Cable glands are a common feature of panel assemblies and electric infrastructure used to mount wires and protect cables. These devices vary widely, with designs for a variety of applications and environmental conditions. Here, we’ll answer some of the most common questions about cable glands. Read on to discover answers to what are cable glands used for, what are the different types of cable glands and how do you choose one for an application?
What Are Cable Glands?
Cable glands are defined as mechanical cable entry modules, which means they are used to attach electrical cables to equipment securely. Unlike household plugins and other conducting electrical connections, cable glands are not made for quick disconnections. Instead, they provide a secure and long-lasting connection to a device. Cable glands go by many names — you may see them referred to as a:
- Cable connector
- Cable fitting
- Cable strain relief
- Cord grip
No matter the name, cable glands serve almost any industry that uses electrical equipment in some capacity. Cord grips are used for cables and wiring in a range of electrical, instrumentation, control and automation systems, offering uses for power, data and telecommunications wires.
What Are Cable Glands Used For?
The first question to answer is why do we use cable glands? In short, cable fittings are considered critical safety devices for electrical installations. Their primary purpose is to act as sealing and terminating devices between a cable and its connected electrical equipment. In this role, cord grips serve a few core purposes:
- Connection protection: The cable gland seals the outer cable sheath, protecting the wiring and electrical enclosure from dust, dirt, moisture and other environmental hazards that may compromise the installation’s functionality. Some cord grips may be designed to provide additional sealing in applications with a higher potential for environmental conditions to come in.
- Strain relief: The cord grip secures the cable to the installation at a fixed angle. This connection provides strain relief and resistance against twisting and pulling forces to prevent disconnection.
Different Types of Cable Glands
With so many applications for cable fittings, there is a huge range of cord grips available. So how many types of cable glands are there? There are as many varieties as there are applications. Most cable fittings are characterized by factors such as materials, armor compatibility and application-specific needs. Below are some of the most common features for cable fittings organized by category:
1. Material Features
The most basic differentiation between cable fitting designs is their materials. Some of the most common materials used for cable glands include:
- Metals: Metallic cable glands are used in a broad range of applications and feature materials like stainless steel, aluminum and nickel-plated brass. Rigid stability, long-term durability and electrical and thermal conductivity are some of the key advantages of this material. Metallic cord grips are ideal for applications where chemical stability and mechanical strength are required. Some examples of applications include the IT, power, medical and chemical industries.
- Plastics: Plastic cable connectors are another popular material choice due to their adaptability and resistance to various corrosive elements. Plastic cable grips are often made of polyamide or nylon and typically come in a claw and seal design, making them highly adaptable. Plastics are also resistant to salt water, weak acids and grease, making them a great choice for various industries. Some examples include telecommunications, marine and flex cable applications.
2. Armor Compatibility Features
Another basic difference between cable strain reliefs is whether they’re suitable for armored or unarmored cables. Industrial cable glands are available for both varieties. Know what type of cable your operation uses to determine the right cord grip for the application, whether you have:
- Armored: Armored cables are designed with an extra layer of protection for damage prevention. This cable often appears in applications where the area may be exposed to an increased threat of mechanical damage. Armoring often comes in a single wire, braided wire or double steel tape. Cable glands designed for armored cables will have design features that make them more compatible with cable armoring.
- Unarmored: Unarmored cables are more basic in design than armored cables and do not have added mechanical protection. These appear in fixed installations without a substantial risk of mechanical damage. Cable glands designed for unarmored cables will not have as many features as those designed for armored ones since they do not need to accommodate specific demanding needs.
3. Application-Specific Features
Another way to define cord grip varieties is by the protection they provide or their ability to suit needs in specific environments. Application-specific cable gland varieties include:
- Electromagnetic compatibility (EMC): Electromagnetic interference (EMI) is an electronic emission that interferes with electronic components and devices. EMC means a device is both protected from EMI and does not emit EMI. EMC cable glands are often used in applications where cables need to be shielded for electromagnetic protection. These cord grips shield the termination point of the cable.
- Marine or waterproof cable glands: Waterproof cable connectors offer a watertight seal to connect a cable or wire to an enclosure. But how do waterproof cable glands work? In most cases, a waterproof cable gland has parts that enter the enclosure through a hole. When the gland is assembled, the enclosure wall is captured between the components and the cable threaded through the grip. When someone tightens the parts, these features create a watertight seal for marine equipment, wastewater treatment facilities and other applications where protection from water is a necessity.
- Electrical cable glands: Many cord grips are useful for electrical applications, but what are electrical cable glands and what differentiates them? Electrical cable connectors are typically metallic and feature some amount of voltage relief or earthing. That feature ensures shorts will not damage the connection.
- Fire-stop cable glands: Fire-stop cable fittings are designed to withstand fire propagation and explosions, an important safety feature for applications with any level of fire risk. This variety can also include explosion-proof and flameproof industrial cable glands.
Cable Gland Designations
You will often see cable glands given specific designations according to BS 6121. This British Standard was originally a standardization method for cable strain reliefs in the industrial sector and specified requirements for different designs. Although this is no longer the most current standard in the EU, it still serves as a valuable designation among manufacturers to communicate types of glands and their key features. Some of the most common types and designations include:
1. Type A Cable Glands
Type A glands may also be referred to as “stuffing glands” and are commonly used on unarmored plastic or rubber-sheathed cables. There are four A-type designations:
- Type A1: Type A1 cable connectors are often plastic glands used to protect the cable’s outer jacket.
- Type A2: Type A2 cable glands may be plastic or brass and feature an IP68-designated seal between the cable’s outer jacket and the gland.
- Type A3: The type A3 cable strain relief is a variation of the type A1 gland. This grip variety includes an electrical bond for the inner jacket of the cable.
- Type A4: The type A4 cable gland is a variation of the type A2 gland. This connector also features an electrical bond for the inner jacket of the cable.
A-type glands are often used in indoor and outdoor applications where armored cables are unnecessary.
2. Type B Cable Glands
Type B cable glands are designed for use on single-wire armored cables made with plastic or rubber sheaths. The glands themselves are made of brass and are designed for securing the cable’s armor and providing an electrical path between the armor and the gland. These cord grip designs are made for use in indoor applications where moisture exposure is low.
3. Type C Cable Glands
Type C cable glands are designed for use on plastic or rubber sheathed cables with armor or braiding. Type C cables are made of brass or stainless steel and serve a similar purpose as the type B cable gland.
The primary difference between the two designations is that the type C cord grip features an IP68-designated seal between the outer sheath and the gland. This seal provides an extra level of protection against moisture and environmental exposure, making this connector design suitable for outdoor applications with a greater need for weatherproofing and waterproofing.
4. Type D Cable Glands
Like B-type cables, type D cables are designed for use on armored or wire braided lines with plastic or rubber outer sheaths. The key difference between this cable gland variation and the type B cable gland is that it features an IP68-designated seal between the inner sheath and the threaded fixing part.
There are two variations of the type D cable gland:
- Type D1: This cable gland is the basic version of the type D design, featuring the IP68 seal between the inner sheath and the fixing component.
- Type D2: This variation has the same seal as the D1 variation and features an electrical bond for the inner sheath of the cable.
5. Type E Cable Glands
Type E cable glands are used on cables with armor or braiding and plastic or rubber outer sheaths. The type E cord grip is often made of brass or stainless steel. It’s similar to the C-type cable connector design, with an armor locking ring and inner and outer seals rated to IP68. The outer seal grips the cable sheath, while the inner seal grips the cable’s bedding layer.
There are two variations of the type E cable gland:
- Type E1: The type E1 cable gland has all the basic features of the E variation.
- Type E2: The E2 variation has all the characteristics of the E1 cord grip design and includes an electrical bond for the inner sheath of the cable.
Type E cable glands are highly suitable for applications with exposure to the elements as the seal features of E variation offer excellent waterproofing and weatherproofing.
6. BS 6121 Suffixes
In addition to the variations above, cord grips with B, C, D, and E designations will also often feature a suffix along with the classification. This suffix indicates the specific armoring the gland is designed for. These suffixes are defined as follows:
- W for single wire armored cables
- T for pliable wire armored cables
- X for wire braided cables
- Y for aluminum strip armored cables
- Z for double steel tape armored cables
In practice, the cable gland will be designated with their cable type first and their protection suitability immediately after. For example, a type C cord grip designed for a single wire armored cable will have a designation of “CW.” If a gland design may be used for more than one armoring variation, all the relevant suffixes will be added after the cable gland type. For example, a type B cable connector designed for both single and pliable wire armored cables will have a designation of “BWT.”
How to Choose a Cable Gland
With so many different cable connector features and designs to sift through, it can be challenging to determine which type of cable gland to use for a specific application and what features to look for. The key to making this choice is to identify the application’s needs first and then eliminate cable fitting options using this information. Some key questions to ask when selecting a cord grip include:
- What is the nature of installation — domestic, commercial or industrial?
- Will the cable gland be in an indoor or outdoor environment?
- What are the temperature conditions for the environment, and how much will they fluctuate?
- Will the cable gland be exposed to moisture, dust, dirt or corrosive elements?
- Will there be any risk factors in the environment, such as an explosive or corrosive atmosphere?
- What is the cable size, and does it feature any armoring? If it does have armor, what type?
Once you have narrowed down your cable gland options to suit your application’s needs, you can then make a final decision based on cost.
Shop Cable Glands From AerosUSA, Inc.
Cable glands are a small yet essential piece of equipment in nearly every industry. Whether you’re working in the aerospace, marine, power, telecom or industrial sectors, cable glands are a key safety feature. The importance of cable fittings can’t be understated, so it’s essential to find quality designs that fit perfectly into your application and environment. AerosUSA can help.
AerosUSA is a leading supplier of wire and cable protection systems. Our products, manufactured by Flexa GmbH, include everything from cable covers and shielding systems to high-quality cable glands. Our experience spans a range of industries, and we carry a selection of products that is just as diverse. On top of it all, we offer quick responses, competitive pricing and fast turnaround times.
Contact AerosUSA today to learn more about cable glands and our selection.