Some words on IP testing and IP marking on luminaires. There is some times misunderstanding on what and why around IP coding. First of all the IP testing is part of the lighting standard. So if a product is safety certified it has also been certified for the IP coding, or at least it should have been when EN 60598 was used. It is part of the safety standard and must have been conducted during the safety test.

The standards to use are EN 60598-1 and EN 60529. The safety standard is EN 60598-1 and describes the actual conditions under which the tests must be executed and describes the criteria for compliance. The EN 60529 describes only the testing methods. This standard can be used as standalone but when the product standard is used as well you are sure that also specific product related conditions are taken into account. So a test report referencing only EN 60529 is not enough.

The IP code looks like the letters IP followed by a numeral. Sometimes writing in specifications as IPXX. The letters IP stand for ingress protection. The first numeral denotes the protection agains solids and the second numeral the protection against fluids.

The minimum code is IP20. Lower is not allowed by the safety standard for lighting. When analyzed; 2 stands for touch protection and the 0 for no protection against liquids. What would lower classifications mean? If it where to be 00 there would be no protection at all and 10 would mean protected agains the back of the hand. Both of which are not desirable in normal household and industrial conditions.

The first numerals are:
2 Touch protected
3 Test probe 2,5 mm
4 Test probe 1 mm
5 Dust proof
6 Dust tight

So the protection gets better when the numbers go up. 2, touch protected, means that no basic isolated part or non-isolated part can be touched. This is tested with a standardized test finger (yes in normalization everything is standardized). The test probes have somewhat different requirements. The probes are of a set length and the diameter is as described above. The probes are not allowed to enter the enclosure. There is a condition where they are allowed to enter the enclosure, being through drain holes or ventilation holes. In these cases it is not allowed that the probe can touch basic or non-insulated parts.

In dust proof luminaires it is still allowed that dust penetrates the enclosure but it may not be deposited in such a way that it could form a path for electricity. In dust tight luminaires dust is not allowed to penetrate. In some products, specifically public lighting (street lighting) a combination is used. The lamp compartment can be for example dust tight whereas the gear compartment is only protected against test probe. This can be important for maintenance purposes. Having a dust tight lamp compartment will reduce the amount of cleaning that needs to be done in the course of the years.

The second numeral is about liquids.
0 No protection
1 Drip proof
2 Dripping under an angle, normally not used for lighting
3 Rain proof
4 Splash proof
5 Jet proof
6 Powerful jet proof
7 Watertight
8 Pressure watertight

In this case 0 is allowed and means no protection. Most products are constructed in this way since we do not need protection in our living room or office. The numeral 1 means drip proof and numeral 2 is normally not used for lighting, it is also drip proof but the luminaire would be under an angle.

Rain proof is for luminaires that are used outside and where water can basically only comes from above. Splash proof is a little more protected because now the water can come from all directions.

Jet proof can be compared to a garden hose while powerful jet proof can be considered as f.e. a fire hose. With powerful jet proof is not meant High pressure cleaner proof. This is something different!

Watertight is suitable for submersing and pressure watertight is basically for continuous underwater use where the depth of possible usage must be marked as well.

The testing methods are described in the EN 60529 but the basics I want to share here to give an idea on how it is done.

Test probes; IP 2/3/4X are of a defined size and it is tried to enter the enclosure of the luminaire. IP5/6X is tested in a special test chamber where a defined powder is circulated for 3 hours. The luminaire is at operating temperature when the test starts and after some time it is switched of to cool and basically the air might be sucked in but dust may not enter.

For the liquids IPX1 the luminaire is placed under a special dripping box. For Rainproof luminaires IPX3 the product is placed in a special test rig where water jets are being directed to the luminaire under an angle of up to 60 degrees and for splash proof (IPX4) in all directions. IPX5/6 is tested with a water jet where there is a difference in flow and nozzle size for 5 and 6.

IPX7 is simply being submersed and IPX8 is being brought to a simulated depth. In all cases the luminaire is being allowed to cool down during the test resulting in the effect that the air inside the luminaire is cooling with the vacuum effect that results.

After testing the product is being subject to some tests to check the insulation integrity and to see if solids/liquids have entered the enclosure.

For all tests the safety standard requires ageing first. So the luminaire must be subjected to the ageing test before being subjected to the actual IP test.