Armoured Cable Gland Types: A Complete Guide
Armoured cables are the key element of any heavy duty electrical installation in the industry, power supply system, subterranean cable installation or any outdoor installation where cables are under the risk of being subjected to mechanical loads, moisture and rough handling. However, any armoured cable is as good as its gland. An incorrectly selected or incorrectly installed gland might ruin the whole protection of a cable, causing water infiltration, insecure earthing or even electrical failure.
Here we will go through different types of armoured cable glands, their principle of operation, applications and tools required for proper installation.
What Is an Armoured Cable Gland?
Armoured Cable Glands are a kind of mechanical joint that connects the armoured cable at the point where it is terminated in an enclosure or casing. Armoured Cable Glands differ from ordinary cable glands in their construction since they incorporate an innovative design that guarantees electrical bonding between the armour of the cable, which consists of SWA or AWA.
A properly installed armoured cable gland performs three critical functions:
- Retention – Ensuring that the cable is held in place tightly to ensure it cannot be removed from the enclosure
- Earth continuity – Connecting the armor of the cable with the enclosure for earth continuity
- Sealing against the environment – Keeping away water, dust, and other contaminants from the panel
Now, let’s look at the different types of armored cable glands available.
1. Standard (Basic) Armoured Cable Glands
This is the most commonly applied type in conventional wiring systems. Such a gland consists of an external seal, armor clamp ring, and internal seal for the inner cable sheath. This basic gland would suit well in indoor installations or semi-indoor installations where there is no need for maximum weather protection.
Best for: General purpose panels, control panels, and machines in indoor locations.
2. Weatherproof (Outdoor) Armoured Cable Glands
Weatherproof glands have additional sealing rings as well as high IP ratings (either IP66 or IP68). They have the unique characteristic of having a neck of the gland that is shrouded or booted in order not to trap water within the gland neck.
Best for: Outdoor junction boxes, street lighting, rooftops, etc.
3. Explosion-Proof (Ex-Rated) Armoured Cable Glands
These glands are applied in explosive conditions such as those found in oil refineries, gas facilities, and chemical processing plants; they should meet either the ATEX or IECEx standards. Their purpose is to ensure that no spark or heat produced within the equipment causes an explosion of the flammable fumes in the vicinity.
Best for: Petrochemical facilities, mining operations, and hazardous zone installations.
4. Double Compression Armoured Cable Glands
It uses double glands, that is, one gland for the outer cover of the cable while the other one is for the armor of the cable. It is a stronger type of gland and gives better earthing than the single compression gland.
Best for: Industrial use where the cable may be put under vibration or strain.
5. Single Compression Armoured Cable Glands
As implied by the title itself, single compression glands consist of a single clamping arrangement that holds the armor and the outer jacket together. These glands are cheaper and easier to handle compared to double compression glands but have relatively lower mechanical integrity.
Best for: Applications that require lower mechanical strength and are cost-effective in nature such as indoor lighting circuits and low-vibration panel joints.
6. Brass Armoured Cable Glands
The cable glands are made up of nickel-coated brass. Therefore, they are highly resistant to corrosion, highly mechanical and offer earth continuity. Brass is the most frequently used material for the manufacture of armoured cable glands due to its toughness and low cost.
Best for: Industrial and commercial purposes, indoors and outdoors, especially when you require balancing between cost and performance.
7. Stainless Steel Armoured Cable Glands
Stainless steel glands will be more preferable to brass glands where there is a likelihood of corrosion since stainless steel glands are resistant to corrosion, chemical action, and salt water.
Best for: Coastal environments, sewage treatment plants, and food production facilities.
8. Indoor Armoured Cable Glands
This is the basic form that is meant for indoor purposes only where they lack the weatherproofing elements that outdoor glands have.
Best for: Indoor use in switchgear rooms, control panels and enclosures of equipment in facilities like detection or monitoring panels for PIR Motion Sensor or photoelectric sensors.
How to Choose the Right Armoured Cable Gland
When selecting an armoured cable gland for your project, consider the following:
- Cable Type and Gland Armor – Ensure that the cable you use is one of the following: SWA (Steel Wire Armor) and AWA (Aluminum Wire Armor). This is because it determines the type of gland to be used.
- Environmental Exposure – If your application is outdoors or requires regular washing then you will need a gland with a higher IP rating.
- Explosion Hazard – Areas with explosive atmospheres will need glands that are certified as being Ex-rated, or explosion-proof.
- Mechanical Stress – An application that has vibrations or movement may benefit from using glands with a double compression system.
- Corrosive Environment – Stainless steel glands are recommended for environments involving marine, chemicals, and food processing.
Installation Best Practices
Proper installation is just as important as choosing the right gland type. Keep these tips in mind:
- De-sheath the cable appropriately — Strip the outer covering and armor from the cable up to the length recommended by the manufacturer, allowing easy, undamaged gripping of the conductors.
- Properly terminate connections — A crimping tool should be used to make solid, low-resistance connections between conductors and terminals/lugs, which are resistant to vibrations.
- Use suitable cable lugs for termination — Where heavy armoured cable made of dissimilar metals (i.e., copper conductors and aluminum busbar) is used, Bimetallic Cable Lugs should be used to avoid galvanic corrosion.
- Secure and route the cabling — Use cable ties to secure the cable, which leads up to the gland, thus avoiding stress on the termination.
- Torque to specifications — Tighten the connection to the correct torque; over-tightening could damage either the armor or seal, while under-tightening fails on both counts.
- Check earth continuity — After installing the cable, always confirm that the armor has been correctly connected to the earth terminal of the enclosure.
Although armoured cable glands may appear to be an insignificant part of an electrical installation at first glance, they have a very significant role to play in terms of mechanical protection, earthing, and environmental protection. The selection of a suitable cable gland depending on its purpose and function such as a weather-proof gland for outdoor panels, an explosion-proof gland for dangerous facilities, or even a plain brass gland for indoor use plays a vital part in determining the overall performance and reliability of the entire cable system.
Frequently Asked Questions (FAQs)
Q1. What is the basic role of an armoured cable gland?
The armoured cable gland ensures physical mounting of the armoured cable as it penetrates into the enclosure. Additionally, it also establishes electrical connection between the armor of the cable and earth.
Q2. What is the distinction between single and double compression glands?
Single compression glands connect the armor and outer layer of sheath through one clamping process, whereas double compression glands utilize two clamping processes and thus provide better mechanical retention as well as earth connection.
Q3. Which armoured cable gland is suitable for outdoor applications?
IP66/ IP68 armoured cable glands are best suited for outdoor applications because these glands have additional sealing to protect the equipment against water, humidity, and variations in temperature.
Q4. Is it necessary for armoured cable glands to be earthed?
Yes, continuity of earth connection between armor of cable and enclosure is extremely important for any faults protection and it must be checked.
Q5. Which type of material should be selected for effective corrosion protection of armoured cable glands?
The stainless steel armoured cable glands are the best choice for effective corrosion protection. They can be used in marine, coastal, or chemical processing environments, whereas the brass glands are ideal for most general applications.
Q6. Which tools and accessories will be required for installing armoured cable glands properly?
A good crimping tool for making terminal connections, Bimetallic Cable Lugs, which are needed when connecting different metals, and cable ties are all essential to ensure a proper installation.
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