If you've ever read a product spec and seen "IP67" or "IP68", you've probably nodded along without being sure what it promised. You're not alone. IP ratings are among the most useful numbers on a spec sheet and among the most misunderstood.
On a boat, that matters. Salt, spray, rain, washdowns and the occasional wave over the bow all test your electronics.
In a van, severe thunderstorms, dusty trails and bugs/debris often identify weak points in your van build.
Here's what an IP rating tells you, and why it should be part of every buying decision.
What Do IP Ratings Mean?
IP stands for Ingress Protection. An IP rating describes how well an enclosure or product resists solids (dust, dirt, fingers, tools) and liquids (spray, jets, immersion) getting inside.
The system is defined by the international standard IEC 60529, so the rating means the same thing whoever makes the product. It gives you a common language for comparing kit, rather than relying on phrases like "weatherproof" or "marine grade", which have no formal definition.
What Do the Numbers Stand For?
An IP rating has two digits, and each one answers a different question.
The first digit (0 to 6) is protection against solid objects and dust. Higher is better.
The second digit (0 to 9) is protection against water. Higher generally means more protection, though not always, as we'll cover below.
So IP68 reads as: a 6 for solids (completely dust-tight) and an 8 for water (protected against continuous immersion).
If a product has only been tested for one of the two, the untested digit is replaced with an X. IPX6, for example, tells you about water resistance but says nothing about dust.
What Each Level Means in Practice
First digit: solids
| Digit | What it means in the real world |
| 0 | No protection |
| 1 | Keeps out objects larger than 50mm, such as the back of a hand |
| 2 | Keeps out objects larger than 12.5mm, such as a finger |
| 3 | Keeps out objects larger than 2.5mm, such as tools and thick wires |
| 4 | Keeps out objects larger than 1mm, such as small wires and screws |
| 5 | Dust protected. Some dust may get in, but not enough to interfere with operation |
| 6 | Dust-tight. No dust gets in at all |
For marine/RV use, a 6 is what you want. Salt crystals and grit are abrasive and corrosive, and they find their way into anything with a gap. If there is a 6 rating, you can sleep easy knowing that there is full protection.
Second digit: water
| Digit | What it means in the real world |
| 0 | No protection |
| 1 | Protected against vertically dripping water |
| 2 | Protected against drips when tilted up to 15° |
| 3 | Protected against spray up to 60° from vertical, like light rain |
| 4 | Protected against splashing from any direction |
| 5 | Protected against low-pressure water jets, like a hose |
| 6 | Protected against powerful water jets, like heavy seas or a pressure-washer style blast |
| 7 | Protected against temporary immersion, up to 1 metre for 30 minutes |
| 8 | Protected against continuous immersion, under conditions set by the manufacturer |
| 9 | Protected against high-pressure, high-temperature jets |
Two things are worth knowing here.
Higher isn't always "better" in the way you'd assume. A product rated IPX6 has been tested against powerful jets, but that doesn't automatically mean it's been tested against immersion. Some products carry more than one rating, such as IPX6 and IPX7, precisely because jets and submersion are different challenges.
IP68 is set by the manufacturer. The standard says an IPX8 product must survive continuous immersion beyond 1 metre, but the exact depth and duration are agreed between the manufacturer and the test, not fixed by the standard. Always check what the depth and time were before assuming it suits your application.
A Real Example: The Scanstrut Cable Seal
If you want to see why IP ratings matter, look at a cable entry point. Every cable you run through a deck or roof is a potential leak, and that's exactly where a good rating counts.
Take the Scanstrut DS30-P Vertical Cable Seal. It's rated IP68 and 100% waterproof, supplied with both pre-drilled and blank inner seals to make installation easier. The split-seal option also means you don't need to remove cable connectors during installation.
There's a practical reason this matters. A conventional cable gland often depends on sealant, which degrades over time under UV, vibration and temperature swings. A mechanically compressed seal that has been tested to IP68 gives you a watertight entry you can trust, and one you can open up and re-use when you upgrade your wiring.
The rating is what turns "we think this is watertight" into "this has been tested and proven to be."
How Are IP Ratings Tested?
An IP rating isn't a marketing claim. To carry one, a product has to pass defined tests under IEC 60529.
Solids testing. For the lower dust ratings, probes of set sizes are applied to the enclosure to see whether they can get in. For the top rating (6), the product is placed in a chamber and a vacuum draws air through it, typically for up to 8 hours, to confirm that no dust penetrates. It's a hard test to pass.
Water testing. This varies with the rating:
- IPX3 and IPX4: water is sprayed or splashed at the product from set angles using an oscillating tube or spray nozzle.
- IPX5 and IPX6: water is fired from a nozzle of a defined size and flow rate at a set distance. For IPX6, that's a 12.5mm nozzle delivering 100 litres per minute from 3 metres, for at least 3 minutes.
- IPX7: the product is submerged to a depth of 1 metre for 30 minutes.
- IPX8: the product is submerged for longer and/or deeper, under conditions agreed with the manufacturer, and must remain watertight throughout.
After each test, the product is inspected. If water or dust has got in to a degree that affects performance or safety, it fails.
Why You Should Consider IP Ratings When You Buy
1. They replace vague claims with evidence. "Waterproof", "weatherproof" and "marine-ready" mean whatever the seller wants them to mean. An IP rating means the product passed a specific, repeatable test.
2. They help you match the product to the location. A charging point in a dry cabin locker doesn't need the same protection as one on an open helm or a cockpit bulkhead. An IP rating lets you buy what you need and avoid both overspending and under-protecting.
3. Failures are expensive and often hidden. Water ingress rarely announces itself. It shows up as corroded connections, intermittent faults, dead electronics and damage behind panels weeks or months later. The cost of the repair is nearly always higher than the cost of the right product in the first place.
4. Safety. Water and electricity are a poor combination. A properly rated product reduces the risk of short circuits and electrical faults, especially on a vessel where you can't just walk away from a problem.
5. Longevity. Products built to a high IP standard tend to be built better overall, with better seals, materials and tolerances. You buy once rather than replacing every season.
6. Peace of mind. Once you're offshore or the weather turns, you want your equipment to keep working without a second thought.
The Bottom Line
The next time you're comparing products, check the rating. Look at both digit then ask yourself where the product will live and what it will be exposed to.
If it will be on a boat, a high IP rating isn't a luxury. It's the difference between kit that survives the marine environment and kit that merely tolerates it.
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