API RO 500, (2012)
10.1.1
This section presents guidelines for classifying locations for electrical installations at locations surrounding oil and gas drilling and workover rigs and facilities on land and on marine fixed and mobile platforms where flammable petroleum gas and volatile liquids are produced, processed, stored, transferred, or otherwise handled prior to entering the transportation facilities.
10.1.2
The following recommendations for determining the degree and extent of classified locations are specific examples of situations commonly encountered in producing and drilling operations and have been developed by experience in the industry. Application of these examples to similar, though not identical, situations should be made with sound engineering judgment, employing material presented in this recommended practice and other publications. Specific examples listed consider only the item discussed and do not take into account the possible influence of adjacent areas classified due to other equipment.
10.1.2 says one can apply to "similar, though not identical, suituations", provided one uses "sound engineering judgment"
So:
Are they? (similar)
Are you ? (using sound engineering judgement)
Possibly we are only getting half the story.
This section uses the terms "guidelines", and "engineering judgement". That leaves it open to interpretation.
What in specific are you look at?