How do Ingress Protection ratings (IP ratings) work?

(information rovided for guidance only, detailed reference advice should be taken from an appropriate compentent agency)

An IP number contains two numbers (i.e. IP65) in most instances which relate to the

 level of protection provided by an enclosure or housing.

The first number relates to protection from solids as follows:

0: No Special Protection 

1: Protected against solid objects up to 50 mm in diameter 

2: Protected against solid objects up to 12 mm in diameter 

3: Protected against solid objects up to 2.5 mm in diameter 

4: Protected against solid objects up to 1 mm in diameter 

5: Dust protected 

6: Dust tight

The second number relates to protection from liquids as follows:

0: No special protection 

1: Protected against dripping water 

2: Protected against dripping water when tilted up to 15° from normal position 

3: Protected against spraying water 

4: Protected against splashing water 

5: Protected against water jet spray 

6: Protected against heavy jet spray 

7: Protected against the effects of immersion 

8: Protected against submersion

Example: IP66 = Dust tight and protected against heavy water jet spray

NEMA (National Electrical Manufacturers Association) ratings can be approximately 

compared to those of the IP system as shown below. Other factors such as corrosion protection are involved in the NEMA system, please refer to official documentation for details.

NEMA 1 =   IP10 

NEMA 2 =   IP11 

NEMA 3 =   IP54 

NEMA 4 =   IP56 

NEMA 4X = IP66 *Addition requirements apply

NEMA 6 =   IP67 

NEMA 12 = IP52 

NEMA 13 = IP54