# IP68 Is Not ATEX: Two Ratings People Confuse Constantly
"It's IP68, so it's fine for the plant."
I have heard that sentence on site more than once, and it is wrong in a way that matters.
IP68 tells you the radio keeps water and dust out.
It tells you nothing at all about whether it can ignite an explosive atmosphere.
## Two standards, two purposes
**IP ratings** come from IEC 60529. They describe how well an enclosure keeps solid objects and water out. That is the whole scope.
**ATEX certification** comes from Directive 2014/34/EU, and in Great Britain from the Equipment and Protective Systems Regulations 2016, built on the IEC 60079 series. It describes whether equipment can be an ignition source in an explosive atmosphere.
A radio can be beautifully sealed and still spark internally. Sealing and explosion protection are not the same engineering problem.
## What the IP digits actually mean
Two digits. The first is solids, the second is liquids.
**First digit — solids and dust**
| Digit | Protection |
|---|---|
| 5 | Dust protected. Ingress not fully prevented, but not enough to interfere |
| 6 | Dust tight. No ingress at all |
**Second digit — water**
| Digit | Protection |
|---|---|
| 4 | Splashing from any direction |
| 5 | Low pressure jets |
| 6 | Powerful jets |
| 7 | Immersion to 1 metre for 30 minutes |
| 8 | Continuous immersion, conditions specified by the manufacturer |
That last row is the one to read carefully.
## IP68 is not a fixed number
Unlike IP67, which means one metre for thirty minutes, **IP68 is defined by the manufacturer**. The standard requires them to state the depth and duration.
So IP68 on its own is a marketing figure. The useful information is what follows it.
Look at how differently manufacturers use it:
- **Entel DTEx** — IP68, 2 metres for 4 hours
- **Motorola R7Ex** — IP66 and IP68, 2 metres for 2 hours
- **Hytera HP715Ex** — IP66, IP67 and IP68, tested per IEC 60079-0:2017 and IEC 60529
- **Hytera PD795IS** — IP67, 1 metre for 30 minutes
Entel's four hours at two metres is genuinely class-leading. Motorola's two hours is excellent. Both are "IP68".
If a supplier quotes IP68 and cannot tell you the depth and time, they are quoting a label rather than a specification.
## Why some ATEX radios show a lower IP number
Here is something that confuses buyers.
The Hytera HP715Ex specification lists **IP64/IP65/IP66/IP67/IP68 per IEC-60079-0:2017 and IEC-60529**.
Why quote IP64 when the radio does IP68?
Because the two standards test differently. IEC 60079-0 applies its own test conditions, and the figure that can be claimed under explosion-protection test conditions is sometimes lower than the figure achievable under the plain ingress standard.
Motorola make the same distinction on the DP4000 Ex Series, which is rated IP67 and separately certified to IP64 under ATEX/IECEx test conditions.
Neither is a weakness. It is two different questions being answered honestly.
## Where dust protection does connect to ATEX
There is one genuine overlap, and it is worth understanding.
For **dust** atmospheres, keeping dust out of the enclosure is part of the protection concept. A dust-tight enclosure stops a combustible dust reaching internal components that could ignite it.
That is why you see IP ratings quoted inside dust markings, such as **II 1D Ex ia IIIC T160°C IP5X** on the Hytera PD795IS.
So for dust, ingress protection contributes to explosion protection. For gas, it does not. Gas will find its way in regardless, which is why the internal circuit has to be intrinsically safe.
## The practical test
When someone tells you a radio is suitable for a hazardous area, ask for the marking, not the IP rating.
You want to see something in this shape:
**II 2G Ex ib IIC T4 Gb**
If all they can produce is "IP68 and MIL-STD-810", you are looking at a rugged commercial radio, not an ATEX one.
Rugged is not the same as safe.
MIL-STD-810 is worth having, incidentally. It covers shock, vibration, thermal shock, humidity and drop testing, and it is a genuine durability standard. It is just answering a different question again.
## The summary
**IP rating** — will water and dust get in?
**MIL-STD-810** — will it survive being dropped, shaken and baked?
**ATEX marking** — can it set fire to my site?
You want all three. Only one of them is a legal requirement in a zoned area.