An IP rating is usually a two-digit grading system that is applied to the enclosure of a mechanical or electrical item, giving customers a clear indication of the item’s resistance to various types of unwanted intrusion. They are used to define levels of sealing effectiveness of electrical enclosures against intrusion from foreign bodies (tools, dirt etc) and moisture.

In the UK, IP codes are assigned in accordance with British standard BS EN 60529:1992. In Europe, they fall in line with IEC standard 60509:1989, and internationally they conform to EN 60529 certification.

IP rating denotes three key metrics:

• Resistance to ingress, accidental or otherwise, by the user
• Resistance to ingress from foreign bodies (dust, dirt etc)
• Resistance to moisture ingress

In general, an IP rating will consist of two digits, occasionally followed by a letter denoting specific materials, hazards or testing scenarios. The most common way you will see such a rating given will be in the format ‘IP43’, ‘IP67’, or similar.

The second digit in an IP rating will be a number between 0-9, denoting the quality of resistance to moisture ingress at varying intensities, angles, depths and pressures of exposure or immersion.

In some cases, an additional letter may be appended to the end of an IP rating, e.g. ‘IP67M’. This is done to indicate either certified resistance to specific materials/hazards, such as oil or high voltages, or a particular scenario in which the IP testing was conducted (for example in moving water).