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Ex CABLEGLANDS & ACCESSORIES
What is a cable gland? Cable entry
Standard Definition: Entry type and/or thread specification
“A device designed to permit the entry of a cable Clearance holes - A locknut will be required to fix
into electrical equipment and which provides the gland securely within a clearance hole. The
sealing and retention. It may also provide other additional use of a serrated washer will provide
functions such as earthing (or grounding), a greater level of fixing security, this is definitely
bonding, insulation, strain relief or a combination worth considering if the equipment is likely to
of these.” be subject to vibration or severe temperature
changes.
In addition to this a cable gland should maintain
the overall integrity of the enclosure into which it Threaded Entries
is to be fitted. Glands can generally be supplied with a male
thread to match the female entry thread. If this
Step 1 – What is the basic construction of the is not possible Thread Adaptors or Reducers can
cable and how do we want to terminate it? be used to match dissimilar threads. If the wall
Unarmoured cables will require the outer thickness will permit, the use of a locknut will
sheath seal within the gland to not only provide provide additional security.
ingress protection but also a degree of retention.
Armoured cables require a gland that features Ingress Protection
a clamping mechanism to terminate the armour The gland selected should maintain the IP
both mechanically and electrically. The gland will integrity of the enclosure. In order to maintain
usually be required to provide ingress protection the required IP rating for different entry types the
by sealing on the outer sheath and retention by following sealing arrangements should be used:
clamping the armour. Typically, armoured cables
feature an inner sheath that the gland may be Clearance Holes - Integral ‘O’ ring seal or nylon IP
required to seal on. washer
Parallel Threaded Entries - Integral ‘O’ ring seal,
Step 2 - The correct gland size IP washer or non-hardening thread sealant
The entry thread (i.e. M20) is not, as often Taper Threaded Entries - Non-hardening thread
perceived the gland size but simply the entry sealant
thread size and specification. It is important to
understand that selection of the correct gland Impact Resistance
size is based solely on the cable dimensions: The gland selected should maintain the impact
• Outer Sheath Diameter integrity of the enclosure. For hazardous location
• and where applicable: equipment the minimum impact resistance
Inner Sheath Diameter is usually 7Nm. Special care should be taken
• Armour / Braid Thickness when selecting Nylon glands as these often have
reduced impact capabilities.
Step 3 – Maintaining the overall integrity of the
installation Material
In order to maintain the overall integrity of The gland should be manufactured from a
the installation it is important to consider the material that is suitable for the surrounding
equipment into which the cable is to be glanded environment and will not react adversely with the
and the surrounding environment. The areas to material of the enclosure into which it is installed.
consider are: In particular it should be noted that Brass, the
Cable entry - Ingress Protection - Impact standard material for metallic glands, can react
Resistance – Material - External Influences - adversely with Aluminium as if moisture becomes
Certification present bi-metallic corrosion may occur. When
using brass glands H2S, SO2 and ammonia are
the most problematic environments. Nickel, tin
or zinc plating can be applied to brass to both
minimize the potential for bi-metallic corrosion
and provide a degree of protection from the
surrounding environment.
