# IP65, IP67, IP68: making sense of the IP rating

What does IP68 actually mean on an industrial sensor? A breakdown of the two digits, the common pitfalls, and how to choose between IP65 and IP68 on site.

Publié le 2026-09-18 par DigitalWan — /en/blog/ip-protection-rating/

## In short

- An IP rating is read digit by digit: the first covers dust, the second water.
- IP68 means dust-tight and resistant to prolonged immersion; IP65 protects against water jets, not immersion.
- An IP68 enclosure does not remove the need for a properly tightened cable gland — that is where water actually gets in.

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On a datasheet, “IP68” takes four characters — and yet it decides how long a sensor will survive in a cable chamber that fills up with every storm. Here is how to read the rating, and what it does not tell you.

## Two digits, two different protections

The IP rating (*Ingress Protection*), defined by standard IEC 60529, is always read the same way: **the first digit covers solid objects, the second covers liquids.**

| Rating | Dust | Water |
| --- | --- | --- |
| IP54 | Protected, limited ingress | Splashing |
| IP65 | Dust-tight | Water jets from any direction |
| IP67 | Dust-tight | Temporary immersion (1 m, 30 min) |
| IP68 | Dust-tight | Prolonged immersion, conditions set by the manufacturer |

Two points are often missed:

- **A higher rating does not always include the one below.** IP67 guarantees temporary immersion, IP68 prolonged immersion — but neither formally guarantees the pressurised jet resistance of IP65. In practice, serious industrial enclosures cover both, but the distinction exists.
- **IP68 is the only rating whose conditions are set by the manufacturer.** Depth, duration, water temperature: these are test parameters, not an absolute value.

## What the IP rating does not cover

This is where most in-service failures actually happen. The IP rating says nothing about:

- **UV exposure**: untreated polycarbonate yellows and turns brittle after a few summers;
- **mechanical impact**: that is the IK rating, an entirely separate scale;
- **corrosion**: a wastewater environment, loaded with hydrogen sulphide, attacks metals and seals;
- **entry points**: a loose cable gland, a pinched probe cable, a connector left open. That is almost always how water gets in.

This is why the enclosures in the range are described as “IP68, UV-resistant polycarbonate”: sealing is not enough if the material ages badly outdoors.

## IP65 or IP68: how to choose

The rule fits in one question: **can the device end up underwater, even for an hour, even once a year?**

- **Yes** — cable chamber, manhole, buried substation, unsheltered outdoor location: IP68. That is the case for the [MSU-SD7](/en/products/msu-sd7/), MSU-MD7, [MSU-XD7](/en/products/msu-xd7/) and MSU-LD7 units and the [MSU-G7](/en/products/msu-g7/) and MSU-SG7 gateways.
- **No** — technical room, indoor cabinet, suspended ceiling, inside an already sealed enclosure: IP65 is enough, and allows a far more compact format. That is the role of the [SU-CD7](/en/products/su-cd7/), an ultra-flat 15 mm sensor explicitly intended for indoor or sheltered environments.

Specifying IP68 everywhere looks cautious, but costs in size and price. Specifying IP65 in a wet structure is scheduling a site visit.

## Three habits at installation

1. **Tighten the cable gland to torque**, with a cable of the right diameter. A gland designed for a 5 mm cable will never seal on a 3 mm one.
2. **Plug what you do not use.** A probe entry left open cancels the rating of the whole enclosure.
3. **Place the sensor out of the run-off path** where possible: under a cover rather than facing the water inlet, above the known high-water mark rather than at the bottom of the structure.

An IP rating is a design guarantee, not blanket insurance. Installation is what decides.
## Frequently asked questions

### What does IP68 mean exactly?

The 6 means the enclosure is completely dust-tight. The 8 means it withstands prolonged immersion in water, under depth and duration conditions defined by the manufacturer. The reference standard is IEC 60529.

### What is the difference between IP65 and IP68?

Both are dust-tight. IP65 protects against water jets from any direction but not against immersion: it suits indoor or sheltered environments. IP68 withstands prolonged immersion and suits outdoor use, including a chamber liable to flood.

### Can an IP68 sensor stay underwater permanently?

The IP68 rating is defined by the manufacturer in terms of depth and duration: it guarantees resistance to prolonged immersion, not permanent operation under several metres of water. For a structure that is regularly flooded, say so at the design stage.