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A guide to cable glands

clock 3.5 minutes | 24 Aug 2018

Metal cable glands and cables entering power box

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.

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

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:

Material
Common applications
Characteristics
Brass cable glands
  • Medical equipment
  • Controlling devices
  • Measuring devices
  • In machinery
  • Corrosion resistance
  • Electrical and thermal conductivity
Nylon cable glands
  • Telecommunications
  • Instrumentation
  • Data cables
  • Electrical power
  • Ideal for use on flexible cables
  • High strain relief
  • Can bear the highest IP rating (IP68)
  • Available in colours for colour coding cables


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.

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