What are the types of cable glands and how to choose them?
The purpose of strain-relief cable glands
Cable glands perform a number of essential roles in cable management. Designed to attach and secure the end of an electric cable and the device it’s connected to, cable glands provide earthing, grounding, insulation, bonding and strain relief. They can also be used to seal cables which pass through bulkheads of gland plates.
They are often located in hazardous or harsh environments where they need to contain electrical sparks of flames, or repel outside contaminants such as dust, dirt and fluids. In addition to this, their job is to stop cables becoming twisted or pulled to ensure a secure connection and continual performance.
So how do you know which cable gland is up to your application? This article will answer that for you and provide you information such as:
How to choose cable glands
There’s a world of choices out there for cable glands and unfortunately no one-size-fits-all option. But it does mean that you can custom select a cable gland based on your parameters. And to do that, you first need to consider a range of environmental and application factors during the consideration process of cable glands.
The role of the environment
It doesn’t matter whether you’re working in aerospace, industrial, marine, power and utility, telecommunications or any other key industry. What’s important is identifying the core application environment of your cable gland. Questions to ask yourself:
- Are you using it indoors or outdoors?
- Will it be situated in a safe industrial zone or a hazardous or explosive environment?
- What’s the temperature and is it constant?
- Is the surrounding area damp or dusty?
- Are there any gases or corrosive materials nearby?
Your answers will help determine the cable gland specs and whether it requires a special protective plating or coating.
The purpose of armouring in cables
Different cables demand different types of cable glands. For example, the requirements for an armoured cable, also called steel wired armoured (SWA) are different to those of unarmoured cables. Armoured, or SWA, cables are used on exterior walls or underground.
|
Type |
Characteristics |
Application |
| Armoured | Extra layer of protection to prevent damage This may be a single wire armour, braided armour, pliable wire armour or double steel tape armour |
Areas where exposed to threat of mechanical damage |
| Unarmoured | More basic than armoured Can have no seal, or have a single outer seal or a double outer seal |
Fixed installations not exposed to risk of mechanical damage |
Does armoured cable need conduit?
Typically, no. They’re armoured for protection. You should use conduit for unarmoured cable, however.
IP-rated cable glands
Cable glands are designed with safety in mind, so they come with an IP rating to ensure you know what you’re getting. The Ingress Protection Marking (IP) rates the glands depending on their design and efficiency throughout different tasks. These ratings often go up to IP68 and IP69K. It’s important to check that any devices placed in explosive atmospheres comply with national or international codes of practice.
What are the types of cable glands?
There are different types of cable glands. Below are examples of cable glands:
These types of cable glands provide excellent strain relief to protect against conductor fatigue caused by flexing cables. IP68 rated, resisting dust, dirt and sand, and withstanding submersion in water for 30 minutes.
Rated IP68 for outstanding protection against the elements. Designed for superior sealing and strain relief, these cable glands are rated IP68 for excellent protection against the environment. With an IP68 rating, these are waterproof cable glands.
Convenient mounting and dismounting without the need for tools. Clicks in for a secure, weatherproof seal, preventing twisting, straining and snagging. The ideal pass-through cable gland for enclosures when saving time matters. Made of nylon 6/6 and TPE.
Cable gland brass types screen against electromagnetic disturbances, enabling enclosures to perform as intended. This nickel-plated brass gland resists corrosion and is rated IP68.
Cable gland size guide
To determine the right cable gland size for armoured and unarmoured, you need to consider:
- Cable diameter
- Construction size
- Cable material.
For armoured cables, you also need to consider:
- The diameter of the inner bedding
- The diameter of the lead covering
- The short circuit fault rating of the cable armour
- The type and size of the armour braid
Cable gland material types
Cable gland materials perform differently depending on the application, environment and cable type.
- Metal cable glands are used in a range of applications, including the chemical industry, technology and areas with high demands on special mechanical and chemical stability. The pros metal cable glands are durability over time, even in wet conditions, and its rigid stability.
- Plastic cable glands have a wide cable range due to their claw and seal design, which makes them extremely adaptable to a wide range of applications. The pros plastic cable glands are are resistance to salt water, grease and weak acids, to name a few.
At a glance:
|
Material |
Common applications |
Characteristics |
| Brass cable glands |
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| Nylon cable glands |
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How to install a cable gland
Cable gland installation depends on the type of gland you’re using, but the basics are the same. You’ll need to follow the relevant codes of practice, your local regulations and the manufacturer’s cable-gland-installation instructions. Installation should only be carried out by a skilled person with experience and knowledge of cable glands.
Note: Take care not to damage loose entry wires.
Getting started
Step 1: Turn off all electrical equipment and disconnect any live wires
Step 2: Make sure your cable gland is compatible with your cables
Step 3: Keep cable glands clear of solvents, chemical substances, and dirt during installation
Installing cable glands
Step 1: Open the cable gland and remove the nut.
Step 2: Peel back the outer sheath of the cable to the same length of the cable gland itself. If there’s an inner metal armour, expose it.
Step 3: Insert the right end of the gland into the cable.
Step 4: Lay the peeled sheath or armour evenly around the gland.
Step 5: Apply the nut, taking care to tighten with a spanner to secure the gland in place.
Extra protection features
Your application or environment may demand the cable gland to possess a specific quality, above and beyond its basic function. That’s where you may consider the following special features:
- Fire-stop cable gland which can withstand fire propagation through a barrier
- Explosion-proof cable glands
- EMI and RFI shielding and associated grounding features to minimise or eliminate electromagnetic or radio frequency interference
- Romex connections to specifically deal romex cables
- Wire mesh for additional strain relief
- Liquid tight cable glands to protect against penetrating oils and waters
Cable gland consideration
There are a few important considerations that fall outside of the categories above. So before you choose a cable gland, also ask yourself:
- Is the wire hole diameter large enough to house all the cables in the system?
- Is the cable diameter sufficient?
- Is the pressure rating high enough for your application needs?
- Is the mounting hold diameter large enough for my cable gland?
- Is the depth and size of the gland thread metric or PG?
- Is there a requirement for stopper plugs to close off any unused cable entries?
Download free CADs and try before you buy
Free CADs are available for most solutions, which you can download for free. You might also find these guides helpful:
Ultimate guide to cable management
Quick guide: industrial components for outdoor cabinets
Quick guide: the small HVAC components for your HVAC design
Guide to cable strain relief and protection
If you’re not quite sure which cable gland will work best for your application, our experts are always happy to advise you, whether it’s with standard cable gland sizes, suitable outdoor cable glands or anything else that you need. We also offer plastic grommets, so we can help you with that too. Whatever your requirements, you can depend on fast despatch. Request your free samples or download free CADs now.
Questions?
Email us at sales@essentracomponents.co.uk or speak to one of our experts for further information on the ideal solution for your application 0345 528 0474.