IEC 60079-17 Explained: Inspection and Maintenance of Electrical Installations

Inspection of Ex equipment helps identify deterioration that could affect explosion protection during operation.

Explosion-protected equipment must remain suitable for its hazardous-area application throughout its service life. Even when equipment was correctly selected and installed, corrosion, vibration, moisture, mechanical damage, and unauthorized modifications can affect its condition over time.

IEC 60079-17 – Explosive atmospheres – Part 17: Electrical installations inspection and maintenance addresses inspection and maintenance factors associated with electrical installations specifically designed for hazardous areas. Its purpose is to help users maintain the integrity of explosion protection during operation.

The standard is relevant to facility owners, electrical maintenance teams, inspectors, reliability engineers, and hazardous-area specialists responsible for the condition of operating installations.

1. Where IEC 60079-17 Fits in the Hazardous-Area Lifecycle

IEC 60079-17 focuses on inspection and maintenance during the operational life of an installation. It works alongside other parts of the IEC 60079 series, each of which addresses a different activity.

Lifecycle activity	Relevant standard
Hazardous-area classification for explosive gas atmospheres	IEC 60079-10-1
General Ex equipment requirements	IEC 60079-0
Design, selection, installation, and initial inspection	IEC 60079-14
Operational inspection and maintenance	IEC 60079-17
Repair, overhaul, and reclamation of Ex equipment	IEC 60079-19

The distinction matters because an installation that met its original requirements may deteriorate after commissioning. Periodic inspection and appropriate maintenance help identify changes that could affect the installed protection.

2. Scope of IEC 60079-17

IEC 60079-17:2023 applies to users and covers factors directly related to the inspection and maintenance of electrical installations specifically designed for hazardous areas where explosive atmospheres may occur.

The standard supplements general electrical installation inspection and testing requirements. It does not replace all electrical inspection requirements, equipment certification, or the requirements for repairing and overhauling explosion-protected equipment. Repair, overhaul, and reclamation are addressed by IEC 60079-19.

The standard's scope also has exclusions. These include underground mining areas, explosive dusts that do not require atmospheric oxygen for combustion, and pyrophoric substances. It is therefore important to confirm that the installation falls within the standard's scope and to consider applicable local regulations and facility procedures.

3. Why Inspection Matters After Commissioning

Hazardous-area equipment can deteriorate for reasons that are not apparent during initial installation. Environmental exposure, vibration, mechanical stress, and maintenance activities can gradually affect components that contribute to explosion protection.

Typical deterioration mechanisms include:

• Corrosion caused by moisture, chemicals, or marine environments.
• Vibration and mechanical stress.
• Water ingress or deterioration of enclosure seals.
• Dust accumulation or contamination.
• Impact damage to enclosures and cable entries.
• Loose connections or deteriorated electrical components.
• Unauthorized changes to equipment or wiring.

Possible findings include loose glands, damaged flameproof joints, missing fasteners, corroded enclosures, damaged cables, or illegible equipment markings. The significance of each finding depends on the equipment, protection concept, and applicable requirements.

An inspection should evaluate the condition and suitability of the installed equipment rather than merely confirm that an Ex marking is present.

4. Inspection Types and Planning

Inspection planning should be based on the applicable standard, equipment condition, environmental exposure, operating experience, and the facility's inspection program. The following terms describe common inspection activities, but they should not be treated as interchangeable or as having identical requirements.

Initial inspection

Initial inspection is associated with verifying a new or modified installation before it is placed into service. IEC 60079-14 addresses the installation requirements and initial inspection. IEC 60079-17 should not be used as a substitute for the initial inspection requirements under IEC 60079-14.

Periodic inspection

Periodic inspection examines the condition of an operating installation at planned intervals. The inspection should identify deterioration, damage, or changes that could affect the integrity of explosion protection.

Sample inspection

Sample inspection examines selected equipment or portions of an installation as part of an appropriate inspection strategy. The selection method and extent must follow the applicable requirements and inspection plan; a sample inspection should not automatically be assumed to replace other required inspections.

Inspection intervals and the appropriate inspection approach should be established using the applicable edition of IEC 60079-17 and the installation's actual conditions. This article does not prescribe a universal inspection interval.

5. What Inspectors Should Check

The inspection must consider the condition of the equipment and the features relevant to its protection concept. Not every item is inspected in exactly the same way.

Depending on the equipment, practical checks can include:

• Condition of enclosures and exposed surfaces.
• Cable glands, entries, and unused-entry plugs.
• Flameproof joints where applicable.
• Fasteners and enclosure closure arrangements.
• Corrosion, cracks, deformation, and mechanical damage.
• Cables, terminations, and visible electrical connections.
• Equipment identification and Ex marking.
• Earthing and bonding connections.
• Evidence of unauthorized modification or unsuitable replacement parts.
• Signs of moisture ingress or other environmental damage.

The required inspection details and acceptance criteria must be taken from the applicable standard, equipment documentation, and facility procedures. A visual observation alone may not be sufficient to determine whether a particular defect affects protection.

6. Inspection Focus by Protection Concept

Different protection concepts rely on different construction and installation features. The inspection focus should reflect the equipment's actual certified protection.

Protection concept	Examples of inspection focus
Ex d	Enclosure condition, flameproof joints, fasteners, cable entries, and evidence of damage or unauthorized modification.
Ex e	Enclosure condition, terminals, cable entries, electrical connections, and signs of deterioration.
Ex i	Equipment identification, circuit integrity, segregation, associated apparatus, and relevant installation condition.
Ex p	Condition of the pressurization or protective-gas arrangements and associated equipment relevant to the protection system.
Ex t	Enclosure integrity, dust ingress protection, and conditions affecting the equipment's temperature requirements.

These are examples, not complete inspection checklists. The actual checks depend on the equipment, protection concept, inspection grade, and applicable standard requirements.

7. Cable Glands and Entries During Inspection

Cable glands and entries form an important interface between the Ex equipment and the electrical installation. A correctly installed gland can still become loose, corroded, damaged, or unsuitable following maintenance or other site activities.

Inspectors should look for evidence of:

• Loose or visibly damaged glands.
• Damaged enclosure threads or cable entries.
• Missing or unsuitable stopping plugs.
• Deteriorated sealing arrangements.
• Mechanical damage to the cable or entry interface.
• Corrosion or signs of water ingress.
• Changes that may not match the original certified arrangement.

For Ex d equipment, particular care is needed when a finding concerns a flameproof entry or joint. Do not assume that tightening, replacing, machining, or modifying a component is an acceptable correction without checking the equipment documentation and applicable requirements.

8. Maintenance and Corrective Action

Inspection identifies conditions that may affect protection. Maintenance and corrective action address those findings and help restore the installation to a suitable condition.

Depending on the defect and permitted procedures, actions may include:

• Correcting an installation deficiency.
• Replacing a damaged component with a suitable approved part.
• Addressing corrosion or environmental damage using an appropriate method.
• Restoring a required enclosure or cable-entry arrangement.
• Correcting an unsuitable wiring configuration.
• Restoring equipment identification where required.
• Removing or formally assessing an unauthorized modification.

Maintenance must respect the equipment certification, manufacturer's instructions, and applicable procedures. If the proposed work affects certified construction or goes beyond the permitted maintenance activity, it should not be treated as an ordinary repair.

9. What to Do When a Defect Is Found

A useful defect-management process connects the inspection finding to an appropriate technical decision and documented corrective action.

1. Identify the equipment. Record the equipment tag, location, protection concept, and relevant marking.
2. Describe the finding. Record the observed condition clearly, including its location and supporting evidence where appropriate.
3. Assess the significance. Determine which protection feature may be affected and consult the applicable equipment documentation.
4. Define the corrective action. Establish whether maintenance, replacement, further technical assessment, or specialist repair is required.
5. Perform the work correctly. Use suitable procedures and parts consistent with the equipment requirements.
6. Verify the correction. Reinspect or otherwise verify the affected item as required.
7. Close the record. Document the completed work, verification result, and any remaining restrictions or actions.

The response to a defect should reflect its technical significance. Where the condition may compromise explosion protection, the responsible facility personnel must assess the appropriate controls and whether the equipment can remain in service under the applicable safety procedures.

10. Inspection Records and Equipment History

Inspection records help maintenance teams track equipment condition, monitor recurring defects, and confirm that corrective actions have been completed.

Useful records may include:

• Equipment tag and location.
• Inspection date and personnel.
• Applicable inspection details and findings.
• Defect classification or priority under the facility's procedure.
• Corrective action and work-order reference.
• Replacement parts or repairs, where relevant.
• Reinspection or verification results.
• Outstanding actions and relevant equipment documentation.

The record format and retention requirements should follow the applicable standard, local requirements, and the facility's management system. Keeping a useful equipment history can also help identify recurring problems related to corrosion, vibration, installation quality, or maintenance practices.

11. Modifications and Repair Boundaries

Changes made during maintenance can affect the original protection arrangement. Examples include drilling an enclosure, changing a cable entry, replacing components with different types, altering wiring, or making changes that are not covered by the equipment documentation.

Before accepting a modification, confirm that it is permitted and that the resulting arrangement remains suitable. Do not assume that a change is acceptable simply because the equipment continues to operate normally.

IEC 60079-17 does not cover the repair, overhaul, and reclamation of explosion-protected equipment; these activities are addressed by IEC 60079-19. The scope of IEC 60079-17:2023 explicitly identifies this distinction.

When the boundary between routine maintenance and specialist repair is unclear, refer the work to personnel competent for the equipment and applicable protection concept.

12. Personnel Competency

Inspection and maintenance of Ex equipment require knowledge appropriate to the work being performed. Personnel must be able to recognize relevant protection features, identify defects, and understand when a finding requires further technical assessment.

Competency arrangements should reflect the assigned activities, which may include:

• Understanding hazardous-area and Ex protection principles.
• Recognizing equipment markings and protection concepts.
• Performing the required inspection activities.
• Identifying conditions that may compromise protection.
• Applying approved maintenance procedures.
• Recording findings and corrective actions accurately.

The required level of competency and supervision should be determined from the applicable requirements and the nature of the work. This overview does not replace formal competency requirements or facility procedures.

13. IEC 60079-17 vs IEC 60079-14 and IEC 60079-19

These three standards address related but distinct parts of the hazardous-area equipment lifecycle.

Standard	Primary focus
IEC 60079-14	Design, selection, installation, and initial inspection of electrical installations in explosive atmospheres.
IEC 60079-17	Inspection and maintenance of electrical installations during operation.
IEC 60079-19	Repair, overhaul, and reclamation of explosion-protected equipment.

The distinction is useful when assigning responsibilities and determining the correct technical procedure. Initial installation requirements, operational inspection, routine maintenance, and specialist repair should not be treated as one interchangeable activity.

14. Practical Inspection Workflow for Operating Facilities

For an operating facility, the inspection process can be organized around the equipment register, applicable requirements, and the facility's maintenance system.

1. Confirm the equipment tag, location, and available Ex documentation.
2. Identify the protection concept and the relevant inspection requirements.
3. Inspect the condition of the equipment and associated installation features.
4. Record observed defects and determine whether further assessment is required.
5. Assign corrective actions to personnel with appropriate competence.
6. Verify completed work and document the results.
7. Update equipment records and carry forward any outstanding actions.

This workflow is a practical overview, not a replacement for the inspection grades, requirements, tables, and procedures in the applicable edition of IEC 60079-17.

Related Reading

• IEC 60079 Series Explained
• IEC 60079-14 Explained: Design, Selection and Installation of Electrical Installations
• IEC 60079-19 Explained: Equipment Repair, Overhaul and Reclamation
• IEC 60079-0 Explained: General Requirements for Ex Equipment
• IEC 60079-1 Explained: Flameproof Enclosures "d"
• IEC 60079-7 Explained: Increased Safety "e"
• IEC 60079-11 Explained: Intrinsic Safety "i"

References

• IEC 60079-17:2023 – Electrical installations inspection and maintenance
• IEC 60079-14:2024 – Electrical installation design, selection, and installation
• IECEx – International certification system for equipment used in explosive atmospheres

This article is an engineering overview. For inspection, maintenance, and repair decisions, consult the applicable standard, equipment documentation, facility procedures, and relevant local requirements.