Essential Tips for Cable Gland Sizing: A Beginner’s Guide

Cable glands are essential components in electrical installations, ensuring cables are safely routed through enclosures, panels, or equipment. They are designed to provide protection from environmental factors such as water, dust, and mechanical stress.

In addition, cable glands help with strain relief and grounding, ensuring cables remain in optimal condition and operate safely over the long term. However, selecting the right size cable gland for a specific application is key to ensuring these protective features work as intended.

In this guide, we’ll take a deep dive into the cable gland sizing process, its importance, and how to choose the right cable gland for your needs.

What Is a Cable Gland?

A cable gland is a mechanical fitting used to secure the end of a cable and provide a seal where the cable enters an enclosure or electrical panel. The gland creates a watertight and airtight seal, preventing environmental factors from affecting the cable or the equipment. The function of the gland is not only to hold the cable securely in place but also to protect the cable from damage due to vibration, external mechanical stress, or environmental conditions.

Cable glands are available in different designs to accommodate various types of cables, including armored, non-armored, and flexible cables. They come in a variety of materials such as brass, stainless steel, and plastic to meet the specific requirements of the application, including protection against corrosion, heat, and chemicals.

Key Functions of Cable Glands:

• Sealing: Protects the cable from external elements such as dust, moisture, and chemicals.
• Strain Relief: Prevents mechanical stress from damaging the cable or affecting its performance.
• Earthing/ Grounding: In certain designs, cable glands provide an earthing mechanism to protect against electrical faults.
• Environmental Protection: Prevents the entry of hazardous materials and ensures safety in hazardous environments.

Why Is Cable Gland Sizing Important?

Choosing the correct size of a cable gland is critical for a number of reasons. A poorly sized cable gland may lead to a range of issues that can compromise both the safety and efficiency of the installation. These issues may include poor sealing, improper strain relief, or damage to the cable insulation, all of which can result in serious safety hazards or failure of the electrical system.

Here’s why sizing matters:

Steps for Sizing Cable Glands

Sizing a cable gland requires careful attention to detail.

Below are the steps you can follow to choose the right size:

1. Measure the Outer Diameter (OD) of the Cable

The first step in sizing a cable gland is to accurately measure the outer diameter (OD) of the cable that will pass through the gland. Use a caliper or micrometer to measure the cable’s diameter at several points, especially if the cable has an uneven shape or irregular insulation.

Ensure that you measure the full cable, including any sheathing or insulation, as this will affect the gland’s fit. Don’t forget to include any additional layers such as armor, braiding, or flexible coatings that could alter the cable’s overall diameter.

2. Consult the Manufacturer’s Sizing Chart

Cable gland manufacturers usually provide sizing charts that match specific cable sizes with the corresponding gland sizes. These charts can help you determine the exact gland size based on the outer diameter of the cable. The sizing chart will typically list the minimum and maximum cable diameters that can be accommodated by each gland.

3. Choose a Gland with the Correct Range

Once you have identified the outer diameter of your cable, select a gland that fits within the range specified in the manufacturer’s chart. Cable glands are typically available in a range of sizes to accommodate cables with varying diameters. It’s important to pick a gland that is neither too small (which would prevent proper sealing) nor too large (which may not provide adequate strain relief or protection).

4. Consider the Type of Cable

The type of cable you’re using will influence the gland size you need. For example:

Armored cables typically require a larger gland to accommodate the cable’s protective layer (armor).
Non-armored cables will need a gland designed for simpler applications.
Flexible cables may require glands specifically designed to hold the flexible strands securely.
Make sure to select a cable gland that is designed to handle the specific type of cable you are working with.

5. Account for Environmental Conditions

If your installation is in a harsh environment, you may need a specialized cable gland that offers additional sealing or protection. Consider the IP rating of the gland, which specifies its resistance to dust and water ingress.

How to Check You Have the Correct Cable Gland Size?

After selecting a cable gland, it’s important to verify that it is the correct size.

Here are some tips to ensure you have the right fit:

Tips for Choosing the Right Cable Gland

Here are a few additional tips to keep in mind when selecting a cable gland:

Material Selection: Consider the material of the gland. For outdoor or industrial applications, choose glands made from corrosion-resistant materials such as stainless steel or brass. For lighter-duty applications, plastic glands may suffice.

IP Rating: Ensure that the gland has the appropriate Ingress Protection (IP) rating for the environment. An IP66-rated gland will be suitable for outdoor use, while IP68 may be required for submerged applications.

Temperature Resistance: If your cables are used in extreme temperature environments, select a gland that can withstand those conditions.

Check for Certifications: Always verify that the cable gland is certified for your specific use case, such as flameproof, explosion-proof, or marine-rated glands.

Conclusion

Selecting the right size cable gland is essential to ensuring the safety, efficiency, and longevity of your electrical installation. By following the steps outlined in this guide, you can make an informed decision and select the right gland for your needs.

The right cable gland provides the necessary protection, strain relief, and sealing to ensure your installation is safe and reliable. Always ensure you meet relevant industry standards and take care to select the correct materials and certifications for your specific application. A properly sized and correctly installed cable gland will not only protect your cables, but will also improve the overall reliability of your electrical system.