What Is a Cable Gland?
Cable glands made of polyamide and nickel-plated brass
A cable gland, also known as a compression fitting or cable entry, leads the cable into the housing in a sealed and strain-relieved manner. Plugs, terminal boxes or control cabinets, control panels, boom boxes, crane blocks or wiring boxes are used as enclosures. A cable gland ensures that the cable is securely sealed at the passage through a side wall or sheet metal plate into the terminal compartment. In addition, it ensures that the control cabinet is protected from external influences (e.g. dust or moisture). Depending on the area of application and environmental influences, additional properties such as EMC compatibility or ATEX approvals for EX-protected areas must be taken into account.
Cable glands don't only seal or relieve the lines, they also prevent the cable from kinking thanks to special anti-kink sleeves. A cable gland therefore protects electrical equipment itself and also ensures that cables connected to a control cabinet continue to function properly.
The classic manufacturers of cable glands include:
- Kaiser GmbH
- OBO Bettermann
Nowadays, metric threads according to DIN EN 60423 are mostly used. In addition to metric threads, PG cable glands (armored steel pipe thread) in accordance with DIN EN 62444 are used in some exceptional cases, mostly in older applications that are converted, repaired or retrofitted. For all cable glands there are corresponding expansions or reductions to be able to adapt the screw connection to any existing thread. If the cable gland is installed in a through hole instead of a thread, it must be locked with a corresponding counter nut.
Areas of application
Cable glands can be found in a wide variety of areas, including the following:
- Electrical engineering
- Automation technology
- Mechanical and plant engineering
- Traffic engineering
- Chemical engineering
- Food industry
Due to their diverse areas of application, they have to meet a wide range of requirements in terms of protection class, continuous use temperature, explosion protection, impact resistance or EMC (electromagnetic compatibility).
Cable glands are available in different qualities. The three common choices include plastic, brass (or nickel-plated brass), and stainless steel . These materials can be combined with sealing inserts made of different materials and matched to the cable diameter as well as the conditions of use and external influences. Elastomers such as acrylonitrile butadiene rubber (NBR), fluororubber (FPM) or silicone (VMQ) can be used as a molded seal.
In chemical engineering and in the food industry, for example, cable glands made of stainless steel (INOX 1.4305) are used. The use of stainless steel is mandatory for hygienic and health reasons or due to the use of sometimes aggressive cleaning agents and chemicals in both industries. Stainless steel is a resistant material and withstands external influences particularly well. Depending on the area of application, other factors should be taken into account in addition to the suitable material.
How do I choose the right cable gland?
The following 3 factors must be considered when making a selection:
1. Thread size
In order to combine the different cable diameters with the thread size intended for the cable gland, the glands are divided into different clamping areas. The metric dimension (M) forms the nominal size for cable glands in combination with the following digits for the thread size.
The following table will help you choose the right cable gland:
2. External influences
Cable glands can be used in a wide variety of environments - the external influences that act on the cables and the screw connection are correspondingly different.
In certain areas of application, the screw connections are exposed to moisture or water. A degree of protection of the plug is necessary here to protect against the ingress of moisture or water into the housing. Depending on the area of application, protection against contact and foreign bodies should also be taken into account.
Depending on the type of external influences to which the cable gland is exposed, it is important to choose a material for the gland that is suitable for the area of application.
As already described, cable glands made of stainless steel are used, for example, in the food and chemical industries.
Brass cable glands are usually used in "hazardous areas", such as those found in the oil and gas industry.
Cable glands with the material property "brass nickel-plated" are often found in very harsh industrial applications or in an EMC-compatible variant with a special shield concept.
Plastic cable glands made of polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF) or polyamide (PA) are also used in industry depending on the application and environmental conditions.
Does igus® offer cable glands?
igus® offers cable glands made of brass (nickel-plated) and polyamide (plastic). A selection of cable glands can be found on our website under Cable glands .
Can't find what you're looking for? We would be happy to assist you in choosing the right cable gland for your application. Contact an igus® expert here.