Ex Equipment Installation & Inspection: IEC 60079-14/17 Guide

Last updated: March 2026 · Based on IEC 60079 (2020 edition) and ATEX 2014/34/EU

Correct installation and ongoing inspection are as important as the equipment certification itself. A perfectly certified Ex d enclosure becomes dangerous if a cable gland is installed incorrectly. This file covers IEC 60079-14 (installation) and IEC 60079-17 (inspection/maintenance).

Installation (IEC 60079-14)

General Principles

1. Only certified equipment may be installed in hazardous areas. verify the certificate (see how to read an ATEX nameplate), EPL, gas group, and temperature class match the zone classification
2. Follow the manufacturer's installation instructions. always available with certified equipment
3. Check for special conditions ("X"). documented in the certificate
4. Use certified accessories. cable glands, junction boxes, conduit fittings must also be Ex certified for the appropriate method
5. Competent personnel only. installers should hold appropriate qualifications (CompEx, IECEx CoPC, or equivalent)

Cable Gland Selection

Cable glands are the most common point of failure in Ex installations.

For Ex d enclosures:

• Cable glands must be Ex d certified
• Never use Ex e cable glands on Ex d enclosures (they cannot withstand explosion pressure)
• Minimum 5 threads or 8mm screw-in depth for parallel threads
• Conical threads (NPT) must be seated completely
• Gland must match cable type (armoured/unarmoured) and diameter range

For Ex e enclosures:

• Cable glands must be Ex e certified (or Ex d, which exceeds Ex e requirements)
• Must maintain IP54 minimum
• Cable diameter must fall within the gland's certified range

For Ex i circuits:

• Cable glands do not need Ex certification (the circuit is inherently safe)
• However, glands must maintain the enclosure IP rating
• IS cables must be segregated from other cables

Earthing and Bonding

• All metallic parts must be bonded to the equipotential bonding system
• Earth continuity must be maintained through the entire installation
• Earth resistance for IS zener barriers: <1 Ω
• Cable armour must be earthed at both ends (or as specified)
• Internal earth connections in Ex d enclosures must be secure and accessible for inspection

Cable Routing

• Intrinsically safe cables: identified by blue colour, routed separately from non-IS circuits
• Minimum separation between IS and non-IS cables per installation standard
• Cables entering hazardous areas must be suitable for the environment (temperature, chemical resistance, UV)
• Unused cable entries must be sealed with certified blanking elements (not standard plugs)

Clearance Distances

Around Ex d enclosures (with flat flame paths):

These clearances prevent accumulation of hot gases escaping from flame paths during an internal explosion.

Inspection (IEC 60079-17)

Three Grades of Inspection

Visual Inspection Checklist

• ☐ Equipment is appropriate for the zone (check marking)
• ☐ No visible damage to enclosures
• ☐ All bolts/fasteners present and tight
• ☐ Cable glands correctly installed and sealed
• ☐ No unauthorized modifications
• ☐ Unused entries properly sealed
• ☐ No corrosion compromising integrity
• ☐ Labels and markings legible
• ☐ Equipment clean (dust accumulation within limits)
• ☐ No temporary/non-certified repairs

Close Inspection Checklist

Everything in visual inspection, plus:

• ☐ Enclosure bolts/fixings all present and correct type
• ☐ Cable glands appropriate for cable type and correctly tightened
• ☐ No evidence of water ingress
• ☐ Earth connections secure
• ☐ Conduit/trunking integrity maintained
• ☐ Sealing compound intact where applicable
• ☐ Temperature class appropriate for actual conditions
• ☐ Cable condition acceptable (no damage, correct sheath)
• ☐ IS circuit separation maintained

Detailed Inspection Checklist

Everything in close inspection, plus:

• ☐ Flame path dimensions within tolerance (Ex d)
• ☐ Flame path surfaces clean, not corroded or painted
• ☐ Internal components match certificate
• ☐ Terminal connections tight (torque check)
• ☐ Insulation resistance acceptable
• ☐ Earth resistance measured and within limits
• ☐ Enclosure seal/gasket condition
• ☐ Cable gland sealing effective
• ☐ IR window integrity (if fitted)
• ☐ Thermographic survey (for electrical connections)

Maintenance

Permitted Activities

• Like-for-like replacement. replacing components with identical certified items
• Re-gasketing. using manufacturer-specified gaskets/seals
• Re-greasing flame paths. non-hardening silicone grease (not on gas detectors)
• Tightening connections. to manufacturer's specified torque
• Cleaning. removal of dust, dirt, corrosion

Activities Requiring Special Attention

• Component replacement with alternative. must verify the alternative is covered by the certificate or obtain an amendment
• Painting. never paint flame path surfaces; enclosure body painting is acceptable
• Cable gland replacement. new gland must be compatible with the enclosure and cable
• Repair of Ex d enclosures. may require recertification per IEC 60079-19

Prohibited Activities

• Modifying certified equipment without recertification
• Welding on Ex d enclosures. changes material properties and dimensions
• Using non-certified spare parts. voids the certification
• Hot work in hazardous areas without a valid hot work permit and gas-free certificate
• Energized work in Zone 0/20 or Zone 1/21 without a formal risk assessment and authorization

Common Installation Errors

Based on industry inspection data, the most frequent non-conformances are:

1. Wrong cable gland type. Ex e gland on Ex d enclosure, or wrong cable diameter range
2. Missing blanking plugs. open cable entries destroy IP and flame path integrity
3. Loose terminal connections. causes heating and potential sparking
4. Damaged cables. mechanical damage to cable sheath in hazardous area
5. Unauthorized modifications. additional holes drilled, non-certified components fitted
6. Inadequate earthing. missing or corroded earth connections
7. Dust accumulation. layer insulates enclosure surface, raising temperature
8. Wrong equipment for zone. Gc equipment installed in Zone 1
9. Missing documentation. no zone classification drawings, no explosion protection document
10. Painted flame paths. paint fills the precisely machined gap, preventing proper flame cooling

Explosion Protection Document (EPD)

ATEX 1999/92/EC requires employers to produce and maintain an Explosion Protection Document covering:

1. Identification of explosion risks and hazards
2. Measures taken to achieve explosion protection
3. Zone classification with drawings
4. Equipment selection criteria
5. Safe working procedures
6. Training and competence requirements
7. Maintenance and inspection schedules
8. Management of change procedures

The EPD must be reviewed when processes, equipment, or operating procedures change.

Competence Requirements

Related Files

• Protection Methods. understand what you're installing
• Ex Markings. verify equipment suitability
• Standards. IEC 60079-14 and 60079-17 in detail
• Certification. certificate verification and special conditions
• EPL. matching equipment to zones