A guide to cable glands
3.5 minutes | 24 Aug 2018
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?
Which cable gland is best for your application?
There’s a world of choices out there 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.
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.
Knowing your cable type
Different cables demand different types of cable glands. For example, understanding how to fit an armoured cable gland is different to that of fitting unarmoured cable glands.
|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|
To determine the right cable gland size for both types, 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
Different 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 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 are resistance to salt water, grease and weak acids, to name a few.
But what’s one of the more popular metals and plastics used for cable glands and why? Here’s a closer look:
|Brass cable glands||
|Nylon cable glands||
Types of mounting
Depending on your application needs, there’s a wide choice of cable gland mounting which includes:
- Adhesive or compound
- Flanged or bolted
- Threaded or nut
- Mount, welded and cast
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
Ratings and standards
Because cable glands are designed with safety in mind, they come with a rating system 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 rating often go up to IP68 and IP69K.
Any cable glands you buy today will also be covered by the new European standard for Cable Glands, EN50262.
It’s important to check that any devices placed in explosive atmospheres comply with national or international codes of practice.
Final selection checklist
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 can also request free samples to ensure the solutions you’ve chosen are exactly what you need. If you’re not quite sure which product will work best for your application, our experts are always happy to advise you.
Request your free samples or download free CADs now.