I'm an Electrical Engineer assigned with the responsibility of reviewing our site hazardous area classification with help from an expert. Would anyone help me find such help since the boundaries marked up on our drawings may not be current with recent codes, experience, etc.? Review of NFPA 497, etc. just leads to confusion since it mentions taking credit for experience, etc. and the boundaries are not clearly defined for a Class 1, Div 2, Groups C&D. Thanks for your help in advance. I have read about looking at OSHA & Other NFPA 500 articles for more details. Is this something the local Fire Marshal can help or are there experts in this field who can review existing drawings and provide a report doing a survey? Nat H. from Houston Texas.