Understanding the Key Requirements of EN IEC 60079 – 0:2018 for Explosive Atmospheres

The PN – EN IEC 60079 – 0:2018 standard outlines the key requirements for the design, testing, and marking of equipment intended for use in explosive atmospheres (Ex). This implies that every designer of Ex equipment, such as motors, sensors, or switchboards, must ensure that no part of the device becomes a potential ignition source. Below, we discuss the principles of designing in compliance with EN IEC 60079 – 0:2018, along with practical examples and common pitfalls to avoid.

Selection of Appropriate Construction Materials

The materials used for the enclosures and components of Ex devices must be chosen to prevent explosion risks and maintain their properties under harsh conditions. The standard emphasizes both metallic and non-metallic materials:

• Light Metals (Al, Mg, Ti, Zr) – Due to the risk of sparking from impact or friction, the standard limits the content of these metals in alloys used for enclosures. For the highest category devices (EPL Ga / Da – for zones 0/20), aluminum and its alloys are generally eliminated or heavily restricted. For example, in zone 0, the total content of Al+Mg+Ti+Zr in the enclosure material is limited to about 10%, with magnesium content restricted to ~7.5%. This means enclosures for the most hazardous zones are typically made from steel, cast iron, or stainless steel rather than aluminum. If a manufacturer uses an alloy with higher aluminum content, the device must be marked with an “X” symbol (special condition) and precautions must be provided in the instructions (e.g., avoid impacts on rusty steel structures that could cause a thermite spark).
• Copper Alloys – The latest edition of the standard highlights the risk in the presence of acetylene (group IIC). Copper acetylides, which are highly sensitive to friction/impact, can form on the surface of copper alloys in contact with acetylene. Therefore, brass/bronze enclosures have limited copper content (e.g., max ~65% Cu) or must be coated with a protective layer (e.g., nickel or tin plating) to isolate copper from the acetylene atmosphere. If designing copper components for group IIC (e.g., brass connectors in a sensor for a gas zone with acetylene), ensure they meet these requirements or apply a protective coating.
• Plastics and Elastomers – Sometimes enclosures (or windows, covers, seals) are made of plastic or rubber. Their “enemies” are aging, temperature, and UV radiation. The standard requires the thermal endurance of such materials to exceed by at least 20 K the maximum temperature the material will reach during device operation. In other words, if an internal element can heat the wall to 80°C, the plastic used should have a temperature index (TI or RTI) of at least 100°C to last without cracking or deforming. Additionally, UV resistance is required for plastics exposed to sunlight – the material must have appropriate certifications (e.g., UL f1) or pass a UV aging test. Designers should use only materials documented by the manufacturer for heat and UV resistance, in accordance with the standard. In practice, GRP (glass-reinforced polyester) enclosures are popular due to their good mechanical strength and environmental resistance, meeting the standard’s requirements.

In summary, construction materials for Ex devices must not become ignition sources themselves. Avoid using bare aluminum in mining enclosures or low-quality plastic that cracks after a year in the sun. Instead, choose steels, brass with protective coatings, and high-grade polymers – and always specify the material used in the documentation (the standard requires specifying the exact type of material, such as alloy or plastic designation, to verify its parameters).

Robust Mechanical Construction of Enclosures

The mechanical construction of Ex devices must be robust enough to withstand operating conditions (impact, pressure, vibrations) without damage that could cause ignition. Here are some practical aspects from the standard and good practices:

• Impact Resistance – The standard requires that the enclosure withstand a specified impact (hammer test or weight drop) depending on the type and application of the device. Typical impact energies in tests range from 4 to 20 J. When designing, select appropriate wall thickness, reinforcing ribs, or use metal enclosures for devices exposed to mechanical damage. Drop and impact tests simulate, for example, a tool falling on the device. For instance, an Ex switch on a panel should withstand an impact without breaking to expose the interior. Ensure your design meets these requirements – material manufacturers often provide impact resistance ratings for their enclosures (IK rating). For Ex zones, high mechanical strength is usually required – e.g., Ex lamp covers must withstand impact because a broken lampshade could allow ignition outside.
• Strength and Security of Fasteners (screws, covers) – All screws that hold enclosure covers or other critical parts must be designed not to loosen by themselves and withstand any internal explosion (for flameproof enclosures Ex d) without breaking. A common mistake is using too small or weak screws – e.g., an M4 screw in soft aluminum can be pulled out. The standard recommends using metric threads with appropriate pitch (standard metric thread, tolerance class 6H/6g) and minimum thread engagement depth. Additionally, if a special screw strength class is required (e.g., 8.8 or stainless steel of a specific class), the manufacturer should specify this, and the device certificate will have an “X” symbol with information that replacement fasteners must be equivalent to the originals. In practice: use high-strength screws, preferably secured against loosening (e.g., by using spring washers, wire locks, or thread-locking adhesive). No screw should “fly out of the enclosure” during normal operation – it’s good to design covers so that screws are permanently attached (e.g., embedded in the cover and not falling out when unscrewed, preventing loss). Remember, a loose screw inside an Ex enclosure can rub against metal and spark or damage components – absolutely prevent this.
• Seal and Joint Security – If the enclosure has a seal (e.g., providing IP tightness), the standard requires that the seal be permanently fixed or shaped so that it does not fall out when opening. Practically: design grooves for seals, use self-adhesive seals or mechanically wedged seals so that the serviceman does not lose the seal or misinstall it when reassembling. An improperly installed or omitted seal poses a risk of dust/gas entering the enclosure. Enclosure latches and closures should require a tool – according to the principle that Ex devices should not be opened with bare hands in the Ex zone. Avoid hand-opened clips; instead, design screws that need to be unscrewed with a wrench. This is a safety requirement – only a conscious person with a tool should be able to open the enclosure, and only after ensuring there is no explosive atmosphere (or the device is disconnected).
• Vibration Resistance – In large machines, vibrations can loosen connections and cause microscopic sparking at contacts or cracking of components. The standard indicates that the impact of vibrations should be considered – e.g., secure threaded connections against loosening and use cables that do not wear out. Example: if designing a large Ex e enclosure on a vibrating motor, use connecting wires to the terminal board so that they do not break (a little slack, flexible materials) and add screw locks (lock nuts, adhesive). Every moving part (e.g., knob, lever) must be designed so that vibrations do not cause it to move to a dangerous position.

In summary, the mechanics of Ex devices are the foundation of safety. A solid enclosure, durable mounts, and refined details (such as seals or screw protections) prevent both gradual damage and sudden failures. Design “industrially resistant” – remember that Ex devices often operate in harsh conditions (refineries, mines, silos) for many years without interruption.

Controlling Maximum Surface Temperature

High surface temperature of a device can initiate an explosion if it exceeds the ignition temperature of the surrounding gas or dust mixture. Therefore, the standard sets clear requirements for the maximum allowable temperature of any external point of the device. Designers must ensure that these limits are not exceeded under any normal operating conditions.

• Temperature Classes (T1–T6) – For gas atmospheres, temperature classes are defined, where T1 is the highest (450°C) and T6 the lowest (85°C) allowable surface temperature. At the design stage, determine which temperature class your device should achieve – e.g., a sensor may require T6 = 85°C if used near gases with low ignition temperatures (e.g., CS₂). This means that no point on the sensor’s enclosure can heat above 85°C. Consider the worst-case scenario: the highest ambient temperature (standardly assumed -20°C to +40°C unless the manufacturer declares otherwise), heating from the sun, internal power losses, etc. The standard requires measuring temperatures during typical tests under extreme conditions declared by the manufacturer. If an element heats significantly (e.g., resistor, power transistor), design a heatsink or move it away from the enclosure so that it does not transfer heat outside beyond the limit. Sometimes temperature limiters or thermal fuses are used – so that even in case of device failure, overheating above the temperature class does not occur.
• Temperature in Dust Atmospheres – For dusts, instead of temperature classes, the maximum surface temperature in °C is often directly given (e.g., T_max = 120°C). Here, the additional factor of a dust layer settling on the device must be considered. Dust forms an insulating layer and can cause the device under the layer to heat even more (thermal blanket effect). The standard requires the manufacturer to specify the maximum dust layer thickness at which the device is safe. The standard assumption is a 5 mm dust layer. If the device can potentially be covered with dust, design it so that with a 5 mm dust cover, it still does not exceed the allowable temperature (often this means additional cooling design margin). Otherwise, the manufacturer must state in the documentation that dust must be regularly removed (e.g., “max. dust layer thickness 2 mm”). Example: an electric motor in a dust zone – its enclosure must not heat more than, say, 150°C if the dust ignites at 200°C, assuming it is covered with a 5 mm flour layer. If the motor structurally reaches 140°C without dust, but with a dust layer could exceed 200°C, it must either be better cooled or require cleanliness maintenance (then the nameplate will have “X” and a cleaning dust instruction).
• Heating in Unsteady State and After Shutdown – Often overlooked aspect: some elements can reach peak temperatures momentarily, e.g., just after power off (choke losing ventilation) or during startup. Ensure that these scenarios do not cause T_max to be exceeded. The standard also mentions marking if some elements remain hot after shutdown – e.g., if you have a heater that stays hot for 10 minutes after shutdown, you must warn the user not to touch/open the enclosure before it cools below the allowable temperature. Practical tip: if your design has, for example, a large capacitor or battery that could heat up, consider adding a thermal sensor disconnecting it in case of excessive temperature.

During design, conduct a thermal balance of the device: estimate power losses, distribute internal elements to dissipate heat, foresee the construction of radiators or fins on the enclosure, etc. Remember that customers may want to use the device in +50°C ambient – if so, you must anticipate and declare, for example, “Ta = -20…+60°C” on the nameplate (ambient temperature). If the equipment is intended for harsh conditions (e.g., near a furnace – ambient +60°C), and you do not design it for that, it may be OK in normal 40°C, but in 60°C it will exceed T6 and be non-compliant. Therefore, honestly define the operating temperature range and design the device accordingly.

Preventing Electrostatic Hazards

Static electricity can accumulate on device surfaces and release a spark during sudden discharge – which in the presence of an explosive atmosphere can cause ignition. The EN 60079-0 standard places great emphasis on this aspect, especially for enclosures and components made of plastics or other non-metals. Designers must anticipate and limit the possibility of dangerous electrification of the device.

• Avoiding Large Insulating Surfaces – If your device has external plastic elements (plastic enclosure, polycarbonate window, paint coating), remember that friction, air or particle flow can electrify the surface. The larger and more insulating the surface, the greater the charge can accumulate. The standard advises limiting the size of non-conductive surfaces or ensuring their sufficient conduction/discharge of charge. In practice: if you must have a large plastic window, use special antistatic material (e.g., with carbon black – often black Ex plastics have this additive) or coat the surface with a conductive coating connected to the ground. Alternatively, the manufacturer may opt for a warning on the enclosure: “Warning – clean only with a damp cloth” (this is a common note for enclosures that may electrify; a damp cloth prevents dry rubbing and charge accumulation). Such a warning is a last resort – it’s better to materially design out the problem so that the warning is not needed (customers prefer not to have usage restrictions).
• Paints, Coatings, and Stickers on Enclosures – Often metal enclosures are painted with powder or other paint. Contrary to appearances, paint is treated as a non-metallic material (insulator) on the surface. If you paint a large body with a thick layer of insulating paint, even though the metal underneath is grounded, the paint surface can electrify locally. It is good practice to limit the paint layer thickness – e.g., the standard states that with paint <0.2 mm on group IIC devices, the risk is lower. Alternatively, antistatic paints (with conductive additives) or dispersive lacquer can be used. An interesting solution is a two-layer coating: first a conductive primer (electrically connected to the enclosure mass), and on it a thin insulating paint layer – then even if someone touches/rubs against the enclosure, charges have a place to escape (to the primer and ground). Also, be careful with stickers, foils, membrane panels – a large plastic sticker on the enclosure is also a potential “charge magnet”. If you must stick a large plastic control panel, consider one with a conductive layer or divide it into smaller segments.
• Isolated Metal Elements – Sometimes metal elements (clamps, decorative strips) are attached to a plastic enclosure, isolated from the ground. Such “hanging” metal can accumulate induced charge and discharge it sparkly to a grounded structure nearby. The standard indicates that even small isolated metal parts should be considered. Therefore: if you use metal screws, grilles, or other additions on a plastic enclosure, try to ground them (e.g., through a conductive insert or additional wire to the mass). Alternatively, ensure they are small enough (low capacity) that the accumulated charge does not exceed the ignition energy – this would require analysis and testing, so it is more practical to minimize such solutions.
• Examples of Electrostatic Hazards: Imagine grain flowing through a plastic funnel – friction causes the funnel to charge. If there is a metal outlet at the bottom, a spark can jump. In Ex devices, we try to avoid this: we use materials with surface resistance <10^9 Ω or even add grounded screening meshes. Another example is a worker wiping dust off an enclosure with a dry cloth – plastic can charge up to several kV! Therefore, it is better for the enclosure to be made of metal or dissipative plastic, or alternatively, the instruction includes a note about cleaning only with a damp cloth (as mentioned). When designing, ask yourself: can someone touch/brush against this part? Can it rub against another material? If so – ensure that no dangerous spark will occur.

In summary, controlling static electricity is often overlooked but a critical aspect. The more plastics in your device, the more you must manage this. In practice, antistatic materials and well-grounded metal elements work best. Sometimes electrostatic resistance tests are required – e.g., rubbing with fur and measuring if discharges occur. A well-designed device will pass such tests without issue.

Eliminating Potential Sources of Electrical Sparking

Besides static and mechanical sparks, an obvious ignition hazard is electrical sparks or arcs from the device’s circuits, as well as other electrical phenomena (e.g., RF radiation). The 60079-0 standard as a general one imposes certain obligations to identify and eliminate these ignition sources at the design level.

• No Open Sparking Contacts – The device must be designed so that in normal operation no contacts spark to the atmosphere. Of course, various types of protection are used in Ex devices (e.g., flameproof enclosures Ex d allow sparking inside, as long as the enclosure withstands, and Ex i intrinsically safe limits spark energy, etc.). As a designer, you must decide which type of Ex protection you are using and select components for that type. Example: if designing an Ex e junction box (enhanced protection, where there can be no hot or sparking elements inside), you cannot place a regular relay with sparking contacts inside – as it would undermine the Ex e concept. Conversely, if designing an Ex d device (flameproof enclosure withstanding internal explosion), you can use normal contacts and elements, but you must ensure that in case of internal explosion, nothing escapes outside (i.e., adhere to gap, thread, etc., dimensions according to Ex d standard). The 60079-0 standard refers to detailed standards (e.g., 60079-1 for Ex d, 60079-7 for Ex e, 60079-11 for Ex i), but generally requires that all device parts are mounted and protected to prevent accidental sparking. Ensure that, for example, no PCB is loose and causes a short circuit, or that a terminal screw does not fall onto the board and cause a short circuit – this may sound trivial, but such things happen, and in Ex can be fatal.
• Discharge of Energy from Components After Disconnection – The standard requires that devices that can be opened do not have dangerous electrical charge on accessible parts inside. Specifically, if the device has capacitors charged above 200 V, they must self-discharge to energy below 0.2 mJ (for group I/IIA) or even 0.06 mJ (for IIB) / 0.02 mJ (IIC) before someone can open the enclosure. In practice, discharge resistors are mounted on capacitors. As a designer, add appropriate resistors to the schematic to discharge capacitors to a safe level within a few seconds. If for some reason you cannot (e.g., very large capacity requiring minutes to discharge), then the device must have a nameplate warning “Do not open for X minutes after shutdown”. No one likes such restrictions, so it is better to design the circuit to discharge capacitors quickly automatically. A similar issue – hot internal elements: if something inside the enclosure (normally not touched) can be very hot, it must either prevent quick enclosure opening or provide a warning. Often cover locks are used – e.g., the cover can only be removed after unscrewing several screws, giving capacitors time to discharge. Additionally, if the device has, for example, batteries that can spark (by shorting) or emit gases, the standard requires special attention (batteries in Ex d can increase explosion pressure). It is best to avoid large batteries in devices for zones 0/20 – if you must have them, refer to detailed requirements in the standard.
• Eddy and Stray Currents – Large electrical devices (e.g., high-power motors) can induce currents in their enclosures or fittings. The standard warns that such currents can spark at bearings or screw connections. Therefore, when designing, for example, an Ex db motor, consider additional bonding connections. Example: a large 100 kW squirrel-cage motor in an Ex d enclosure – during startup, currents induce in the metal enclosure, which can flow through bearings. If the bearings are not insulated, sparking can occur at the race and ball contact (microscopic, but in methane, that’s enough). In such cases, the designer uses, for example, special shaft grounding devices or insulated bearings to prevent currents from flowing through mechanical parts. Similarly with large doors and covers – if current flows through the hinge and vibrations interrupt contact, sparking occurs. Therefore, all metal-to-metal connections should be made to ensure electrical continuity (e.g., several screws instead of one, additional grounding bridges between the cover and the body). The standard mentions that protection can be additional conductive screws or grounding wires. It is also important to protect against corrosion – a rusty screw connection can lose electrical contact and start sparking when current flows. So if your design anticipates current flow (even short-circuit currents through the enclosure), ensure good galvanic connections of all parts and protect them against loosening and rust.
• Limiting RF Radiation – In the age of wireless devices, remember that strong radio transmitters can heat metal elements (like a microwave oven) or cause sparking at uncompressed joints. The 60079-0 standard establishes RF power limits emitted by devices operating in the Ex zone. For the range 9 kHz – 60 GHz, power thresholds are provided (e.g., ~6 W for most groups, ~2 W for group IIC) above which emission requires evaluation. If designing a device with a radio module (Wi-Fi, LTE, telemetry transmitter) – ensure that either the transmitter power is below the thresholds considered safe, or that you have appropriate Ex certificates for the radio part. In practice, most small transmitters (Bluetooth, WiFi) have low power around <0.1 W, so they do not pose a problem. But, for example, a 5 GHz radio link connecting devices with 10 W ERP power could theoretically ignite vapors by heating a metal antenna. When designing an Ex device with wireless communication, always check the antenna marking and mounting requirements – often the certificate will specify which antenna can be used and where.

In summary: analyze every possible source of sparking or hot spark in your electrical device. From contacts to capacitors, from bearings to antennas – there can be an ignition hazard everywhere. Apply appropriate measures: intrinsically safe circuits, flameproof enclosures, temperature protections, grounding – depending on the needs. If something potentially remains not fully safe, remember to add warnings and conditions in the documentation (although it’s better to avoid this through proper design).

Proper Ex Marking and Components

Ex device marking is not just a formality but also a summary of the key safety features you have provided in the design. The 60079-0 standard specifies in detail what the nameplate of a device intended for Ex zones should contain. As a designer, you must know these requirements and prepare appropriate markings and use certified components during device construction.

• Marking According to Category and Type of Protection – Each device must be marked with the group and category symbol (for ATEX, e.g., II 2G – meaning group II device, category 2, for gas zone 1) and the Ex code specifying the protection. Example full marking: II 2G Ex db IIC T4 Gb. What does it mean? Let’s break it down:
  • II – explosion group (II for surface industry, I for mining),2G – device category (2 for zone 1 for gas; G means gas, D dust),Ex d – type of protection (here flameproof “d”; can also be Ex e for enhanced, Ex i for intrinsically safe, etc., possible combinations),b – protection level (EPL Gb corresponds to category 2G, this is an additional IEC symbol – in ATEX 2G and EPL Gb mean essentially the same, but EPL is usually given at the end of the code),IIC – gas subgroup (IIC – most explosive gases, like hydrogen, acetylene; IIB – intermediate; IIA – mildest),T4 – temperature class (max. 135°C surface),Gb – EPL (Equipment Protection Level) as above, here Gb meaning high protection level in gas atmosphere.Sometimes there is also Ta = -20°C...+50°C if the ambient temperature range deviates from the standard.For dusts, similarly, it can be II 2D Ex tb IIIC T120°C Db (dust-tight enclosure “t”, for conductive dusts IIIC, max 120°C, EPL Db).
  As a designer, you must know from the start of the project what the final Ex code of your device should be, as many specific requirements depend on it. If, for example, the goal is II 3G Ex nA IIC T3 Gc (device for zone 2 with non-sparking protection), the requirements are somewhat milder than for II 2G Ex d IIC T3 Gb. However, compliance with 60079-0 is mandatory for all categories, so there is no shortcut – but, for example, allowable enclosure materials are different for 3G (more aluminum can be used) than for 1G. Ensure that the documentation (nameplate, manual) contains all required information:
  • full Ex code,
  • manufacturer’s name and address,
  • device model,
  • certificate number (after obtaining),
  • ambient temperature range, if different from standard,
  • serial number or year of production,
  • CE mark and notified body number (for ATEX),
  • any “X” or “U” symbols (explained below).
• Ex Components and “U” Symbol – If your device uses so-called Ex components (Ex Component), meaning elements that are not a complete device themselves but have a certificate for use in Ex devices (marked with a U symbol at the end of the certificate), you must consider their limitations. An example of an Ex component could be: a flamepath (flameproof bushing), an ungrounded Ex e terminal block, a leaded diode for an intrinsically safe circuit – they often have a separate component certificate. When designing, use such certified components, as it facilitates the entire device certification. But remember: an Ex component always has specified usage conditions – e.g., a flamepath Ex d housing may require you to mount it in a wall of min. thickness X and tighten with torque Y. Or an Ex e terminal is certified for a specific range of wires, and you must adhere to that. The “U” symbol means that the component does not receive a separate CE mark and does not work alone – its parameters must be included in your design. In the final device marking, components do not appear as separate codes (you do not write “Ex Component U”), but in the manual you must include information about the components used (usually found in the test report). Practical advice: use components from reputable companies with current certificates for 60079-0:2018 standards – this will save you potential issues during compliance assessment.
• Certificates and Technical Documentation – Already at the design stage, think about certification requirements. The 60079-0 standard requires the preparation of documentation including, among others: a list of materials (discussed in point 1), enclosure drawings, schematics, results of calculations and analyses (e.g., thermal), as well as a user manual. The manual must include all special conditions for safe use (the “X” symbol on the certificate will indicate that there are such conditions). As a designer, it is best to know yourself whether your device will need “X”. Example special conditions:
  • limitation of maximum ambient temperature (if it only works correctly up to +50°C, the user must know this),
  • requirement for periodic dust cleaning (e.g., remove dust weekly to not exceed 5 mm),
  • prohibition of use in certain mixtures (e.g., aluminum enclosure – avoid atmospheres with rusty dust, as aluminum hitting rust gives a thermite spark),
  • requirement to use specific covers (e.g., radiation shields if applicable),
  • information on allowable clearances and replacement of elements (e.g., “if the seal is damaged, replace only with original part no…”). The nameplate usually cannot accommodate these descriptions, there is only the “X” symbol at the end of the certificate number. Details must be in the documentation. Ensure that all unusual aspects of your design are included in the manual.
• Example of Marking and Components: Suppose you are designing an industrial camera for zone 1 (gas) and 21 (dust). It has a flameproof Ex d enclosure with a small glass window. The marking could be: II 2GD Ex db IIC T5 Gb Ex tb IIIC T100°C Db. You must fit both the gas and dust parts on the nameplate (for dusts, instead of temperature class, we give max °C). If the window is a certified component (e.g., Ex d quartz window with cert. U), integrate it according to guidelines – it probably needs to be pressed or screwed with specific adhesive. In the documentation, describe this assembly. You also use cable glands with Ex certification (otherwise your product will not obtain a comprehensive certificate). Finally, on the camera nameplate, you also give the CE mark, the notified laboratory number, and, for example, “Prot. X” if, for example, the paint on the enclosure is thicker and you require the user not to set the camera in zone 0 (this is just an example). Every element, from screws to seals, that has Ex significance must meet standards – use certified washers, bushings, etc. This will ensure no surprises during certification.

In summary, Ex markings are the “language” by which the device communicates its safety features to the world. The designer must ensure it speaks truthfully and completely – and that a truly safe construction is behind it. Always use the latest editions of standards, check if your intended marking is correct. Errors in markings or lack of information are common reasons for certification delays.

Practical Tips for Designers

After discussing the standard’s requirements and pitfalls, here are some practical tips that will make life easier for Ex device designers and increase the chances of smooth certification and safe operation in the field:

• Consider Service and Maintenance in the Design – Ex devices often require periodic inspections (e.g., seal replacement every few years, gland checks). Design so that service is simple and safe: e.g., use uniform screws throughout the device (so the serviceman doesn’t mix them up); make clear markings on replaceable elements (seal with a colored marker, whether it still has good elasticity); design the interior so that access to consumable parts does not require disassembling half the device (the longer the device is open in the zone without protection, the greater the risk). Good practice: create checklists for service – and think about them already during design. If, for example, you know that a protective spark gap in the circuit needs checking, maybe expose it so it’s visible from the outside through an inspection window? Such details distinguish an average design from a great one.
• Test Prototypes in Realistic Conditions – Before sending the device to the lab for testing, conduct your own tests from an Ex perspective. Clean the room, sprinkle some flour into the air (as dust) and see if any part of the device heats up excessively (of course, don’t ignite anything! it’s about simulating dust contamination). Rub the enclosure intensively with a cloth – do you feel a discharge? Run the device in a chamber from -20°C to +60°C and check if the enclosure doesn’t crack and parameters hold. Hit various places with a hammer of known energy (according to the standard) – better you find a weak point in the enclosure than for an auditor to do it in front of witnesses. Take the prototype to the plant (of course, to a safe place) and show it to an experienced maintenance engineer – ask what would break after a year according to them. Such feedback can reveal, for example, “here oil will collect and the seal will swell”. Better to revise the design earlier than later fight failures at the client’s site.
• Collaborate with the Certification Body from the Start – Ex certification (ATEX/IECEx) is a complex process. A good practice is to contact the chosen body (e.g., Ex lab) already at the conceptual design stage. You can present them with a preliminary design and ask about the most critical issues. Often lab experts will suggest: “better use a different material here, because this test may not pass” or point out novelties in the standards. It’s an investment that pays off – you’ll avoid many iterations. Remember, standards are sometimes interpreted – and labs have Interpretation Sheets for standards. Consulting at the source allows you to design for certification, not “and then we’ll see”.
• Look at the Whole Installation, Not Just a Single Device – Although as a designer you focus on your device, be aware that it will be part of a larger whole in the Ex zone. Think about how it will be mounted and used. Will the user have to insert batteries? If so, maybe add a safety switch so they can’t be replaced under voltage. Will the device be connected to another? Maybe it’s worth providing a unified cable interface so no makeshift solutions are made in the field. Make life easier for installers – e.g., by adding a second spare gland (plugged) for future connection of another cable, instead of someone drilling a new hole on site (which is prohibited without re-certification!). The more user-friendly your design is, the less risk there is that someone will do something dangerous with it.
• Pay Attention to Execution Details – With a finished product, details can determine compliance. For example, surface roughness on Ex d flame joints – the standard requires it not to exceed a certain value (usually 6.3 μm Ra). If you don’t ensure this in drawings and execution, it may turn out that a series of enclosures has too rough contact surfaces and does not meet the standard (a spark can pass). Or, for example, seal materials – they must withstand expected temperatures and not react with the atmosphere. Ensure you use the right rubber grades (e.g., VMQ for low temps, FKM for higher, etc.) and that this is documented. In Ex, the devil is often in the details – hence the importance of maintaining a bill of materials and specifications for each part.

Using Supplementary Standards and Experiences

Finally, remember that EN IEC 60079-0 is just the beginning. These are general requirements, but in Ex design practice, many other harmonized ATEX standards and knowledge sources are used:

• Other Parts of the 60079 and 80079 Series – Depending on the type of device protection, specific requirements apply: e.g., if making a flameproof enclosure, you must meet the EN 60079-1 standard, for increased safety 60079-7, for intrinsically safe circuits 60079-11, for dust protection by enclosure 60079-31, etc. For non-electrical (mechanical) devices, which can also be ignition sources, there are standards EN ISO 80079-36 and 80079-37 – they apply, for example, to pumps, gearboxes, fans in Ex zones. If your product contains mechanical parts that can spark or heat up, it’s worth looking into them. Example: when designing a mechanical mixer for an Ex zone, you must look not only at 60079-0 but also at 80079-36, which talks about maximum bearing clearances (so the rotor doesn’t rub against the housing, causing sparks).
• Installation and Usage Standards – Although you may not be involved in installation, it’s worth knowing the guidelines of EN 60079-14 (design and installation) and 60079-17 (maintenance). You’ll learn, for example, what qualifications a person opening your device must have, how leak tests are conducted, how often equipment in zones is inspected. This knowledge allows you to adapt the design to facilitate these activities. For example, from the installation standard, it follows that in zone 0, aluminum enclosures are not allowed – you already know this and won’t design one.
• Field Experiences (Feedback) – If you have access to end users or engineers dealing with Ex in plants, it’s worth collecting their opinions. Often a small comment from the factory (“These plastic covers crack in winter”) can point out what to improve. It’s also good to analyze failure and accident reports (publications, HSE databases, etc.). You learn what mistakes were really made in the past. E.g., a known case: explosion at a gas station because an Ex e fixture had a cracked seal – water got in, corrosion, sparking… Such a story makes you think, for example, to add a moisture sensor to important Ex cabinets that warns before it’s too late.
• Training and Literature – The Ex field is constantly evolving. It’s worth attending training, conferences, and reading industry literature. New editions of standards, new interpretations – all can affect your next project. Ensure you have the latest edition of the standard (EN IEC 60079-0:2018 is the latest at the time of writing, but there may be another edition in a few years). Also follow the IECEx site and the so-called “Ignition Risk Assessment” guidelines for devices.

In conclusion: designing devices for explosive atmospheres is a responsible task, but also satisfying when you see your product working safely in harsh conditions. The key is awareness of hazards and strict adherence to standards – and EN IEC 60079-0 is the foundation on which you base the entire project. By following the principles described above, paying attention to details, and avoiding common mistakes, you have a good chance of creating a device that successfully passes the certification process and serves users reliably for years in Ex atmospheres. Good luck in designing – may sparks be only a synonym for good teamwork, not a threat in the device!

FAQ: EN IEC 60079-0:2018