Single and double compression, polyamide, Ex and EMC cable glands — materials, metric, PG and NPT threads, hole sizes, how to size a gland by cable diameter and the standards that apply.
A cable gland is a small part that does four jobs at once: it holds the cable, seals the entry, protects the cable from being pulled out and — on armoured cables — earths the armour. This guide explains the types of cable glands, their materials and thread sizes, how to size them correctly and the standards that apply.
The enclosure is only as well sealed as its weakest entry. A wrongly sized gland is one of the most common reasons an IP66 panel lets in water.
A single seal grips the outer sheath of the cable. They are used for unarmoured cables, mainly indoors, and for armoured cables in dry indoor locations where only armour clamping is needed.
The standard choice for armoured cables in Indian industry. A first seal grips the inner sheath, a cone and ring clamp the armour wires, and a second seal grips the outer sheath. This gives sealing on both sheaths plus a solid earth connection to the armour.
Plastic glands for flexible and unarmoured cables on control panels, machines and plastic enclosures. They are light, do not corrode and are quick to fit. Many are rated IP68 with the right sealing washer.
In areas with flammable gas or dust, glands must be certified for the type of protection of the equipment — for example Ex d (flameproof) or Ex e (increased safety). Some flameproof installations need barrier glands filled with compound. Selection follows the IEC 60079 series and the area classification; certified glands are marked with their Ex rating.
For screened cables on drives and instruments, EMC glands make a 360° contact with the cable screen to keep electrical noise out of the panel.
| Material | Where it suits |
|---|---|
| Brass | General industrial use, indoors and outdoors in normal atmospheres |
| Nickel-plated brass | Better corrosion resistance and appearance; outdoor and humid areas |
| Stainless steel 316 | Coastal, offshore, chemical and food plants |
| Aluminium | Light weight; used with aluminium enclosures |
| Polyamide (nylon) | Unarmoured and flexible cables, plastic enclosures, corrosive areas |
Match the gland to the enclosure and the environment, just as you would for enclosure material. A brass gland in a stainless enclosure near the sea will corrode long before the enclosure does.
Three thread systems are common:
For metric glands fitted with a lock nut, the clearance hole in the gland plate is usually about 0.5 mm larger than the thread size:
| Thread | Clearance hole (approx.) |
|---|---|
| M16 × 1.5 | 16.5 mm |
| M20 × 1.5 | 20.5 mm |
| M25 × 1.5 | 25.5 mm |
| M32 × 1.5 | 32.5 mm |
| M40 × 1.5 | 40.5 mm |
| M50 × 1.5 | 50.5 mm |
| M63 × 1.5 | 63.5 mm |
Always check the gland manufacturer's data for the exact hole size and the minimum spacing between glands, so lock nuts and spanners fit.
A gland is chosen by the cable's diameters, not by its conductor size in mm². Two cables of the same mm² can have very different outer diameters depending on the insulation, the number of cores and the armour.
A gland that is too big will not seal; one that is too small will crush the cable or not close at all.
For more on Indian standards for enclosures and accessories, see our guide to Indian Standards (BIS).
VERCHO Enterprises supplies cable glands, gland plates, cable management and panel accessories for panel builders and projects, and VERCHO Engineering Solutions manufactures enclosures with gland plates punched to your cable schedule. Send us your cable schedule and enclosure details at info@verchogroup.com.
For any question, please write to us at info@verchogroup.com — or send it straight from this page. Our engineering team will reply by email.
