IP Ratings

IP ratings are a set of physical standards defined in IEC60529 (SEN60529:1991).
They relate to the protection which enclosures give against the ingress of particles or water.
IP ratings are expressed as two digits (e.g. IP55).
The first digit defines the level of protection against contact and particles, whilst the second digit defines the level of protection against water.

First Digit	Protection against contact	Protection against particles	Second Digit	Protection against water
0	No special protection	No special protection	0	No special protection
1	with back of a hand	Large foreign bodies >50mm dia	1	dripping vertically
2	with a finger	Medium foreign bodies >12.5mm dia	2	dripping at an angle <15 from vertical
3	with tools and wires etc > 2.5mm thick	Medium foreign bodies >2.5mm dia	3	spray <60 from vertical
4	with tools and wires etc >1mm thick	Medium foreign bodies >1mm dia	4	spray from all directions
5	complete protection	Dust allowed but not affect function	5	jets from a nozzle in all directions
6	complete protection	Dust proof	6	high pressure jets
			7	temporary immersion
			8	permanent immersion
Degrees of Protection to IEC 144(BS5420)