What is "environmental protection?"
The ability of an enclosure to protect a piece of equipment from outside elements
(such as rain, or to keep fingers away from electrical circuits) is called
"environmental protection" and is often specified by "IP" ratings (standing for
"ingress protection"), which are specified by European Standard IEC 60529.
Naturally, higher degrees of protection can increase the cost of a product, and
should be applied only when necessary to ensure safe and functional operation of
the product in the environmental conditions and application in which it will be
used. Please refer to the appropriate sections of IEC 60529 for complete
information on the standard. The following is a brief summary of the IP rating
system.
The first digit of the IP designation describes the degree of protection against
access to hazardous parts.
The second digit designates the degree of protection against water.
The third digit describes the degree of protection against mechanical impact, and
is often not specified.
1st
Protection against
foreign objects
2nd
Protection against
water
3rd
Protection
against
mechanical
impacts
0
Not protected
0
Not protected
0
Not protected
1
Protected against
objects greater than
50 mm diameter
1
Protected against
dripping water
1
Impact 0.225 joule
2
Protected against
objects greater than
12 mm diameter
2
Protected against
dripping water when
tilted up to 15
degrees
2
Impact 0.375 joule
3
Protected against
objects greater than
2.5 mm diameter
3
Protected against
spraying water
3
Impact 0.60 joule
4
Protected against
objects greater than
1.0 mm diameter
4
Protected against
splashing water
5
Dust protected
5
Protected against
water jets
6
Dust tight
6
Protected against
heavy seas
n/a ----5
Impact 2.00 joule
n/a -----
n/a -----
7
Protection against
the effects of
immersion
n/a -----
8
Protection against
submersion
n/a -----
n/a -----
7
Impact 6.00 joule
n/a ----9
Impact 20.00 joule
Example: A rating of IP-21 indicates that the enclosure offers protection from
objects greater than 12-mm in diameter, such as a typical person's finger or a
metal rod (indicated by the first digit being "2"), and protection from water dripping
onto the unit without the unit becoming electrically unstable or unsafe through
shorting or other loss of insulation effectiveness (indicated by the second digit
being "1"). The third digit is often not specified.
The first number defines the level of protection against penetration of solid objects into the
housing.
Example: - scored a 5 out of 6
The second number defines the level of protection against penetration of liquids into the housing.
Example -ROCKY scored 4 out of 8
Additional information can be found in the 1976 IEC Publication,
Classification of Degrees of Protection Provided by Enclosures.
Number Degree of Protection
Number Degree of Protection
No protection against contact or
0
0
No protection.
entry of solids.
Protection against accidental
Protection against drops of condensed
contact by hand, but not deliberate
water. Condensed water falling on
1
1
contact. Protection against large
housing
objects. (greater than 50mm)
shall have no effect.
Protection against contact by fingers.
Protection against drops of liquid.
Protection against medium-size
Drops of falling liquid shall have no
2
2
foreign
effect when housing is tilted to 15
objects. (greater than 12mm)
degrees from vertical.
Protection against contact by tools,
Protection against rain. No harmful
3
wire, etc. Protection against small
3
effect from rain at angle less than 60
foreign objects.(greater than 2.5mm)
degrees from vertical.
Protection against contact by small
tools and wires. Protection against
Protection against splashing from any
4
4
small foreign objects. (greater than
direction.
1mm)
5
6
Complete protection against contact
with live or moving parts. Protection
against harmful deposits of dust.
Complete protection of live or moving
parts. Protection against penetration
of dust.
5
6
7
8
Protection against water jets from any
direction.
Protection against conditions on ships'
decks. Water from heavy seas will
not enter.
Protection against immersion in water.
Water will not enter under stated
conditions of pressure and time.
Protection against indefinite immersion
in water under a specified pressure.
Dust protection
Water protection
First
Brief
Second
characteristic
Brief
description
characteristic
numeral
description
numeral
0
Non-protected
0
Non-protected
Protected against solid
1
Protected against dripping
objects greater than 50mm
1
water
Protected against solid
Protected against dripping
2
objects greater than
2
water when tilted up to 15°
12.5mm
Protected against spraying
Protected against solid
3
water
3
objects greater than
Protected against splashing
2.5mm
4
water
Protected against solid
4
Protected against water
objects greater than 1mm
5
jets
5
Dust-protected
Protected against heavy
6
Dust tight
6
seas
Protected against the
7
effects of immersion
Protected against
8
submersion
The IP Rating often includes a third digit denoting impact resistance.