Topic

Ingress protection

Aspects of enclosure protection are dealt with in BS EN 60529 (formerly IEC 629), and you will come across ‘IP’ numbers when you buy enclosures. In this context, IP now stands for ‘International Protection’ rather than ‘Ingress Protection’ and the number1 usually consists of IP plus two digits. The first of these digits refers to the protection given against intrusion by solid objects (and of course by people), the second to the protection given against liquids. Generally, the higher the number, the better the protection given. A summary of the codes is contained in Table 1 – occasionally supplementary letters will also appear.

1 A third number that is commonly omitted refers to protection against mechanical impacts.

Table 1: Meaning of IP Protection Numbers
  First number Second number
0 No protection No protection
1 Protected against solid foreign objects up to 50 mm diameter (back of hand) Protected against vertically dripping water e.g. condensation
2 Protected against solid foreign objects up to 12.5 mm diameter (finger) Protected against dripping water up to 15° from vertical
3 Protected against solid foreign objects up to 2.5 mm diameter (tool) Protected against direct spray of water (0.07 l/m) up to 60° from vertical
4 Protected against solid foreign objects up to 1 mm diameter (wire) Protected against direct spray of water (0.07 l/m) from all directions
5 Dust-protected (limited ingress allowed, with no harmful deposit) Protected against low pressure jet (12.5 l/s) of water from all directions
6 Dust-tight (totally protected against dust) Protected against high pressure jet (100 l/s) of water
7   Protected against the effect of temporary immersion between 15cm and 1m
8   Protected against long periods of immersion under pressure

In terms of affording protection against water, some penetration of water is generally permitted, although this may be varied by the appropriate technical committee. In general, if any water has entered the enclosure, it shall not: