IP67 and IP68 are not two points on one scale. The first is a defined test; the second lets the manufacturer define it — which is where selection goes wrong.
An IP rating is a two-digit code for how well an enclosure keeps out solid objects and water, defined in IEC 60529. The first digit covers solids, the second covers water. IP67 and IP68 share the same first digit — full protection against dust — and differ in the second, which is where the misunderstanding starts: IP67 is a defined test, IP68 is a defined category whose test conditions the manufacturer states.
That single sentence decides more sourcing arguments than any other line in this article.
| Digit | Level | What it means for a harness |
|---|---|---|
| First (solids) | 4 | Protected against objects over 1 mm — effectively a wire blocked by a mesh or a grommet |
| 5 | Dust-protected — some dust ingress is permitted, none that interferes with operation | |
| 6 | Dust-tight — no ingress at all under the test | |
| Harnesses are normally specified at 6. A lower first digit means the connector was chosen on cost, not on the environment. | ||
| Second (water) | 4 | Splashing water from any direction |
| 5 | Water jets from a nozzle, low pressure | |
| 6 | Powerful water jets, higher pressure | |
| 7 | Temporary immersion — the standard condition is 1 m for 30 minutes | |
| 8 | Continuous immersion — depth and duration stated by the manufacturer | |
| IP67 | IP68 | |
|---|---|---|
| Immersion condition | Fixed by the standard: 1 m, 30 minutes | Agreed by the manufacturer and stated on the datasheet — commonly 1.5 m or deeper, for a longer period |
| Comparable between suppliers? | Yes — every IP67 claim describes the same test | Only if both state their conditions. Two IP68 parts can be tested to very different severities. |
| What it suits | Parts that get splashed, rained on, or briefly submerged — road spray, wash-down, a puddle crossing | Parts that live under water, or that must survive a submersion event whose duration is not controlled |
| Common error | Assuming 1 m for 30 minutes covers a sustained splash at pressure | Treating the rating as evidence without reading the stated depth and duration |
So the answer to "is IP68 better than IP67" is: it is stricter only if the stated depth and duration are stricter. An IP68 part tested at 1 m for 30 minutes is an IP67 part with a different label. Ask for the condition, in writing, before treating the higher number as the safer choice.
Two suppliers can both claim IP67 and produce very different parts, because the number does not describe how the test was run:
A supplier who can answer all four has done the test properly and knows exactly what it does and does not prove. A supplier who answers only with the number has read the datasheet.
IP69K adds protection against close-range high-pressure, high-temperature water jets and is the rating to ask for on anything cleaned with a pressure washer — construction machinery, food processing equipment, some agricultural applications. It is not "higher than IP68"; it tests a different exposure. A part can be IP69K and fail an immersion test, and vice versa.
More importantly, the IP code says nothing about three conditions that decide whether a harness survives in the field:
Cold climate does not show up in an IP rating at all, and it changes the material selection more than a supplier's datasheet usually admits. Three effects matter:
An ingress rating is a property of the whole assembly, not of the connector alone. Four things have to be right at the same time:
That is why an IP requirement belongs in the specification rather than in the part number: it constrains the seals, the moulding, the test and often the choice of connector family, and it needs to be on the drawing before the part is quoted. For the families where this comes up most:
Only if the stated conditions are more severe. IP67 is a fixed test — one metre for thirty minutes — while IP68 is a category in which the manufacturer states the depth and the duration. IP68 tested at one metre for thirty minutes is the same performance as IP67 under a different label. Before treating the higher figure as the safer choice, ask for the depth and duration in writing; if the supplier cannot state them, the IP68 claim is a marketing position rather than a test result.
It says nothing about temperature cycling, chemical or salt exposure, vibration, flex life, or low-temperature flexibility. Those five decide most field failures on a harness, and each is qualified by a different test. A part can hold a valid IP67 rating and still fail after two winters because the seal took a compression set, or fail at sixty thousand kilometres because the jacket hardened and cracked at the cold end of its range. Specify those separately, and ask for the qualification evidence for each.
State the low end of the operating temperature explicitly and treat it as a materials decision rather than a note. That means checking the insulation material against the cold extreme rather than the ambient, re-checking the minimum bend radius at that temperature — a radius that is fine at 20 ℃ can crack a jacket at −30 ℃ — and asking for a thermal cycling result on the seals rather than an ingress test alone. If the assembly is also flexed, the flex qualification has to be run at the cold extreme too, because a cycle count established at room temperature does not transfer.
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