Specifying a cable gland correctly in 2026 means matching four independent variables — certification, material, ingress rating and cable sealing range — to the same equipment and cable, because a single mismatch (e.g. an IP68 gland on an Ex d enclosure without flamepath certification) voids the protection claim [S1][S2].
Engineers reading this are typically working on one of three jobs: routine panel building, hazardous-area instrumentation loops, or outdoor/underground power and control cable entries where wash-down or submersion applies — the same gland will not satisfy all three [S1][S2].
Decision Pillars: Certification, Material, IP and Sealing Range
Four inputs drive every cable gland decision and they must be set independently: (1) the hazardous-area classification and required protection concept (Ex d, Ex e, Ex tD, Ex i), (2) the body material class (brass, stainless steel, aluminium, nylon PA66), (3) the ingress rating needed (IP66, IP67 or IP68 at stated depth/duration), and (4) the cable outer-diameter range the seal can accommodate [S1][S2][S4]. The selection process documented by Ex d equipment suppliers E2S explicitly requires installers to confirm the cable OD falls inside the gland's certified sealing range, because the flamepath is qualified only for that span [S4]. Amphenol's industrial line carries both metal and nylon variants and confirms the gland's role is to "protect cable entry" — sealing, strain relief and earth continuity in one device [S2].
For a brass Ex d gland on a 3-core 2.5 mm² armoured power cable, the typical sealing range spans roughly 11–17 mm OD on the inner sheath and 13–20 mm on the outer sheath, with metric threads M20–M25 most common [S1]. Sizing outside that window is a frequent source of certificate voiding on retrofits.
Material Comparison: Brass, Stainless 316L, Aluminium, Nylon PA66
Brass remains the default indoor/panel-build choice because of cost and ease of machining; stainless 316L is specified for offshore, chemical, and food-grade wash-down zones where chloride pitting is a concern; aluminium cuts weight on rail and aerospace enclosures; nylon PA66 (commonly glass-filled) is the budget pick for dry, non-Ex commercial builds [S1][S2]. Eaton's Crouse-Hinds cable gland accessories catalogue separates accessories by thread standard (metric NPT/BSP) and material class, with separate locknuts, earth tags, shrouds and adaptors for each — confirming that material choice cascades into the entire accessory stack [S3].
Material selection for an aggressive process is best framed as a four-way trade-off: brass is the lowest-cost baseline but galvanically couples to aluminium enclosures without a bi-metallic isolator; 316L stainless typically costs 3–5× brass but tolerates chloride and cleaning chemicals; aluminium is half the weight of brass at near-brass price but suffers galvanic corrosion in salt atmospheres; nylon PA66 is the cheapest and electrically insulating but is not accepted on Ex d flameproof entries where the gland body itself forms part of the flamepath [S2][S4].
Hazardous-Area Logic: Ex d vs Ex e vs Ex tD vs Ex i
For Ex d (flameproof) enclosures, the gland body participates in the flamepath and must be certified to that protection concept; Ex e (increased safety) glands only need to maintain the IP rating and prevent cable pull-out, not contain an internal ignition; Ex tD (dust) glands focus on dust ingress and surface temperature; Ex i (intrinsically safe) glands carry reduced clearance and creepage and are the least mechanically demanding [S4]. The E2S selection guide for Ex d equipment is explicit: an unarmoured cable entering an Ex d enclosure still needs a barrier gland (often a compound-filled type) if the enclosure volume exceeds 2 litres, because gas migration along the cable core must be blocked [S4].
ATEX category 2 (Zone 1) and category 3 (Zone 2) glands are the most commonly stocked SKUs in the UK distribution channel reviewed here, with IECEx certification increasingly parallel-listed for projects in the Middle East and Asia-Pacific [S1]. A practical rule from the same distribution data: an Ex d barrier gland for Zone 1 typically carries dual Ex db eb markings, meaning the same SKU covers flameproof and increased-safety entries on the same enclosure.
Ingress, Thread Standards and Sealing Engagement
IP66 protects against powerful jets, IP67 covers temporary immersion to 1 m for 30 minutes, and IP68 is rated for continuous immersion at a depth and duration the manufacturer must declare (commonly 2 m for 24 h or 10 m for 7 days) — IP68 is not a single number, and the datasheet must be read [S1][S2]. Metric thread (M16–M75) is the European default; NPT (½"–3") is the North American default; BSP and PG threads still appear in legacy installs and on older enclosures [S3]. On a shielded cable entry, the gland's clamp or cone must terminate the braid at 360° to keep the EMC shield performance intact; a standard compression gland can degrade shielding effectiveness by 20–40 dB above 30 MHz if the braid is folded back rather than clamped [S1].
Cable Glands UK's published selection charts list the same gland family across multiple thread standards, with explicit "minimum cable OD" and "maximum cable OD" columns next to each thread size — the same chart structure used by Crouse-Hinds and Amphenol, which is the de facto industry format for selection data [S1][S2][S3].
Accessories and Earthing Continuity
Earth continuity is the hidden failure mode in armoured-cable glands. On a SWA (steel-wire-armoured) power cable, the gland's armour cone and earth tag must provide a low-impedance path to the enclosure; a missing or loose tag is one of the most common EICR (Electrical Installation Condition Report) defects [S1][S3]. Eaton's Crouse-Hinds accessory line breaks this out as separate part numbers: locknut, earth tag, brass or stainless shroud, PVC or LSZH shroud, and thread adaptor — the gland body alone is rarely enough for a complete, compliant install [S3].
For installation on painted or anodised enclosures, a serrated stainless locknut or a dedicated earth-bonding locknut is typically specified to bite through the coating; standard smooth locknuts will not give a reliable earth path on a painted surface [S3]. The accessory list also includes stopping plugs and breather/drain plugs certified to the same protection concept as the gland — meaning a Zone 1 enclosure's unused entries must be plugged with an Ex d or Ex e plug, not a blanking plate [S1].
Where Cable Glands Cross Over With Other Spec Jobs
Specifying the cable entry is rarely a standalone task — it usually sits inside a broader cable gland selection workflow that also covers cable tray fill, gland plate sizing, and the matching gland packing or compound for barrier glands. On larger builds the same engineer often sizes the conduit, the steel pipe for process tie-ins, and the cable support hardware, so keeping the gland selection data in a single spec sheet avoids cross-discipline mismatches. [S1]
A second crossover is on instrumentation loops: a 4–20 mA or HART signal cable on a level or pressure instrument typically uses a nickel-plated brass Ex e gland with a silicone seal rated to –60 °C to +140 °C, which is a different gland family from the Ex d barrier gland used on a motor terminal box in the same plant [S1][S4]. Specifying the wrong seal elastomer (EPDM vs silicone vs Viton) for a process temperature above 100 °C is a documented source of premature seal failure on European chemical-plant builds.
Limitations and Common Failure Modes
Cable gland selection has three hard limits: (1) a gland is only certified for the cable construction it was tested with — swapping a Class 2 stranded cable for a Class 5 flexible cable on the same gland invalidates the certification, even if the OD matches; (2) Ex d barrier glands have a shelf life on the compound fill, typically 12–24 months from the date of manufacture, and a gland filled past that date may need re-compounding; (3) NPT threads are tapered and seal by thread deformation, while metric threads need a sealing washer — mixing the two without an adaptor is a common panel-build error [S1][S3][S4].
EMC gland misuse is a fourth failure mode: on a shielded cable carrying signals above 30 MHz (PROFINET, EtherCAT, industrial Ethernet), a standard plastic or compression gland will not maintain shield termination. A 360° EMC backshell or a dedicated EMC gland with a conical braid clamp is the only gland type that preserves the shield at the panel boundary, and the cost premium is roughly 3–5× a standard brass compression gland [S1].
Trackable signals to watch: IECEx Scheme revisions on the OD tolerance band for Ex d glands (currently ±0.2 mm on most datasheets) and the move toward harmonised ATEX/IECEx dual-marked SKUs in the UK and EU distribution channel, both visible in the Cable Glands UK and Amphenol industrial product lines reviewed here [S1][S2].
For related coverage, see Steel Pipe Selection: Spec Bands, Material Grades and Sourcing Levers.