UK IP68 means an enclosure is dust-tight (the first digit, “6” — no ingress of dust at all) and protected against continuous immersion in water under conditions specified by the manufacturer (the second digit, “8” — exceeding the IP67 envelope of 1 metre for 30 minutes). It is the rating for permanent or long-duration underwater deployment: sub-sea instrumentation, mining applications with persistent water, and deep-fluid handling equipment.
The North American equivalent is NEMA 6P — for prolonged submersion at limited depth. As with the other IP/NEMA pairings, dual specification is common for equipment supplied across both markets.
The defining characteristic of IP68 — different from every other IP rating — is that the test conditions are not standardised. The manufacturer specifies the depth and duration, and the rating only applies under those specific conditions. Always read the spec sheet, not just the rating line.
How IP68 is tested
IEC 60529 (adopted as BS EN 60529 in the United Kingdom and ANSI/IEC 60529 in the United States) specifies that IP68 conditions must exceed IP67 (which is 1 metre depth for 30 minutes), but does not prescribe the exact depth or duration. The manufacturer designs the test based on the intended deployment and publishes the conditions alongside the rating. Typical IP68 specifications cover:
The dust-tightness portion of the test (the “6” digit) is identical to IP65/IP66/IP67 — partial-vacuum talcum-powder chamber for 8 hours.
Because the test conditions are manufacturer-specified, two products both labelled “IP68” can have meaningfully different protection envelopes. An IP68 rating that covers 1.5 m for 30 minutes is appropriate for an outdoor sensor that might briefly flood; an IP68 rating that covers 5 m for 24 hours is appropriate for sub-sea monitoring equipment. The label is the same; the protection is not. For the full IP rating structure and how IP68 compares to the other commonly-specified ratings, see our overview of ingress protection ratings.
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Depth. most commonly between 1.5 m and 3 m. Some specialist sub-sea equipment is rated for 10 m, 50 m, or deeper, with the depth published as part of the rating.
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Duration. most commonly between 30 minutes and 24 hours. "Continuous" can mean the device's full service life for permanently-deployed equipment.
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Water type. typically clean fresh water at ambient temperature. Salt water, chlorinated water, or heated water require separate validation.
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Pressure. for deep submersion, the static water pressure at depth becomes the dominant test condition rather than ingress mechanics.
When IP68 is the right specification
IP68 is appropriate for industrial computing deployments where the equipment will be submerged for longer than 30 minutes, deeper than 1 metre, or on a permanent basis:
For brief or accidental submersion (fording streams, occasional flood events, deck wash that could pool), IP67 is the right rating — IP68’s specification overhead is unnecessary and adds cost. For high-pressure or high-temperature wash-down (food and beverage cleaning, sanitary processing), IP68 is the wrong rating entirely — specify IP69K.
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Sub-sea instrumentation. sensors, monitoring equipment, and control systems for offshore oil & gas, marine research, or sub-sea infrastructure. Depth and duration ratings should match the deployment depth with margin. UK HSE / DSEAR with ATEX zone marking applies for hazardous-area offshore deployments; US OSHA / NEC Class I Division 1 / 2 applies for equivalent US deployments.
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Mining applications with persistent water. equipment in flooded shafts, drainage systems, or operations where water accumulation is continuous. UK HSE Mines Inspectorate / US MSHA approval may layer on top of IP68 in coal and metalliferous mining.
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Deep-fluid handling. equipment in cooling water systems, hydraulic fluid handling, chemical processing where the device sits in or below the liquid surface.
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Permanently submerged marine equipment. hull-mounted sensors, sub-deck monitoring on vessels, bilge equipment that operates submerged rather than just surviving submersion. UK MCA / Lloyd's Register or US USCG / ABS marine approvals may layer on top of IP68 in regulated maritime applications.
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Specialist outdoor deployments. equipment in flood-prone locations where the deployment must continue functioning while submerged, not merely survive immersion.
IP68 vs IP69K — they are not on the same scale
A common misunderstanding: because IP69K has a higher number than IP68, it must offer greater protection. This is not the case. The two ratings cover different scenarios:
An IP69K device is rated for sanitary wash-down but NOT for being submerged. An IP68 device is rated for submersion but NOT for high-pressure heated cleaning. Some equipment (particularly food-processing computers that must survive both daily wash-down and occasional submersion) carries a dual IP68/IP69K rating, validated separately for each scenario.
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IP68. covers continuous immersion at static water pressure. Tested by submerging the enclosure for an extended period.
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IP69K. covers high-pressure, high-temperature water jets per DIN 40050-9. Tested with 80°C water at 8—10 MPa from a close-range nozzle — but the enclosure is NOT submerged during the test.
NEMA equivalent
IP68 corresponds approximately to NEMA 6P in the North American enclosure type system. NEMA 6P covers prolonged submersion at limited depth, similar to the typical IP68 envelope. NEMA 6 corresponds more closely to IP67 (occasional submersion).
For coastal and offshore deployments, NEMA 6P stainless variants are typically specified for the corrosion resistance NEMA adds to the rating — IP68 alone does not test for salt-water corrosion. Equipment supplied to North American oil & gas, naval, or coastal infrastructure projects typically carries dual “IP68 / NEMA 6P stainless” specification.
Common misunderstandings
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IP68 conditions are not standardised. Two products both rated IP68 may have entirely different protection envelopes (1.5 m for 30 min vs 5 m for 24 hours, for example). Always check the manufacturer's published test conditions.
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IP68 does not cover sanitary wash-down. For daily cleaning with high-pressure heated jets (food, pharma, dairy), specify IP69K — not IP68.
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IP68 ratings can degrade with depth cycling. Gaskets that survive static submersion at the rated depth may fail under repeated pressure cycling. Deployments involving repeated dive cycles should specify depth-cycling validation, not just static rating.
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IP68 does not guarantee operation underwater. only enclosure integrity. Touchscreens, displays, RF antennae and similar functional elements may not work submerged, even if the enclosure remains sealed.
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Salt water is not fresh water. Most IP68 tests use clean fresh water at ambient temperature. Salt-water deployment requires separate corrosion validation (typically via NEMA 4X / 6P) on top of the IP rating.
Things Embedded IP68 equipment
Things Embedded supplies IP68-rated equipment for sub-sea, marine, mining and permanently-deployed outdoor applications across UK and US markets. Because IP68 specifications vary by manufacturer, the engineering specification process starts with the deployment depth and duration — not the catalogue rating. Dual IP68 / NEMA 6P specification is standard for North American buyers, with marine or hazardous-area approval layered on as required.
If you would like help specifying the right IP68 build for your deployment, send us:
…and we will shortlist practical options. Call +44 (0)1785 558 300 or email sales@things-embedded.com.
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Depth envelope. maximum static depth, including margin, in metres.
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Duration envelope. minutes, hours, days, or continuous (permanent deployment).
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Water type. fresh, salt, chlorinated, heated — each requires separate validation.
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Approval requirements. UK MCA / Lloyd's Register or US USCG / ABS for marine; UK HSE / DSEAR / ATEX or US OSHA / NEC Class I Division for hazardous-area; UK HSE Mines or US MSHA for mining.
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Service-cycle expectations. single deployment, repeated dives, or long-life static install.