Ex d Enclosures – NEW Flameproof Ex d Enclosures For Zone 1 & Zone 2 Hazardous Areas

Published 22 Mar 2017

Ex d Enclosures

Ex d Enclosures | Design | Supply | Stock | UK & Export Sales

  • By Chris Dodds : estimated reading time 5 minutes

Ex d Enclosures

In this article we introduce the Ex d range of electrical enclosures distributed by Thorne & Derrick and also provide an overview of the meaning and implication of the explosion protection concept referred to as Ex d, commonly called Flameproof, for the purposes of defining hazardous area equipment classification.

Thorne & Derrick, the Explosive Atmosphere Experts and Main UK Distributor for Marechal, are now supplying the Technor EJB range of Ex d enclosures to clients involved in the installation, maintenance and inspection of hazardous area locations.

Technor, the specialist manufacturer of Ex d flameproof and hazardous area products, joined the Marechal Electric Group in 2013 – since 1969 Technor have been a leading manufacturer of hazardous area lighting, enclosures and control panels for potentially explosive atmospheres.

Marechal are a worldwide leader for over 60 years in the manufacture of ATEX plugs and sockets utilising their innovative Decontactor products.

Contact T&D to discuss your requirements for Ex d enclosures, junction boxes, control stations and hazardous area lighting products.

Flameproof Exd

What Does Flameproof Mean?

Definition: design does not prevent flammable or explosive gases/vapours entering the apparatus, however it is a type of explosion protection in which parts that can ignite an explosive atmosphere are placed in an enclosure that can withstand the pressure developed during an internal ignition of an explosive mixture without suffering damage and which prevents the transmission of that explosion atmosphere surrounding the enclosure.

  • Suitable for use in Zone 1 and Zone 2 hazardous areas
  • Live maintenance is NOT permitted on the electrical enclosure
  • No unauthorised modifications to certificated enclosure are permitted
  • Components not to be removed from flameproof equipment

IEC 60079-1 (EN 60079-1): Explosive Atmospheres

Part 1: Equipment Protection By Flameproof  Enclosure “d”

EPL/Category and Zones of Use

This part of IEC 60079 contains the specific requirements for the construction and testing of electrical apparatus with the type of protection flameproof enclosure “d”, intended for use in potentially explosive gas atmospheres.

Flameproof enclosures and electrical equipment may be used in areas requiring Explosion Protection Level (EPL) ‘Gb’ and ‘Gc’ or Category 2 and 3 only.

Use with Gas Subdivisions: Certified flameproof enclosures and electrical equipment would have been designed for use with a particular Group II gas subdivision.

➡ Purchase IEC 60079-1:2014/COR1:2018

Flamepaths & Enclosures

The most critical part of a flameproof enclosure ‘Ex d’ is the so-called flame path.

Flameproof or Exd enclosures are strong enough to withstand the effects of an internal explosion should a gas enter the enclosure and ignite. The effects of the explosion must not be transmitted to the surrounding atmosphere where ignition of any gases surrounding the enclosure could occur due to the passage of flame from the enclosure under such conditions. Flamepaths are built into such enclosures as a means of preventing this; all points where gas could enter or leave the enclosure such as opening cover lids, joints or cable entry points have explosion protection.

Ex d Flameproof Enclosures

Thorne & Derrick can ensure the safe specification and supply of explosion-proof Ex d enclosures used to house electrical apparatus for use in explosive atmospheres, including Zone 1 and Zone 2 (Gas) and Zone 21 and 22 (Dust).

Ex d Enclosures – Technor EJB

Technor EJB enclosures are classified to international hazardous area classifications with ATEX, IECex and TRCU certification, with ingress protection IP65 to IP67 and an operational ambient temperature range of + 60°C to – 50°C.

Ex d enclosures are manufactured to provide explosion protection according to Exd 11B and Exd 11B + H2 and are suitable for installation within explosion proof areas in the the oil, gas petrochemical, pharmaceutical, food, beverage and utility industries.

Technor EJB enclosures can be equipped with the following hazardous area certified components:

  • Pushbuttons
  • Selector Switches
  • Indicator Lamps
  • Potentiometers
  • Rotary Switches
  • Tempered Windows

T&D Sales Engineers work closely with clients to provide customised and bespoke Ex d enclosures including internal electrical equipment such as hazardous area isolators, contactors, relays, transformers, terminals, measuring instruments, electronic devices, power supplies, PLC devices and anti-condensation heaters.

Typical Applications

Ex d enclosures are available in a wide range of dimensions and 3 material versions: galvanised carbon steel, AISI 316L stainless steel and marine grade aluminium with low copper content. Enclosures are used for instrument housing, control, check, connection, automation, interruption and/or protection use and can be equipped with pushbuttons, pilot lamps and selector switches for hazardous areas.

Hazardous Area Certification & Marking For Enclosures


  • Ex-d IIB T(**) Gb or Ex-d IIB+H2 T(**) Gb
  • Ex-tb IIIC T(**) Db IP65 or 66 or 67
  • ** T6/T85°C, T5/T100°C, T4/T135°C, T3/T200°C

II 2(1) GD

  • Ex-d [ia Ga] IIB T6 Gb or Ex-d [ia Ga] IIB+H2 T6 Gb
  • Ex-tb [ia Da] IIIC T85°C Db IP65 or 66 or 67

II 2(2) GD

  • Ex-d [ib] IIB T6 Gb or Ex-d [ib] IIB+H2 T6 Gb
  • Ex-tb [ib] IIIC T85°C Db IP65 or 66 or 67

under IEC Ex directive, junction boxes and enclosures are suitable for IIB group of gases/dusts only 

♦ Download the technical specifications, ordering details and further information about Technor EJB Ex d Enclosures:


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➡ View our complete range of Hazardous Area Enclosures for Zone 1 & Zone 2 potentially explosive atmospheres.

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See Marechal Plugs for further information or visit hazardous area plugs for use in potentially explosive atmospheres.

Hazardous Area Electrical Distributors


Thorne & Derrick are leaders in the development and distribution of Product Innovations that deliver significant improvements to clients plant, people and operational safety in the explosive atmosphere industries.

Your proactive problem solvers experienced in succession planning for the replacement of obsolete, non-conformant and legacy equipment in hazardous areas.

Your first-choice provider of innovative and competitive solutions to ensure ATEX & IECEx Compliance for Hazardous Area Electrical, HVAC & Process Instrumentation Equipment to UK and international projects.

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