What is NEN-EN-IEC 60079?
NEN-EN-IEC 60079 is the Dutch and European adoption of the international standard IEC 60079 for explosion-proof electrical installations in gas and dust atmospheres. It applies to equipment, wiring and installation practice in explosive Zones (Ex zones).
In OT systems, NEN-EN-IEC 60079 is crucial when deploying components such as Sensors, switchgear, PLCs and drives within ATEX Zones in industries such as chemicals, oil & gas, hydrogen, food and bulk storage.
🧠 Purpose of NEN-EN-IEC 60079
- Prevent ignitions caused by electrical equipment
- Safe design, installation, inspection and maintenance
- Protect people, the environment and business continuity
- Compliance with ATEX directives for CE marking in Europe
- Uniformity with international practice (IEC 60079)
🔥 Zone classification (Ex environments)
| Zone | Type of hazard | Description |
|---|---|---|
| Zone 0 | Gas – continuous risk | An explosive gas mixture is present almost permanently |
| Zone 1 | Gas – frequent risk | An explosive gas mixture is frequently present during normal operation |
| Zone 2 | Gas – occasional | Present only briefly and rarely |
| Zone 20 | Dust – continuous | An explosive dust cloud is present almost permanently |
| Zone 21 | Dust – frequent | Frequently or periodically during normal operation |
| Zone 22 | Dust – occasional | Temporarily and unexpectedly |
The zone determines which type of Ex equipment is required under NEN-EN-IEC 60079.
🔐 Methods of protection under NEN-EN-IEC 60079
| Code | Method | Application |
|---|---|---|
| Ex d | Flameproof enclosure | Enclosure contains an internal explosion |
| Ex e | Increased safety | No sparks or hot surfaces |
| Ex i | Intrinsically safe | Low energy = no possible ignition |
| Ex p | Pressurised enclosure | Keeps the explosive atmosphere out |
| Ex n | Limited risk (zone 2) | For applications with low explosion risk |
| Ex t | Dust protection | No ignition sources in dust-laden zones |
✅ Equipment marking under the standard
A certified device for a gas environment may carry the following label:
Ex II 2 G Ex e IIC T3 Gb
| Code element | Description |
|---|---|
| Ex | For explosive atmospheres |
| II | Group II = industry (group I = mining) |
| 2 | Equipment category (1 = very high, 2 = high) |
| G / D | Gas (G) or dust (D) environment |
| Ex e | Method of protection |
| IIC | Gas group (IIC = most explosive, e.g. hydrogen) |
| T3 | Temperature class (max. surface 200 °C) |
| Gb | Equipment protection level (Ga = very high, Gb = high, Gc = normal) |
🔁 Relationship with other standards and legislation
| Standard / directive | Relationship to NEN-EN-IEC 60079 |
|---|---|
| ATEX 2014/34/EU | European directive based on IEC 60079 |
| IEC 60079 | International source version – technically equivalent to NEN-EN-IEC |
| NEN 1010 | National low-voltage standard, aligned with explosion-proof design |
| IEC 61439 | Switchgear cabinets in Ex zones must be specifically certified |
| IEC 60204-1 | Ex addendum required for machines in explosive atmospheres |
⚠️ Common mistakes in practice
- Installation of uncertified or unsuitable components in Ex zones
- Wrong cable glands or incorrect earthing
- Equipment with an inadequate temperature class for the zone and gas group
- No documentation or maintenance plan in line with standard part 60079-17 (inspection)
- No personnel training in line with 60079-14 (installation) and -17 (inspection)
📌 In summary
NEN-EN-IEC 60079 specifies how electrical equipment can be safely used in explosive Zones. The standard is essential for any OT environment in which gases, vapours or dust clouds pose risks to people and equipment.