IP Rating (Electrical Enclosures – Ingress Protection)

The IP Rating specifies protection of electrical equipment against the ingress of water and foreign objects, and against dangerous contacts in general. The following table describes significance of the first and the second digit in the IP Rating.

Electrical Enclosure Types and Ingress Protection Values

The first digit in the IP Rating signifies protection against dangerous contacts/ingress of foreign objects.
Ingress Protection Values of the First Digit:
IP0x No Protection
IP1x Objects > 50 mm
IP2x Objects > 12 mm
IP3x Objects > 0.5 mm
IP4x Objects > 1 mm
IP5x Dust-Protected
IP6x Dust-Tight

The second digit in the IP Rating signifies protection against ingress of water.
Ingress Protection Values of the Second Digit:
IPx0 No Protection
IPx1 Vertically Dripping Water
IPx2 75 to 90 Degrees Dripping Water
IPx3 Sprayed Water
IPx4 Splashed Water
IPx5 Water Jets
IPx6 Heavy Seas
IPx7 Effects of Immersion
IPx8 Indefinite Immersion

Example:
plastic junction box has IP Rating of 55:

junction box protected against dangerous contact of "any object"
against regress of foreign objects – "partial dust protection" (not entirely dust-tight)
against regress of water jets coming from "any direction"