures 85mm wide x 85mm deep x 53mm high.  

HOW TO ENTER

To be in with a chance of winning a Hylec welcome pack which includes 12 x Debox S, Debox SL, Debox SM40 and Debox 11 enclosures, pens, chocolates, a desk calendar, an ice scraper and a football, just choose the right answer to the following question:

Q:  How many Debox 11 entry points have a threaded entry for M20 cable glands?

1. Ten
2. Two
3. Eight

Deadline for entries 28/2/2023

Usual T&Cs apply

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