IP66 vs IP67: What Is the Difference?

IP66 and IP67 are ingress protection ratings under IEC 60529 that share the same dust rating and test different water hazards. The first digit, 6, means both are dust tight. The second digit is where they part: 6 is a powerful water jet test and 7 is an immersion test.

It is easy to assume a higher second digit always means better protection, but the standard does not work that way for jets and immersion. An enclosure that survives sitting under water may still let in a hard jet, because the jet strikes the seals with a force still water never applies. Equally, an enclosure that shrugs off a hose may leak when held under water with the pressure acting on every seal at once. That is why rugged computers often list two ratings, such as IP66/IP67.

IEC 60529 sets out each test in detail. The table summarizes the parts that matter when choosing between them.

Our IP rating chart sets both ratings alongside IP65, IP68 and IP69K.

Neither is better in general. Each is better for its own hazard, so the right choice depends on what the site will throw at the equipment:

Outdoor equipment rarely faces only one kind of water. A computer on a quayside is hit by spray and may be flooded by a storm surge. A camera controller on a road verge is rained on and splashed by traffic, and its cabinet may stand in floodwater. A vehicle computer is pressure-washed with the vehicle and sometimes driven through deep water.

For those sites, look for both codes on the datasheet. If only one is listed, ask the manufacturer whether the other test was run. The rating also holds only with the connectors as tested, so unused ports need their sealing caps and cables need rated glands or sealed M12 connectors. Our guide to what IP66 means covers the jet test in more detail.

An IP code describes one tightly defined test on a new enclosure. It says nothing about several things that decide whether a sealed system lasts outdoors:

High pressure and heat. Neither test uses hot water or a pressure washer at close range. Vehicle wash bays and food plants need IP69K for that.

Condensation. A sealed box that warms up by day and cools at night can draw in moist air through its seals and collect water inside. Conformal coating, desiccant or a breather vent with a membrane deals with this.

Ageing seals. Gaskets harden with UV, heat and cleaning chemicals. The rating holds only while seals are intact and covers are refitted correctly after maintenance.

Corrosion and ice. IEC 60529 has no salt, chemical or icing test. Specify the enclosure material and coating separately, or look at NEMA 4X where corrosion matters.

Sealed industrial computers handle water without vents or fans. Heat leaves through the chassis instead, so the enclosure can be closed completely and gasketed at every joint. Panel PCs are usually sealed on the front only, which is enough when the back sits inside a cabinet, while fully sealed versions are rated on every face.

Our IP66 computers and IP67 computers list their ratings on each product, and our front IP66 panel PCs suit enclosures and machine doors that are hosed from the front.

We supply IP66 and IP67 computers and panel PCs with sealed connectors, cables and mounting matched to the site, and integrate and test each system before it ships. Tell us how the equipment will meet water, and we will recommend the rating to suit.