The most reliable approach is to follow a measurement-based selection process rather than choosing a gland by appearance or nominal size alone.
Step 1: Measure the Cable's Outside Diameter
Use a digital caliper to measure the outside diameter of the finished cable. Include the outer jacket and any relevant shielding or armour according to the gland manufacturer's instructions.
Measure at several points along the cable.
Avoid compressing a soft cable jacket.
Record any significant variations in cable diameter.
Check the maximum relevant diameter against the product's permitted range.
Do not use the conductor cross-section, such as 0.5 mm² or 0.75 mm², as a substitute for the cable's outside diameter.
Step 2: Match the Measurement to the Clamping Range
Compare the measured cable diameter with the range listed in the gland's datasheet.
For example, if a particular PG9 gland is rated for a cable OD of 4–8 mm, a cable measuring 6 mm falls within the specified range. If the cable is close to the upper or lower limit, confirm the manufacturer's guidance before making a selection.
Step 3: Check Thread and Mounting Compatibility
The gland must fit both the cable and the enclosure. Before ordering, verify the thread designation and pitch, thread outer diameter, required mounting-hole dimensions, panel thickness, and available clearance.
PG and metric threads should not be assumed interchangeable simply because their diameters appear similar.
Step 4: Evaluate Environmental Conditions
Consider exposure to moisture, dust, oil, chemicals, temperature changes, vibration, and mechanical loads. Select the material, sealing design, and ingress protection rating according to the actual operating conditions.
An IP rating should be verified against the product documentation and specified installation conditions rather than assumed from the product description.
Step 5: Verify the Complete Assembly
Before purchasing in quantity, confirm compatibility among the cable, gland, sealing components, enclosure, and installation method. For critical applications, verify the assembled cable entry through the appropriate inspection and testing procedures.