EExde and EExe


Thread Starter


I need advice regarding HAC.

a) What are the differences between EExd and EExde certification for a control box? The control box will consists of relays, terminals, wirings etc. The box is required for chemical injection skid control on a offshore platform and shall be located at a Zone 1 area.

b) Next I need advice if a EExe box that contain relays, terminals, wirings etc can be used on a Zone 1 area?

Please help. Thanks.

Bruce Durdle

Pchan, For a control box to be certified as EExd it must be fully flameproof. A box certified as Eexde will usually actually be an Increased Safety enclosure with internal components such as switches and relays which are Exd protected.

A box cannot be certified as pure Ex e if it contains sparking parts such as relays or switch contacts. It will generally contain terminals and wiring, or passive components such as lamps.

But your best source of information is the manufacturer's certification, and the appropriate standards that the equipment has been constructed to.

Hope this helps.


Your question of the use of an EExe box needs to be clarified. Was the EExe certified enclosure fitted out with the relays, etc. by the supplier? If they were, then the certification refers to the completed enclosure relays and all, and can be installed in Zone 1 area.

If on the other hand if you have purchased an empty enclosure that has a EExe label, that was then fitted out by you, unless all components you have installed are individually certified to EExe and are in compliance with any limitations imposed by the Certifying body with regards to the Enclosure you CANNOT install and use that enclosure anywhere other than a Safe area as the unit is not certified.

Generally enclosures are manufactured as housings for cable terminals, etc. and the conditions of the certification will determine the maximum number and size off the can be installed, also taken into account is the number of gland entries to maintain the impact rating of the enclosure with forms part of the EExe certification.
The main part is you should not be able to purchase an empty enclosure that has a EExe certification label fitted as the enclosure "Fit" out must be taken into account. Hope this helps.
1) An EExd box is a flameproof only box, i.e. a large metal box containing potentially sparking equipment, high temp equipment and the box does not allow propagation of any flames/explosions, etc. to the surrounding atmosphere. An EExde box in my experience is usually a flameproof box with EExe terminations located in or attached directly to the box and the unit is certified as a whole.

You can fit relays terminals as long as the limitations of the certificate allow it. Failure to strictly adhere to the condition of the certificate will usually invalidate the certification regardless of whether you or anybody else consider it safe/low risk.

2) I'd be surprised if an EExe box alone allowed the fitting of standard relays. The above advice on the certification applies. You can't just get an EEx(anything) box and stick whatever in it and assume its safe and/or certified. Get the certificate, read it and stick to the limitations described therein. Whether you are allowed to use EExe in Zone 1 depends upon local statutory provisions. In the European Union for gas EExe as a type of protection is allowed in Zone 1.

Hope this helps.

Thanks Sandy for your explanation.

Yes, the EExe certified enclosure is fitted out with the relays, etc. by the supplier. So, can be used on a Zone 1 area.

Now, what does in mean when the certification is EExde?
BASEEFA is the British Approvals Service for Electrical Equipment in Flammable Atmospheres.
EN 50 014 and 50 018 require EEx mark for electrical equipment in flammable or explosive atmosphere.

For motors that would be: Flameproof (type d) motors are based on a type of protection in which the parts which can ignite an explosive atmosphere are placed in an enclosure that can withstand the pressure developed during an internal explosion of an explosive mixture and which prevents the transmission of the explosion to the explosive atmosphere surrounding the enclosure.

Increased Safety (type e) motors are not flameproof and not built to withstand an internal explosion. The design is based on additional measures to give increased security against the possibility of excessive temperatures
and the occurrence of sparks and arcs, such as increased safety terminals within an IP55 terminal box. It applies only to equipment, no parts of which produce sparks or arcs or exceed the limiting temperature in normal service.

Hope these makes sense to your needs.