The IP rating - what does it mean when buying test equipment?

6 December 2013

Somewhere in the fine print of most test equipment product literature you’ll find an IP rating. “IP” stands for ‘ingress protection’ – in other words, the degree to which an instrument can withstand invasion by foreign matter.

Established by the IEC (International Electrotechnical Commission), in their Standard 529, the IP rating system is used as a guide to help end users protect the life of the instrument they are working on as well as help them make a more informed purchase decision by ensuring that the piece of test equipment is designed to work in the environment(s) that he/she faces.

The IP rating is comprised of two digits, each signifying a separate characteristic.  The designation indicates how well the item is sealed against invasion by foreign matter, both moisture and dust - the higher the number(s), the better the degree of protection. What would a typical rating of IP54 tell a buyer about the application capabilities of a model? If you want to sound thoroughly knowledgeable, that’s IP five-four, not fifty-four.  Each digit relates to a separate rating, not to each other. Remember, the IP rating should appear in all product literature.

Question the quality of equipment you are purchasing if the literature does not show an IP rating.

Protection against access to hazardous parts (first digit)
Number Description
0 Non-protected
1 Protected against access with back of hand (50 mm)
2 Protected against access with jointed finger (12 x 80 mm)
3 Protected against access with a tool (2.5 mm)
4, 5, 6 Protected against access with a wire (1.0 mm)


Protection against ingress of solid foreign objects (first digit)
Number Description
0 Non-protected
1 Objects equal or greater than 50mm
2 Objects equal or greater than 12.5mm
3 Objects equal or greater than 2.5mm
4 Objects equal or greater than 1mm
5 Dust protected
6 Dust tight


Protection against Ingress of liquids (second digit)
Number Description
0 Non-protected
1 Water dripping vertically
2 Water dripping, enclosure tilted up to 15°
3 Spraying water, up to 60° angle from vertical
4 Splashing water, any direction
5 Jetting water, any direction
6 Powerful jetting water, any direction
7 Temporary immersion in water
8 Continuous immersion in water