What Is Equipment Protection Level (EPL)? Ga, Gb, Gc, Da, Db and Dc Explained

Equipment Protection Level (EPL) helps engineers determine whether hazardous area equipment provides sufficient protection for a specific gas or dust zone.

Introduction

Selecting explosion-protected equipment involves more than checking the protection method. Engineers must also verify whether the equipment provides an appropriate level of protection for the hazardous area where it will be installed.

This is where the concept of Equipment Protection Level (EPL) becomes important.

Introduced within the IEC 60079 standards, EPL provides a risk-based approach to equipment selection by defining the likelihood that equipment can become an ignition source under specific operating conditions.

Understanding EPL helps engineers correctly match equipment to hazardous area zones and avoid common specification mistakes.

What Is Equipment Protection Level (EPL)?

Equipment Protection Level (EPL) is a classification system defined in IEC 60079 that indicates the level of protection provided by equipment intended for use in hazardous areas.

An EPL designation reflects the probability that equipment could become an ignition source.

In simple terms:

Equipment Protection Level (EPL) Summary

EPL	Protection Level	Suitable Zones
Ga	Very High	Zone 0, Zone 1, Zone 2
Gb	High	Zone 1, Zone 2
Gc	Enhanced	Zone 2
Da	Very High	Zone 20, Zone 21, Zone 22
Db	High	Zone 21, Zone 22
Dc	Enhanced	Zone 22

• Higher EPL = Higher protection level
• Lower EPL = Lower protection level
• EPL helps determine where equipment can be safely installed

EPL classifications exist for:

• Gas atmospheres
• Dust atmospheres
• Mining applications

This article focuses on gas and dust atmospheres commonly encountered in industrial facilities.

Why Was EPL Introduced?

Historically, equipment selection was based primarily on hazardous area zones.

However, different protection concepts can provide different levels of safety even when intended for the same zone.

EPL was introduced to:

• Improve risk assessment
• Simplify equipment selection
• Harmonize protection concepts
• Provide additional safety margins

Today, EPL is commonly included in IECEx certificates and equipment markings.

EPL Categories for Gas Atmospheres

EPL Ga

Equipment with EPL Ga provides a very high level of protection.

The equipment remains safe:

• During normal operation
• During expected faults
• During rare faults

Suitable for:

• Zone 0
• Zone 1
• Zone 2

Examples:

• Ex ia intrinsically safe equipment
• Certain encapsulated devices

EPL Gb

Equipment with EPL Gb provides a high level of protection.

The equipment remains safe:

• During normal operation
• During expected disturbances

Suitable for:

• Zone 1
• Zone 2

Examples:

• Ex d flameproof equipment
• Ex e increased safety equipment
• Ex p pressurized systems

EPL Gc

Equipment with EPL Gc provides an enhanced level of protection for less hazardous environments.

Suitable for:

• Zone 2 only

Examples:

• Ex ec equipment
• Ex n-type equipment

EPL Categories for Dust Atmospheres

EPL Da

Provides a very high level of protection.

Suitable for:

• Zone 20
• Zone 21
• Zone 22

EPL Db

Provides a high level of protection.

Suitable for:

• Zone 21
• Zone 22

EPL Dc

Provides an enhanced level of protection.

Suitable for:

• Zone 22

EPL and Hazardous Area Zones

The relationship between EPL and zones can be summarized as follows:

A higher EPL can generally be used in a lower-risk zone.

For example:

• Ga equipment can be installed in Zone 1 and Zone 2
• Gb equipment can be installed in Zone 2
• Da equipment can be installed in Zone 21 and Zone 22

The reverse is not permitted.

How EPL Appears on Equipment Markings

EPL is usually displayed as part of the equipment marking.

Example:

Ex db IIC T6 Gb

Breaking this down:

• Ex = Explosion protected equipment
• db = Flameproof protection
• IIC = Gas group
• T6 = Temperature class
• Gb = Equipment Protection Level

The EPL immediately indicates that the equipment is suitable for Zone 1 and Zone 2 installations.

Common Misunderstandings About EPL

EPL Is Not the Same as Zone

A hazardous area zone describes the environment.

An EPL describes the protection capability of the equipment.

EPL Does Not Replace Protection Concepts

EPL complements protection methods such as:

• Ex d
• Ex e
• Ex i
• Ex p
• Ex t

Both the protection concept and EPL must be considered during equipment selection.

Higher EPL Does Not Always Mean Better Choice

Selecting equipment with unnecessarily high protection levels may increase:

• Cost
• Weight
• Complexity
• Maintenance requirements

Equipment should be selected based on actual hazard assessment and project requirements.

Practical Example

Consider a motor installed in a Zone 1 refinery area.

The motor nameplate indicates:

Ex eb IIC T4 Gb

The EPL designation is Gb.

Since Zone 1 requires equipment with EPL Gb or higher, the motor is suitable for installation.

If the motor were marked Gc, it would only be suitable for Zone 2 and could not be installed in Zone 1.

Common EPL Selection Mistakes

Confusing EPL with Hazardous Area Zones

A hazardous area zone describes the environment, while EPL describes the protection capability of the equipment. They are related but not interchangeable.

Selecting Gc Equipment for Zone 1

Equipment marked Gc is intended for Zone 2 applications. Installing it in Zone 1 may violate project specifications and safety requirements.

Ignoring Dust EPL Classifications

Many engineers focus on gas classifications while overlooking Da, Db, and Dc ratings for combustible dust environments.

Over-Specifying EPL Requirements

Selecting the highest EPL available may increase project cost, weight, and maintenance complexity without providing meaningful operational benefits.

Frequently Asked Questions (FAQ)

What does EPL stand for?

EPL stands for Equipment Protection Level, a classification defined in IEC 60079 that indicates the level of protection provided by hazardous area equipment.

What is the difference between EPL and Zone?

A hazardous area zone describes the probability of an explosive atmosphere being present, while EPL describes the protection capability of the equipment.

Can Ga equipment be installed in Zone 1?

Yes. Equipment with EPL Ga provides a higher level of protection than required for Zone 1 and may also be installed in Zone 2.

Is EPL required for IECEx certification?

Yes. EPL is commonly included in IECEx certification and equipment markings to indicate suitability for hazardous area applications.

What EPL is required for Zone 2?

Zone 2 applications typically require equipment with EPL Gc or higher.

Conclusion

Equipment Protection Level (EPL) is a key concept within IEC 60079 that helps engineers match hazardous area equipment to the appropriate operating environment. By understanding the relationship between EPL, hazardous area zones, and protection methods, engineers can make safer and more effective equipment selection decisions.

Whether evaluating Ex d, Ex e, Ex i, or Ex p equipment, EPL provides an additional layer of confidence that the equipment offers the required level of protection for the intended application.

References