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Ingress Protection (IP) ratings measure how resistant a device is against solids and water. You will find one on enclosures and devices everywhere – in your home, at work and out on the street. But do you know what the rating means and how to work out what you need?

What do the numbers mean?


After IP, the first number refers to protection against solids; the bigger the number, the smaller the particle the protection prevents:

1 – protection against solids bigger than 50mm, such as large pebbles or a hand.  Something like chainlink fencing perhaps.

2 – ingress protection from solids wider than 12.5mm. Imagine something like chicken wire and the protection that would provide.

3 – solids greater than 2.5mm would not be able to penetrate, such as a small screwdriver.

4 – protection from solids of 1mm is provided at this level. Gravel or large sand particles would not be able to penetrate

5 – Limited protection from dust, for 2 – 6 hours

6 – Complete protection from dust.


The second digit refers to the protection from water. The higher the number, the more protection there is:

1 – Protection from vertically falling water drops, with limited ingress within 10 minutes.

2 – Similar to 1, but there would be limited ingress if the casing was tilted by up to 15 degrees.

3 – The case would protect from water falling at up to a 60 degree angle for up to 5 minutes

4 – Protection from splashed water from any direction for up to 5 minutes

5 – low pressure, focused, water jets would not ingress a casing with an liquid IP of 5

6 – High pressure water jets are no match for a 6 rating

7 – Casings with this IP rating can be immersed in fresh water up to a metre deep for up to 30 minutes. A common rating for watches and mobile phones

8 – Further protection when compared to 7. This liquid IP rating provides protection for long periods.


Indoor or outdoor?

When you’re considering what level of ingress protection you need, think about where the device will be used – indoors or outdoors.  If the device is purely for indoor use, a TV remote control for example, IP44 (protection from >1mm and splashes) will work.  If your device will be used outdoors, you will need a higher protection level.

Additional letters?

Sometimes you may see an additional letter on an IP rating:

D – when wires are pressing against the casing

F – is oil resistant as well

H – for high voltage apparatus

M – when the device is in motion

S – when the device is still. Both M & S show more stringent testing has taken place

W – in certain weather conditions

K – under elevated pressure situations

What does your device need?

When you’re starting to design a new device and you’re looking at the casing, think about its usage. When working out what level of ingress protection it needs, consider where it is likely to be used and where it may get used. Most consumer electronics, for example, are mostly used indoors, but may get taken outside. If you’re working from home, who wouldn’t want to work in the garden on a nice day? but if it starts raining or getting really windy, one drop of rain or some dust being blown around shouldn’t permanently damage a laptop or phone.

If your device is for use outside most of the time, a higher IP rating will be needed. You’ll also need to start thinking about corrosion protection at this point too. We’ll cover that very soon.


If you are developing a new device casing, or having issues with a current one, let’s talk and see how we can help.  If you’d like to download a copy of our IP rating guide, you can do that here. You can also get the IP ratings for all Sunon fans by clicking here.