A three-digit number is used to provide an IP Rating to a piece of electronic or to an enclosure for electronic equipment.
The three digits represent three different forms of environmental influence:
- The first digit represents protection against ingress of solid objects
- The second digit represents protection against ingress of liquids
- The third digit represents protection against mechanical impact damage.
The third digit is often omitted, resulting in a 2-digit IP Rating covering ingress against solid objects and liquids only. The larger the value of each digit, the greater the protection from that influence.
As an example, a product rated as IP573 would be better protected against environmental factors than another similar product that was only rated as IP432. The third digit (mechanic impact) may be omitted.
Most marine products are usually rated as IPx, the x signifying the omitted third digit, mechanical impact.