International standard IEC 60529 classifies the level of protection that electrical appliances provide against the intrusion of solid objects or dust, accidental contact, and water. The resulting ingress protection rating is identified by a code that consists of the letters IP followed by two or three digits and an optional letter. The digits ('characteristic numerals') indicate conformity with the conditions summarized in the tables below. The third character is often omitted, resulting in a 2 digit IP rating covering ingress protection against solid objects and liquid only. Where nothing is said with regard to one of the first two digits, it is replaced with the letter X.
For example, an electrical socket rated IP22 is protected against insertion of fingers and will not be damaged or become unsafe when exposed to vertically or nearly vertically dripping water. IP22 or IP2X are typical minimum requirements for the design of electrical accessories for in-door use.
First digit
Protection of persons against contact with or approach to live parts and against contact with moving parts (other than smooth rotating shafts and the like) inside the enclosure and protection of the equipment against ingress of solid foreign bodies.
| Level | Object size protected against | Effective against |
|---|---|---|
| 0 | — | no protection against contact and ingress of objects |
| 1 | >50 mm | any large surface of the body, such as the back of a hand, but no protection against deliberate contact with a body part |
| 2 | >12.5 mm |
fingers or similar objects |
| 3 | >2.5 mm |
tools, thick wires, etc. |
| 4 | >1 mm |
most wires, screws, etc. |
| 5 | dust protected |
ingress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment; complete protection against contact |
| 6 | dust tight |
no ingress of dust; complete protection against contact |
Second digit
Protection of the equipment inside the enclosure against harmful ingress of water.
| Level | Protected against | Details |
|---|---|---|
| 0 | not protected | — |
| 1 | dripping water |
Dripping water (vertically falling drops) shall have no harmful effect. |
| 2 | dripping water when tilted up to 15° |
Vertically dripping water shall have no harmful effect when the enclosure is tilted at an angle up to 15° from its normal position. |
| 3 | spraying water |
Water falling as a spray at any angle up to 60° from the vertical shall have no harmful effect. |
| 4 | splashing water |
Water splashing against the enclosure from any direction shall have no harmful effect. |
| 5 | water jets |
Water projected by a nozzle against enclosure from any direction shall have no harmful effects. |
| 6 | heavy seas |
Water from heavy seas or projected in powerful jets shall not enter the enclosure in harmful quantities. |
| 7 | the effects of emersion |
Ingress of water in harmful quantity shall not be possible when the enclosure is immersed in water under defined conditions of pressure and time. |
| 8 | submersion |
The equipment is suitable for continuous submersion in water under conditions which shall be specified by the manufacturer. |
Third digit
An optional third digit can be added to indicate how well the device is protection against mechanical impact damage. The table lists both the impact energy in joules, as well as the mass of a test opject that will provide this impact energy if dropped from the given height above the impact surface.
| Level | Impact energy | Equivalent drop mass and height |
|---|---|---|
| 0 | — | — |
| 1 | 0.225 J |
150 g dropped from 15 cm |
| 2 | 0.375 J |
250 g dropped from 15 cm |
| 3 | 0.5 J |
250 g dropped from 20 cm |
| 5 | 2 J |
500 g dropped from 40 cm |
| 7 | 6 J |
1.5 kg dropped from 40 cm |
| 9 | 20.0 J |
5.0 kg dropped from 40 cm |
References
- IEC 60529: Degrees of protection provided by enclosures (IP Code). International Electrotechnical Commission, Geneva.