What’s the difference between… IP ratings?
QI want to replace my ancient Nokia phone with a smartphone. I’ve settled on Android, as I don’t want to pay the ‘Apple tax’. As a retiree I spend time at my local spa, so I’d like a handset I can use by the pool. However, I’m confused by the varying claims. Some are said to be water-resistant, while others are water-proof. I read somewhere that Samsung phones are water-proof to ‘IP68’, but others are only ‘IP67’. Are the numbers a percentage? Surely a phone would need to be ‘IP100’ to be truly waterproof? Cynthia Clark
AThe numbers are not percentages. The ‘IP’ part of the codes stands for ‘International Protection’, though it’s often called ‘Ingress Protection’. These standards are defined by the International Electrotechnical Commission ( www.iec.ch). While the full document runs to hundreds of pages, interpreting these IP codes is straightforward – once you know how.
Each of the two digits in an IP code conveys a particular type of protection. The first digit defines protection against solid matter; the second relates to liquids.
The scale for protection against solid matter ranges from 0 (no protection at all) to 6 (completely dust-tight). Most top-end smartphones are now at level 6. For liquids, the range goes from 0 to 9. Confusingly, though, a higher number on this particular scale does not necessarily mean better – because each number denotes a particular type of resistance.
For example, a 7 means a smartphone can be immersed in water of up to one metre for up to 30 minutes; an 8 means beyond a one-metre depth, but not necessarily for up to 30 minutes (because manufacturers are free to specify different durations). A 9 means a device is resistant to hightemperature water jets, but not necessarily waterproof or submersible.
To keep things simple, a handset with an IP67 or IP68 rating should be fine for poolside use, or even for a shallow dip. But avoid the sea – the ratings are based on fresh water, not salt water.