IEC 60079 Explosive Atmospheres Compliance
It is always case dependent. Not only with IEC 60079. For general, there are my seven "NOs":

1) no thermal chokes (enclosure/surface temp growth up/down too high)

2) no thermal differential (enclosure/surface temp inequality)

3) no electrical sparks (while connecting power, on, off, etc)

4) no vibration (with freq/mags sensible by the environment)

5) no electric/magnetic fields (with params sensible by the environment)

6) no focused irradiation (ir, uv, others sensible by the environment)

7) no other stimuli you find sensible by the environment

How to design such devices?

When you are facing safety problem, you need to analyze


the environment you need to operate in,
the scenario(s) how your device interacts (within) the environment
the factor(s) and direction(s) your devices impacts the environment with
the limits the impact is insensible (safe) for the environment


When you know this, next you harmonize your (initial) design step-by-step, trial-and-error (trial-and-error-and-error-and-error :-] depending on the experience your have/can access) to the state in which:


its impact to the environment does not exceed the safety limits and/or
its behavior does not predictably run out of safety enabled scenarios


My notice for you is the following:

1) read all the parts of the standard series, beginning from the first, to get better understanding of the safety regulation approach and details

2) read some books related to the standard (generally standards authors like to write related books because they give them money and additional points in the science world :-)

3) read information about similar devices, buy one or two and examine, but have a respect for third-party's intellectual property, of course.