Protection classes and degrees of protection – Criteria of hardware components for mobile applications

In many application cases of automation and the robotization of mobile systems, various hardware components are exposed to unfavorable conditions like high temperatures, water, dirt, permanent vibrations or shocks. In these extreme situations the components also need to work flawlessly to ensure the functionality of the whole system. To guarantee the reliability in such conditions, the components are tested in different  domains. Last week we dealed with the topic “Resistance of vibration and shock“. Accordingly, today’s article is about protection classes and degrees of protection as a further criterion of hardware components.

Die neue Gehäusevariante des Modular Control Systems

The current available “box” of the Modular Control System is marked with the degree of protection IP67. The new version of enclosure is currently in the development and will also satisfy IP67.

In colloquial speech, the terms of “protection classes” and “degrees of protection” are often confused. Operators often desperately look for “IP-protection classes” (e.g. IP-protection class 65) and only get protection classes I, II and III. That is because IP-protection class does not exist. On the one hand there are protection classes and on the other hand there are degrees of protection, including an IP-Code.

Degrees of protection – protection against environmental influences and physical contact with people

Using an IP-Code (International Protection Codes) refers to the so-called “degree of protection“. It defines the operational safety of the device and gives information about the environmental influences that do not affect its functionality. Electronic equipment is protected by the utilization of enclosures to prevent penetration of dust, pollution, water or other unwanted influences of the environment. The protective effects provided by the enclosures is specified with two indicators. The first code number (1-6) gives information about the solid particle protection. The second code number (1-9) gives information about the liquid ingress protection. In case there is the indicator “0”, no protection is guaranteed. Also an “X” can be there – it shows a free position if one of the two indicators is not listed.

The two indicators taken together forms the IP-Code. Our Generic Control Box “Ruggedized” for example is marked with the code IP67. That means it is completely dust tight and the ingress of water in harmful quantity shall not be possible when the enclosure is immersed in water up to 1m. For example a very low level of protection would be an enclosure with the degree of protection IP11. Such an enclosure protects any large surface of the body, such as the back of a hand, but no protection against deliberate contact with a body part. In addition the enclosure protects against dripping water. The highest level of protection is characterized with the degree of protection IP69. It defines a fully dust tight enclosure with an protection of water in powerful jets with high pressure against the enclosure from any direction.

The following tables will give you an overview about the IP-Codes according to DIN EN 60529 and their exact meaning.

1. Code number (solid particle protection):

Level Protection against particles
Protection against contact
0 no protection no protection
1 object size >50mm any large surface of the body, such as the back of the hand
2 object size >12.5mm fingers or similar objects
3 object size >2.5mm tools, thick wires, etc.
4 object size >1.0mm most wires, screws, etc.
5 dust protected full protection against contact
6 dust tight full protection against contact

2. Code number (liquid ingress protection):

Level Protection against
0 no protection
1 dripping water
2 dripping water when tilted up to 15°
3 spraying water at any angle up to 60° from the vertical
4 splashing of water from any direction
5 water jets from any direction
6 powerful water jets from any directions
7 immersion under defined conditions of pressure and time
8 continuous immersion
9 powerful high temperature water jets

Protection classes – classification and labeling of electronic equipment

Further indicators besides the degree of protection are the protection classes. In Germany only the protection classes I, II and III are allowed. Protection class 0 has no protective earth-connection and for that reason it is not allowed in Germany.

Class I symbol:

Schutzklasse I

The protection class I always contains a protective earth conductor. All possible conductors are connected with it, so that in emergencies electricity can be grounded. Corresponding devices are marked with the here shown ground symbol.
(e.g. used at electric motors)

Class II symbol:

Schutzklasse II

The protection class II contains a strengthened or doubled isolation to completely separate the electronic devices. The conductors are not connected with a ground line like it is done in protection class I. Protective conductors act as active conductors and for that reason they are not allowed to be connected with the enclosure.
(e.g. at power tools and household appliances)

Class III symbol:

Schutzklasse III

The last one of the protection classes is the protection class III. It shows if the devices are suited with an safety extra-low voltage. In case a device is marked with the protection class III, no electricity may flow which could fatally injure people or animals. Also, no protective conductor is used here. The devices are driven separately.
(e.g. at small equipment up to AC 50V or DC 120V)


In order to give a binding statement about the operational safety of electronic devices these indicators of the degrees of protection and the protection classes are a helpful labeling. They allow to understand which devices can be used without any problems under specific environmental influences (degrees of protection). In addition they give information about how electric shocks are prevented (protection classes).


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