Equipment Without Certificates According to IEC Standards

It's a big standard. Put really simply:

1) Industrial gear allowed if installed in Ex d flame proof enclosures (refer IEC 60079.1)

2) Simple apparatus (mechanical switches and read switches, etc - nothing with energy storage or conversion elements) protected by an intrinsic safety barrier or galvanic isolator located in the safe zone (non-hazardous area) or fitted into a suitable Ex rated enclosure if located in the hazardous area (refer IEC 60079.11)

3) Industrial gear allowed in Ex e rated enclosures under certain circumstances as long as it is installed in Zone 22 ONLY and all controls, windows, glands, etc penetrating Ex e enclosure are Ex rated also (refer IEC 60079.31)

There may be other exceptions for mechanical gear, etc that I have missed.

Good answer. The technique of pressurisation, Ex p is also applicable to equipment like large motors which have sparking commutators or sliprings. Need for clean air supply & certified enclosure, monitoring & control system limits usefulness compared to Ex d but could be used for hydrogen & other risks Ex d cannot meet.

<slaps head>

Of course, I should have remembered that as I have designed and commissioned a number of Ex p solutions over the years.

Referring to post #1, even a "simple" switch must be insulated for 500V [not sure if AC or DC, I think AC is correct] along with its cable/ terminals - using the "blue IS" terminals has its merits.

This is because e.g. a short to frame in an Ex d motor with earth cable CSA equal to live cable will raise frame of motor [and its skid] to 1/2 supply voltage to ground. A switch on its skid connected to earth at intrinsic safety barrier could spark to local metal if just, say, 12V rated.

There are also material limitations, which apply - magnesium or even some aluminium alloy enclosures could cause ignition if a steel hammer dropped on them.

Cadmium plating became the preferred corrosion treatment for parts of electric kit, but I remember a "panic" when it was discovered that spark ignition energy in an IS circuit was halved? compared to zinc plate on which limits were proven. Having a big safety factor between ignition & IS barrier limits was justified.

An earlier "system-shock" was the lid blowing off an overloaded Ex(d) junction box containing only terminals/cable in a mine. It turned out the terminal insulation decomposed & burnt with tracking & high temperature. Prior to that, it was accepted all sorts of kit could be put in Ex d enclosures without regard to material, quantity & fault level.

While the Ex d boxes are designed to handle the explosion inside pressure piling is a real problem and can easily cause the box to rupture if careful consideration to component placement and compartmentation is not considered.

It is all in the standard, which is there to be read and understood.

https://webstore.iec.ch/publication/628

There is a page in Wikipedia with this information therein.

https://en.wikipedia.org/wiki/Electrical_equipment_in_hazardous_areas

Ask for training in the safe use of electrical equipment in potentially explosive atmospheres. This is not a topic for the untrained.

https://en.wikipedia.org/wiki/CompEx

Dear all

Thanks for answers