The IP code (IEC 60529) describes protection against solids and water. For outdoor lighting, the second digit is the one that matters day to day.
The ratings you will see
| Rating | Water protection | Typical outdoor use |
|---|---|---|
| IP65 | Water jets from any direction | Wall-mounted and elevated luminaires |
| IP66 | Powerful water jets | Exposed coastal positions, bridges |
| IP67 | Temporary immersion | In-ground luminaires, flood-prone areas |
| IP68 | Continuous immersion (conditions set by maker) | Buried luminaires with standing water, water features |
Ratings are only half of it
Most outdoor failures we see come from installation, not from the luminaire body:
- Cable entries, use the specified glands and seal unused entries.
- Joints and connectors, field joints need a rating equal to the luminaire, ideally gel-filled or moulded.
- Drainage, in-ground luminaires need a drained gravel bed. A sealed box sitting in a water-filled hole will eventually draw water in through the cable as it cools at night.
- Thermal cycling, luminaires that heat and cool daily "breathe". Pressure-equalising valves and good seals handle this; improvised sealing does not.
Specify for the position
Choose the rating for the worst case at that location, the base of a slope, a coastal façade, a fountain edge, rather than one rating for the whole project.