IP ratings explained

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Auer Signal is a global leading manufacturer of signaling technology, operational in 70+ countries. The company produces stack lights, visual-, audible-, visual-audible and explosion proof signaling devices.

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What is an IP rating?

The IP rating provides information about the resistance of an electrical device against solid objects and liquids. Many electrical devices, such as signaling devices from Auer Signal, are exposed to a wide variety of environmental conditions for many years. These include outdoor applications such as marine or vehicle applications and indoor applications such as industrial manufacturing. The IP rating indicates whether the device is suitable for the environmental conditions of the desired application.

IP protection rating P series from Auer Signal

The most common degrees of protection for Auer Signal products are IP65, IP66 and IP67. The degree of protection of our signal devices can be found on our website under the technical data of the respective product. They are also marked with the symbol below and the corresponding IP code on the website.

IP66 symbol


The abbreviation IP stands for International Protection, but is often colloquially referred to as Ingress Protection. Next to the abbreviation IP there are two numbers, the so-called IP Code. Each digit stands for a certain degree of protection against the ingress of foreign bodies, contact or water.

Which IP standards exist?

The criteria of the IP codes are defined in two standards:

  • IEC 60529
  • ISO 20653

The international standard IEC 60529 is the basis for the definition of the "degrees of protection provided by enclosures", the so-called IP codes. The ISO 20653 standard deals primarily with the degrees of protection for vehicles. In addition to the numbers, the IP codes of the ISO standard sometimes also include the letter "K", which indicates a difference in the test specification to IEC 60529. For example, IPx9 (IEC 60529) and IPx9K stand for "protection against liquids during high-pressure cleaning and steam jet cleaning", but the specification is slightly different.


Although ISO 20653 is an internationally valid standard for IP ratings, other standards for protection classes are gaining acceptance in some countries. The ISO standard was created by the International Electrotechnical Commission (IEC) and is specified in Europe and Asia.

In the United States, Canada and Mexico, the American standard NEMA 250 is widely used for the protection of enclosures for electrical equipment.

The NEMA 250 standard contains 13 different degrees of protection, which cannot be converted one-to-one to the IP codes of the ISO or IEC standard. The IP rating is therefore not equivalent to the NEMA standard, which also takes into account other factors such as corrosion resistance or the mechanical load of an enclosure.

The NEMA test procedure is also a basic requirement for UL certification. The UL mark has a similar status in the USA as the CE marking in Europe.

What do the digits after “IP” mean?

The degrees of protection are indicated by an abbreviation consisting of the two unchanging letters I and P and two digits for the degree of protection. The first digit stands for protection from solid objects or materials. The second digit provides information about protection against moisture or liquid.

If one of the two digits is not given, for example because it is not known or necessary, this missing digit is replaced with an X (e.g. IPX6).

The IP code breakdown below gives an overview of the meaning and composition of the IP codes. Strictly speaking, the term IP rating is incorrect, as the term protection class has its own meaning in relation to electrical equipment. However, the addition "IP" makes it clear to most experts that the IP ratings are meant.

Code breakdown:

First digit


ISO 20653IEC 60529Protection against touch/contactProtection against solid objects
00No protection
No special protection of persons against direct contact with active or moving parts
No protection
No protection of the equipment against ingress of solid foreign bodies
11Protection against contact with large surfaces (e.g. hand contact)Protection against large foreign bodies (∅ ≥ 50 mm)
22Protection against contact with the fingerProtection against medium-sized foreign bodies (∅ ≥ 12 mm)
33Protection against contact with tools and wiresProtection against small foreign bodies (∅ ≥ 2,5 mm)
44Protection against contact with fine tools and small wiresProtection against granular foreign bodies (∅ ≥ 1 mm)
5K5Complete protection against accidental contactProtection against dust deposits inside (dust protected)
6K6Complete protection against accidental contactProtection against dust ingress (dust-tight)

Second digit


ISO20653IEC60529Liquid ingress protection
00No protection against liquid ingress
11Protection against dripping water (vertical)
Drops of water falling vertically shall have no harmful effect
22Protection against dripping water (oblique)
Drops of water falling at any angle up to 15 degrees from the vertical shall have no harmful effect
33Protection against spray water
Drops of water falling at any angle up to 60 degrees from the vertical shall have no harmful effect
44Protection against splash water
Water splashed against the equipment from all directions must not have any harmful effect
4KProtected against splash water with increased pressure on all sides
55Protection against water jets
A water jet (nozzle) from any angle shall have no harmful effect
66Protection against strong water jets
Water must not penetrate the equipment in harmful quantities during temporary flooding
6KProtected from strong jets of water at elevated pressure
77Protection against immersion
Water must not penetrate in harmful quantities when the equipment is immersed in water under the specified pressure and time conditions (up to 1 meter depth for 30 minutes)
88Protection against permanent immersion
Water must not penetrate in harmful quantities if the equipment is permanently immersed under water (more than 1 metre deep)
9Protection against water during high-pressure cleaning and steam jet cleaning in agriculture
9KProtection against water during high-pressure cleaning and steam jet cleaning for road vehicles

Which IP rating is suitable for outdoor applications?

For the universal use of signalling devices for outdoor applications, we recommend a protection class of at least IP65. Most of Auer Signal's signal lights and signaling devices fulfil the IP65 and IP66 protection classes and are therefore readily suitable for outdoor applications. Devices with this degree of protection are dust-tight and can withstand moisture, rain and water in large quantities.

Whether a higher protection class is required in a special case depends on further environmental conditions. In special climatic conditions such as high humidity, ice, strong temperature fluctuations or the formation of condensation, a higher protection rating may well be required.

In comparison, a conventional socket outlet for outdoor use requires a protection rating of at least IP44.


Most of our signaling devices have a high IP rating of IP65 or IP66 and are therefore suitable for outdoor use.

Our highly resistant P and N series are used on cranes, among other things, where they are exposed to extreme weather conditions.

The ASML multi-tone sounder with an IP rating of IP66 is suitable for maritime applications, since in addition to the high protection class, stainless steel screws are installed in the device. Thus, the sounder withstands even contact with seawater.

In addition to the A Series acoustic signaling devices, the Q Series lights are also popular when it comes to the use of outdoor lights. Traffic light systems with two or three Q Series lights regulate traffic in front of entrance gates or barriers. With the IP rating IP66, the devices are ideally suited for this purpose. However, the series Q is also used in special environmental conditions such as a coal mine, where the units are exposed to high levels of dust.

Which IP ratings do I need for indoor applications?

For indoor signaling device applications, the respective environmental conditions must be taken into account. In principle, IP43 is sufficient for universal applications in factories and buildings. However, if the environment is exposed to a large amount of dust or foreign bodies such as chips in a carpentry workshop, we recommend IPX6.

If there is a possibility that the signal device may come into contact with water or steam during indoor use, such as in a kitchen, greenhouse or through a sprinkler system, IP64 rating is advisable.


Auer Signal small horns are among the classic examples of indoor applications. They are used in garages and car parks, among other places, to warn against dangerous exhaust fumes. The optical-acoustic combinations of the K+H series are IP43 protected and therefore ideally suited for indoor applications.

Signal towers as well as panel-indicator lights and buzzers are primarily used for indoor applications. In most cases, however, this is not due to the IP ratings, but to the type of application. Our signal towers, such as PC7 or CT5, have IP66, IP67 and IP65 and would therefore also be suitable for outdoor applications. In most cases, however, they are used indoors, on machines or in shops.

The same applies to our panel mount products like our panel mount buzzers. These devices are particularly suitable for use in control cabinet construction or industrial automation and are therefore rarely used outdoors. These devices, such as our M22 series, are also suitable for outdoor use due to their high IP65 protection rating.


Examples of common IP ratings


Products with the IP rating IP20 are protected against solid foreign bodies with a diameter of 12mm or more and against contact with fingers. These products are not protected against the penetration of water.


Electrical devices with with the IP rating IP44 are protected against solid foreign bodies (∅ ≥ 1 mm) and splash water from all directions. This degree of protection is recommended for outdoor sockets.


If a product has the IP rating IP54, it is protected against dust deposits and contact. Splash water from all directions also does not penetrate into the inside of the housing.


Electrical devices with IP rating IP55 are protected against dust deposits and water jets from any angle.


Electrical devices with the IP rating IP65 are protected against dust ingress and contact. The housing protects the inside of the device against water jets from any angle. The M22 series from Auer Signal have the IP rating IP65 and, on request, as a pre-wired model, they can have the IP rating IP67.


The IP rating IP66 stands for complete protection against accidental contact and is dust tight. The housing protects the interior from strong jets of water. Most of our signaling devices have the IP rating IP66. These products are suitable for both indoor and outdoor applications.


Signal devices with the IP rating IP67 are dust tight and protected against contact. In addition, no water can penetrate the housing when temporarily submerged (up to 1meter depth for 30 minutes).

Signal lights of our P series - the Tough with the IP ratings IP67 and IP66 are convincing in extreme applications in dust, ice, rain and heat.

The N series - the Performer is also specially designed for outdoor use and have the IP ratings IP65 and IP67.


Electrical devices with the IP rating IP68 are dust-tight and protected against permanent immersion. Devices with this degree of protection are suitable for use under water, for example, for pool lighting.


The IP69 protection rating means that a device is fully protected against the ingress of dust and against contact. According to the IEC 60529 standard, the number 9 stands for protection against water from high-pressure cleaners or steam jet cleaning. This IP protection rating corresponds to the highest protection class.

Series P


The IP rating IPX4 means that a device is protected against water spray from all directions. The X is a placeholder because the IP code for protection against contact and foreign bodies is not known.


The IP rating IPX7 stands for protection when temporarily submerged (up to 1meter depth for 30 minutes). The X stands for the unknown degree of protection. In principle, however, if the degree of protection against water is high, this degree of protection also protects against the penetration of foreign bodies or contact.

How does an IP rating test work?

Auer Signal tests and checks all signal devices in its own test laboratory. Our laboratory and our test equipment are tested once a year by the TÜV. This ensures that our systems comply with standards and that the test results meet the IP protection class standards.

The most important components for the IP rating test are an electrical turntable on which the signal device is mounted. The speed of the turntable can be adapted to the test criteria. Also necessary is a calibrated water pump that delivers the required litres per minute. Depending on the test procedure, certain blasting nozzles with different diameters are used.

In addition to conducting IP rating tests, Auer Signal is certified for the UL Hosedown Test, which is required for the American NEMA protection rating.

Our trained and certified testing staff adheres to all necessary standards for testing in accordance with the standards.

What is the difference between IP ratings and protection classes?

The terms IP rating and protection class must be distinguished from each other. We like to talk about the protection class, when actually the IP rating is meant. The protection class, however, refers to the measures that are taken with electrical devices to protect against dangerous voltages. The IP rating provides information about the degree of protection against the ingress of solid objects or materials and liquids.


There are four protection classes, from protection class 0 to protection class 3. Devices with protection class 0 have the lowest protection because they do not have any protective measures against electric shock. Devices with protection class 3 are secured with safety extra-low voltages or protective extra-low voltages and represent the highest protection class.

The table below gives an overview of the protection class symbols and their meaning.

Protection classMeaning Symbol

Basic insulation is given, but no other protection.
Not approved in Austria and Germany.

1A protective earth conductor is present in the equipment.
In the case of movable equipment, the protective earth conductor is installed in the plug.
icon protection class 1
2Double or reinforced insulation is given as protection between the mains circuit and the output voltage.
There is no connection to the protective conductor.
icon protection class 2
3The unit is protected by a safety extra-low voltage (SELV/PELV).
A safety transformer according to DIN VDE 0570-2-6 / EN 61558-2-6 is required.
icon protection class 3

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