Cutting and preparing
Use a conduit cutter, not a hacksaw: swarf stays in the corrugation and later damages the cable sheath. Cut perpendicular and exactly in a corrugation valley so the gland insert grips the next crest. Blow the conduit clean after cutting.
Pulling in cables without damage
Pull with a fish tape and pulling sock, never on the conductors. Use soap-based lubricant on long runs and pull steadily — stopping and restarting doubles the friction. Always pull before fitting the glands, while the run is still straight.
Tightening and checking the gland
Check the O-ring is present and undamaged, seat the conduit to the stop and secure the gland body in the enclosure wall with the lock nut. Then tug the conduit briefly: it must not move. Over-tightening crushes the seal and cracks plastic glands under vibration.
Clamping, bends and maintenance
Clamp every 300 to 500 mm and always just before and after a bend. Respect the stated bend radius; a kink is permanent and forms a leak path. Include the conduit run in annual inspection: look for cracks at the gland, UV discolouration and clamps loosened by vibration.
| Nominal size | Clamp spacing | Min. bend radius | Gland |
|---|---|---|---|
| NW 10–12 | 300 mm | 25 mm | M12–M16 |
| NW 17–23 | 400 mm | 45 mm | M20–M25 |
| NW 29–36 | 500 mm | 75 mm | M32–M40 |
| NW 48 | 600 mm | 110 mm | M50 |
Frequently asked questions
- How do I test whether a conduit system is really sealed?
- With a 0.2 bar pressure test on the enclosure and soapy water on the glands, or more simply: spray with a hose and check the enclosure for moisture after an hour.
- Can I replace a damaged section without dismantling everything?
- Yes, with a conduit coupling of the same IP rating. Cut out the damaged part, fit the coupling and clamp within 150 mm on both sides.
- Does a metal conduit need earthing?
- If it is part of the EMC shield or can be touched: yes. Use EMC glands with contact springs at both ends and measure continuity.
Read next
- How do you calculate nominal size and conduit length?40% fill ratio, bend radius allowance and installed length: the three formulas with real numbers.
- Which cable protection conduit to choose: PA, PP or metal?Material, profile and gland system together decide whether a conduit lasts for years. Choose in three steps.
- What do IP ratings mean for cable protection conduits?The two digits explained, plus why a conduit only achieves an IP rating together with its gland.