I select cable glands for intrinsic safety systems from the complete Ex i circuit and actual equipment entry. Ex i identifies intrinsic-safety protection. Apparatus, associated apparatus, cable, and their interconnection establish the electrical-energy limits. An ‘IS gland’ label cannot establish them. IS means intrinsically safe. The gland normally neither detects nor interrupts that energy; it preserves its assigned cable and enclosure interfaces.
First, I resolve system parameters, location, equipment protection concept, cable construction, and certificate conditions. Then match cable range, entry, functions, materials, and environmental evidence to that arrangement.
Key takeaways
- Do not treat a cable gland as an energy-limiting barrier or protective device.
- Follow the actual equipment-entry protection concept and certificate conditions, even when the circuit itself is Ex i.
- Keep the Ex i circuit reference, protective earth, armour continuity, screen termination, and enclosure bonding as separate electrical paths.
- Match the complete gland, cable, entry, accessories, environment, and installation instructions.
- Treat blue cable and catalogue wording as identification aids, not proof of conformity.
Start with the Ex i system, not an “IS gland” label
Intrinsic safety (Ex i) is a protection technique in which the electrical circuits themselves are designed so they cannot cause ignition under the conditions covered by the applicable protection level and assessment. The public scope of IEC 60079-11:2023 addresses construction and testing of intrinsically safe apparatus and associated apparatus connected to intrinsically safe circuits. It does not define an ordinary cable gland as the component that performs the circuit’s energy limitation.
An intrinsically safe system is the assessed interconnection of intrinsically safe apparatus, associated apparatus, and cables. IEC 60079-25:2020 with Amendment 1:2025 covers its design, construction, and assessment. I check compatible voltage, current, capacitance, inductance, and other declared values at that system boundary.
Associated apparatus is equipment that contains both intrinsically safe and non-intrinsically safe circuits, or otherwise affects the safety of the intrinsically safe circuit, within its declared scope.
Before selecting the entry, I establish:
- Location classification, protection level, gas or dust group, temperature requirements, ambient range, and jurisdiction.
- Field apparatus and associated apparatus or barrier, with certificates, schedules, and instructions. A schedule lists covered construction and conditions.
- Permitted interconnection and cable parameters used in the system assessment.
- Cable cores, conductors, insulation, screen, drain wire, armour, bedding, outer sheath, and overall diameter.
- Enclosure and its actual entry protection concept.
Separate energy safety from cable-entry functions
I assign the gland its declared entry functions: jacket protection, retention, enclosure protection, and designated electrical contacts. These may support a safe installation. They cannot replace apparatus, cable assessment, or system documentation.
| Boundary or function | Where it is established | What the gland may contribute |
|---|---|---|
| Ex i energy limitation. | Field apparatus, associated apparatus, cable data, interconnection, and system assessment. | Normally none; do not invent voltage, current, capacitance, or inductance parameters for an undeclared gland. |
| Cable-facing seal. | Around the cable layer named by the gland design. | Environmental sealing when cable range, shape, material, preparation, and assembly match the evidence. |
| Cable retention and strain transfer. | At the gland’s retention or clamping system and any external support. | Resistance to specified cable movement or pull within the product’s declared configuration. |
| Enclosure-entry boundary. | Gland thread or clearance hole, wall, shoulder seal, locknut, and any adaptor. | Maintains the permitted entry connection and wall seal when the complete stack matches. |
| Armour termination. | Dedicated armour cone, ring, clamp, or other declared contact. | Mechanical and electrical continuity only when the gland is designed and verified for the exact armour. |
| Screen termination. | Cable screen, contact element, gland body, enclosure, or separate termination. | A controlled screen contact only where the exact arrangement requires and provides it. |
| Protective bonding. | PE or equipotential-bonding path defined by the equipment and installation. | Part of the path only where designated contact parts and evidence support that duty. |
Match the actual equipment entry protection concept
An Ex i circuit does not define every enclosure entry’s protection concept. The equipment may rely on intrinsic safety or use Ex e, Ex d, Ex p, or Ex t at the entry. Those letters identify different protection concepts. I follow the actual enclosure arrangement and its limits for gland and accessories.
IEC 60079-14:2024 covers Ex electrical-installation design, selection, installation, and initial inspection. Installation selection remains separate from apparatus construction and system assessment. Matching thread or cable diameter alone cannot authorize substitution. A valid circuit assessment cannot approve an incompatible entry.
I read equipment marking, certificate, schedule, and instructions together. Confirm geometry, allowed threads and accessories, seals, and any specified gland type. For a pressurized enclosure, the Ex p cable-entry guide addresses the pressure boundary. Apparatus, cable, and interconnection records still establish Ex i energy limits.
If the entry concept is unresolved, I use the hazardous-area gland selection guide to establish it and the complete entry evidence before completing the system calculation.
Map cable construction before choosing the gland
I describe the layer the gland seals or grips. Record overall diameter and tolerance, roundness, sheath material, surface, and temperature range. Identify armour, screen, braid, corrugations, and drain wire. Check inner bedding or sheath dimensions when armour is terminated or more than one layer is sealed.
I use the cable specification and declared data for electrical parameters, mechanical fit, environmental resistance, and entry suitability. Blue sheath can aid identification. It cannot replace the cable record or resolved entry arrangement.
Illustrative enclosure entry: a blue cable passes through a metal gland to a terminal area, while a separate green-and-yellow lead bridges the door and enclosure.
I use marking, certificate, schedule, and instructions for the permitted entry concept. Cable data, gland data, and design establish fit, certificate coverage, screen or armour termination, and bonding paths.
For armour, I record type, dimensions, material, and assigned electrical role. For screen, specify where and how it terminates. The gland must contact the exact layer it is designed for. Electromagnetic compatibility (EMC), armour handling, and hazardous-area suitability are separate functions.
Keep screen, armour, bonding, and circuit reference separate
I keep these four conductive paths separate:
- The Ex i circuit reference or functional earth belongs to the circuit design and associated-apparatus instructions.
- Protective earth (PE) or equipotential bonding manages exposed conductive parts and fault conditions according to the equipment and installation design.
- Cable armour continuity may provide mechanical protection, bonding, or another assigned function depending on the cable system.
- Cable screen termination controls the screen’s intended electrical or EMC behavior and may follow equipment-specific instructions.
I include the gland in a path only when its contacts, panel joint, accessories, and assembly are designed for that duty. Material alone cannot choose the termination scheme.
I follow the defined arrangement for insulating washers, bushes, earth tags, jumpers, and screen contacts. Insulation may interrupt required PE, armour, or EMC continuity. A locknut through paint may leave a bond undefined. The cable-gland bonding and grounding guide explains complete paths. The gland body cannot prove them by appearance.
Check the complete gland and entry geometry
IEC 62444:2010 sets construction and performance requirements and tests for complete glands. I use that complete-product scope. It cannot prove compatibility with every hazardous-area enclosure, cable, accessory, or Ex i system.
For the proposed gland, I record:
- Sealing and retention intervals for the relevant layer, including cable tolerance.
- Thread form, size, usable length, shoulder, seal, and mating hole or internal thread.
- Wall thickness, seating surface, coating, locknut, engagement, and permitted adaptor or reducer.
- Required armour or screen-contact ranges.
- PE or equipotential-bonding path and contact hardware.
- Entry ambient and cable temperatures, fluids, ultraviolet exposure, corrosion, washdown, dust, vibration, and movement.
- Marking, certificate scope and schedule, instructions, and covered accessories.
An ingress protection (IP) code applies to an enclosure boundary, not intrinsic-safety energy parameters. I match its evidence separately. The IEC 60529 guide explains why a gland label cannot rate the whole enclosure. IP cannot replace hazardous-area entry evidence or Ex i assessment.
Read certificates within their actual scope
I search the certificate by identifier and compare it with the exact product. Check maker, type, marking, protection concept, protection level, group, temperature and ambient limits. Then verify cable, entry, accessories, and schedule. The IECEx Certified Equipment Scheme overview describes online certificates and their scope. A listing is useful only when the equipment and conditions match.
For EU supply, the European Commission ATEX page explains Directive 2014/34/EU and conformity assessment for equipment and protective systems. Check that route separately from IECEx. Neither label can be inferred from the other. The ATEX and IECEx comparison explains the market and certificate distinction.
I include a gland electrical parameter only when an authoritative document declares the exact value and explains its assessment role. Otherwise, apparatus and cable records supply electrical values. The gland remains within its declared entry functions.
Use this selection sequence
- Define location and jurisdiction. Record zone or division, protection level, group, temperature limits, and regulatory route.
- Resolve the Ex i system. Identify apparatus, associated apparatus, interconnection, cable data, certificates, and compatibility assessment.
- Identify the entry. Read marking, protection concept, schedule, drawing, and instructions.
- Describe cable layers. Record sheath, bedding, armour, screen, diameters, tolerances, and preparation.
- Assign entry functions. Name parts for cable sealing, retention, wall sealing, armour or screen termination, and bonding.
- Match geometry and exposure. Check opening, wall and accessories, shoulder seal, temperature, media, corrosion, movement, and external support.
- Confirm the whole assembly. Match gland type, marking, certificate conditions, instructions, cable range, and permitted accessories.
- Install that arrangement. Prepare, tighten, support, close unused entries, and terminate according to the applicable documents.
Preserve the chosen arrangement during installation
Before assembly, I compare gland and accessories with the resolved design. Check undamaged cable within range. Prepare armour, screen, bedding, and sheath to instructed dimensions and order. Keep strands, foil, braid, and drain wires away from seals unless the drawing places them there.
I preserve thread engagement, panel seal, locknut seating, adaptor order, and intended contacts. Coating removal, sealant, earth tags, or insulating washers must belong to the documented arrangement. Provide external supports where weight, route, movement, or bends would load the entry.
After assembly, I inspect parts, armour exposure, seals, jacket, supports, and entry parts. Visual inspection cannot settle every claim. Verify the Ex i calculation through the system assessment. Check hidden contacts by the specified method, protection concept through equipment records, and ingress through assembly-specific evidence.
Conclusion
I begin intrinsic-safety gland selection with the system assessment. It establishes energy limits and compatible interconnection. Resolve apparatus, associated apparatus, cable parameters, location, and compatibility first. Then follow the equipment’s actual entry protection concept and certificate conditions.
I match cable layers, entry geometry, sealing, retention, environment, and assigned armour, screen, or bonding duties. Keep their responsibilities distinct. The acceptable choice is the documented complete gland and accessory arrangement covering the real cable, enclosure, paths, and installation.
FAQs about cable glands for intrinsic safety systems
Do cable glands limit energy in an intrinsically safe circuit?
Normally, no. The Ex i energy limitation is established by the field apparatus, associated apparatus or barrier, cable data, and their assessed interconnection. A gland provides only the mechanical, environmental, entry, and electrical-contact functions declared for its exact design. Do not assign it voltage, current, capacitance, or inductance limits unless an authoritative document explicitly does so.
Does every Ex i circuit need a specially marked “IS cable gland”?
No. Selection follows the actual equipment-entry protection concept, certificate conditions, cable, environment, and jurisdiction. Some entries require a specifically certified hazardous-area gland; others may be governed by a different documented arrangement. A marketing label alone does not establish suitability, and the Ex i circuit designation does not replace the equipment entry requirements.
Can a metal cable gland be used with an intrinsically safe circuit?
Material alone does not decide the answer. A metal gland may be appropriate when its entry, environmental, sealing, retention, bonding, armour, or screen duties match the exact design. It may be unsuitable when those conditions do not match. Follow the equipment, cable, system, and gland instructions instead of treating metal as automatically safe or unsafe.
Should a gland’s capacitance and inductance be included in the Ex i calculation?
Only when an exact authoritative product or system document declares those electrical parameters and places them inside the assessment. Do not invent values for an ordinary gland. In a typical system, the declared characteristics of the apparatus, associated apparatus, interconnecting cable, and wiring arrangement provide the relevant electrical inputs.
Is blue cable enough to identify a compliant Ex i installation?
No. Blue can help identify an intrinsically safe circuit, but colour does not prove cable electrical parameters, protection level, gland compatibility, entry certification, bonding, or correct installation. Verify the cable type and data, the complete Ex i system, and the equipment-entry arrangement independently.
Sources and technical references
- IEC 60079-11:2023, Explosive atmospheres - Part 11: Equipment protection by intrinsic safety “i” - International Electrotechnical Commission, accessed 2026-09-25.
- IEC 60079-25:2020 with Amendment 1:2025, Intrinsically safe electrical systems - International Electrotechnical Commission, accessed 2026-09-25.
- IEC 60079-14:2024, Explosive atmospheres - Part 14: Electrical installations design, selection and installation - International Electrotechnical Commission, accessed 2026-09-25.
- IEC 62444:2010, Cable glands for electrical installations - International Electrotechnical Commission, accessed 2026-09-25.
- IECEx Certified Equipment Scheme overview - IECEx, accessed 2026-09-25.
- Equipment for potentially explosive atmospheres (ATEX) - European Commission, accessed 2026-09-25.