The requirement follows the conditions in a particular area, not the name of the industry. A refinery, warehouse or grain facility can contain several classifications and ordinary locations within the same site.
Start with the classification documentation
OSHA requires each room, section or area to be considered individually. Obtain the site's classification drawing and identify the substances involved, their likely release conditions and the extent of the classified area. Ventilation and detection systems must be assessed within that process; adding them does not automatically remove a classification.
Distinguish gas, dust and fibers
Class I concerns flammable gases and vapors; Class II concerns combustible dust; Class III concerns ignitable fibers and flyings. The applicable division and group matter. A light selected for a refinery gas hazard is not automatically appropriate for grain dust or metal dust.
Zone systems describe gas and dust hazards with different markings and equipment requirements. Do not convert between Division and Zone approvals using only a short comparison table.
Choose an approved protection technique
Explosionproof construction is one permitted approach for the locations covered by its approval. Intrinsic safety, dust-ignitionproof construction and other techniques can be appropriate within their own certified scope. OSHA's hazardous-location rule recognizes several methods; it does not require the same enclosure design everywhere.
Include temporary work
Maintenance lights, cord connectors and portable equipment enter the same work area as permanent equipment. Temporary duration is not an exemption from the location requirements. Tank entry also brings atmospheric, access and electrical considerations that must be assessed separately.
Specify equipment with usable evidence
Record the exact model, complete marking, certificate or listing, supply, cord configuration and permitted mounting. If the required configuration is not covered by the available documentation, resolve that gap before use. Hand lamps, string assemblies and supported work lights serve different tasks; the format alone does not establish approval.
References: OSHA 1910.307 — Hazardous (classified) locations · UL Solutions — North American hazardous-area certification · IECEx — Equipment certification questions