Introduction
Measuring cable gland size sounds simple — but if you measure the wrong thing, you’ll order the wrong size. This guide shows you exactly how to measure for the right cable gland.
What to Measure
You need to measure two things:
- The cable outer diameter — To match the gland’s cable range
- The enclosure hole size — To match the gland’s thread size
How to Measure the Cable
Measure the outer diameter of the cable jacket — not the individual wires inside. Use calipers for accuracy.
Where to measure: Measure the thickest part of the cable. Don’t measure near the end where the jacket might be damaged.
What to look for: The cable outer diameter must fall within the gland’s cable range. For example, if the gland range is “6–12mm,” your cable should be between 6mm and 12mm.
How to Measure the Enclosure Hole
If you’re replacing an existing gland, measure the drill hole in the enclosure. This tells you the thread size you need.
Common drill hole sizes:
- M12 gland = 12.5mm hole
- M16 gland = 16.5mm hole
- M20 gland = 20.5mm hole
- M25 gland = 25.5mm hole
- M32 gland = 32.5mm hole
Size Conversion Chart
| Gland Size | Cable Range (mm) | Drill Hole (mm) |
|---|---|---|
| M12 | 3–6 | 12.5 |
| M16 | 5–10 | 16.5 |
| M20 | 6–12 | 20.5 |
| M25 | 10–14 | 25.5 |
| M32 | 13–18 | 32.5 |
Common Mistakes
- Measuring the wires, not the cable — Always measure the outer jacket
- Choosing too small — If the cable is at the top of the range, size up
- Forgetting the drill hole — The gland must match the enclosure hole
- Mixing thread standards — M20 and PG13.5 are close but not interchangeable
FAQ
What if my cable is 11mm? What size gland?
An M20 gland (range 6–12mm) works. The cable is near the top of the range, so the seal will compress properly.
Can I use a larger gland than needed?
If the gland is too big, the seal won’t compress fully around the cable. It’s better to size down to the right range.
How do I know what size my enclosure hole is?
Measure the hole with calipers. The gland must match the hole size and thread type.
Conclusion
Measure the cable outer diameter and match it to the gland’s cable range. Measure the enclosure hole to determine the gland size. When in doubt, size up slightly — it’s better to have a little room than to force a cable that’s too big. Contact us for help with size selection.
