The second number in the IP rating represents how well sealed the unit is against water. Whether it is coming from a high pressure hose during washdown or simply from liquid splashing off a production line, making sure the unit is sealed is vital prolonging the life of essential electronics.
IP ratings use two numbers, and occasionally additional letters, to designate the level of sealing the unit has against solids and against dust. As defined in international standard IEC 60529, the rating delineates the degrees of protection against the intrusion of solid objects (including body parts like hands and fingers), dust, and water in electrical enclosures. The standard aims to provide users with a quantifiable standard in place of vague and generic terms such as “sealed” and “waterproof”
The first number represents how well the unit can prevent solids from entering the unit. This includes large objects such as fingers, bolts, and wires but also fine dust all of which can harm and disrupt internal components.