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A company installs a new LED sign outside its warehouse. It works fine for about a month. Then a heavy storm rolls through on a Friday night. By Monday, half the lights are flickering and the control box is full of condensation. The installer shrugs and says, “It was supposed to be waterproof.”
That scene plays out all the time with outdoor equipment, and the blame usually lands on a misunderstood spec: the IP rating. If you buy connectors or switches, you have seen IP67 and IP68 on listings. They look similar. They are not the same.
This guide covers what the numbers mean, how IP67 and IP68 compare, and what a rating does and does not guarantee.
What an IP Rating Actually Tells You
An IP rating comes from the IEC 60529 standard, which defines how well an enclosure protects what is inside. IP stands for Ingress Protection.
The key word is enclosure. The rating describes the housing of a specific product as tested: a connector shell, a switch body, a junction box. It does not describe the terminals inside, nor parts outside that tested assembly.
The rating also assumes correct assembly, as the product leaves the factory.
Understanding the Two Digits in an IP Rating
Every IP code has two digits, and each one tests a different enemy.
First Digit: Solids and Dust
The first digit runs from 0 to 6 and covers solid objects, from a hand down to fine dust. A 0 means no protection. A 5 means some dust can enter but not enough to interfere with operation. A 6 means dust-tight: no dust gets in at all.
That is why IP6x codes dominate connectors and switches. In a dusty setting like a farm, that first digit matters as much as the second.
Second Digit: Liquids and Water
The second digit runs from 0 to 8 and covers water, from light dripping to full submersion. The short version:
Two notes. The tests use clean water, not salt water or chemicals. For a rating of 8, the standard sets no depth or time; the manufacturer chooses and publishes them.
- 0: no protection
- 1 to 4: dripping and spraying water
- 5: water jets from a nozzle
- 6: powerful water jets
- 7: temporary immersion in water
- 8: continuous immersion, with depth and duration set by the manufacturer
IP65 vs IP66 vs IP67 vs IP68: The Everyday Version
These four ratings show up constantly on connectors and switches. Here is what each one means in practice:
A quick way to choose: rain and splashes only, IP65 is enough. Possible dunking in a flood, IP67 covers that. Submerged for days, go IP68 and check the published depth and duration.
One nuance: a higher second digit does not mean the product passed every lower test. An IP68 connector may never have been tested with the jet spray of IP66, so check the datasheet.
- IP65: dust-tight and protected against water jets. Fine for rain, hose-downs, and outdoor exposure where nothing sits in standing water.
- IP66: dust-tight and protected against powerful water jets. Built for heavy washdown conditions, like food plants cleaned with high-pressure hoses. The jump from 5 to 6 is mostly about how hard the water hits the surface.
- IP67: dust-tight and protected against temporary immersion. This is the rating people usually mean when they say “waterproof.” It can be dunked and survive, but it is not designed to live underwater.
- IP68: dust-tight and protected against continuous immersion. It can stay submerged as long and as deep as the manufacturer specifies. This is the rating for gear that lives underwater.
What an IP Rating Doesn’t Tell You
A lot of field failures start here. Two IP67 connectors from different brands can behave very differently in the same rainstorm, because the rating describes the result, not the method.
Sealing Method
A molded or potted connector uses solid material, with no joint to fail. A connector that relies on an O-ring or gasket depends on that rubber staying soft, seated, and compressed. O-ring designs can be perfectly fine, but the seal is only as good as the part and the assembly. Ask how the seal is made and what the material is rated for. Silicone, NBR, and EPDM behave differently in heat and cold.
Installation Quality
The rating assumes the product was installed as the manufacturer intended. That is where things go wrong:
Any of these turns an IP67 part into something closer to IP40. The rating only holds when you follow the mounting instructions.
- Connector halves not fully seated or locked.
- Cable glands tightened by hand instead of to spec.
- Gaskets pinched, twisted, or missing after a repair.
- Panel cutouts larger than the mounting spec, leaving a gap around the switch.
How to Choose for Common Applications
There is no single best rating. The right choice depends on what the equipment will face.
Outdoor Panels and Enclosures
For a wall-mounted control panel or junction box, water arrives as rain, splashes, and hose-downs. IP65 or IP66 covers nearly all of these, and both keep dust out completely. Immersion protection is usually overkill here.
The parts that break the enclosure matter as much as the box itself. Industrial power connectors and durable industrial sockets should carry their rating in the datasheet, and the panel cutout has to match the mounting spec. Rocker switches with sealed housings protect the control surface the same way, but a sloppy cutout defeats the gasket. Water will find any gap you leave.
EV Chargers
EV charging stations sit outside for years, in rain, snow, and road spray. The wet-side connectors typically need at least IP67, and many designs go to IP68 for connectors that could sit in standing water. If your site could flood, IP68 with a published depth rating is safer.
Solar Installations
Solar wiring runs through junction boxes, combiner boxes, and rooftop penetrations. IP65 or IP66 is common for rooftop boxes, while connectors that can sit in standing water on flat roofs should move up to IP67. Also think about heat. Black boxes in full sun get hot, and gaskets age faster.
Marine and Coastal
Salt water changes the conversation. IP ratings are tested with clean water, so a rating alone does not tell you how a product will survive salt spray or constant damp. Weigh housing material and corrosion resistance as much as the rating. Molded connectors are often preferred because they have fewer joints for salt to work into.
Common Misconceptions About IP Ratings
A few myths cause most of the confusion.
IP68 is not automatically better than IP67. It is better for submersion, but an IP68 product may not have been tested for jet spray, and its limits can be modest. Compare the published conditions, not the number.
An IP rating does not mean the product is waterproof forever. Seals wear, gaskets age, and repeated plugging takes a toll. Ratings are tested on new parts in a lab.
A higher second digit does not cover everything below it. Each rating is its own test. Verify which tests were actually run.
The rating only holds when the product is installed per the manufacturer’s instructions.
Waterproof does not mean it handles any liquid. The tests use clean water. Solvents, oils, and salt water are different challenges.
Match the rating to the conditions the part will face. Rain and hoses call for IP65 or IP66. Temporary dunking calls for IP67. For gear that lives underwater, IP68, with depth and duration in writing. Install it right; the seal only works if you let it. When in doubt, ask for the datasheet.
