WHEN choosing components, the environment in which they will be used is key. Dusty packing facilities, sandy outdoor terrain, the ocean bed - they all pose high risks to electronic equipment.

Steam, sand, dust, rain, oil, even insects: they can all sneak into the tiny crevices in a system, through a seam or moving part.

Phrases like ‘waterproof’ or ‘sealed’ offer no real guidance - which is where the industry-standard IP rating comes in.

The IP stands for Ingress Protection, and is followed by two numbers. The first number relates to solids - dust, dirt, sand - and the second details how much water a device can with withstand. The higher the protection, the higher the numbers.

For designers planning for the future, using an insufficiently-sealed component could shorten the life of expensive and complex machinery in a hostile environment.
But not all switches need the same protection - which is why a good supplier offers a range of options for the perfect match.  

Take, for example, two pushbutton switches - the OTTO LP9, and the Marquardt series 5000, both supplied by Nexus

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The OTTO LP9 is watertight to IP68S. This shows it can withstand long periods of immersion under pressure, and has full dust protection (the ‘S’ means that the switch was motionless during water testing).

The Marquardt switch can be configured to two different IP standards - IP 40 and IP 54 - depending on a client’s needs. So it can simply keep out solids over 1mm - such as passing large insects - or offer some additional protection against dust and splashing water.

NEMA ratings,these are more commonly found in the United States - with US companies increasingly adopting the IP rating too.
What the numbers mean:

First digit (solids)
0 - No protection (or at least, no tested rating)
1 - Protection against solid objects larger than 50mm (for example, if accidentally touched by a hand)
2 - Protection against solid objects larger than 12mm (e.g. fingers)
3 - Protected against solid objects larger than  2.5mm - such as wires and tools
4 - Protection against solid objects larger than 1mm, like nails, screws, and larger insects
5 - Some protection against dust and small solids - enough to ensure that the ingress doesn’t damage the component
6 - Full dust protection, including a vacuum seal, tested against continuous airflow.
Second digit (liquids)
0 - No protection, or no protection rating for moisture
1 - Protection against vertically falling droplets - like condensation. If the item is upright, no damage should be caused.
2 - Protection against vertically dripped or sprayed water, to a limit of 15° off vertical.
3 - Protection against direct sprays of moisture at up to a 60° angle from vertical.
4 - Limited ingress from splashing water coming from any directions. This test is for a minimum of 10 minutes, and permits limited ingress with no damaging effects
5 - Protection against low-pressure jets of water directed from any angle, again allowing some ingress
6 - Protection against strong jets of water, such as those on a ship’s deck.
7 - Protected against damage from temporary immersion between 15cm and 1m in a test lasting 30 minutes.
8 - Protected against long periods of immersion under pressure.
9 - Protection against high-pressure, high-temperature jet sprays - a standard mainly seen in road vehicles.

Photo by Sharon Pittaway on Unsplash