IP Ratings – Ingress Protection (IP) ratings is the standard rating for sealing electrical devices against dust and moisture.

IP Rated Enclosures
First Digit (intrusion protection)
0No special protection
1Protection from a large part of the body such as a hand (but no protection from deliberate access); from solid objects greater than 50mm in diameter.
2Protection against fingers or other object not greater than 80mm in length and 12mm in diameter.
3Protection from entry by tools, wires etc, with a diameter of 2.5 mm or more.
4Protection against solid bodies larger than 1mm (eg fine tools/small etc).
5Protected against dust that may harm equipment.
6Totally dust tight.
Second Digit (moisture protection)
0No protection.
1Protection against condensation.
2Protection against water droplets deflected up to 15° from vertical
3Protected against spray up to 60° from vertical.
4Protected against water spray from all directions.
5Protection against low pressure water jets (all directions)
6Protection against string water jets and waves.
7Protected against temporary immersion.
8Protected against prolonged effects of immersion under pressure.

IP Ratings look like this: IP65, IP45, IP54, etc.

Example: An IP65 rating means it is totally dust tight and is protected from low pressure water jets.