When you specify a cable gland IP rating, you are really specifying how much trust you put in that seal. IP65, IP66, and IP68 all sit at the top of the ingress-protection scale, but they are not interchangeable — they describe different test conditions, and choosing the wrong one means either an over-engineered cost or a failed seal the first time a hose points at the enclosure. For buyers sourcing brass cable glands or stainless steel cable glands, this guide explains what each code actually guarantees and where each belongs.
What the IP Code Means
IP stands for Ingress Protection, defined in IEC 60529. The two digits after “IP” are specific:
- First digit (0–6) — protection against solid objects and dust. “6” means totally dust-tight.
- Second digit (0–9) — protection against water. Here the numbers 5, 6, and 8 mean very different things.
So IP65, IP66, and IP68 all share the “6” (dust-tight). They differ only in the water test — and that difference is the whole story.
IP65, IP66, IP68: What Each Rating Guarantees
IP65: Dust-Tight and Water-Jet Resistant
IP65 is tested against a 6.3 mm nozzle delivering 12.5 L/min from 3 meters for at least 3 minutes. It survives rain, splashing, and light hose-down. It does not survive a sustained jet or immersion. Use IP65 glands for indoor-to-outdoor transitions, control panels in covered areas, and general industrial enclosures that see weather but not pressure washing.
IP66: Dust-Tight and Powerful Water Jet
IP66 steps up to a 12.5 mm nozzle at 100 L/min, roughly a high-pressure cleaner, for at least 3 minutes. The seal must hold against a deliberate, forceful jet from any direction. Choose IP66 where equipment is hosed down for sanitation (food, pharma washdown) or sits where spray is routine. The multi-hole cable glands used for bundled cables in washdown zones typically target IP66.
IP68: Dust-Tight and Continuous Immersion
IP68 is the only one of the three tested by immersion, not jet. The depth and duration are agreed between manufacturer and user (commonly 1 m for 30 minutes, but often specified higher). It is for cables that are continuously or periodically submerged — underwater pump housings, outdoor junction boxes in flood-prone locations, and marine decks. Note that IP68 says nothing about jets; a gland can be IP68-rated yet fail a power-wash test unless it is also IP66.
| Rating | Dust | Water test | Typical use |
|---|---|---|---|
| IP65 | Dust-tight | Low-pressure jet (12.5 L/min) | Weather-exposed indoor/outdoor panels |
| IP66 | Dust-tight | High-pressure jet (100 L/min) | Washdown, food/pharma, spray zones |
| IP68 | Dust-tight | Continuous immersion (depth by spec) | Submerged pumps, marine, flood zones |
Material and Seal Quality Drive the Rating
The IP number is only as good as the gland’s sealing elements. A brass or stainless body with a degraded or wrong-compound elastomer seal will leak long before the metal fails. In coastal and chemical plants, the choice between brass and stainless steel cable glands for marine environments matters as much as the IP code, because corrosion around the seal is what ultimately breaks the ingress barrier. Matching the thread type — metric, PG, NPT, or G — to the enclosure is equally important; a mismatched thread voids the seal regardless of rating.
Common IP Rating Mistakes
- Assuming IP68 covers jets. It does not. For washdown, confirm IP66 too.
- Rating the gland but not the install. A perfect IP68 gland on an un- torqued locknut, or on a cable outside the clamp range, leaks at the entry.
- Ignoring the cable OD window. Each gland clamps a specific cable outer-diameter range. A too-small cable leaves a gap; a too-large cable is never sealed.
- Over-specifying. IP68 costs more and is pointless on a dry indoor panel. Pay for the rating you actually need.
Thread Type: The Other Half of the Seal
The IP rating protects against water entry along the cable and through the seal face. The thread protects against entry between the gland and the enclosure wall. Metric (M), PG, NPT, and G threads are not cross-compatible, and forcing one into another cracks the enclosure or leaves a spiral leak path. Our detailed NPT vs metric cable glands comparison covers how to pick the correct thread for your region and application.
IP67 and IP69K: The Neighbors Worth Knowing
Two related codes often appear on the same datasheets. IP67 is immersion up to 1 m for 30 minutes — similar intent to IP68 but a fixed, lower depth. IP69K is a high-pressure, high-temperature jet test (80 °C water at 100 bar from close range) used for vehicles and equipment that are steam-cleaned. If your enclosure faces washdown with hot, high-pressure equipment, IP69K-rated glands and enclosures are the spec, not IP66. Do not assume IP68 covers this — it does not.
Torque: The Silent Partner of the IP Rating
An IP68 gland only performs to rating if the locknut and compression nut are torqued to the manufacturer’s value. Under-torquing leaves the elastomer seal partially relaxed; over-torquing cracks the gland body or squeezes the seal past its recovery range. Both leak. The IP number on the box is a tested condition, and the test included a specified torque. Replicating it in the field is part of honoring the rating. For armored or lead-sheathed cables the sealing torque is even more critical, as discussed in our guide on torque values that guarantee IP68 waterproof seals on armored cable.
Vent Plugs and Pressure Equalization
Sealed enclosures breathe thermally: as the box heats and cools, internal pressure cycles. A perfectly sealed gland plus a sealed enclosure can draw moisture in through tiny paths as it cools, or bulge gaskets as it heats. Vent plugs (breathable membranes) equalize pressure while blocking water, which is why they are common on outdoor IP68 installations. The interaction between gland sealing and enclosure venting is a design step, not an afterthought, especially in solar and telecom cabinets exposed to wide daily temperature swings.
IP Rating vs Cable Diameter Window
Finally, remember the IP rating and the clamp range are independent specs. A gland rated IP68 still only seals the cable it is sized for. Ordering by IP code alone, without checking the cable outer-diameter window, is the most common cause of a “rated” gland that leaks in practice. Always cross-check both numbers on the datasheet.
Quick Environment-to-Rating Reference
To make selection concrete, match the duty to the rating rather than guessing:
- Indoor panel, no direct water — IP65 is more than enough; IP66/IP68 would be unused cost.
- Outdoor enclosure, rain and splashing only — IP65, provided the cable diameter is within the gland’s clamp range.
- Food, pharma, or regular washdown — IP66 as the minimum; pair with a hygienic-design gland and smooth surfaces.
- Marine deck, bilge, or submerged pump — IP68 with a confirmed immersion depth, plus corrosion-resistant material (see our brass vs stainless steel marine guide).
- Steam-cleaned or vehicular wash — IP69K-rated gland and enclosure, not IP68.
This reference assumes the thread type and cable OD are also correct. A perfect rating on the wrong thread, or outside the clamp window, still leaks — the IP number is necessary but not sufficient on its own.
Documentation and Certification
An IP rating claim is only useful with the test report behind it. For regulated or export work, request the third-party ingress-protection test certificate and confirm the exact test conditions — depth and duration for IP68, pressure and nozzle for IP66. Beware supplier claims of “IP68” with no stated immersion depth; the code without the agreed condition is meaningless. Similarly, certifications such as CE, UL, or ATEX (for hazardous areas) are separate from the IP rating and must be checked independently. A gland that is IP68-rated but not certified for your region or hazard zone is not compliant regardless of its sealing performance, so verify both the IP test report and the applicable product certification before specifying.
Multi-Hole Glands and IP Rating
When several cables enter one enclosure, a multi-hole cable gland seals them through a single entry while keeping the same IP rating. Each hole clamps its own cable OD, so the IP performance depends on every individual bore being correctly sized — a multi-hole gland with one oversized bore leaks just like a single gland would. Treat each bore as its own IP-critical seal and verify the cable range per hole, not just the overall gland rating.
Specify the Right Cable Gland IP Rating
Matching the IP rating to the actual water exposure — jet vs immersion vs weather — keeps your enclosure sealed without paying for protection you will never use. Niuli Electric supplies brass, stainless steel, and multi-hole cable glands in metric, PG, NPT, and G threads, with elastomer seals matched to the duty.
Need a Cable Gland Recommendation?
Tell us your environment (weather, washdown, submerged), cable OD, and thread type. We will specify the correct IP-rated gland.
Frequently Asked Questions
What do the two digits in IP65 actually mean?
The first digit (6) means dust-tight — no ingress of dust under the test condition. The second digit (5) means protection against water jets from a 6.3 mm nozzle. Together, IP65 is fully dust-sealed and resistant to splashing and light spray, but it is not rated for immersion.
Is IP66 better than IP65, and do I need it?
IP66 resists far more powerful water jets (around 100 L/min at close range versus 12.5 L/min for IP65). Choose IP66 where there is heavy hosedown, driving rain, or washdown; IP65 is enough for indoor splash and light outdoor spray.
Can I fit an IP68 gland on an IP65 application?
Yes — IP68 (continuous immersion) is a superset of IP65, so it will perform. But it is usually costlier and bulkier, so specify the rating the environment actually demands rather than over-buying on every junction.
Does the IP rating cover both the cable-to-gland and gland-to-box seals?
The rating only holds when both seals are correct: the cable clamp grips the right cable diameter and the enclosure thread is sealed with the proper washer or O-ring. A loose or mismatched gland breaks the seal regardless of the printed rating.
Are plastic and metal glands equally rated?
The IP number depends on the design and seals, not the material, so both nylon and brass/stainless glands can reach IP68. The material choice is about the environment: brass or stainless for corrosive, hazardous (Ex), or outdoor sites; nylon for light, non-sparking indoor use.
