What Is Ex ec? Increased Safety Protection for Zone 2 Hazardous Areas

Among the various protection concepts defined within the IEC 60079 series, Ex ec is one of the most commonly encountered methods for electrical equipment installed in Zone 2 hazardous areas. Modern hazardous area projects frequently specify Ex ec certified lighting fixtures, junction boxes, instrumentation equipment, control stations, and terminal enclosures because they provide a practical balance between safety, simplicity, and cost.

Many engineers are familiar with legacy Ex nA equipment but remain uncertain about how Ex ec relates to previous standards. Understanding this relationship is important because current IEC standards increasingly use Ex ec as the preferred protection concept for many Zone 2 applications.

Quick Answer

Summary Table

Parameter	Ex ec
Protection Concept	Increased Safety for Zone 2
Standard	IEC 60079-7
Typical EPL	Gc
Hazardous Area	Zone 2
Ignition Sources Allowed	No ignition source during normal operation
Typical Equipment	Lighting, terminal boxes, control stations, instrumentation enclosures
Gas Atmospheres	IIA, IIB, IIC depending on certification

What Is Ex ec?

Ex ec is an increased safety protection technique designed to reduce the probability of ignition by implementing enhanced construction requirements and limiting the possibility of sparks, arcs, or excessive temperatures during normal operation.

The protection concept assumes that equipment is installed in Zone 2 locations where explosive gas atmospheres are not normally present. As a result, the required protection level is lower than equipment intended for Zone 1 or Zone 0.

A typical marking may appear as:

Ex ec IIC T4 Gc

This marking indicates:

• Ex = Explosion protected equipment
• ec = Increased safety protection for Zone 2
• IIC = Suitable for the most severe gas group
• T4 = Maximum surface temperature 135°C
• Gc = Equipment Protection Level for Zone 2

Why It Matters

Ex ec equipment is widely used because many industrial facilities contain extensive Zone 2 classified areas. Selecting Ex d equipment everywhere often increases project costs, weight, installation complexity, and maintenance requirements.

Where engineering studies confirm a Zone 2 classification, Ex ec equipment may provide a more practical solution while maintaining compliance with hazardous area requirements.

Industries commonly using Ex ec equipment include:

• Oil and gas production facilities
• LNG terminals
• Refineries
• Petrochemical plants
• Chemical processing facilities
• Tank farms
• Offshore platforms

Relationship Between Ex ec and Ex nA

One of the most common misconceptions is that Ex ec and Ex nA are completely different protection concepts.

In reality, many applications previously certified as Ex nA under IEC 60079-15 are now commonly certified as Ex ec under IEC 60079-7, although the concepts are not strictly identical. Modern IEC standards increasingly transition equipment toward Ex ec certification under IEC 60079-7.

Characteristic	Legacy Ex nA	Ex ec
Primary Standard	IEC 60079-15	IEC 60079-7
Zone	Zone 2	Zone 2
EPL	Gc	Gc
Current Industry Direction	Legacy approach	Preferred modern approach
Common New Certifications	Less common	Increasingly common

How Ex ec Prevents Ignition

Ex ec protection focuses on eliminating ignition sources during normal operating conditions.

Design measures commonly include:

• Improved insulation systems
• Enhanced creepage and clearance distances
• Temperature control measures
• Secure electrical connections
• Protection against loose conductors
• Mechanical construction improvements
• Reduced likelihood of sparking contacts

Unlike Ex d equipment, Ex ec does not rely on containing an internal explosion. Instead, it aims to prevent ignition from occurring in the first place.

IEC 60079 Requirements for Ex ec

IEC 60079-7 establishes detailed construction and testing requirements covering:

• Electrical clearances
• Creepage distances
• Terminal design
• Conductor retention
• Temperature limitations
• Material selection
• Ingress protection performance
• Mechanical strength

Manufacturers must demonstrate compliance through type testing and certification by recognized certification bodies.

Equipment Protection Level (EPL) for Ex ec

Ex ec equipment is associated with EPL Gc.

EPL	Typical Zone	Protection Level
Ga	Zone 0	Very High
Gb	Zone 1	High
Gc	Zone 2	Enhanced

Engineers should verify that the required EPL from the hazardous area classification study matches the EPL provided by the equipment certification.

Typical Applications of Ex ec Equipment

LED Lighting Fixtures

Many industrial LED luminaires are certified Ex ec because lighting equipment generally operates without producing sparks during normal operation.

Terminal Boxes

Terminal enclosures frequently utilize Ex ec certification where Zone 2 classification allows simpler installation compared to flameproof equipment.

Control Stations

Selected control stations and operator interfaces may use Ex ec construction when ignition sources are appropriately controlled.

Instrumentation Equipment

Transmitters, analyzers, and monitoring systems often employ Ex ec certification for Zone 2 installations.

Ex ec vs Ex eb

Characteristic	Ex ec	Ex e
Typical EPL	Gc	Gb
Typical Zone	Zone 2	Zone 1
Protection Level	Lower	Higher
Application	Less hazardous areas	More demanding areas
Cost	Generally lower	Generally higher

Ex ec vs Ex d

Characteristic	Ex ec	Ex d
Protection Method	Prevent ignition	Contain internal explosion
Typical EPL	Gc	Gb
Typical Zone	Zone 2	Zone 1
Weight	Lighter	Heavier
Maintenance	Simpler	More stringent

Practical Engineering Guidance

When selecting Ex ec equipment:

1. Verify the area classification is Zone 2.
2. Confirm the required EPL is Gc.
3. Check gas group compatibility.
4. Verify temperature class requirements.
5. Review ambient temperature limitations.
6. Confirm enclosure IP rating.
7. Ensure certification is valid and current.
8. Verify installation practices comply with IEC 60079-14.

Ex ec equipment should never be selected solely based on cost advantages. Hazardous area classification remains the primary driver of equipment selection.

Certification Considerations

Engineers should review complete certification markings rather than relying only on the protection concept.

Important items include:

• IECEx Certificate of Conformity
• ATEX certificate where required
• Gas group rating
• Temperature class
• EPL designation
• Ambient temperature range
• Special conditions of use (X marking)

Common Mistakes

• Assuming Ex ec is suitable for Zone 1.
• Ignoring EPL requirements.
• Selecting equipment based solely on gas group.
• Ignoring ambient temperature limitations.
• Confusing Ex ec with Ex e.
• Assuming all legacy Ex nA equipment automatically meets modern requirements.
• Evaluating only part of the equipment marking.

Frequently Asked Questions

Is Ex ec suitable for Zone 1?

No. Ex ec equipment is generally intended for EPL Gc applications in Zone 2.

What EPL does Ex ec provide?

Ex ec equipment provides EPL Gc.

Does Ex ec replace Ex nA?

Modern certification practices increasingly use Ex ec as the preferred approach for many applications previously covered by Ex nA.

Can Ex ec be used with IIC gases?

Yes, if the certification marking specifically includes IIC.

Is Ex ec safer than Ex d?

They use different protection principles and are intended for different hazardous area conditions.

What standard governs Ex ec?

IEC 60079-7.

Can Ex ec equipment be installed outdoors?

Yes, provided environmental ratings, IP protection, ambient temperature limits, and certification requirements are satisfied.

Conclusion

Ex ec is a modern increased safety protection concept designed for Zone 2 hazardous areas and EPL Gc applications. It provides a practical solution for many industrial installations by preventing ignition sources during normal operation rather than containing explosions. Understanding the relationship between Ex ec, Ex e, Ex d, and legacy Ex nA equipment helps engineers select compliant and cost-effective equipment while maintaining hazardous area safety requirements.

Related Reading

Technical Review

References

1. IEC 60079-0: Explosive Atmospheres – Equipment – General Requirements.
2. IEC 60079-7: Explosive Atmospheres – Equipment Protection by Increased Safety "e".
3. IEC 60079-14: Explosive Atmospheres – Electrical Installations Design, Selection and Erection.
4. IECEx Certified Equipment Scheme Documentation.
5. IECEx Operational Documents and Certification Guidance.