I hope that the following information which is given below will be of some help to you. 

The British Standard EN 60529 outlines an international classification sysyem for the sealing effectiveness of enclosures of electrical equipment against the intrusion into the equipment of foreign bodies from i.e. hands, fingers, tools, dust and moisture etc. This classification system utilizes the letters IP which stands for Ingress Protection followd by two or three digits. A third digit is sometimes used. An "X" is used for one of the digits if there is only one class of protection; i.e. IPX4 which addresses moisture resistance only. You may find this used in the IEE Regulation covering bathroom regulations.

Degrees of protection for the first digit.

The first digit of the IP code indicates the degree that persons are protected against contact with moving parts (other than smooth rotating shafts, etc.) and the degree that equipment is protected against solid foreign bodies intruding into an enclosure.

0	No special protection
1	Protection 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.
2	Protection against fingers or other object not greater than 80mm in length and 12mm in diameter.
3	Protection from entry by tools, wires, etc., with a diameter of thickness greater than 1.0mm.
4	Protection from entry by solid objects with a diameter or thickness greater than 1.0mm
5	Protection from the amount of dust that would interfere with the operation of the equipment.
6	Dust tight.

Degrees of protection for the second digit.

The second digit indicates the degree of protection of the equipment inside the enclosure against the harmful entry of various forms of moisture (e.g. dripping, spraying, submersion, etc.)

0	No special protection
1	Protection from dripping water.
2	Protection from vertically dripping water.
3	Protection from sprayed water.
4	Protection from splashed water.
5	Protection from water projected from a nozzle
6	Protection against heavy seas, or powerful jets of water.
7	Protection against immersion.
8	Protection against complete, continuous submersion in water.

Submersion depth and time must be specified by the end-user. The requirement must be more onerous than IP67.