How to Calculate Cable Gland Size and Find the Right Option for You

Cable glands are vital components in many networks and systems. They can reduce strain and wear on cables at terminals, provide environmental protection and sealing, and effectively secure connections, which makes them a must-have in many industrial applications.

However, for a seemingly simple product, there are numerous variations in terms of specifications and a large number of individual cable glands available, so it is important to carefully consider which product you need to ensure compatibility and high performance. Here, the experts at Northern Connectors explain how to calculate cable gland sizes, the considerations you need to make based on the type of cable you are using, and how to get advice for a specific application if you are still stuck.

How should I start to work out the cable gland size I need?

Wherever possible, you should aim to use cable glands produced by the same company that manufactured the other components in your system, to ensure maximum performance and efficiency. If you know which company’s products you need to use, it is usually relatively simple to find a table that will detail the specifications and sizes for their cable glands, including any conversions you need to make. By taking measurements or referring to the technical specifications of the wires and cables you intend to use, you can quickly find the right size of product.

The main things to consider are the cable size, whether it is an armoured cable and the cable's internal construction. There are differences between unarmoured and armoured cables when calculating the appropriate cable gland size. When measuring an unarmoured cable to fit a gland, consider the entire diameter of the cable as this will be the most important measurement.

For armoured cables you may need to divide your measurement to account for the diameter of the inner bedding, the armouring, any lead covering and the outer sheath separately. This is because you may need to remove the outer cable sheath and, potentially, some of the armouring to install the cable gland correctly, and you need to ensure that it will fit properly when you do so to maintain a tight environmental seal around your cable.

If there is threading you will also need to know the gauge in order to install a suitable cable gland. You should determine whether you will need to remove armouring from your cables during the planning phases of your network so that you can ensure that you choose a suitable gland for an armoured cable.

There are many factors that can affect cable gland size, so if you are still unsure what size or specifications you need, you can contact Northern Connectors for advice tailored to your exact application.

What are the variations in cable gland specifications?

Beyond different cable gland sizes, you should also consider factors like the material, the type of gland and the operating needs of your network when choosing a cable gland. For example, some glands are designed to withstand extreme temperatures or are flameproof, and will be better suited to systems that require heat resistance. Other glands have a higher pressure rating, meaning that they can operate under extreme conditions and factors like this will strongly affect the suitability of a given gland for your application.

Cable glands can be made of plastic (usually PVC), rubber, nylon, steel, brass or aluminium, and each type is most suitable for a different type of system, so this is one of a number of fundamental differences that are also important to consider. Other such considerations include whether you need a single seal or double seal gland, and whether or not you need an armoured gland for your application.

Find out more

If you want to know more about Cable Glands or need guidance with selecting a suitable solution for your application, Northern Connectors is here to help.

We stock Cable Glands from a number of industry-leading brands including PMA and HUMMEL. 

You can explore the Glands & Cable Protection section of our website, call us on 01744 815001, or complete our online contact form and we will be in touch at the nearest opportunity.