Although it is not really “new” any longer; OSHA revised 1910.307 in 2007 and many of the facts that are presented in this article may be “news” to a lot of you. Many of the “new” requirements in 1910.307 Hazardous (classified) Locations are often not well understood or not even known. This article, which has been extracted from an assortment of OSHA and NFPA documents, will lay out the new and existing requirements of 1910.307 Hazardous (classified) Locations and provide some explanation of the requirements.