Cable Glands
This page on Cable Glands and Barrier Glands is an excerpt from the original
Armoured Cable Glands webpage and is reproduced here, courtesy of
Control And Instrumentation.com
Why Use Cable Glands?
- To firmly secure cable entering a piece of equipment
- To maintain the
ingress protection (IP rating) of the piece of equipment (minimum of IP54 for "e" and "n" type enclosures. Where the enclosure wall thickness is less than 6mm a sealing washer or thread sealant will be required to maintain IP54 protection)
- To maintain earth continuity between a piece of equipment and any armouring in the cable
- To ensure containment of an internal explosion in flameproof equipment
British Standard for Cable Glands
The Code of Practice for selection, installation and inspection of cable glands used in electrical installations is covered in British Standard BS 6121-5 1989 Mechanical cable glands.
Cable Gland Selection
When selecting cable glands, always consider:
- Electrolytic action between two dissimilar metals (gland and enclosure). Shortened lifetime for the glands and the cable entries can result if incompatabile materials are used.
- Degreee of Ingress Protection required
- Certification of gland for use in Hazardous areas
- Standard gland or barrier gland required
- Size of cable being terminated
- Size of cable entry on peice of equipment
What is a Barrier Gland?
Barrier glands are similar to normal cable glands, except a compound sealant material is used to seal around the individual cores of the cable ensuring the inside of the cable is gas tight as well as the outside.
When Should a Barrier Gland be Used?
There are numerous details to consider when deciding if a barrier gland should be used. A useful rule of thumb is; if the hazardous area requires IIC apparatus, or if the volume of the enclosure is greater than 2 litres then it is likely you will need to use a barrier gland.
BS EN60079-14 ElectricalAapparatus for Explosive Gas Atmospheres Part 14 -
Electrical Installations in Hazardous Areas (other than Mines) provides a detailed selection process for deciding if a barrier gland is required.
Gable Gland Sizing
A guide to cable gland sizing is provided in the table below, however reference should be made to the British Standard referenced above or to the manufacturer's guidlines.
Nominal Conductor
Area (mm2) |
Number of cores (600/1000V) |
| 1 |
2 |
3 |
4 |
5 |
7 |
10 |
12 |
19 |
27 |
37 |
48 |
| 1.5 |
-- |
20S |
20S |
20S |
20S |
20S |
20 |
25 |
25 |
25 |
32 |
32 |
| 2.5 |
-- |
20S |
20S |
20S |
20 |
20 |
25 |
25 |
25 |
32 |
41 |
40 |
| 4 | -- | 20S | 20S | 20 | 20 | 20 | 25 | 25 | 32 | 40 | -- | -- |
| 6 |
-- |
20 |
20 |
20 |
This chart is for guidance only.
Consult relevant British Standards before making final selection. |
| 10 |
-- |
20 |
25 |
25 |
| 16 |
-- |
25 |
25 |
25 |
| 25 | -- | 25 | 25 | 32 |
| 35 |
-- |
25 |
32 |
32 |
| 50 | 20 | 32 | 32 | 40 |
| 70 |
25 |
32 |
40 |
40 |
| 95 | 25 | 40 | 40 | 50 |
| 120 |
25 |
40 |
50 |
50 |
| 150 | 32 | 50 | 50 | 63 |
| 185 |
32 |
50 |
50 |
63 |
| 240 | 40 | 50 | 63 | 63 |
| 300 |
40 |
63 |
63 |
75 |
| 400 | 50 | 63 | 75 | -- |
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