EN 60529 describes an international classification system for the sealing effectiveness of enclosures of electrical equipment against the intrusion into the equipment of foreign bodies and moisture. This classification system utilises the letters IP followed by two or three digits.

The first number refers to the protection against solid objects and the second against liquids. The higher the number the better the protection; see below for a summary.

IP Protection Number Summary

FIRST NUMBER

0 No protection
1 Protected against solid objects up to 50mm eg accidental touch by hands
2 Protected against solid objects up to 12mm eg fingers
3 Protected against solid objects up to 2.5mm (tools and wires)
4 Protected against solid objects up to 1mm (small tools and wires)
5 Protected against dust, limited ingress (no harmful deposit)
6 Totally protected against dust

SECOND NUMBER

0 No protection
1 Protection against vertically falling drops of water eg condensation
2 Protection against direct sprays of water up to 15 degrees from vertical
3 Protection against direct sprays of water up to 60 degrees from vertical
4 Protection against water sprayed from all directions - limited ingress permitted
5 Protected against low pressure jets of water from all directions - limited ingress permitted
6 Protected against low pressure jets of water (use on shipdeck)- limited ingress permitted 7 Protected against the effect of immersion between 15cm and 1m
8 Protected against long periods of immersion under pressure

Note that there is a third number which is commonly omitted which refers to protection against mechanical impacts.

THIRD NUMBER, when used concerns protection from impact; it is seldom used.