IEC 60079-7 Explained: Increased Safety "e"

Many electrical devices used in hazardous areas do not normally produce sparks, arcs, or excessively hot surfaces during operation. However, under abnormal conditions such as loose connections, insulation failure, or excessive temperatures, these devices could still become potential ignition sources.

To address this risk, the explosion protection industry developed the concept of Increased Safety "e" (Ex e), a protection technique that relies on enhanced design measures to reduce the likelihood of ignition.

The technical requirements for this protection concept are specified in IEC 60079-7 – Explosive Atmospheres – Part 7: Equipment Protection by Increased Safety "e".

Unlike flameproof protection (Ex d), which allows an internal explosion to occur and then contains it, Ex e protection seeks to prevent ignition from occurring in the first place. This is achieved through improved insulation, increased creepage and clearance distances, secure electrical connections, temperature control, and enhanced mechanical construction.

Because many commonly used hazardous area products—including junction boxes, terminal boxes, motors, lighting fixtures, and instrumentation enclosures—are designed according to IEC 60079-7, this standard is one of the most important documents within the entire IEC 60079 series.

This article explains what IEC 60079-7 is, how the Ex e protection concept works, and the key requirements that engineers, inspectors, and maintenance personnel should understand.

Quick Answer

What Is IEC 60079-7?

IEC 60079-7 is one of the most widely used standards within the IEC 60079 series because it governs a protection concept that is extensively applied to electrical equipment installed in Zone 1 and Zone 2 hazardous areas.

The standard applies to electrical equipment that does not normally produce sparks, arcs, or excessive temperatures during operation but requires additional protective measures to reduce the risk of ignition.

Examples of equipment commonly designed according to IEC 60079-7 include:

• Junction boxes.
• Terminal boxes.
• Lighting fixtures.
• Terminal compartments.
• Control stations.
• Electric motors.
• Instrumentation enclosures.
• Cable glands.

The standard works together with IEC 60079-0, which establishes the general requirements applicable to explosion-protected equipment.

Why Is IEC 60079-7 Important?

Many industrial electrical devices operate without producing sparks or arcs during normal service conditions. Nevertheless, improper design, loose terminals, overheating, contamination, or insulation failure can create ignition hazards.

IEC 60079-7 establishes additional construction requirements intended to reduce these risks and improve the reliability of electrical equipment operating in explosive atmospheres.

The standard helps ensure:

• Reduced likelihood of electrical faults.
• Improved insulation integrity.
• Reduced risk of overheating.
• Improved reliability of electrical connections.
• Enhanced resistance to environmental influences.
• Safer operation in hazardous areas.

Because Ex e equipment is often simpler and lighter than flameproof equipment, it has become one of the most popular protection concepts for many industrial applications.

How Does Increased Safety Protection Work?

The fundamental principle of Ex e protection is straightforward: eliminate or minimize potential ignition sources by applying additional engineering measures.

Rather than containing an explosion, Ex e equipment is designed so that ignition is highly unlikely to occur during normal operation and under specified abnormal conditions.

Typical protective measures include:

• Enhanced insulation systems.
• Increased creepage and clearance distances.
• Secure electrical connections.
• Improved mechanical construction.
• Temperature control measures.
• Enhanced environmental protection.

Through these measures, IEC 60079-7 significantly reduces the probability that electrical equipment will become an ignition source in a hazardous atmosphere.

Scope of IEC 60079-7

IEC 60079-7 specifies the requirements for the construction, testing, and verification of equipment protected by Increased Safety "e".

The standard applies to equipment and components that do not normally produce sparks, arcs, or excessive temperatures during operation and that incorporate additional protective measures to reduce the probability of ignition.

The standard is commonly applied to:

• Terminal boxes.
• Junction boxes.
• Electric motors.
• Lighting fixtures.
• Terminal compartments.
• Connection devices.
• Certain electrical accessories and components.

IEC 60079-7 works together with IEC 60079-0, which provides the general requirements applicable to explosion-protected equipment.

Major Requirements of IEC 60079-7

Although the standard contains extensive technical requirements, the major topics generally include:

• Creepage and clearance distances.
• Electrical connection requirements.
• Temperature limitations.
• Insulation requirements.
• Ingress protection requirements.
• Mechanical construction requirements.
• Component requirements.
• Type testing and verification.

These requirements are intended to minimize the possibility that equipment may become an ignition source.

Creepage and Clearance Distances

One of the most important principles of Increased Safety protection is maintaining adequate separation between conductive parts.

IEC 60079-7 therefore specifies minimum:

• Creepage distances.
• Clearance distances.
• Insulation coordination requirements.

These distances help prevent:

• Electrical tracking.
• Flashover.
• Short circuits.
• Unintended arcing.

The required distances depend on several factors, including:

• Rated voltage.
• Pollution degree.
• Material group.
• Environmental conditions.

Proper creepage and clearance distances are fundamental to achieving Ex e protection.

Electrical Connection Requirements

Loose electrical connections can generate excessive heat and may become ignition sources.

IEC 60079-7 therefore places considerable emphasis on the design and integrity of electrical connections.

Requirements may include:

• Suitable terminal design.
• Secure conductor retention.
• Resistance to loosening.
• Current carrying capability.
• Temperature rise limitations.

These requirements explain why Ex e terminal blocks and junction boxes are often designed with robust terminals and specific tightening instructions.

Temperature Requirements

Excessive temperatures are one of the most common ignition sources in hazardous areas.

IEC 60079-7 therefore establishes requirements intended to limit:

• Maximum surface temperatures.
• Temperature rise within equipment.
• Hot spots on terminals and conductors.
• Abnormal operating temperatures.

The standard works together with IEC 60079-0 to ensure compliance with the assigned temperature class, such as:

• T1
• T2
• T3
• T4
• T5
• T6

These requirements help ensure that equipment surfaces cannot ignite the surrounding explosive atmosphere.

Ingress Protection Requirements

The protection concept relies heavily on maintaining the integrity of insulation and electrical clearances.

For this reason, IEC 60079-7 generally requires an enclosure that provides an appropriate degree of protection against dust and moisture ingress.

Typical ratings encountered in Ex e equipment include:

• IP54
• IP55
• IP56
• IP65
• IP66

The required ingress protection level depends on the equipment design and intended application.

Component Requirements

IEC 60079-7 also establishes requirements for components used inside Ex e equipment.

Examples include:

• Terminals.
• Insulating materials.
• Conductors.
• Connection devices.
• Internal components that may influence temperature rise or electrical clearances.

Every component used within an Ex e assembly must be suitable for maintaining the intended level of protection throughout the equipment's service life.

Type Testing and Verification

Before equipment can be certified as Ex e, manufacturers must demonstrate compliance with the applicable requirements of IEC 60079-7 through testing and assessment.

Depending on the equipment type, verification activities may include:

• Temperature rise testing.
• Dielectric strength testing.
• Impact testing.
• Ingress protection testing.
• Verification of creepage and clearance distances.
• Mechanical strength testing.

These tests ensure that the equipment can safely operate in hazardous areas without becoming an ignition source under the conditions specified by the standard.

Advantages of IEC 60079-7

IEC 60079-7 has become one of the most widely used standards in hazardous area engineering because the Increased Safety protection concept offers several practical advantages for many types of electrical equipment.

Unlike some other protection methods, Ex e protection prevents ignition from occurring in the first place by applying enhanced construction requirements and reducing the probability of faults that could become ignition sources.

Key advantages of IEC 60079-7 and the Ex e protection concept include:

• Simpler construction compared to flameproof equipment.
• Typically lighter and more compact than Ex d equipment.
• No requirement to contain an internal explosion.
• Suitable for many common industrial devices.
• Reduced maintenance requirements.
• Generally easier installation and inspection.
• High reliability and long service life.
• Suitable for Zone 1 and Zone 2 applications.

These advantages explain why Ex e protection is widely used for junction boxes, terminal boxes, lighting equipment, motors, and instrumentation enclosures.

Limitations of IEC 60079-7

Although Increased Safety protection offers many benefits, it is not suitable for every type of electrical equipment.

Because the protection concept is based on preventing ignition rather than containing an explosion, it has several important limitations.

• Not suitable for equipment that normally produces sparks or arcs.
• Cannot generally be used for switching devices without additional protection methods.
• Requires careful control of temperatures and electrical clearances.
• Improper modifications can compromise protection integrity.
• Environmental contamination may affect insulation performance.
• Requires proper installation practices to maintain certification.

For these reasons, engineers should carefully evaluate whether Ex e is the most appropriate protection concept for a particular application.

Relationship Between IEC 60079-7 and IEC 60079-0

IEC 60079-7 does not replace IEC 60079-0. Instead, it supplements the general requirements by adding the specific requirements necessary for Increased Safety protection.

The relationship can be summarized as follows:

Standard	Purpose
IEC 60079-0	General requirements applicable to Ex equipment.
IEC 60079-7	Additional requirements specific to Increased Safety "e".

Therefore, equipment certified as Ex eb or Ex ec must comply with both standards simultaneously.

Typical Applications of Ex e Equipment

Equipment designed according to IEC 60079-7 is widely used throughout the process industries because many electrical devices do not normally generate sparks or arcs during operation.

Typical applications include:

• Oil and gas production facilities.
• Petrochemical plants.
• Refineries.
• LNG facilities.
• Chemical processing plants.
• Hydrogen production facilities.
• Power generation plants.
• Pharmaceutical manufacturing facilities.

Examples of equipment commonly certified according to IEC 60079-7 include:

• Ex e junction boxes.
• Ex e terminal boxes.
• Ex e motors.
• Ex e lighting fixtures.
• Ex e terminal compartments.
• Ex e instrumentation enclosures.
• Ex e cable glands.

Equipment Protection Levels Under IEC 60079-7

IEC 60079-7 recognizes different levels of protection depending on the degree of safety provided by the equipment.

Marking	EPL	Typical Application
Ex eb	Gb	Zone 1 and Zone 2
Ex ec	Gc	Zone 2 only

Ex eb equipment provides a higher level of protection and is suitable for Zone 1 applications, while Ex ec equipment is intended only for Zone 2 hazardous areas.

Common Misunderstandings About IEC 60079-7

Ex e Equipment Can Contain Internal Explosions

No. Unlike Ex d equipment, Ex e equipment is not designed to contain an internal explosion. The protection concept is based on preventing ignition from occurring.

Any Ordinary Junction Box Can Be Used as Ex e

Incorrect. Ex e equipment must comply with the specific construction, testing, and certification requirements of IEC 60079-7.

Ex e Equipment Can Include Sparking Components

Generally no. Equipment that normally produces sparks or arcs usually requires another protection concept, such as Ex d or Ex p.

Ex e and Ex ec Are the Same

No. Ex eb provides Equipment Protection Level Gb and is suitable for Zone 1 applications, whereas Ex ec provides Equipment Protection Level Gc and is intended only for Zone 2 applications.

Loose Connections Are Not a Safety Concern

Incorrect. Loose terminals can generate excessive temperatures and become ignition sources, which is why IEC 60079-7 places significant emphasis on connection integrity and temperature rise testing.

Why Engineers Should Understand IEC 60079-7

Even engineers who are not directly involved in product design frequently encounter Ex e equipment during specification, procurement, installation, inspection, and maintenance activities.

A basic understanding of IEC 60079-7 helps engineers:

• Select suitable equipment for hazardous areas.
• Understand Ex eb and Ex ec markings.
• Avoid improper modifications.
• Identify non-compliant installations.
• Improve inspection and maintenance practices.
• Reduce the likelihood of ignition incidents.

Because Increased Safety protection is so widely applied throughout industry, IEC 60079-7 remains one of the most important standards for anyone working with explosion-protected equipment.

Frequently Asked Questions (FAQ)

What is IEC 60079-7?

IEC 60079-7 is the international standard that specifies the requirements for equipment protection by Increased Safety "e". The standard establishes additional construction measures intended to reduce the likelihood of ignition in explosive atmospheres.

What is the principle of Ex e protection?

The Ex e protection concept is based on preventing ignition from occurring by eliminating or minimizing potential ignition sources such as excessive temperatures, loose electrical connections, insulation failures, and unintended arcing.

Can Ex e equipment contain sparks or arcs during normal operation?

Generally, no. Ex e equipment is intended for devices that do not normally produce sparks or arcs during operation. Equipment containing sparking components usually requires another protection concept, such as Ex d or Ex p.

What is the difference between Ex eb and Ex ec?

Ex eb equipment provides Equipment Protection Level (EPL) Gb and is suitable for Zone 1 and Zone 2 applications. Ex ec equipment provides EPL Gc and is intended only for Zone 2 hazardous areas.

Why are creepage and clearance distances important?

Adequate creepage and clearance distances help prevent flashover, electrical tracking, and unintended arcing, all of which could become ignition sources in hazardous areas.

Why are loose terminals dangerous in Ex e equipment?

Loose electrical connections can generate excessive heat and create ignition hazards. This is why IEC 60079-7 places significant emphasis on terminal design, connection integrity, and temperature rise limitations.

Conclusion

IEC 60079-7 is one of the most widely applied standards in the explosion protection industry because it governs the Increased Safety protection concept used by many common electrical products installed in hazardous areas.

Rather than containing an explosion, Ex e protection seeks to prevent ignition from occurring by applying enhanced construction requirements, improving insulation integrity, controlling temperatures, and ensuring reliable electrical connections.

Because junction boxes, terminal boxes, motors, lighting equipment, and instrumentation enclosures frequently rely on Ex e protection, a solid understanding of IEC 60079-7 is essential for engineers involved in specification, installation, inspection, and maintenance activities.

Understanding the requirements of IEC 60079-7 also helps prevent common mistakes such as improper modifications, inadequate terminal tightening, and the misuse of Ex ec equipment in Zone 1 applications.

Technical Review

References

• IEC 60079-7 – Explosive Atmospheres – Part 7: Equipment Protection by Increased Safety "e".
• IEC 60079-0 – Explosive Atmospheres – Part 0: Equipment – General Requirements.
• IECEx System – International Certification System for Equipment Used in Explosive Atmospheres.
• International Electrotechnical Commission (IEC).
• EN IEC 60079-7 – Explosive Atmospheres – Equipment Protection by Increased Safety "e".
• IEC 60079 Series – Explosive Atmospheres.