Overview: This is a brief introduction about IP Code in Wikipedia, refer to the link below the article to view all about IP Code.

The IP Code, or Ingress Protection Code, classifies and rates the degree of protection provided by mechanical casings and electrical enclosures against intrusion, dust, accidental contact, and water.
For example, a product with IP46CH (maybe won't exist in theory), the 46CH followed IP means as follows the table.
1st: solid particle |
4 |
> 1mm (Most wires, slender screws, large ants, etc.) cannot ingress |
2nd: liquid ingress |
6 |
Water projected in powerful jets no harmful effects. Test duration: 1 minute per square meter for at least 3 minutes Water volume: 100 liters per minute (0.37 impgal/s) Pressure: 100 kPa (15 psi) at distance of 3 meters (9.8 ft) |
3rd: additional |
C |
Tools > 2.5mm |
4th: supplementary |
H |
High voltage apparatus |
It means this high voltage apparatus device can prevent solid particles > 1mm ingress in usual, but tools < 2.5mm could ingress with personnel against. And it has the best waterproof level below the soak requirement.
According to standard. The 1st digit ranged from 0 (no protect) to 6 (complete protect) degree marked solid particle protection. The 2nd digit ranged from 0 (none) to 8 (Immersion, 1 meter / 3 ft / 3 in or more depth). And the optional 3rd / 4th letter for other protections. Those 2 digits allowed to replace with the letter X when insufficient data has been gathered to assign a protection level.

There used to be another number ranged from 0 to 9 for impact resistance degrees before the optional letters. It was replaced by IK code in standard EN 62262.
That’s all about the short introduction about IP code and IPX6. See also the link follows to learn more.
Ref: IP Code in Wikipedia