IP53, IP66 - what do they actually mean?

The IP (Ingress Protection) code describes what elements a product is protected against.
The first digit stands for protection against foreign objects (like dust), the second for protection against moisture.

IP53 ("semi-rugged") means:

- IP5X: The device is protected against harmful quantities of dust (dust-protected)
- IPX3: The device is protected against spraying water up to 60° from the vertical

IP66 ("fully-rugged") means:

- IP6X: The device is completely protected against dust (dustproof)
- IPX6: The device is protected against powerful water jets