Comment on glands for SWA Cable
Universal glands for SWA cable are now supplied by several manufacturers. Their specific installation details should be referred to.
Some glands have a reversible clamp ring to widen the range of cable diameters, types of armour and braid that may be accommodated.
The gland body material is normally brass, but alternative materials including some plastics may be used. Finishes on metallic glands may include nickel and chromium plate to meet corrosion resistance or other needs.
Aluminium cannot be used due to chemical reaction between aluminium and rust.
manufacturers specific glanding-off details should be followed.
What glands are suitable for Ex d enclosures?
Certified d or de (may need barrier gland).
What glands are suitable for Ex e enclosures?
Certified d, e or de.
What glands are suitable for Ex n enclosures?
Certified d, e or de.
Comment on glands for MICC cable.
For entry into an Ex d flameproof enclosure the standard MICC termination pot is suitable, provided that the gland is an approved type where the threads form a flame path with the enclosure body. Refer to manufacturers documentation.
For entry into an Ex e enclosure and also for intrinsically safe use, some manufacturers provide increased safety seals (Ex e) that are suitable for use in applications with cables having one, two, three, four or seven conductors.
What are the general rules for glands?
- Glands may be certified against the IEC standards as Ex e, Ex d or they may be dual certified Ex de with the gland body carrying the identification marking.
- Glands may have extra deluge protection.
- avoid cable strain; prevent and remove any cable strain on the gland.
- ingress protection seal washers may be required.
What are the specifications for Ex d glands?
- thread should preferably be metric pitch 1.5mm but other forms may be available from manufacturers.
- thread fit should be medium/fine tolerance fit.
- threaded entry hole should be six threads minimum
- engaged thread length should be five full threads minimum.
What are the specifications for Ex e glands?
- glands marked according to certificate and may be used with threaded or unthreaded entry enclosures.
- for threaded entries, unless the length of thread engaged is at least 6mm an IP seal washer, on the outside is required to maintain IP54. Threads are to be square to surface.
- When glands are fitted into a clearance hole an IP rating of IP54 is maintained using a neoprene or nylon seal ring on the outside of enclosure with an internal lock nut to retain the gland. A star washer may be specified to maintain earthing integrity.
- armour must be clamped by the gland.
- An external earth tag, if required, is fitted between gland body and the seal washer to ensure sound electrical contact.
What are the gland markings?
- manufacturer
- gland type in accordance with the standard
- certification details, including the certification body and certificate number are also required where relevant. Some details may be included in the packaging.
For gland markings what does A symbolise?
Outer seal only.
For gland markings what does B symbolise?
Armour lock only.
For gland markings what does BARR symbolise?
inner barrier seal, outer seal and armour lock.
For gland markings what does C symbolise?
Equal to A+B
For gland markings what does D symbolise?
inner seal and armour lock
For gland markings what does E symbolise?
inner seal, outer seal, armour lock.
For gland markings what does W symbolise?
Single wire armour
For gland markings what does X symbolise?
Braid armour.
For gland markings what does Y symbolise?
Aluminium strip armour (not suitable).
For gland markings what does Z symbolise?
Tape armour.
When are barrier glands required?
Barrier glands may be required when direct entry into a flameproof Ex d enclosure is required.
In Zones 1 + 2, if the cable is not round, compact and has extruded bedding then, in all cases, a barrier gland is required.
For cables that are round, compact with extruded bedding and where there is an internal source of ignition:
Zone - Gas Group Required - Internal Volume - Barrier Gland
1 & 2 - IIC (ie hydrogen) - any - required
1 - IIA or IIB - > 2litre - required.
1 - IIA or IIB - < 2litre - not required.
2 - IIA or IIB - any - not required.
Where there is no internal source of ignition in zones 1 or 2 or where not required as above use any suitable certified Ex d or de gland.
Fore more information refer to relevant standards, EEMUA - A practitioners handbook or the appropriate superior technical authority.
