IECEx Cable Gland Selection Guide For Hazardous Area Zones

Published 09 Oct 2019

Cable Glands Hazardous Area Zones

  • uploaded by Chris Dodds | Thorne & Derrick Sales Marketing Manager

In this Blog titled IECEx Cable Gland Selection Guide For Hazardous Area Zones we will cover the following sections of the classification and guidance document for the selection of cable glands for hazardous areas:

  • Cable Type / Cable Gland Type
  • Hazardous Area Protection Method
    – When to use a Barrier Gland
  • Environmental Conditions
  • Installation / Inspection Considerations

Credit to ➡ International Electrotechnical Commission System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres (IECEx System).

Cable type & Cable gland type

Unarmoured Cable Type & Cable Glands

W – Single wire armour SWA
or Aluminium wire armour AWA

X – Braid

T – Pliable wire armour

Y – Aluminium strip armour

Z – Double steel tape armour

A – Single seal only
B – Armour clamp only
C – Armour clamp and seal on outer sheath
D – Armour clamp and seal on inner sheath
E – Armour clamp and seal on inner and outer sheath

Hazardous Area Cable Glands

Hazardous Area Cable Glands

Each cable gland type has sub-sets:

e.g.

E1W = E1W cable glands with IP66 seals on inner and outer cable sheath

E2W = As E1W type cable gland but E2W cable glands are with an electrical bond for a metallic inner sheath (e.g. lead sheathed cable)

Cable glands are often named to describe their function, e.g. E1FX, E1FW.

Cable Gland Size

The cable gland size must be selected to match the cable size.

IEC 60079-14:10.2 Selection of Cable Glands

The cable gland shall be selected to match the cable diameter. The use of sealing tape, heat shrink tube or other materials is not permitted to make the cable fit to the cable gland.

Hazardous Area Protection MethodATEX

Ex d / Ex e / Ex nR

The protection method MUST meet or exceed the protection level of the equipment that the cable gland is connected to. This is a requirement of IEC 60079-14: Clause 10.2.

Extract from Table 10 of IEC 60079-14

Explosion Protection Technique For The Equipment Cable Gland Protection Technique
Ex d    Ex e   Ex nR
Ex d X
Ex e X X
Ex nR X X X
Ex i Group II X X X
Ex p X X X

When to use a barrier gland

Barrier glands are always certified Ex d, but can be used in an Ex e environment.

How do you know when to use them?

When to Use a Barrier Gland – Ex d

A barrier gland MUST be used in an Ex d environment unless the cables:-

  • Circular and compact
  • Have an extruded bedding or sheath
  • Use non-hygroscopic fillers

When to use a barrier gland - Ex d

Old Rules in IEC 60079-14

Old Rules in IEC 60079-14

New Rules – Barrier Gland Ex d

The cable entry system shall comply with one of the following:

a) Cable glands sealed with setting compound (barrier cable glands)
b) Cables and glands meeting all of the following:
– cable glands comply with IEC 60079-1 and are certified as equipment
– cables used comply with 9.3.2(a)
– the connected cable is at least 3 m in length;
c) indirect cable entry using combination of flameproof enclosure with a bushing and increased safety terminal box;
d) mineral-insulated metal-sheathed cable with or without plastic outer covering with appropriate flameproof cable gland complying with IEC 60079-1;
e) flameproof sealing device (for example a sealing chamber) specified in the equipment
documentation or complying with IEC 60079-1 and employing a cable gland appropriate to the cables used. The sealing device shall incorporate compound or other appropriate seals which permit stopping around individual cores.

The sealing device shall be fitted at the point of entry of cables to the equipment.

The cable entry system shall comply with one of the following:

a) Cable glands sealed with setting compound (barrier cable glands)
b) Cables and glands meeting all of the following:
– cable glands comply with IEC 60079-1
– cables used comply with 9.3.2(a)
(They shall be circular and compact. Any bedding or sheath shall be extruded. Fillers, if any, shall be non- Hygroscopic)
– the connected cable is at least 3 m in length

The HSE in the UK has issued a bulletin stating that installations to the ‘new rules’ may not be safe and has suggested that the old flowchart used.

If in doubt USE A BARRIER GLAND.

CMP PX2K-REX RapidEx – Revolutionary Sealing Solution for Barrier Cable Glands

Barrier Glands

Barrier Glands

 

When to use a Barrier Gland – Ex d

Barrier glands should also be used:-

  • In Ex e applications when there is a risk of gas migrating down a cable. (IEC Ex 60079-14 clause 9.3.2)
  • In Ex nR applications where the cable is not sealed. (IEC Ex 60079-14 clause 10.8)

Modern ‘liquid resin’ barrier glands are easy to install.

Barrier Glands - Ex d

Environmental Conditions

Four main areas to cover in this section:

• Temperature
• Ingress protection (IP)
• Dissimilar metals
• Corrosive environments

Temperature

  • Cable glands do not have a ‘T’ rating
  • Under existing IEC Ex rules, the temperature rating of a cable gland does not have to include the thread sealing gasket
  • Responsible cable gland manufacturers test and certify their cable glands and sealing gaskets together

Ingress Protection (IP)

A sealing gasket may be needed to maintain the IP rating of the assembly.

(IEC Ex 60079-14 clause 10.2)

Check that the thread sealing washer has been tested with the cable gland as part of the certification process. (The IP rating will be shown on the IEC Ex certificate.)

Dissimilar Metals

  • Ideally the cable gland should be made of the same material as the equipment and the cable armour it is connected to
  • For most equipment electroless nickel plated brass is the best option
Brass gland fitted to an aluminium enclosure

Brass gland fitted to an aluminium enclosure

Superior Marine grade nickel plated brass gland fitted to an aluminium enclosure

Superior Marine grade nickel plated brass gland fitted to an aluminium enclosure

Corrosive Environments

Corrosive environments may typically include:-

  • Salt / salty water
  • SO2
  • NH3

For many corrosive environments a good quality nickel plated brass cable gland is the best choice

  • Not all plating is equal
  • Specify at least 10 microns of plating thickness

(The rules on plating thickness changed with the 2014 edition of IEC 60079-1. Clause 5.1 now allows a thickness greater than 8 microns.)

Not all electroless Nickel Plating is equal - Before & After Salt Spray Test

Not all electroless Nickel Plating is equal – Before & After Salt Spray Test

For highly corrosive environments the choices are either:-

  • Stainless steel
  • Specialist corrosion protected cable glands

Installation / Inspection Considerations

Choose cable glands that are:-

• Easy to install
• Don’t have parts that can get mixed up
• Don’t have loose parts
• Can be inspected easily

Further Reading 

ELECTRICAL & PROCESS INSTRUMENTATION EQUIPMENT

FOR EXPLOSIVE ATMOSPHERES

Thorne & Derrick International, based in the UK, are Specialist Distributors of Hazardous Area & Explosion Proof Equipment with IECEx & ATEX Certifications to the onshore and offshore oil, gas, petrochemicals and process industries.

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ATEX Process Instrumentation

Trace Heating | System Design & Supply

Further Reading