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Ysebaert

Should a simple apparatus be covered by an ATEX certificate?

The definition of simple apparatus can be found in the harmonised European standard EN 60079-11 article 5.7 (= intrinsically safe equipment).

Examples :

  • switches
  • junction boxes (*)
  • resistors
  • thermocouples

This standard is only applicable to electric equipment. These simple apparatus are excluded from the 2014/34/EU directive because they have no intrinsic ignition source. In consequence, they don’t have to follow the conformity procedures and don’t have to be labelled following this directive.

Attention, this does not automatically implies that every simple apparatus is suitable for every application of the end user. Polyester boxes of category 1G for example should be antistatic. So, the user should decide for himself (risk analysis of the potential ignition sources) whether the simple apparatus is suitable for his application.

Because not every user possesses the necessary technical skills, certified terminal boxes are often the best solution!
(*) This is also confirmed by a supplement in the latest edition of EN/IEC 60079-14 (2013) (cfr. FAQ van 15-05-2014).

The same reasoning should be followed for non-electrical simple apparatus (plastic container, tube, chair,…). However, there is no definition for non-electrical simple apparatus, and in any case, end user should evaluate this separately. In fact, the problem is being shifted from the economic to the social directive. In case of discussion the ATEX Standing Committee will take a decision, as it has been done for the valves operated by human force.

To what extent can I make alterations to my Exd housing?

As a general rule, you should always ask the manufacturer's advice before making the alterations. They can determine the right way to do it.

A distinction should be made between a simple replacement and a substantial alteration.

Practical example: in an Exd certified housing, you can replace a defective fuse or circuit-breaker with a new one, provided that it has the same rating. It goes without saying that a 6A circuit-breaker cannot just be replaced by a 16A one.

In that case, it is a change and the manufacture will have to check whether the certification is still valid and whether other changes are necessary. They will have to amend the technical dossier, and possibly provide a new Ex label.

It is not allowed to add equipment into an Exd housing. Such a substantial change must always be done via the manufacturer.

Even making extra holes or enlarging existing holes is not allowed.

Read also our FAQ about repair and maintenance.

Does a washer have to be added to a cable gland or a plug in an Exe application?

In Exe applications, in practice it is almost always mandatory between a cable gland, adapter or plug and a housing.

This washer is necessary to guarantee the minimum IP54 requirement for Exe.

Only if the wall of the housing is thicker than 6 mm and it concerns a tapped hole may the washer be omitted (sealing via screw thread).

What requirements are imposed on cables in the Ex zone?

Cables are no apparatus as described in the ATEX114 directive. Cables are not considered as an ignition source assuming that they are electrically and mechanically adequately protected. 

Specifically for Ex environments, these requirements are described in standard EN 60079-14: IEC2013.

Cables with low tensile strength sheaths shall not be used in hazardous areas unless installed in conduit.

Low tensile strength means lower than:

  • 2,5 N/mm² for PVC
  • 15,0 N/mm² for other materials

Cables for fixed installation in the Ex zone must meet one of the following requirements:

  • Cables shall be sheathed with thermoplastic, thermosetting, or elastomeric material. they shall be circular and compact*. Any bedding or sheath shall be extruded. Fillers, if any, shall be non-hygroscopic.
  • Cables should be mineral insulated metal sheathed.
  • Special, e.g. flat cables with appropriate cable glands. They shall be compact* and any bedding or sheath shall be extruded. Fillers, if any, shall be non-hygroscopic.

* Where there is a likelihood that gas or vapour migration may occur through the interstices between individual cores of a cable (suspicion of insufficient filling mass), then the informative test in Annex E shall be considered.

In Exd applications, it is recommended to make sure that your cable is at least 3m long. In combination with the conditions: cable in accordance with the above-mentioned requirements and cable gland certified as a device compliant with EN 60079-1, you will avoid having to use a barrier cable gland

The hazardous area end of each unused core in multi-core cables shall either be connected to earth or be adequately insulated by means of termination suitable for the type of protection. Insulation by tape alone is not permitted.

Application in zone 0 and/or 20?

Occasionally, we get a request for a price quote for equipment that must be suitable for zone 0 and/or 20. In the majority of cases, this requirement is actually not correct, and equipment suitable for zone 1 and/or 21 will suffice.

A zone 0, for example, is in or close to the spout of a tank.
One type of equipment often found in this zone is sensors that relay an Exi signal outside this zone.

If you encounter zone 0/20 in specifications, it is advisable to pause for thought.

How is an ATEX classification structured?

An ATEX classification seems very complex. However, it contains a lot of very useful information.
We dissect the structure using an example: the classification for an ATEX LED floodlight:

Ex II 2 G Ex d e op is IIC T4 Gb
Ex II 2 D Ex tb IIIC T80°C Db

  • Ex → Ex-symbol
  • II → Group
  • 2 G/D → Category
    • 1G = gas zone 0
    • 1D = dust zone 20
    • 2G = gas zone 1
    • 2D = dust zone 2
    • 3G = gas zone 2
    • 3D = dust zone 22
  • Ex → Ex-symbol
  • d / e / op is / tb → Protection manner
  • IIC / IIIC → Explosion group
    • I = mine gas
    • II = gas
    • III = dust
    • A/B/C : depending on the detonation energy and the construction of the route that the flammable gas mixture flames takes
      depending on the size of the particles and the electrical (non-)conductivity of the dust
  • T4 → Temperature class (gas), depending on the maximum surface temperature of the electrical material
  • T80°C → Maximum surface temperature of the electrical material (dust)
  • Gb / Db → EPL, indicates where the material may be used
    • Ga = suitable for zone 0, 1, 2
    • Gb = suitable for zone 1, 2
    • Gc = suitable for zone 2
    • Da = suitable for zone 20, 21, 22
    • Db = suitable for zone 21, 22
    • Dc = suitable for zone 22

For more information, please refer to our previously published FAQs on marking, and to the ‘Standards & Principles’ document.

Which documents must be delivered by whom according to ATEX 114?

A manufacturer must ensure that the product is accompanied by instructions and safety information as well as a copy of the corresponding EU declaration of conformity or declaration of compliance (components). It is up to the manufacturer to decide which relevant information is included.

Each individual product should in principle be accompanied by these documents, thus also products supplied in bulk or packaging units. This does not mean that the full instructions must be in paper form. It is also sufficient to add just one set of documents per shipment of identical goods.

ATEX components must also be accompanied by instructions and safety information. These instructions will, however, mostly contain information on how to incorporate it into the future ATEX product.

Both the importer and the distributor should ensure that the product is accompanied by instructions and safety information as well as a copy of the corresponding EU declaration of conformity or declaration of compliance (components).

The manufacturer, the importer and the distributor have the obligation to provide instructions and safety information with the product in a language determined by the Member State concerned. Any economic operator thus has the obligation to make these instructions available (translated). It is advisable to define by contract who will be in charge of this translation.

An overview of the different protection methods for electrical appliances on 01/04/18

With the publication of new editions of Ex standards, many changes have taken place in the protection methods over the years.

The table below gives a summary of the protection methods and their current coding (April 2018).

Practically, this means that most (classic) protection methods are divided into 3 (supplemented with an a, b and c that we also find in the EPL marking).

In addition to these protection methods (for electrical appliances), there are also others for devices with mechanical, pneumatic, hydraulic... ignition sources.

 

EPL

Type of protection

Code

According to

‘Ga’

Flameproof enclosures

‘da’

IEC 60079-1

Intrinsically safe

‘ia’

IEC 60079-11

Encapsulation

‘ma’

IEC 60079-18

Two independent types of protection each meeting EPL ‘Gb’

 

IEC 60079-26

Protection of equipment and transmission systems using optical radiation

‘op is’

IEC 60079-28

Special protection

‘sa’

IEC 60079-33

‘Gb’

Flameproof enclosures

‘d’ = ‘db’

IEC 60079-1

Increased safety

‘e’ = ‘eb’

IEC 60079-7

Intrinsically safe

‘ib’

IEC 60079-11

Encapsulation

‘mb’

IEC 60079-18

Oil immersion

‘o’ = ‘ob’

IEC 60079-6

Pressurized enclosures

‘px’ or ‘py’

IEC 60079-2

Pressurized room

‘pv’

IEC 60079-13

Powder filling

‘q’ = ‘qb’

IEC 60079-5

Fieldbus concept (FISCO)

 

IEC 60079-27

Protection of equipment and transmission systems using optical radiation

‘op is’, ‘op sh’ or ‘op pr’

IEC 60079-28

Special protection

‘sb’

IEC 60079-33

‘Gc’

Flameproof enclosures

‘dc’

IEC 60079-1

Intrinsically safe

‘ic’

IEC 60079-11

Encapsulation

‘mc’

IEC 60079-18

Oil immersion

‘oc’

IEC 60079-6

Increased safety

‘ec’

IEC 60079-7

Non-sparking

‘nA’

IEC 60079-15

Restricted breathing

‘nR’

IEC 60079-15

Sparking equipment

‘nC’

IEC 60079-15

Pressurized enclosures

‘pz’

IEC 60079-2

Fieldbus concept (FNICO)

 

IEC 60079-27

Protection of equipment and transmission systems using optical radiation

‘op is’, ‘op sh’ or ‘op pr’

IEC 60079-28

Special protection

‘sc’

IEC 60079-33

 

‘Da’

Intrinsically safe

‘ia’

IEC 60079-11

Encapsulation

‘ma’

IEC 60079-18

Protection by enclosure

‘ta’

IEC 60079-31

Special protection

‘sa’

IEC 60079-33

‘Db’

Intrinsically safe

‘ib’

IEC 60079-11

Encapsulation

‘mb’

IEC 60079-18

Protection by enclosure

‘tb’

IEC 60079-31

Pressurized enclosures

‘pD’ or ‘p’

IEC 60079-2

Special protection

‘sb’

IEC 60079-33

‘Dc’

Intrinsically safe

‘ic’

IEC 60079-11

Encapsulation

‘mc’

IEC 60079-18

Protection by enclosure

‘tc’

IEC 60079-31

Pressurized enclosures

‘pD’ or ‘p’

IEC 60079-2

Special protection

‘sc’

IEC 60079-33

 

What are the rules concerning the use of Barrier Glands?

Under EN 60079-14:2013, it now suffices, for round cables with enough filling mass and a length greater than 3m, to use an Exd cable gland certified as an apparatus - i.e. a "normal" cable gland with rubber.
In practical terms, this means that one is no longer obliged to select a barrier cable gland in accordance with figure 2.
Our EBU and KBA cable glands with rubbers are sufficient for this.

​You’ll find a more detailed explanation in this article.

Although the figure 2 in question has disappeared from the 2013 edition, you will undoubtedly see it appear in old publications. And so for clarity´s sake we are still keeping the following out-of-date information available.

Our certificate for cable glands has been altered by adding cable glands of the type BARRIER. These glands were designed especially for use in Exd applications, according to figure 2 in the EN / IEC 60079-14:2007.

To be short, glands with compound (= barrierglands) should always be used in Exd applications, except in the following situations :
- A simple junction box (= only terminals)
- Gasgroup IIB + zone 2
- Gasgroup IIB + zone 1 + enclosure volume < 2 liter

In these cases, the use of a classic Exd gland (single or double compression) with seals is sufficient.

So, it is not obligatory to always use barrierglands in Exd application !
Since zone 2 is the largest ex-zone and most of the vapours are part of gasgroups IIA or IIB.

To be complete, we also point out that there is an exception for Exd glands (with seals) that are SPECIFICALLY tested for a unique type/brand of cable. This exception (which is extremely rare in practice) is planned to be cut out the next edition of the standard.

For Exde combinations (= Exd box with connection area in Exe box) the standard Exe glands may be used.

Our BARRIER glands are composed identically to the classic (P)PA(P)-glands. However an extra metal ring is added in the body which will be filled with a compound.

Can Ex[i] modules be placed in an Exe housing?

A common misconception is that any material marked with "i" is intrinsically safe and may therefore be used on its own or in an Exe housing in the Ex zone.

Far from true! A clear distinction must indeed be made between i and [i].

An intrinsically safe circuit consists of an intrinsically safe device and a so-called associated apparatus. All electrical circuits of an intrinsically safe device are intrinsically safe, and the device may therefore be installed in the Ex zone.

A device such as BT851.1 control panel, which is marked Ex II 2 G Ex ib IIC T6 Gb, may be installed on its own or in an Exe housing in the Ex zone.

Associated apparatus contain both intrinsically safe and non-intrinsically safe circuits, and are designed so that the non-intrinsically safe circuits cannot influence the intrinsically safe circuits. They must therefore always be installed in the safe zone. To indicate this, brackets are used.

The MTL barrier MTL5511 is marked Ex II (1) G [Ex ia Ga] IIC and must therefore be installed in the safe zone. Alternatively, this module can also be placed in an Exd housing in the Ex zone.
The classification of this cabinet could then look like this:
Ex II 2 (1) G Ex d [ia IIC Ga] IIB T4 Gb.

Can fuse terminals be installed in an Exe housing?

We regularly receive price requests for a terminal box with fuse terminals.
The customer assumes that a fuse terminal (for instance UT4-HESI) is available in an ATEX version and may therefore be placed in an Exe housing.
Several ordinary connection terminals (for instance UT4) do indeed have an ATEX certificate.
Fuse terminals and by extension separation terminals will however always cause a spark, however small, inherent to their function, and are therefore not suitable for use in an Exe housing.
Like other non-ex components, fuse terminals and separator terminals must therefore always be installed in an Exd housing.

Does an Ex casing always need to be earthed externally?

According to general requirements of the standard for explosive atmospheres EN 60079-0 (Article 15.1.2), electrical equipment with a metal casing MUST have an external connection for an equipotential conductor (except for double insulation, equipment for mobile use...).

On a plastic casing, you will not find an external grounding bolt in most cases (classic Ex terminal box). This may however occur in certain applications:

  • metal cable glands (offshore plate)
  • power cable without ground conductor
  • ...

We also find specific regulations for explosive atmospheres in the AREI regulations:

AREI Article 108.03: The masses and the external conductive parts installed in potentially explosive areas MUST be connected to an additional equipotential equalization connection. The masses of intrinsically safe material don’t need to be connected to the potential equalization connection unless specified as mandatory by the installation instructions. The additional equipotential equalization connection meets the requirements of Article 73 with regard to the implementation.

AREI article 73: The following minimum cross-sections must be observed in all cases: minimum cross-section of 2.5 mm² when the conductors are mechanically protected, minimum 4 mm² when they are not mechanically protected.

In summary, we can state as a general rule for the installer that when an external grounding is present on a casing (metal or plastic), it must also be connected.

Can Ysebaert draft my zoning plan?

Often customers can’t answer when we ask in which zone a certain device will be deployed.
A zoning plan must be drafted by the operator of the installation. This will happen in most cases in cooperation with a recognised inspection body.

Thus, Ysebaert is not authorised to draw up a zoning plan and, consequently, cannot provide advice on that issue.

However, the following table will already give you an idea:

ZoneDescriptionExample
0Includes areas where an explosion hazardous gasatmosphere is continuously present- inside of a vessel
- inside of reactor chambers
1Includes areas where an explosion hazardous gasatmosphere is occasionally present- near filling holes
- near zone 0
- near pumps and valves
2Includes areas where an explosion hazardous gasatmosphere is rarely and for a short time present- near zone 0 or 1
- near flange connections with flat seals
20Includes areas where an explosion hazardous dustatmosphere is continuously present- inside of a grain silo
21Includes areas where an explosion hazardous dustatmosphere is occasionally present- near filling holes
- near zone 20
22Includes areas where an explosion hazardous dustatmosphere is rarely and for a short time present- near zone 20 or 21
 

Where can I find out whether a particular product is covered by the ATEX114 directive?

Not all equipment that you use and/or install in the ex-zone is covered by the ATEX Directive 2014/34/EU.

This is not always clear and sometimes causes confusion. That is why the Guidelines have included a list of frequently encountered material, the so-called Borderline List.

This list is not complete, it only clarifies some common inquires and provide examples of products within or outside the scope of the ATEX Directive 2014/34/EU. 
The list does not replace the vital risk assessment of potential ignition sources (according to EN 1127) of each individual product.

Is Ex ia the only protection method permitted in zone 0?

The best-known and most widely used type of protection for zone 0 is still Ex ia.

However, the following protection methods can also be used for applications within zone 0:

  • ma = encapsulation (EN 60079-18)
  • da = explosion-proof housing (EN 60079-1)
  • op is = Protection of equipment and transmission systems involving optical radiation; (EN 60079-28)
  • sa = special protection (EN 60079-33)

In addition to these protection methods, a combination of at least two independent protection methods, each with EPL 'Gb', can also be included in the possibilities to grant the whole an EPL 'Ga' (EN 60079-26).

Is there a limitation on the length of conductors in an Exe box?

Under EN 60079-14, the average length of the conductors may not be longer than the half diagonal of the housing, given that calculations and type studies are conducted on this basis.
So you mustn´t overdo it by bringing in many loops of reserve lengths.
Extra length current-carrying conductors could cause the internal temperature to rise so that the temperature class is exceeded.
For the same reason it is advisable to have no more than 6 conductors run in cable channels.

Can I enter the Ex zone while wearing my digital wristwatch?

The short answer is: yes, you can enter the Ex zone while wearing a simple wristwatch with battery (whether or not it is “digital”).

However, a smartwatch is not a simple wristwatch!
Smartwatches and all other battery or solar-driven personal equipment must either have an appropriate Ex classification or first undergo a risk analysis.
 

What harmonised standards are associated with the ATEX114?

The current harmonised standards of the ATEX95 retain their legal presumption of conformity under the new ATEX114 directive, because the essential safety and health requirements have not been modified.
In March 2016 the first list of harmonised standards associated with ATEX114 was published together with the last list associated with ATEX95, and the content of the two lists was identical.

May a product still be delivered with an EC conformity declaration that makes reference to the old Directive?

All EC conformity declarations before 20 April 2016 had to refer to ATEX95. All products that were already in the distribution chain prior to this date can still be delivered with their EC conformity declaration referring to ATEX95. After all, these products were legally put onto the EU market, so there is no need to adapt the provided documents.
Products put onto the market or self-manufactured products commissioned as of 20 April 2016 must refer to directive ATEX114 in their EU conformity declarations.

Because the Directive requires that the EU conformity declaration always accompany the product, for manufacturers it was very awkward to replace them from one day to the next. Many manufacturers thus included the following statement in their EC conformity declaration: ´The object of the declaration described above is in conformity with the relevant Union harmonisation legislation: Directive 94/9/EC (until April 19th, 2016) and Directive 2014/34/EU (from April 20th, 2016)´.

Which information must be applied on the product by whom?

It is up to the manufacturer to decide whether to apply a series, type or batch number. Of course this has implications in terms of traceability and a possible recall.
The manufacturer must apply its (trade or brand) name or postal address on the product. This information could also be made available inside the product, but it should always be easily accessible by the market surveillance authorities.
The address shown does not necessarily have to be the address where the manufacturer is actually based. It can also be the address of an authorised representative or customer service. The address must be specific enough for correspondence by post. Not all addresses include a street name and/or number.

The name and address of the importer and manufacturer must be shown on the product, unless both belong to the same group and the company established in the EU takes full responsibility as the manufacturer. An exception to this rule is made for small products or products to which a name and address cannot be applied. The importer is allowed to open the packaging of such products. In this case, the information must be shown on the packaging or in a document accompanying the product.

The address does not have to be translated. With certain alphabets it is impossible to identify this information.

A distributor does not have to apply its contact details on the product.
Only the manufacturer or importer is obliged to do this.

What is the correct order of marking when multiple protection methods are applicable on the same apparatus or assembly?

Over the past few years the known harmonised European standards of the EN 500xx-serie have been replaced one by one by their substituter of the EN/IEC 600xx-serie.

Apparatus and assemblies certifiied according to the EN 500xx-serie have markings sorted by their importance. The most important protection method is placed first.

Apparatus and assemblies certified according to the EN 600xx-serie are marked alphabetically.

This means that within the 'old' standards, one could clearly indicate wether you were dealing with an 'EExde' or 'EExed' application, where within the 'new' standards the marking will always be 'Exde'.

This may cause confusion. For example, it is not always clear whether a fitting has an Exe enclosure with Exd components or whether the fitting is Exd with an Exe connection compartment.

Is an ATEX certificate valid forever?

Contrary to popular belief, an ATEX certificate is not valid forever.

An ATEX certificate is always linked to the current edition of specific standards. These standards are valid for a limited time only and therefore also restrict the certificate itself.

When a particular edition of a linked standard is no longer valid, the manufacturer has two options:

The manufacturer can have its certificate upgraded by a Notified Body to meet the standards’ most recent editions. This usually involves the addition of an annex to the original certificate.

The manufacturer can also evaluate the changes to the new edition and their impact on the product. If the manufacturer’s evaluation shows that the product still meets the new edition’s requirements, the manufacturer can include this in the EU declaration.
An ATEX certificate that has seemingly expired because of references to expired standard editions may therefore still be valid if it is combined with an amended EU declaration.

What are temperature classes and how are they determined?

The ignition temperature depends on the type of gases present and their characteristics. The temperature of explosion proof equipment must never be allowed to become a source of self-ignition in the surrounding atmosphere.
Group II electrical equipment is therefore categorised in the following temperature classes based on the maximum surface temperature:

Temperature classMaximum surface temperature
T1450°C
T2300°C
T3200°C
T4135°C
T5100°C
T685°C

The maximum surface temperature of an electrical device must always be lower than the ignition temperature of the gas or vapour mixture in which it is used.

This maximum surface temperature is determined differently depending on the protection method.
Ex d devices are built to withstand an internal explosion, so their maximum surface temperature will only be determined on the outside of the device.
For Ex e devices, the inside temperature will also be taken into account to determine the device’s maximum surface temperature.

What is the meaning of IIIA, IIIB en IIIC ?

Similar to the classification of gases in IIA, IIB and IIC groups, dusts are also categorised in groups IIIA, IIIB and IIIC.

Depending on the ignition and sparking characteristics of an explosive mixture, gases and vapours are divided into explosion groups. Categorisation criteria are the gap dimensions, the minimum ignition energy respectively, that have been determined empirically for the various gases.

The classification in dust explosion groups is based on the size and the electric conductivity of the explosive dust (conductive = resistivity less than or equal to 10³ Ohm.m). Everything that exceeds 500µm and is conductive is included in group IIIA. Smaller, non-conductive particles belong to group IIIB, while smaller particles that are also conductive are categorised in group IIIC.

Electrical equipment is marked to indicate for which group (A , B or C) it is designed. Group IIC or IIIC has the most severe characteristics and can also be used for respectively gases or dusts in subdivisions A and B.

LocationGroupExamples
Mines susceptible to firedampIMethane
Other locations with risks for gas explosionsIIAPropane, Octane, Acetone, Ammonia
 IIBEthylene, Carbon monoxide
 IICHydrogen, Carbon disulphide, Acetylene
Locations with risks for dust explosionsIIIACombustible flyings
 IIIBNon-conductive dust
 IIICConductive dust

Can an Ex d enclosure be filled completely?

The dimensions of an Ex d enclosure mounting plate must be considered very carefully. All too often it is assumed that the mounting plate can be filled completely.

However, sufficient space in all directions is required. This requirement is more stringent for IIB + H2 and IIC applications than for Ex d IIB applications.

It must also be prevented that the temperature inside the enclosure gets too high, particularly if Ex i modules have been built in.
Ex i circuits must also be clearly separated from the other circuits.

Enclosure heaters must be placed in the right way.
Obstructions or fans have a significant impact on events in case of an explosion.

We should always remember that a wide range of factors must be taken into account when assembling an Ex d enclosure.

Can a metal cable gland be fitted to a plastic housing?

The logical rule is that cable glands and housings are made of the same material: metal cable glands should be screwed on to metal housings and plastic cable glands should be screwed on to plastic housings.

However, in practice this may lead to some problems:

  • Stainless steel housings: stainless steel cable glands are very expensive.
  • Aluminium housings: aluminium cable glands may gall after some time.
  • Potential differences between different metals (thermocouple effect) cause corrosion.

If you fit a metal cable gland to plastic, the cable gland must be grounded.

We have the following solutions for our CP series:

  • Offshore plate on the inside of the cabinet: elegant, easy solution.

        

  • Individual grounding plates on the outside of the cabinet: end user must apply grounding to every plate himself.

        

  • Individual threaded earth plates on the inside of the cabinet: expensive solution and only up to M32.

        

What must be taken into account when installing a radiation source?

When one has to install a dimmer switch, badge reader or other radiation source in the Ex zone, one often proceeds on the assumption that there is absolutely no problem with using an Exd housing.
However, one mustn’t lose sight of the fact that optical radiation can also be an ignition source. Just think of sunlight which, provided that it is focused by e.g. a lens, can trigger combustion.
With laser light, the energy - even with a non-focused beam and over a long distance - can be great enough to make combustion possible.
The following table (EN 60079-28, 5.2.2) establishes the maximum radiation values:

Apparatus groupIIIAIIAIIBIICIIC
Temp. class T3T4T4T4T6
Temp. class (°C)<150<200<135<135<135<85
Power (mW)15015035353515
Irradiance (mW/mm²)
(surface area not exceeding 400mm²)
20*20*5555

* For irradiated areas greater than 30mm² where combustible materials may intercept the beam, the 5mW/mm² irradiance limit applies.

How do I check NPT screw thread in Exd applications?

To check NPT screw thread one starts from the rules according to the NPT standard ANSI / ASME B1.20.1, old EN 50018 and new EN 60079-1.

In the case of male screw thread, the rules of the NPT standard are identical to that of the Exd standard.
The working method for testing an Exd cable gland with a ring gauge is thus the same as that of standard material.

When female screw thread is involved, however, there is a difference between the NPT standard and the Exd standard EN 60079-1.
The working method for testing female NPT screw thread with a plug gauge consequently requires the necessary knowledge.

Contact us if you’d like more information on this.

How close can an Ex d enclosure be fitted to another object?

When installing flameproof enclosures, you must take into account the minimum distance between the flame path and any fixed obstacles external to the material itself, such as walls, steel constructions, pipes, other material, etc.
Unless the material has been tested at a smaller distance in a documented test, the following minimum distances must be respected (table 13, EN 60079-14):

Gas GroepMinimum afstand mm
IIA10
IIB30
IIC40

May a gasket be added to a cable gland or a plug in an Exd application?

Theoretically it is allowed to equip Exd cable glands, adaptors or plugs with a gasket - on condition, however, that there has to be a minimum of 5 complete threads of contact. This applies for both straight (metric) and conical (NPT) wire.
Thus in practice (simply) adding your own gasket for a metric adaptor, plug or cable gland is not recommended!

The application of grease to the screw thread is allowed if it is a suitable grease, meaning: non-hardening, non-metallic and non-flammable, and as long as the earthing remains assured.

Can I connect two adaptors in an Exd application? Can I add a plug to an adapter?

Article 13 of the current edition of EN60079-1: 2014 (Exd standard) states that only 1 adapter is allowed per hole. The same article also states that it is not permitted to install a stop in such an adapter.

"Each entry shall have no more than one thread adapter when an adapter is used. A blanking element shall not be used with an adapter."

The term adapter refers to both a reducer and enlarger (see drawing C2 in annex C).

To what extent can I perform maintenance and repairs on my Ex equipment myself?

The economic directive 2014/34/EU (=ATEX114) deals with free trading in Ex devices in Europe. Installation of these Ex devices falls under the social directive ATEX137 and the standard EN60079-14. Maintenance and repairs are also not dealt with in the ATEX114, but are described in the respective standards EN60079-17 (inspection and maintenance) and EN60079-19 (repairs).

In contrast to the ATEX114 directive, the IECEx Scheme does have modules that deal with maintenance/repair and competencies of persons. Since only ATEX114 certified products may be installed in Belgium (Europe), this is not relevant at present.

EN60079-17 (edition 2013) article 4.2: ‘Qualification of personnel’ states that inspections and maintenance may only be performed by ‘experienced personnel’. They must have knowledge of the different protection methods, general principles concerning zoning, installations, the content of this standard, the business rules and - last but not least - the NATIONAL legislation. This knowledge can be acquired through education/training on a regular basis. The participation in such training courses must be documented and demonstrable.

EN60079-19 (edition 2010) article 4.2: ‘Statutory requirements for repair facility’ states that a repair of Ex material may be performed by the manufacturer, the end user or a third party, but that all of these must be aware of the specific requirements in the NATIONAL legislation. Furthermore, this standard requires that the repairer possess a quality system which contains the various procedures for repair. Naturally, all actual repairs performed on devices must be recorded and documented. Annex B contains training and competency requirements for both those in charge and those who perform the work.

The NATIONAL legislation on repairs on Ex equipment is briefly but powerfully described in article 106 of the General Regulations for Electrical Installations. It is stated therein that they may only be performed by the manufacturer, possibly his ‘extended workbench’ or a so-called authorised Ex workshop which stands under the supervision of an authorised inspection organisation. 

Conclusions:
Thus, on top of the European requirements, Belgium requires that an authorised Ex workshop stand under the supervision of an authorised inspection organisation.

May a user take a standard housing for a simple Exi terminal box?

Until recently it was permitted to use a standard housing for a pure Exi terminal box.

However, a restriction has been imposed on this in article 16.5 of the latest edition of EN/IEC 60079-14 (2013): the use of a standard housing is still allowed only when a single circuit is involved.

In practice, therefore, one will almost always have to use a housing that meets the requirements of EN 60079-0 with regard to impact resistance, ageing, UV resistance, etc. … which basically means an Exe housing.

Which plastics can be used in function of the different zones and present vapours?

The EN/IEC 60079-0 and EN/IEC 60079-14 enforce requirements in order to avoid ignitions caused by electrostatic charges of external non-metallic parts of electric devices.
Non-metallic parts such as plastic covered cable trays, films, foils, paints, plastic mounting plates,...

The following prescriptions are applicable in GAS zones:

a) The most common solution is to use a plastic with reduced surface resistance, with a maximum of 1GOhm (measured at 50% ± 5% relative humidity).

b) Another possibility is to reduce the maximum surface area depending on the zone and gas group (table 5 of article 6.5 EN/IEC 60079-14, values in mm²) :

Equipment Protection LevelGroup IIAGroup IIBGroup IIC
EPL Ga50002500400
EPL Gb10000100002000
EPL Gc10000100002000

The values in the above table can be multiplied by a factor 4 if the surrounding area of the non-metallic part can be considered a 'conductive and earthed frame'.

If the external parts of the electric device consist of different non-metallic parts, these parts may be judged one by one following table 5. This on condition that the parts are each surrounded by a 'conductive and earthed frame'.

For long parts with non-metallic surfaces, the surface area need not be considered, but the diameter or widths shall be limited (table 6 of article 6.5 EN/IEC 60079-14, values in mm) :

Equipment Protection LevelGroup IIAGroup IIBGroup IIC
EPL Ga331
EPL Gb303020
EPL Gc303020

c) In case of a non-metallic layer bonded to a conductive surface, the breakdown voltage shall be ≤4 kV or the thickness of the non-metallic layer is limited (table 7 of article 6.5 EN/IEC 60079-14, values in mm) :

Equipment Protection LevelGroup IIAGroup IIBGroup IIC
EPL Ga220,2
EPL Gb220,2
EPL Gc220,2


d) An electric device for fixed installation (not for mobile applications) with non-metallic parts that does not comply to one of the above solutions, can only be delivered with a certificate with an 'X' at the end. An additional warning plate must inform the user about the risks of the device. This means that the responsibility has moved from manufacturer to user. This last one must make sure that the device will only be installed in areas without any danger of ignition by electrostatic (de)charges, in case of a normal use, cleaning, ....

The following prescriptions are applicable in DUST zones:

In case of a non-metallic layer bonded to a conductive surface, the plastic shall comply to one of the following requirements.

a) The most common solution is to use a plastic with reduced surface resistance, with a maximum of 1GOhm (measured at 50% ± 5% relative humidity).

b) The breakdown voltage shall be ≤4 kV.

c) An electric device for fixed installation (not for mobile applications) with non-metallic parts that does not comply to one of the above solutions, can only be delivered with a certificate with an 'X' at the end. An additional warning plate must inform the user about the risks of the device. This means that the responsibility has moved from manufacturer to user. This last one must make sure that the device will only be installed in areas without any danger of ignition by electrostatic (de)charges, in case of a normal use, cleaning, ....

Why are metal locknuts to be used with plastic Exe glands?

When Exe glands (plastic or metal) are mounted in an Exe housing in combination with a locknut, this last one should be a metal one.
Since the combination gland-nut should also resist the impact- and aging tests (for plastics) as described in the EN 60079-0.

This means in practice that a regular plastic locknut after a severe winter and/or a warm summer would break while undergoing this impacttest.

Of course there are suitable plastics which allow to create an 'ex-plastic-locknut'. However, certification of this product would not be useful.
This is why most of the EU-type examination certificates of plastic Exe glands include the instruction, in case of the need of a locknut, to use a metal one.

What's the difference between apparatus marked with 'Ex' and 'EEx'?

Over the past few years the known harmonised European standards of the EN 500xx-serie have been replaced one by one by their substituter of the EN/IEC 600xx-serie.
On 1.10.2008 the EN 50014 (= general rules for electric apparatus) has also been replaced by the EN 60079-0. From that day on for manufacturers of Ex-material it has become difficult to produce and sell their products marked following the 'old' EN 50014. Indeed the legal suspicion of conformity disappears when a standard is no longer being called harmonised following the directive 2014/34/EU in the Official Journal of the EU.

This means practically that manufacturers have to check whether there products still meet these new standars, eventually make some constructive adjustments, having updated their certificates and subsequently adapt the matching declarations of conformity.

Apparatus marked following the EN 600xx standards are marked with 'Ex' instead of the 'old' known European 'EEx'.

When are round ( ) and when are square [ ] brackets used in the classification code?

An intrinsically safe circuit consists of an intrinsically safe apparatus and a so called associated apparatus. All current circuits of an intrinsically safe apparatus are intrinsically safe, thus the apparatus can be placed within the Ex-zone.

For example : IS magnetic valve of category 1G with marking Ex ia IIC T6

Associated apparatus contain both intrinsically safe and non-intrinsically safe circuits. They are developed in a way that the non-intrinsically safe circuits don’t affect the intrinsically safe circuits. Thus, they should always be placed in the safe zone. Brackets are used to make this clear.

For example : galvanic isolator of category (1)G with marking [Ex ia]IIC

Square brackets are used in the classic Cenelec classification of associated apparatus while round brackets are used to define the category.

Is an authorized assessment organisation the same as a Notified Body as referred to in the directive 2014/34/EU?

A Notified Body following the Directive 2014/34/EU is not to be confused with an authorized assessment organisation.
The last one does only an independent inspection on site before starting up the installation. So there is no judgement of compliance to the directive 2014/34/EU needed for the installation itself, on condition that the used apparatus and assemblies have had a proper judgement.
An authorized assessment organisation can not execute a product inspection nor deliver an ATEX certificate following the Directive 2014/34/EU.

Should apparatus of group II always be marked with A, B or C?

Only for the protection methods flameproof housing (Exd) and intrinsic safety (Exi) electric apparatus of group II are divided in gasgroups IIA, IIB or IIC.
This subdivision is based on the maximum experimentally defined gap (MESG) for flameproof housings and the minimum ignition current (MIC) for apparatus of intrinsic safety.

Examples :

  • junction box increased safety with marking Ex e II T6
  • junction box intrinsic safety with marking Ex ia IIC T6
  • flameproof housing with marking Ex d IIB T3
  • housing with overpressure with marking Ex p II T4
  • magnetic valve with marking Ex em II T5

Apparatus with marking IIC have the most severe conditions. This means that IIB apparatus are also suited for IIA applications, and IIC apparatus are also suited for applications in need of IIA or IIB.

According to the latest edition of EN 60079-0 the marking of all protection methods must be supplemented with A, B or C.

Which documents are to be supplied by the manufacturer?

A manufacturer is only obliged to deliver the declaration of conformity (EU-declaration), or written attestation of conformity in case of components, and the relevant installation and maintenance instructions.

The supply of the EU type certificate (commonly known as ATEX certificate) is not a legal obligation. Nevertheless, this contains a lot of additional information that often can’t be found on the documents to be supplied legally.

Although it is not obliged, it is generally agreed that all health and safety related instructions must be supplied in paper form, since it cannot be assumed that the user has access to the means of reading instructions supplied in electronic form or made available on an internet site.

The instructions must contain drawings and diagrams necessary for repair of the equipment. However, as an alternative the manufacturer can include in his documentation a statement that specific repair, maintenance and/or overhaul of the equipment shall only be conducted by the manufacturer himself, or by a repairer he has qualified or authorized.

Can an Exd cable gland be used in an Exe application?

There is no clear answer to this, since it depends on the edition of the EN 60079-1 (Exd standard) under which this Exd cable gland is certified.

Over the various editions, the tests prescribed in the EN 60079-7 (Exe) and the EN 60079-1 (Exd) were sometimes identical, at other times divergent.  
It is therefore recommended in an Exe application to always use a cable gland with heightened safety (Exe), or one that is dual-certified (Exde).

A cable gland with heightened safety cannot be used in a flameproof housing.

Can a user assemble an apparatus himself, based on componentcertificates (“U” at the end)?

Components are parts, essential for the safe working of apparatus and safety systems, but not having an autonomic function.

Examples :

  • connection terminals
  • empty flameproof enclosures
  • push buttons, signal lamps, A-meters,…
  • ballasts for fluorescent lighting
  • Ex MCB’s, relays

Components following the ATEX95 Directive should not be marked CE !
Indeed, they can’t be subject to all tests described in the Directive and matching Cenelec standards. This is the reason why component certificates (with “U” at the end) don’t mention the temperature class. The certificate or the manual states the final temperature class should be determined at a (later) installation in a housing.

Even an empty housing (= also a component) is certified without temperature class, since the manufacturer is not aware of what will be built in by the customer at a later time.

Unlike for example the Low Voltage Directive, an assembler can not rely on the CE’s of the components. This is why the directive demands a complete certificate of a Notified Body for zones 1 and 21 (categories 2G and 2D). In principle, self certification is allowed for zones 2 and 22. But how can an assembler determine the final temperature class when these of the different parts are not known ?

In practice, an assembly of components becomes an apparatus as meant in the directive.When an end-user builts himself an apparatus, he is automatically considered as being a manufacturer which implies all his responsibilities and duties.

What is the meaning of the different characters in the Exn classification?

Exn is based on the European harmonised standard IEC 60079-15.

This protection method could be achieved in five different ways :

  • non sparking apparatus (nA)
  • housing with simplified overpressure (nP (= z-purge))
  • apparatus with limited energy (nL)
  • housing “restricted breathing” (nR)
  • sparking apparatus (nC) of which the contacts are well protected, in another way than restricted breathing, apparatus with limited energy and simplified overpressure.

In the latest edition of the EN 60079-15, there are only 3 ways left:

  • non sparking apparatus (A)
  • housing “restricted breathing” (R)
  • sparking apparatus (C) :
    - Enclosed-break device nC = attenuated version of Exd
    - Hermetically sealed device nC = external atmosphere can not penetrate (seal = soldering, brazing, welding, ...)
    - Non-incendive component nC = because of their design, the contacts can not cause ignition
    - Sealed device nC = can not be opened during normal operation

Apparatus that meet this standard (= category 3G) is only suited for use in zone 2 (gasexplosions). There is no automatic relation with a possible installation in zone 22 (dustexplosions), for which apparatus of category 3D are needed.

Can an apparatus in the safe zone be subject to the ATEX114 directive?

Safety, control and regulating devices are located in the safe zone, but they are necessary to guarantee the safe working of an apparatus located in the Ex-zone having reference to danger for explosion.

Examples :

  • motor protection switches for an Exe motor
  • Exi barriers and modules
  • central circuit board of a gas detection system
  • electronic module to guard the temperature of a bearing
  • PTC relay of an Ex motor

Safety, control and regulation devices are the only equipment that are subject to both the Low Voltage as the ATEX114 Directive.

Due to this double condition (always in combination with an apparatus in the Ex-zone and having reference to danger for explosion) it is avoided that every apparatus located in the safe zone and having an accidentally connection to the Ex-zone (for example by a cable), should be subject to the 2014/34/EU Directive.