How to choose a metal cable gland for IP68 environments: A Complete Guide

    When working with electrical installations in harsh, submerged or continuously wet environments, IP68-rated enclosures demand equally reliable sealing components, and the metal cable gland is one of the most critical parts to get right. A poorly selected cable gland can compromise the entire IP68 rating, allowing water, dust, and debris to penetrate the enclosure, leading to short circuits, equipment failure, and even safety hazards. Unlike standard cable glands, those designed for IP68 environments must withstand continuous immersion in water at significant depths, maintain a dust-tight seal over long periods, and resist corrosion and mechanical stress. This guide breaks down the key factors to consider when selecting the right metal cable gland for these demanding conditions, helping engineers and installers make informed decisions that protect long-term equipment performance. First, start by confirming the core IP68 compliance requirements for your specific application. The IP rating system defines IP68 as completely dust-tight and protected against continuous immersion in water deeper than 1 meter, but the exact depth and duration can vary between manufacturers. Many manufacturers label their glands as IP68-rated, but some only test to the minimum standard, while others are certified for depths of 10 meters, 50 meters, or even greater. Before making a selection, check the official certification documents to ensure the gland meets the depth and immersion duration required for your project. For example, an underwater sensor installation at 20 meters needs a gland tested for that specific depth, not just a general IP68 rating. You should also verify that the entire assembly—including the sealing washer, locknut, and body—maintains the IP68 rating under expected operating temperatures and mechanical stresses, as some low-quality glands only hold the rating at room temperature with minimal vibration. Next, select the appropriate metal material based on the installation environment, as corrosion resistance is non-negotiable for long-term IP68 performance. The most common metal options are brass, 304 stainless steel, and 316 stainless steel, each suited to different conditions. Brass with nickel plating offers good general corrosion resistance for dry or mildly humid outdoor IP68 applications, but it can degrade quickly in saltwater or chemically aggressive environments, which will break down the seal over time. 304 stainless steel is a popular mid-range option, providing better corrosion resistance than brass for most industrial and outdoor use, but it is still vulnerable to pitting in coastal or high-chlorine environments. For submerged applications, marine installations, or sites with exposure to chemicals or acids, 316 stainless steel with its added molybdenum content is the best choice, as it resists corrosion and pitting far better than other common metals. Choosing the wrong material will lead to gradual degradation of the metal body, which will eventually break the IP68 seal even if the gland was correctly rated initially. Additionally, match the cable gland size precisely to both your cable diameter and enclosure thread size. Even a small mismatch can create gaps that compromise the IP68 rating. Most metal cable glands come with a specified clamping range for cable outer diameters, and you must ensure your cable’s diameter falls within the middle of this range, not at the extreme upper or lower limit. If the cable is too small for the gland, the sealing rubber cannot compress enough to create a watertight seal; if it is too large, you will not be able to tighten the gland properly, leaving gaps for water to penetrate. You also need to match the thread type and size to the opening on your IP68 enclosure—common thread types include NPT, PG, and metric, and mixing types will lead to poor sealing even with thread tape. For extra protection in high-vibration or deep-water applications, consider adding a thread sealant or O-ring to the connection between the gland and enclosure to reinforce the IP68 rating. Furthermore, consider the mechanical demands and environmental factors specific to your installation to add extra layers of protection. If your installation is exposed to constant vibration, such as on a marine vessel or industrial machinery, look for metal cable glands with integrated strain relief. Strain relief prevents the cable from being pulled or twisted out of the gland over time, which would break the IP68 seal. If you need to maintain electromagnetic compatibility (EMC) for sensitive electronics, choose a metal cable gland with conductive sealing inserts that provide electrical shielding, blocking electromagnetic interference while maintaining the IP68 watertight seal. It is also important to check the temperature rating of the sealing components, because the rubber or elastomer seal that creates the IP68 barrier can degrade in extreme temperatures. For example, silicone seals work well in low-temperature submerged environments, while EPDM seals offer better resistance to high heat and UV exposure for outdoor above-water IP68 installations. Finally, always source your metal cable glands from reputable manufacturers that provide clear certification and test data. Many low-cost uncertified glands claim to meet IP68 standards, but they often use poor-quality sealing materials or thin metal that fails within a few years of installation. Investing in a certified gland from a trusted supplier may cost slightly more upfront, but it prevents costly downtime, equipment replacement, and safety issues that come from a failed seal. After selecting the correct gland, be sure to follow the manufacturer’s installation instructions carefully—over-tightening can damage the seal, while under-tightening leaves gaps that compromise the IP68 rating. By following these key steps, you can select a metal cable gland that maintains a reliable IP68 seal for decades, protecting your electrical equipment even in the harshest submerged and dusty environments.