Single vs. Double Compression Cable Gland: Which Heavy Duty Solution Do You Need?

In the case of industrial electrical installations, choosing the appropriate cable gland is not just a question of size, it’s a safety necessity. Although the standard brass glands are commonly used in the industry, knowing when to choose a Double compression cable gland over a single compression variant can guarantee the long-term safety of your system.
This guide explores the technical differences between these two types of glands so you can find the right solution for heavy duty and hazardous applications.

Understanding the Core Differences

To the untrained eye, many brass glands look identical. However, the internal mechanisms define their application scope.

Single Compression: The Basic Standard

A single compression gland is meant for lighter applications. It has a seal that is made at just one point; usually, it is gripping the outer sheath of the cable.

Best for: Unarmored cables or indoor environments where moisture ingress risk is low.

Limitation: If the outer seal fails, there is no backup protection for the electrical connections inside.

Double Compression: The Heavy Duty Standard

The Double compression cable gland is engineered for tough conditions and protection. It has a two-part sealing system as the name indicates:

Outer Seal: Compresses the outer cable sheath, preventing moisture and dust from entering the gland body.

Inner Seal: Compresses the inner bedding (insulation) of the cable.

This dual-seal system is a must when considering Single compression vs Double compression cable gland performance. If the outer seal is broken due to extreme weather or accidental damage, the inner seal will still keep the enclosure intact which makes it the best choice for heavy duty brass cable glands.

Single vs. Double Compression Cable Gland

Why Choose a Double Compression Cable Gland?

Double compression is frequently a requirement for engineers dealing with Steel Wire Armored (SWA) cables. The gland consists of a specific cone and clamping ring that securely holds the armor wires in a proper manner. This gives:

Earth Continuity:Ensures the armor is effectively grounded.

Mechanical Retention:Prevents the cable from being pulled out under tension.

Ingress Protection:Offers higher IP ratings (typically IP66 or IP67) suitable for outdoor and marine environments.

It’s a common practice in the industry to use double compression brass cable glands, although the choice of finish may depend upon certain environments. For instance, in corrosive atmospheres like chemical plants or coastal regions where normal brass may be subject to tarnishing or seizing, Nickel plated brass cable glands are recommended.

Sizing Matters: Precision is Key

One typical mistake in procurement is the sizing issue. Only the outer diameter of the cable needs to be matched in the single compression method. Nonetheless, the Brass cable glands sizes for dual compression are much more significant.
The gland seals on both the inner bedding and the outer sheath, hence you need to measure both diameters accurately. In case of a mismatch on the inner seal, the "double" protection becomes ineffective and the gland's performance is brought down to that of a single compression unit.

Trust Pioneer Power International For Your Connections

The decision of using a single or double compression cable gland is totally dependent on the environmental risks and the type of cable. In case of general indoor applications, single compression is the way to go economically. On the other hand, double compression gland is the minimum requirement for safety in case of outdoor, hazardous, or armored cable applications.
Pioneer Power International, is the place to be if you need a manufacturer for high-precision brass glands that comply with worldwide industrial standards. Our engineering team ensures that every gland you get, whether it is the heavy duty double compression type or the nickel-plated one for corrosion resistance, meets rigorous safety specifications.

Frequently Asked Questions:

How does the sealing mechanism technically differ in a Single vs. Double Compression Cable Gland?

A single compression gland only seals the outer sheath, whereas a double compression cable gland uses a dual-seal system. It compresses both the inner bedding and the outer sheath simultaneously. This design prevents water from traveling along the armor wires even if the outer seal fails, making it ideal for heavy-duty applications requiring critical ingress protection.

Is a Double Compression Cable Gland mandatory for SWA (Steel Wire Armored) cables?

Yes, double compression cable glands are standard for outdoor or hostile installations of armored SWA cables. They use a special cone and ring to grip the steel wires, ensuring earth continuity and mechanical retention (pull-out resistance), unlike standard single compression brass glands which struggle under heavy stress.

When should I specify Nickel Plated Brass Cable Glands over standard brass for double compression?

Nickel-plated brass cable glands are best for corrosive environments (marine, chemical, sewage plants). The nickel coating protects the strong brass from rust and tarnishing. For heavy-duty, humid, or slightly acidic projects, this plating prevents thread seizing, thus preserving the compression seals.

Why are Brass Cable Glands Sizes more critical to measure when using double compression glands?

Double compression cable glands require precise measurement of both the Cable Inner Diameter (bedding) and Outer Diameter (OD) for correct sizing, making it less forgiving than single compression, which only needs the OD. If the inner seal doesn't fit the bedding tightly, the double protection fails, rendering the gland no better than a single compression type.

Can Double Compression Cable Glands be used for both flameproof (Ex d) and increased safety (Ex e) applications?

High-quality double compression cable glands are often dual-certified for Ex d (flameproof) and Ex e (increased safety). The durable brass body contains internal explosions (flameproof) and the double sealing prevents gas/dust ingress (increased safety). Always verify the selected gland's required hazardous area certifications. Refer to IEC 62444:2010 for more information on global standards.