October 10, 2026
To choose the right PG cable gland size, measure the finished cable’s outer diameter, select a gland whose published clamping range includes that measurement, and confirm the enclosure’s thread, hole size, and thread length. The PG number identifies the thread standard and nominal thread size; it does not state the exact cable diameter the gland can accept. I also check cable construction, sealing requirements, material, environmental exposure, and certification before ordering.
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Before selecting a gland, I collect five pieces of information: the finished cable diameter, the enclosure entry thread, the enclosure wall thickness, the operating environment, and the required certification. A digital caliper is preferable because it gives a direct measurement in millimeters, while a flexible measuring tape can help with large or irregular cables. I also inspect whether the cable has armor, braid, a thick jacket, a molded connector, or an unusually flexible outer surface.
The cable entry must support both mechanical retention and environmental sealing. For a control panel, that usually means checking the hole diameter, thread length, internal clearance, and the enclosure’s IP requirement. For outdoor equipment, I additionally check exposure to ultraviolet light, rain, oil, vibration, temperature changes, and possible water accumulation around the entry point.
I begin by measuring the cable exactly as it will pass through the gland. The measurement must include the complete outer jacket, armor, braid, conduit layer, or protective covering that will sit inside the clamping seal. I do not measure individual conductors, insulation thickness, or the cable’s nominal cross-sectional area because those values do not define the gland’s sealing diameter.
Take measurements at three points near the intended entry location and record the largest stable reading. If the cable is oval, compressed, corrugated, or flexible, rotate the caliper and measure both the narrowest and widest dimensions. For example, a cable measuring 8.7 mm, 8.9 mm, and 9.0 mm should be treated as approximately 9.0 mm when comparing it with a clamping range.
After measuring the cable, compare the result with the gland manufacturer’s clamping range. If a PG gland is specified for 6–12 mm, the measured cable should fall inside that interval, but I avoid selecting a size where the cable sits directly at the minimum or maximum limit unless the datasheet specifically permits it. A position near the center of the range generally gives the sealing insert more working adjustment.
The PG number alone does not tell me whether the gland fits. Two glands with different PG sizes can have overlapping cable ranges, while two products with the same PG designation may have different clamping ranges because of their body design, sealing insert, or material. I therefore use the exact product table rather than relying on a general PG cable gland size chart.
Next, I identify the enclosure’s thread standard. Common possibilities include PG, Metric, and NPT, and these threads are not interchangeable simply because their outside diameters appear similar. I check the thread designation, pitch, major diameter, hole diameter, and available thread length using the enclosure drawing or a thread gauge.
A PG9 gland must be installed in a compatible PG9 entry, subject to the actual hole and thread specifications. An M20 gland is not automatically suitable for a 20 mm cable because M20 describes the gland thread, not the cable’s outside diameter. Likewise, replacing an M16 gland with an M20 gland may require a larger enclosure hole, a suitable adapter, or a new mounting position.
The enclosure entry hole must be large enough for the gland body but not so large that the shoulder or sealing washer cannot cover the opening. I compare the gland’s required mounting-hole diameter with the actual hole, including any burrs, paint, powder coating, or distortion around the edge. A hole that is oversized can reduce the available bearing surface and make sealing more difficult.
Thread length is also important when the enclosure wall is thick or when an internal locknut, earth tag, or bonding washer is required. A short-thread gland may not provide enough engagement through a thick wall, while a long-thread version may interfere with internal components. I check the gland drawing against the enclosure’s wall thickness rather than assuming all PG glands have the same thread length.
For indoor control panels with limited chemical and mechanical exposure, nylon PG cable gland sizes are often considered because they provide electrical insulation and low weight. For equipment exposed to impact, vibration, oil, heat, or mechanical loading, brass PG cable gland sizes may be more appropriate when their material and plating specifications meet the application. The correct choice depends on the enclosure, cable, temperature range, and installation conditions.
I also check whether the gland body, sealing ring, locknut, and washer use compatible materials. In a wet or corrosive environment, dissimilar metals can create corrosion concerns, particularly when moisture and conductive contaminants remain around the entry. For outdoor equipment, I verify ultraviolet resistance and the temperature range stated in the product documentation.
The required IP rating depends on the complete cable entry assembly, not just the gland label. I check whether the rating applies to the stated cable diameter, the specified locknut and washer arrangement, and the installation orientation. An IP68 marking does not automatically mean that every gland is suitable for permanent underwater service because immersion depth, duration, sealing method, and installation conditions may be limited by the product specification.
Cable construction can also change the selection. Armored cables may require an armored gland with armor clamping and earth bonding, while flexible cables may need a sealing insert designed to tolerate movement. A gland intended for an ordinary round jacket may not hold a flat, oval, corrugated, or heavily braided cable with the same sealing result.
For ordinary industrial equipment, I check the applicable product standard and the manufacturer’s test information. For hazardous areas, I do not substitute a general-purpose waterproof gland for a certified cable gland; I verify the required protection concept, gas or dust classification, temperature range, cable type, and installation method. The certificate and selection table must match the exact gland construction, accessories, and cable diameter range.
Procurement teams should retain the datasheet, product designation, material specification, and certification record with the equipment documentation. This prevents a later replacement with a visually similar gland that has a different thread, sealing range, or approval status. Sager can be included in a supplier comparison when its selected PG Type cable connector matches the cable diameter, enclosure thread, environmental requirements, and documentation needed for the project.
A PG cable gland size chart normally includes the PG designation, thread dimensions, mounting-hole requirement, cable clamping range, body length, and sometimes the wrench size. I read the chart from the measured cable diameter first, then confirm the thread and mounting dimensions. The correct row must satisfy both the cable range and the enclosure entry requirement.
| Selection item | What I check | Why it matters |
|---|---|---|
| PG designation | PG7, PG9, PG11, PG13.5, PG16, PG21, PG29, or another specified size | Identifies the compatible PG thread family |
| Cable clamping range | Minimum and maximum finished cable diameter | Determines whether the seal can grip the cable |
| Mounting-hole diameter | Required enclosure hole size | Prevents an oversized or undersized entry |
| Thread length | Usable external and internal engagement | Ensures the gland can pass through the wall and accept accessories |
| Material | Nylon, brass, plated brass, or another specified material | Matches mechanical, chemical, electrical, and environmental needs |
| IP rating | Rating under the stated test arrangement | Establishes resistance to dust and water under defined conditions |
| Certification | Standard, certificate, temperature, and cable conditions | Required for regulated or hazardous-area installations |
General conversion charts are useful for generating candidate sizes, but they cannot replace the exact manufacturer datasheet. Product dimensions vary by sealing insert, locknut, body style, and certification. I use a chart for the first comparison and the product’s certified selection table for the final order.
I measure the cable after all permanent outer layers are installed, including the jacket, braid, armor covering, heat-shrink transition, or protective sleeve that will enter the gland. I use a caliper without compressing a soft jacket, take readings at several points, and record the largest consistent diameter. If a connector is already attached, I check whether it can pass through the gland body; many gland bodies cannot accept an oversized molded connector.
A 3 mm cable should not be assigned a gland solely because a chart lists a nearby nominal size. I compare 3 mm with the minimum and maximum clamping limits for the selected product, then check whether the sealing insert can compress around such a small cable without leaving a leakage path. If the cable is below the stated range, I choose a smaller gland or a specifically designed reducer rather than tightening the cap beyond the manufacturer’s instructions.
A gland that is too large may leave the sealing insert under-compressed, allowing water, dust, or cable movement at the entry. A gland that is too small may damage the jacket, prevent the cap from closing correctly, or create excessive stress during installation. In both cases, replacing the gland with a size whose published range fits the measured cable is safer than relying on extra tightening.
Borderline measurements require additional care. If the cable sits near the range limit, I confirm the diameter after installation conditions are considered, including temperature, compression, braid, and movement. For a thick enclosure wall, I select the correct thread length; for multiple cables, I use separate glands or a certified multi-cable entry rather than forcing two cables through one standard gland.
Drip loops can reduce water tracking toward the enclosure, but they do not correct a mismatched gland. If an entry continues to leak, I inspect the cable surface, sealing ring, washer orientation, thread engagement, enclosure-hole condition, cap torque, and installation angle. I also check whether the cable is being pulled sideways or whether a connector, bend radius, or internal strain is loading the seal.
PG and Metric cable glands use different thread systems, so the key issue is compatibility with the enclosure rather than which system appears more familiar. Metric glands are identified by thread diameter and pitch, such as M16 or M20, while PG glands use a PG designation with its own dimensional system. A Metric gland should not be installed in a PG hole without a correctly specified adapter or a redesigned entry.
| Comparison point | PG cable gland | Metric cable gland |
|---|---|---|
| Thread identification | PG designation | M designation plus thread size and pitch |
| Main selection reference | Cable range and PG thread | Cable range and Metric thread |
| Replacement concern | Must match the existing PG entry | May require a new hole or adapter in a PG enclosure |
| Typical documentation need | PG dimensions and clamping range | Metric dimensions, pitch, and clamping range |
| Best selection method | Verify the actual PG datasheet | Verify the actual Metric datasheet |
I do not assume that a larger thread provides a larger cable capacity. Thread size and cable clamping range are separate specifications, and the same principle applies when comparing PG, Metric, and NPT products. If the enclosure is already drilled, I select a gland that matches the existing entry or use a documented conversion component that preserves sealing and mechanical retention.
Before ordering, I complete this checklist:
How to Choose the Right PG Cable Gland Size starts with the finished cable’s outside diameter, not the conductor size or the PG label. I then match that measurement to the gland’s clamping range, confirm the enclosure thread and hole requirements, and check thread length, material, cable construction, IP rating, and certification. This sequence reduces the risk of leakage, cable movement, jacket damage, and incompatible replacements.
For a practical installation, I recommend recording the cable measurement, enclosure thread, wall thickness, environmental conditions, and selected product code in the project documents. I also compare the exact manufacturer datasheet instead of treating a general conversion chart as final evidence. Whether I am evaluating a Sager PG Type cable connector or another supplier’s gland, the final choice must fit the measured cable and the verified enclosure entry under the stated operating conditions.
