An IP68 label on a cable gland looks reassuring, but it is not a fixed promise. The “8” in IP68 means continuous immersion beyond one meter — yet the exact depth and duration are set by each manufacturer, not by the standard. Two glands can both carry an IP68 rating while one is tested at 1.5 meters for 30 minutes and the other at 10 meters for 72 hours. This guide explains what the IP68 rating on cable glands actually means, how the sealing mechanism works to achieve it, how the rating is tested, and why installation mistakes are the most common reason a rated gland still leaks.

What Does the IP68 Rating Actually Mean?

The IP (Ingress Protection) code is defined by IEC 60529 and uses two digits. The first digit covers protection against solid objects and dust; the second digit covers protection against water. For IP68:

• 6 — dust-tight. No dust can enter the enclosure under the standard’s dust-chamber test.
• 8 — protected against continuous immersion in water beyond one meter, at a depth and duration specified by the manufacturer.

The critical detail is the word “manufacturer-specified.” IEC 60529 requires IP68 to be more severe than IP67 (which is fixed at 1 meter for 30 minutes), but it does not define a universal depth or time for IP68. Every manufacturer must state the exact test conditions behind its rating, and those conditions vary widely between products.

This is why the rating alone is not enough information. When comparing IP67 vs IP68 waterproof ratings, you should ask for the stated immersion depth and duration, not just the two-digit code.

How an IP68 Cable Gland Creates a Watertight Seal

A cable gland earns its IP68 rating through coordinated sealing at two separate points. If either seal fails, the whole assembly fails the immersion test.

Seal 1: Around the Cable

The primary seal sits between the cable jacket and the gland body. Inside the gland, an elastomer sealing ring (usually EPDM or NBR) surrounds the cable. When the dome nut or compression nut is tightened, it drives a pressure cone forward, which compresses the sealing ring radially inward from all sides at once. This creates a 360-degree contact surface against the cable jacket, closing off the path where water could track along the cable surface.

Seal 2: At the Enclosure Wall

The secondary seal closes the gap between the gland body and the enclosure or panel. It is usually a flat gasket or an O-ring on the mounting thread, compressed as the gland is torqued into its threaded entry. Without this seal, water travels through the threads even on an otherwise well-made IP68 gland. A missing or pinched O-ring is one of the most common causes of a failed rating in the field.

The gland body itself is not the sealing element — the elastomer is. But the housing material has to hold its shape and clamping force under compression without creeping, cracking, or deforming over time. That is why the choice between nylon, brass, and stainless steel matters for long-term performance even when all three can reach the same IP68 rating at installation.

How IP68 Cable Glands Are Tested

IP68 testing follows the immersion procedure in IEC 60529. A fully assembled gland — with cable, locknut, and O-ring in place, exactly as it will be installed — is submerged in water at the manufacturer’s stated depth for the stated duration. After the test, the gland must show no water ingress that would reach live parts or affect normal operation, and the seal must remain intact on inspection.

Because the test conditions are negotiated between manufacturer and customer, the same IP68 code can cover very different real-world capability. Before specifying a gland for an application with real submersion risk — submersible pumps, underground wiring, marine equipment, outdoor junction boxes — check the datasheet for the exact depth and duration, and confirm the test was performed on the full assembly rather than on the gland alone.

IP68 vs IP67 vs IP69K: Where Each Rating Belongs

The most common confusion around IP68 is treating it as a linear upgrade from lower ratings. It is not. Each rating tests a different kind of water exposure, and choosing the wrong one either underprotects the installation or adds cost for protection you never use.

IP69K is not “better” than IP68 — it is a different test for high-pressure cleaning. A gland can pass IP68 yet fail IP69K, and vice versa. Select based on your worst realistic exposure, not the biggest number.

Why a Rated IP68 Gland Still Leaks in the Field

Most IP68 failures are installation failures, not product failures. The rating is only valid when the gland is assembled and installed the way it was tested. The three most common causes are:

• Cable diameter mismatch. Every gland seals within a published clamping range. If the cable’s outer diameter falls outside that range, the sealing ring cannot compress enough to make a watertight contact. Measure the cable with calipers rather than trusting printed specs, and match it to the gland’s sealing range and cable OD measurement before installing.
• Wrong torque. Under-tightening leaves the seal uncompressed; over-tightening deforms the elastomer, cracks plastic bodies, or crushes cable conductors. Follow the manufacturer’s torque specifications for each sealing point , ideally with a calibrated torque wrench.
• Missing or misplaced sealing components. Forgetting the thread O-ring, installing the gland without its sealing washer, or letting the O-ring pinch during tightening opens a water path through the threads. Check every component against the assembly drawing.

How to Choose a Genuine IP68 Cable Gland

When evaluating an IP68 cable gland, look beyond the label:

• Ask for the test report. A reputable supplier can state the depth, duration, and test standard behind the rating.
• Check material suitability. UV-rated nylon suits outdoor and solar wiring; nickel-plated brass adds strength and EMC shielding for industrial panels; stainless steel resists salt and chemicals for marine and offshore use. The IP68 nylon cable gland guide covers the material trade-offs in more detail.
• Match thread and entry size. The gland thread (Metric, PG, NPT) must fit the enclosure entry, and the cable OD must fall inside the clamping range.
• Plan the full enclosure seal. A gland is one entry point in a wider system. When several cables enter the same outdoor enclosure, the complete IP68 junction box wiring approach shows how the gland, box, and cable work together to hold the rating.

Conclusion

An IP68 rating on a cable gland means dust-tight protection plus continuous immersion beyond one meter, under conditions the manufacturer defines. The rating is achieved by two coordinated seals — one around the cable and one at the enclosure wall — and it is only as good as the test behind it and the installation in front of it. When you need a gland for real submersion duty, check the stated depth and duration, verify the material suits the environment, and install it to the manufacturer’s torque and sealing requirements. Get those right, and the IP68 rating will protect the cable entry for the life of the equipment.

FAQ

Does IP68 mean a cable gland can be submerged at any depth?

No. IEC 60529 defines IP68 as continuous immersion beyond one meter, but the exact depth and duration are specified by the manufacturer. Check the datasheet for the stated test conditions — for example, 1.5 meters for 30 minutes or 10 meters for 72 hours.

Is IP68 always better than IP67 for cable glands?

Not necessarily. IP67 is fixed at 1 meter for 30 minutes, while IP68 covers continuous immersion beyond one meter. If the gland only faces rain or occasional pooling, IP67 delivers the same dust-tight sealing at lower cost. Choose IP68 when the gland may be submerged or buried for extended periods.

Does the material of a cable gland change its IP68 rating?

Nylon, brass, and stainless steel glands can all reach IP68. The material affects long-term durability — corrosion resistance, temperature range, and mechanical strength — not the rating itself at installation.

Why does a cable gland leak even when it is marked IP68?

Most leaks come from installation errors: a cable outside the gland’s clamping range, incorrect torque on the compression nut, or a missing thread O-ring. The rating only applies when the gland is assembled and installed exactly as tested.

Is IP69K a higher rating than IP68?

It is a different test, not a higher grade. IP69K (ISO 20653) verifies resistance to high-pressure, high-temperature water jets for washdown environments. A product can pass IP68 and fail IP69K. Choose based on the actual exposure: immersion for IP68, pressure cleaning for IP69K.