Cable glands & Nuts
In trailer construction and truck electrical installation, correct cable entry is essential for the long-term reliability of the entire electrical system. Every point where a cable enters an enclosure, junction box or connection housing is a potential weak point. Moisture, dust, vibration and mechanical stress will degrade connections over time if that entry point is not properly sealed and secured. Cable glands and lock nuts with PG thread are designed for exactly this purpose, and they are used extensively throughout the truck and trailer sector.
The PG designation stands for Panzergewinde, a standardised thread profile in accordance with DIN 40430. This profile is widely established in vehicle electrics, trailer construction and bodywork because it is available in a wide range of sizes and fits standard cable entries in enclosures and junction boxes. From the smallest size PG7 for thin sensor cables to the larger PG29 and PG36 for heavy cable bundles in central distribution housings, each size covers a specific cable diameter range. This flexibility makes the PG system applicable throughout the full electrical architecture of a semi-trailer or heavy goods vehicle.
The cable gland itself mechanically secures the cable and provides a closed transition between the cable and the enclosure wall. A sealing ring of the correct PG size closes the gap between the gland and the cable, preventing moisture and dust from entering the enclosure. Where IP68 protection is required, for instance at locations exposed to prolonged water spray or high-pressure cleaning, the sealing function of the gland is critical for installation reliability. In a cable gland truck conduit combination, the transition between the closed nylon conduit and the cable entry of the enclosure is fully sealed, so that the cable harness remains protected along its entire length.
The lock nut is the securing element fitted on the inside of the enclosure. Without a lock nut, a gland can work loose due to vibration, which is a constant factor in a moving vehicle. The lock nut clamps the enclosure wall between itself and the gland body, preventing the connection from shifting or loosening. This applies to both metal versions, typically zinc-plated for corrosion resistance, and plastic versions with a black finish. The black version matches dark-coloured enclosures and black cable glands, which is a common standard in trailer construction.
For the PG gland trailer application, there are two basic variants. The first is the straight cable gland for individual cables, and the second is the gland specifically designed for use with a protective conduit. This conduit gland, such as those designed for closed nylon conduit systems, connects to the end of the conduit and creates a dustproof, mechanically stable transition to the enclosure. The PG size of the gland corresponds to the conduit dimension, ensuring an accurate fit and preventing the cable harness from moving at the entry point.
For cable entry HGV applications, the cable diameter and the enclosure wall thickness must both be taken into account. Each PG size has its own external thread dimensions and its own cable diameter range. PG7 is suitable for cables from 3 to 6.5 mm, PG9 for slightly larger cables, PG11 for diameters of 5 to 10 mm, PG13.5 for 6 to 12 mm, PG16 for 10 to 14 mm, PG21 for 13 to 18 mm, and the larger sizes PG29 and PG36 for bundles up to 25 and 32 mm respectively. Selecting the correct PG size for each cable entry ensures both the mechanical securing function and the sealing integrity.
In the day-to-day work of trailer construction and truck electrical installation, cable glands and lock nuts are used consistently in junction boxes, power distribution points, lighting control housings, and connection points on refrigeration units and hydraulic groups. The technician installs them wherever cables enter an enclosure, combining them with sealing rings and protective conduit to create a complete and robust cable entry. Dekoff supplies cable glands and lock nuts in the standard PG sizes, in both metal and plastic versions, meeting the requirements that the truck and trailer sector places on vibration resistance, sealing performance and service life.