I think you mean bonding grounding in a hazardous location since the Grounding Grid is located outdoor, so is not in hazardous area.
See: Grounding and bonding practices for hazardous areas
It is very interesting, ScottyUK. I know only 10 steam generation power stations of 150 to 750 MW units, and 12 Combined Cycles of 75 to 300 MW gas turbine units and I didn't remarks somewhere outdoor a closed or confine area to be hazardous location. Could be so kind and be more specific?
You can not assume that by virtue of being outdoors that a hazardous area does not exist, contrary to what you wrote. Such locations exist in most if not all CCGT plants, especially at the fuel handling areas which are typically outdoor or partially outdoor. I can only assume that what you wrote is not what you intended to say: perhaps you can clarify what you mean?
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If we learn from our mistakes I'm getting a great education!
Open air installation does not present an explosion danger. The danger may be fire in a location close to a purge box or above a waste pool where the liquid fuel may float on the surface.
On partially open area-let's say confined area- the floor is concrete and I don't recommend hiding electrode under this concrete. One could make a foundation grounding [Uffer].
Nevertheless this is only a rhetoric issue since the grounding grid is not only permitted but very recommended in all type of location-hazardous or not.
As the grid is buried about 2-2.5 feet under the ground no hazard will occur even in case of a shortcircuit. If somebody would be afraid of temperature arise during a shortcircuit he could dimension the copper for 80% of maximum admissible temperature-auto ignition temperature of methane being 580 -could be 580*.8=464 degrees C –and welded connections [brazed or cadwelded].
I agree that the buried grid presents a minimal ignition risk, but it is an interesting and very valid point regarding the temperature rise of a conductor under fault conditions. I do not recall an explicit reference to such circumstances in the UK regulations - I will have to check when I am back at work.
I can not agree that open air installations are not hazardous. An ATEX Zone 0 outdoor area is unusual, but Zone 1 and Zone 2 areas are very common in outdoor installations in plants fuelled by natural gas or by the lighter distillate fuels such as naphtha.
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If we learn from our mistakes I'm getting a great education!
