How Nylon Cable Glands Provide Ip68 Waterproof Seals

When a cable gland fails, the first sign is rarely a puddle you can see. It’s more often corrosion inside a junction box, a nuisance trip, or downtime you can’t explain until you open the enclosure. If your equipment runs outdoors, underground, in washdown areas, or anywhere exposed to moisture, the small fitting at the cable entry point is doing more work than most specifications give it credit for. Nylon cable glands are one of the most widely used components in that seal — and also one of the most misunderstood. This article walks you through exactly how nylon cable glands achieve an IP68 waterproof rating, what separates a genuine watertight cable gland from one that only sounds like one, and how to choose the right nylon cable glands for your next project.

What an IP68 Waterproof Rating Actually Promises Your Business

IP68 is not a marketing label — it’s a classification defined under IEC 60529, the international standard for enclosure protection ratings. The two digits tell you two separate things. The first digit (6) means complete protection against dust ingress, with no particles entering the enclosure under vacuum-assisted test conditions. The second digit (8) means the component is protected against continuous immersion in water beyond 1 meter, at a depth and duration that the manufacturer defines and discloses.

That last point matters for your procurement decisions. IP68 is not a single fixed test — suppliers specify their own immersion depth and time within the “beyond 1m” tier. When you’re sourcing ip68 cable glands for a project with real submersion or heavy washdown exposure, you should always ask your supplier for the exact depth and duration behind their IP68 waterproof rating, not just the rating itself.

Rating	Dust Protection	Water Test	Typical Use Case
IP66	Full protection against dust	Powerful water jets from any direction	Outdoor panels, washdown areas
IP67	Full protection against dust	Temporary immersion up to 1m, 30 minutes	Occasional flooding, low-lying enclosures
IP68	Full protection against dust	Continuous immersion beyond 1m (depth/time set by manufacturer)	Submersible pumps, underground wiring, marine equipment

How Nylon Cable Glands Physically Create That Seal

A watertight cable gland doesn’t rely on a single barrier — it’s built from two coordinated seal points, and understanding both helps you evaluate whether a product is actually engineered for the rating it claims.

The primary seal sits between the cable jacket and the gland body. Inside the gland, an elastomer sealing ring (typically EPDM or NBR) surrounds the cable. When you tighten the dome nut, it compresses this ring radially and axially around the cable jacket, closing off any gap where water could track in along the cable surface.

The secondary seal sits between the gland body and the panel or enclosure wall, usually through a flat gasket or O-ring compressed as the gland is torqued into its threaded entry. Both seals have to hold simultaneously for the assembly to meet an IP68 waterproof rating — a gland that only seals well at the cable but leaks at the panel interface will still fail an immersion test.

The nylon body itself isn’t the sealing element — the elastomer is. But the nylon housing has to hold its shape and clamping force under that compression without creeping, cracking, or deforming over time, which is where material selection becomes just as important as the seal design.

Why Nylon Is the Material Your Business Should Specify for Watertight Applications

Polyamide (nylon 66) is the standard housing material for watertight cable gland construction across most industrial and commercial applications, and for good reason:

• Dimensional stability under compression — nylon maintains consistent clamping force on the internal seal, which is what keeps the IP68 waterproof rating intact over years of service, not just at time of installation.
• Flame retardance — quality nylon cable glands are molded in UL94 V-2 or better flame-retardant grades, which matters for panels and enclosures with fire-safety requirements.
• Chemical and oil resistance — nylon holds up against many industrial lubricants, fuels, and cleaning agents that would degrade lower-grade plastics over time.
• Non-conductive and lightweight — unlike metal glands, nylon adds no risk of galvanic corrosion against dissimilar metals and reduces overall enclosure weight, which matters at scale across large installations.
• Cost efficiency at volume — for businesses specifying hundreds or thousands of entry points across a product line, nylon delivers IP68-grade performance at a materially lower per-unit cost than machined metal alternatives.

You can review BOESE’s full nylon cable glands range, or browse the full range of cable glands if your project also calls for metal options.

Choosing the Right Nylon Cable Gland for a True IP68 Seal

An IP68-rated gland only performs to that rating when it’s matched correctly to your cable and application. Three specification points matter most:

1. Thread type. Your gland’s thread has to match the tapped hole in your enclosure — metric (M12, M20, M25, etc.) and PG threads are not interchangeable, and forcing the wrong thread type is one of the fastest ways to break a seal before the gland is even fully installed. If you’re unsure which your equipment uses, this comparison of PG vs metric cable gland threads walks through how to identify and select the correct one for your business.

2. Cable outer diameter. Every nylon cable gland has a defined clamping range, and the cable has to fall within that range for the elastomer seal to compress evenly. Too loose, and the seal can’t close the gap; too tight, and you risk deforming the cable jacket or the seal itself. Before ordering, it’s worth taking a few minutes to calculate your cable outer diameter so the gland you order actually fits.

3. Core count and cable type. Multi-core cables, flat cables, and round single cables all seal differently, and gland sizing shifts accordingly. If your project involves multi-conductor cable, this cable gland size chart is a useful reference for matching gland size to core configuration.

Getting these three details right before you order is the single biggest factor in whether your installed glands actually hold an IP68 waterproof rating in the field.

Installation Practices That Preserve the IP68 Rating

Even a correctly specified nylon cable gland can underperform if it’s installed incorrectly. A few practices protect the rating you’re paying for:

• Torque to the manufacturer’s spec — over-tightening a nylon dome nut can crack the housing or over-compress the seal, while under-tightening leaves a gap for water ingress.
• Inspect the elastomer seal before installation — nicks, tears, or debris on the sealing ring will compromise the primary seal regardless of how well the gland is torqued.
• Keep the cable jacket smooth at the entry point — deep scoring or flattening from strippers or clamps creates a channel for water to track along.
• Confirm the panel cutout is flat and clean — burrs or warping around the threaded hole prevent the secondary gasket from seating evenly.
• Re-check torque after initial thermal cycling — for outdoor or high-vibration installations, a follow-up inspection after the first weeks in service catches any settling before it becomes a leak point.

FAQs

What does IP68 mean for a cable gland?

IP68 means the gland provides complete protection against dust ingress and is rated for continuous immersion in water beyond 1 meter, at a depth and duration set by the manufacturer’s own testing.

Are nylon cable glands as waterproof as metal cable glands?

Yes. Waterproofing comes from the internal elastomer seal design, not the housing material. A well-engineered nylon cable gland can achieve the same IP68 waterproof rating as a metal equivalent for most industrial and commercial applications.

Can nylon cable glands be used outdoors in direct sunlight?

Standard nylon can degrade under prolonged UV exposure. If your installation is permanently outdoors, ask your supplier for UV-stabilized nylon cable glands to maintain long-term mechanical performance and seal integrity.

What is the maximum immersion depth for an IP68 cable gland?

There’s no single industry-wide maximum — IP68 only specifies “beyond 1 meter,” and manufacturers publish their own tested depth and duration. Always request the specific figures from your supplier for applications with real submersion risk.

How do I know if a cable gland is genuinely rated IP68 or just marketed that way?

Ask for the manufacturer’s test report or certification showing the specific IEC 60529 test conditions used, including immersion depth and time. A supplier that can’t produce this documentation likely hasn’t independently verified the rating.

Do nylon cable glands need additional sealant or tape?

Typically no, provided the thread type matches the enclosure and the gland is torqued correctly. Some installers add thread sealant on the panel-side thread for extra insurance in high-vibration or extreme-exposure environments.

What cable diameter range works with a standard IP68 nylon cable gland?

It varies by gland size, generally spanning a few millimeters within each size designation. Always check the specific clamping range for the gland size you’re considering rather than assuming based on thread size alone.

Can I reuse a nylon cable gland after removing the cable?

It’s not recommended for IP68 applications. The elastomer seal takes a compression set around the original cable, and reinstalling with a different cable — or even the same cable — often can’t reliably reproduce the original seal.

What’s the difference between PG and metric thread nylon cable glands?

PG threads follow an older German standard with a different pitch and diameter system than metric (ISO) threads. They are not interchangeable, and using the wrong type on an enclosure will prevent the gland from seating and sealing correctly.

How often should IP68 cable glands be inspected or replaced?

For critical or continuously submerged applications, an annual visual inspection is a reasonable baseline. Replace any gland showing cracking, seal hardening, or loss of clamping force rather than waiting for a visible leak.