ATEX Module G Explained: Unit Verification Under Directive 2014/34/EU

Most explosion-protected equipment is certified through standard conformity assessment procedures such as Module B combined with Module D, Module E, or Module F. However, these procedures are not always suitable for one-off equipment, custom-built systems, or products manufactured in very limited quantities.

For these situations, Directive 2014/34/EU (ATEX) provides an alternative conformity assessment procedure known as ATEX Module G, officially referred to as Unit Verification. Instead of approving a product design or production system, Module G requires an ATEX Notified Body to examine and verify each individual unit before it can be placed on the European market.

Because every unit is assessed individually, Module G is typically used for unique or custom-engineered explosion-protected equipment where conventional production-based conformity assessment procedures are not practical.

This article explains how ATEX Module G works, when it can be used, the responsibilities of manufacturers and Notified Bodies, and how Unit Verification differs from other conformity assessment procedures under Directive 2014/34/EU.

Quick Answer

What Is ATEX Module G?

ATEX Module G is the Unit Verification conformity assessment procedure established in Annex IX of Directive 2014/34/EU.

Unlike other conformity assessment procedures that evaluate a product design or an entire production process, Module G focuses on verifying a single finished product. Every individual unit must be inspected and assessed by an ATEX Notified Body before it may be legally placed on the European market.

During the verification process, the Notified Body confirms that the completed equipment complies with the applicable requirements of Directive 2014/34/EU, including the relevant Essential Health and Safety Requirements (EHSRs).

Once compliance has been demonstrated, the Notified Body issues the documentation required to support the manufacturer's Declaration of Conformity for that individual unit.

Why Does ATEX Module G Exist?

Most ATEX conformity assessment procedures are designed for products manufactured repeatedly under controlled production conditions. In these situations, evaluating the product design or the manufacturer's quality management system provides confidence that every production unit will remain compliant.

However, some explosion-protected equipment is manufactured only once or in very limited quantities. Examples include custom-engineered control panels, special industrial machinery, prototype equipment, or products designed specifically for a particular installation.

For these cases, approving a production system offers little benefit because there may never be another identical unit. Instead, Directive 2014/34/EU allows each individual product to be independently verified before being placed on the market.

Module G therefore provides a practical conformity assessment route for equipment that cannot reasonably be assessed through conventional production-based procedures.

When Is Module G Used?

Manufacturers typically choose Module G when explosion-protected equipment is produced as a unique or limited-production product rather than through serial manufacturing.

Typical examples include:

• Custom-built explosion-protected control panels.
• One-off electrical equipment designed for a specific industrial project.
• Prototype equipment requiring ATEX compliance.
• Special-purpose machinery manufactured in very small quantities.
• Explosion-protected equipment that does not fit conventional production certification routes.

Although Module G can be applied to equipment requiring third-party conformity assessment, manufacturers should always confirm that Unit Verification is an appropriate conformity assessment procedure for the specific equipment covered by Directive 2014/34/EU.

Responsibilities of the Manufacturer

Although every unit is independently verified by an ATEX Notified Body, the manufacturer remains legally responsible for ensuring that the equipment complies with Directive 2014/34/EU.

Before submitting equipment for Unit Verification, the manufacturer is expected to complete the design, prepare the required technical documentation, and ensure that the product satisfies the applicable Essential Health and Safety Requirements (EHSRs).

The manufacturer's responsibilities typically include:

• Designing equipment that complies with Directive 2014/34/EU.
• Preparing complete technical documentation.
• Identifying the applicable harmonized EN IEC 60079 standards.
• Providing the equipment for examination by the ATEX Notified Body.
• Issuing the EU Declaration of Conformity after successful Unit Verification.
• Applying the CE and ATEX markings in accordance with the Directive.

Even though the Notified Body performs the verification, legal responsibility for the equipment always remains with the manufacturer.

Responsibilities of the ATEX Notified Body

Under Module G, the ATEX Notified Body performs an independent assessment of each individual product before it is placed on the European market.

The verification typically includes reviewing the technical documentation, examining the completed equipment, and confirming that it complies with the applicable provisions of Directive 2014/34/EU.

Depending on the product, the Notified Body may perform or witness:

• Visual examinations.
• Dimensional inspections.
• Electrical testing.
• Functional testing.
• Explosion protection verification.
• Review of design calculations.
• Verification of equipment marking.

The extent of the assessment depends on the complexity of the equipment and the applicable protection concept.

Once conformity has been demonstrated, the Notified Body issues the documentation confirming successful Unit Verification for that individual product.

Technical Documentation Requirements

Manufacturers must prepare technical documentation before submitting equipment for Unit Verification.

The documentation enables the Notified Body to determine whether the equipment complies with the Essential Health and Safety Requirements and the applicable harmonized standards.

Although the exact contents vary depending on the product, the documentation typically includes:

• General product description.
• Engineering drawings.
• Electrical schematics.
• Bill of materials.
• Design calculations.
• Risk assessment.
• Applicable EN IEC 60079 standards.
• Equipment marking details.
• Operating instructions.
• Supporting test reports where available.

The quality and completeness of the technical documentation have a significant impact on the efficiency of the Unit Verification process.

Unit Verification Process

Although the exact assessment varies depending on the equipment, the Unit Verification procedure generally follows a structured sequence.

1. The manufacturer completes the equipment design.
2. Technical documentation is prepared.
3. The manufacturer submits the equipment and documentation to an ATEX Notified Body.
4. The Notified Body reviews the documentation.
5. The finished equipment is examined and tested where necessary.
6. Compliance with Directive 2014/34/EU is confirmed.
7. The Notified Body issues the Unit Verification documentation.
8. The manufacturer issues the EU Declaration of Conformity.
9. The CE and ATEX markings are applied before the equipment is placed on the European market.

Unlike production-based conformity assessment procedures, this process is repeated for every individual product submitted under Module G.

Which Equipment Typically Uses Module G?

Module G is not intended for routine mass production. Instead, it is commonly used where each unit is unique or manufactured in very limited quantities.

Typical examples include:

• Custom-engineered explosion-protected control panels.
• Special-purpose industrial machines.
• Prototype explosion-protected equipment.
• Research and development equipment intended for commercial use.
• Unique equipment designed for a specific customer or project.
• Products manufactured as a single unit.

For manufacturers producing large quantities of identical equipment, conformity assessment procedures based on production quality assurance are generally more practical than Unit Verification.

Advantages of ATEX Module G

ATEX Module G offers several advantages for manufacturers producing unique or limited-production explosion-protected equipment.

Because each individual product is assessed independently, manufacturers are not required to establish a production quality assurance system solely for a single project or one-off application.

Key advantages include:

• Suitable for one-off or custom-built equipment.
• No requirement for serial production.
• Each individual unit receives independent verification by an ATEX Notified Body.
• Ideal for project-specific engineering solutions.
• Provides flexibility for equipment manufactured in very small quantities.
• Demonstrates compliance with Directive 2014/34/EU without implementing production-based conformity assessment procedures.

For manufacturers supplying specialized equipment rather than standard catalog products, Module G provides an efficient conformity assessment route while maintaining the high level of safety required under the ATEX Directive.

Limitations of ATEX Module G

Although Module G is highly flexible, it is generally unsuitable for mass-produced equipment.

Because every individual product must undergo separate verification, the procedure can become both time-consuming and costly when applied to large production volumes.

Manufacturers should also recognize that Unit Verification does not replace their legal responsibilities under Directive 2014/34/EU.

Even after successful verification by an ATEX Notified Body, the manufacturer remains responsible for:

• Product conformity.
• Technical documentation.
• EU Declaration of Conformity.
• Correct equipment marking.
• Compliance after the equipment has been placed on the market.

For manufacturers producing large numbers of identical products, conformity assessment procedures such as Module B combined with Module D or Module E are generally more practical and cost-effective.

ATEX Module G vs Module B

Although both Module G and Module B involve an ATEX Notified Body, they serve different purposes within the conformity assessment framework.

Feature	Module G	Module B
Official Name	Unit Verification	EU-Type Examination
Primary Focus	Verification of each finished unit	Evaluation of product design (type)
ATEX Notified Body	Required	Required
Typical Application	Custom-built or one-off equipment	Series-produced equipment
Verification Scope	Every individual product	Representative product design (type)
Suitable for Mass Production	No	Yes, when combined with Modules D, E or F

In simple terms, Module B approves a product design that will be manufactured repeatedly, while Module G verifies every individual product before it is placed on the market.

Common Misunderstandings About ATEX Module G

Module G Is Only for Prototype Equipment

No. Although Module G is frequently used for prototypes, it is also suitable for custom-built machinery, project-specific control panels, and other equipment manufactured as individual units or in very limited quantities.

Module G Eliminates the Need for Technical Documentation

Incorrect. Technical documentation remains one of the most important requirements of Unit Verification. Without adequate documentation, the ATEX Notified Body cannot determine whether the equipment complies with Directive 2014/34/EU.

The ATEX Notified Body Becomes Legally Responsible for the Product

No. The Notified Body independently verifies the individual unit, but legal responsibility for product conformity always remains with the manufacturer.

Module G Can Be Used Instead of Every Other Conformity Assessment Procedure

Not necessarily. Manufacturers should select the conformity assessment procedure permitted by Directive 2014/34/EU for their equipment category and intended application. Module G is intended for situations where Unit Verification is appropriate, not as a universal replacement for production-based conformity assessment procedures.

Frequently Asked Questions (FAQ)

What is ATEX Module G?

ATEX Module G is the Unit Verification conformity assessment procedure defined in Annex IX of Directive 2014/34/EU. Under this procedure, an ATEX Notified Body examines and verifies each individual explosion-protected product before it is placed on the European market.

Does Module G require an ATEX Notified Body?

Yes. Unlike ATEX Module A, Unit Verification always requires the involvement of an ATEX Notified Body. The Notified Body independently examines each completed product to confirm compliance with Directive 2014/34/EU.

When should manufacturers use Module G?

Module G is typically used for one-off, custom-built, prototype, or limited-production explosion-protected equipment where production-based conformity assessment procedures are not practical.

Can Module G be used for mass-produced equipment?

Although technically possible in certain situations, Module G is generally not intended for serial production because every individual unit must undergo separate verification. Manufacturers of standard products usually use Module B together with Module D, Module E, or Module F.

Does Module G require technical documentation?

Yes. Manufacturers must prepare complete technical documentation before submitting equipment for Unit Verification. The documentation enables the ATEX Notified Body to assess compliance with the applicable Essential Health and Safety Requirements (EHSRs).

Who remains legally responsible after Unit Verification?

The manufacturer always retains legal responsibility for the conformity of the equipment. The ATEX Notified Body independently verifies the individual product, but responsibility for compliance under Directive 2014/34/EU remains with the manufacturer.

Conclusion

ATEX Module G provides a specialized conformity assessment procedure for explosion-protected equipment that is manufactured as individual units or in very limited quantities. Instead of evaluating a product design or production system, Unit Verification focuses on confirming that each completed product complies with the applicable requirements of Directive 2014/34/EU.

Because every unit is independently examined by an ATEX Notified Body, Module G is particularly well suited to custom-engineered equipment, prototype machinery, and project-specific explosion-protected products that cannot easily be certified through conventional production-based conformity assessment procedures.

Understanding how Module G differs from procedures such as Module B, Module D, Module E, and Module F helps manufacturers select the most appropriate conformity assessment route while ensuring that explosion-protected equipment can be legally placed on the European market.

Technical Review

References

• Directive 2014/34/EU of the European Parliament and of the Council relating to equipment and protective systems intended for use in potentially explosive atmospheres.
• European Commission – ATEX Guidelines for Directive 2014/34/EU.
• European Commission – Blue Guide on the Implementation of EU Product Rules.
• EN IEC 60079 Series – Explosive Atmospheres.
• ISO/IEC 80079 Series.