Cable glands play an important role in electrical installations by providing secure cable entry, mechanical retention, and, where required, electrical continuity between armoured cables and equipment.
When working with steel-wire armoured (SWA) cables, two commonly used options are BW and CW cable glands. Although both are designed for SWA cables, they are intended for different installation conditions and sealing requirements.
Choosing between a BW and CW cable gland depends mainly on the installation environment, the level of protection required and how the cable enters the electrical equipment.
In this guide, we explain the key differences between BW and CW cable glands, their applications and the factors to consider when selecting the right gland.
What Is a BW Cable Gland?
A BW cable gland is a brass cable gland designed for use with steel wire armoured cables, particularly in indoor and dry environments.
Its primary functions are to secure the cable, clamp the armour wires, and provide electrical continuity through the armour. Unlike a CW gland, the traditional BW design does not provide a seal around the outer sheath of the cable. This makes it suitable where an external waterproof or environmental seal is not required.
BW glands are commonly found inside electrical enclosures, control panels, switchgear, and other dry indoor installations. They can be a practical choice where the cable entry is protected from direct exposure to rain, water, and other environmental conditions.
What Is a CW Cable Gland?
A CW cable gland is also designed for steel wire armoured cables, but it incorporates an additional sealing arrangement around the outer sheath.
The seal helps provide environmental protection at the point where the cable enters an enclosure. Depending on the specific manufacturer’s design, CW glands are commonly available with IP-rated protection, with IP66 being a typical specification for suitable products.
Because of this additional sealing feature, CW cable glands are commonly used for outdoor, exposed, damp, or otherwise demanding environments. They can also be used indoors where additional environmental protection is required.
BW vs CW Cable Glands: What Is the Difference?
The fundamental difference between BW and CW cable glands is the outer sheath sealing arrangement.
Both types can provide mechanical retention and electrical continuity by clamping the armour wires. The CW design adds an environmental seal around the outer cable sheath, while a traditional BW gland does not.
Feature | BW Cable Gland | CW Cable Gland |
Cable type | Steel wire armoured cables | Steel wire armoured cables |
Typical environment | Indoor and dry | Outdoor, damp or exposed |
Armour clamping | Yes | Yes |
Mechanical retention | Yes | Yes |
Electrical continuity | Yes | Yes |
Outer sheath seal | No | Yes |
Environmental protection | Limited compared with CW | Higher, depending on product rating |
Typical use | Indoor electrical equipment | Outdoor and exposed installations |
The exact IP rating and performance should always be confirmed against the manufacturer’s technical specification because ratings can vary between products.
Why Does the Outer Sheath Seal Matter?
The outer sheath protects the internal construction of an armoured cable from the surrounding environment. At the point where the cable enters an enclosure, the cable gland becomes part of the overall protection system.
With a BW gland, the armour is secured mechanically and electrically, but there is no compression seal around the outer sheath. A CW gland adds a sealing component that grips the cable’s outer sheath, providing additional protection against environmental ingress.
This difference is particularly important when a cable entry is exposed to rain, humidity, water spray, or other environmental conditions.
BW Cable Glands: Applications
BW cable glands are generally suited to indoor environments where the cable entry is not exposed to significant moisture or weather conditions.
Typical applications include:
- Indoor electrical enclosures
- Control panels
- Switchgear
- Distribution equipment
- Industrial control cabinets
- Dry plant rooms
- Indoor machinery
For these applications, the primary requirements may be mechanical retention and electrical continuity rather than an external weatherproof seal.
However, the actual installation requirements should always be checked before selecting the gland.
CW Cable Glands: Applications
CW cable glands are designed for applications where an environmental seal around the cable’s outer sheath is required.
They are commonly used for:
- Outdoor electrical equipment
- External control panels
- Outdoor junction boxes
- Industrial installations
- Exposed cable entries
- Damp or moisture-prone environments
- Equipment requiring an IP-rated cable entry
CW glands can also be used indoors when the installation requires additional environmental sealing.
The specific protection level depends on the gland design and installation, so the manufacturer’s stated IP rating should always be checked.
BW vs CW: Which Cable Gland Should You Choose?
The simplest way to approach the decision is to start with the installation environment.
If the SWA cable is entering equipment located in a dry indoor environment, a suitable BW gland may be appropriate where an outer sheath seal is not required.
If the cable is installed outdoors or in a moisture-exposed environment, a CW gland is generally the more appropriate choice because it provides a seal around the outer sheath.
A simple rule of thumb is:
BW for dry indoor applications. CW where an environmental seal is required.
However, this should not replace checking the actual product specification, cable construction, enclosure requirements, and applicable installation standards.
How to Choose the Correct BW or CW Cable Gland Size
Choosing between BW and CW is only the first step. The gland must also be the correct size for the cable.
Cable size is not determined only by the conductor cross-sectional area. The gland needs to accommodate the actual dimensions of the cable, including its overall diameter and armour dimensions.
Manufacturers therefore provide gland selection charts showing the suitable gland size for particular cable constructions and dimensions.
For example, BW and CW glands may be available in sizes such as 20S, 20, 25, 32, 40, 50, 63, and 75, but the correct size depends on the cable’s dimensions and construction.
Before ordering, check:
- Cable overall diameter
- Diameter under the armour
- Armour wire size
- Cable construction
- Gland size
- Enclosure entry thread
- Manufacturer’s sizing chart
Do not select a gland based solely on the cable’s conductor size.
Common Mistakes When Selecting BW and CW Glands
One of the most common mistakes is choosing a BW gland for an exposed outdoor installation simply because it fits the cable. The fact that a gland mechanically fits the cable does not mean that it provides the required environmental protection.
Another mistake is choosing a gland based only on the conductor size. Cable construction and actual dimensions also need to be considered.
It is also important not to assume that every CW gland has the same IP rating. Always check the manufacturer’s technical documentation for the specific product.
Finally, correct installation is essential. The gland, cable, enclosure, accessories, and installation method all need to work together to achieve the required level of protection.
BW vs CW Cable Glands: Quick Selection Guide
Installation requirement | Recommended consideration |
|---|---|
Dry indoor environment | BW may be suitable |
Indoor environment requiring environmental sealing | CW may be suitable |
Outdoor installation | CW is generally preferred |
Moisture or water exposure | Choose a suitable sealed gland such as CW |
SWA cable requiring armour termination | BW or CW, depending on environment |
High environmental exposure | Check gland rating and consider a specialised design |
Hazardous area | Use a gland specifically certified for the applicable hazardous-area requirements |
The table is a general selection guide. The final choice should always be based on the cable manufacturer’s requirements, gland manufacturer’s specifications, installation conditions, and applicable standards.
Making the Right Choice Between BW and CW Cable Glands
BW and CW cable glands serve similar fundamental purposes, but their sealing arrangements make them suitable for different installation conditions.
BW cable glands are generally intended for dry indoor applications where an outer sheath environmental seal is not required. CW cable glands incorporate an additional outer sheath seal and are commonly selected for outdoor, damp, or exposed installations where environmental protection is needed.
When selecting a gland, consider the cable construction, cable dimensions, installation environment, required IP protection, thread type, and any applicable standards or certification requirements.
Choosing the right gland is not simply about selecting BW or CW. It is about matching the gland to the cable and the conditions in which it will be installed.
Find the Right Cable Gland for Your Application
Looking for reliable cable glands for SWA and other electrical applications?
Explore Raiden Electric for cable gland solutions and product information. For a specific installation, always check the relevant technical specifications and sizing information to ensure the selected gland is suitable for your cable and application.
BW vs CW Cable Glands: Frequently Asked Questions
A standard BW gland is generally intended for dry indoor applications because it does not provide the same outer sheath environmental seal as a CW gland. For outdoor or exposed installations, a suitably rated CW gland is generally the more appropriate choice.
Yes. Both BW and CW glands are commonly designed for steel wire armoured cables. Both can provide mechanical retention and electrical continuity through the cable armour, while CW glands additionally provide an environmental seal around the outer sheath.
Not necessarily. They are designed for different installation conditions. BW can be suitable for dry indoor applications where an outer sheath seal is not required, while CW is generally selected where environmental sealing is needed.
Yes. CW glands can be used indoors as well as outdoors. If an indoor installation requires additional environmental sealing, a CW gland may be appropriate.
The correct gland size depends on the cable’s construction and dimensions, including its overall diameter and armour dimensions. Always use the manufacturer’s sizing chart rather than selecting the gland based only on conductor size or thread size.