Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at

December 29, 1992

(Name Withheld)

Dear (Name Withheld):

This is in response to your letter of November 18, in which you requested information on the Occupational Safety and Health Administration (OSHA) requirements for "area classification drawings" for petrochemical plants. In your letter, you inquired about the relationship of the OSHA standard to standards of the National Fire Protection Association (NFPA 497), American Petroleum Institute (API 500), and to the National Electrical Code (NEC Article 500). You also requested information on how OSHA enforces and assesses penalties for non-compliance with its rules and regulations.

Your questions will be answered in the order of their presentation.

OSHA does not provide, require and thus cannot enforce "area classification drawings" for petrochemical plants. The illustrative drawings found in the private standard-setting literature of NFPA 497, API 500 and NEC 500 are not required by an OSHA standard. The OSHA requirements for the installation of electrical equipment and wiring in hazardous (classified) locations at petrochemical plants, found at 29 CFR 1910.307, Hazardous (classified) locations, and at the "Definitions" section of 1910.399, are similar to the standards of the above-mentioned standards orginizations.

Section 5(a)(1) of the OSH Act (General Duty Clause) requires each employer to provide to his employees employment and a place of employment free from recognized hazards likely to cause death or serious physical harm. Since the requirements of 1910.307 are general in nature, OSHA may seek to use particular standards of NEC 500, NFPA 497, and API 500 for reference to show industry-recognized hazards when a General Duty violation is present.

OSHA enforces its standards and regulations as a result of inspections of the workplace. Inspections may occur as a result of employee complaints, referrals from other agencies, accidents, or a targeted inspection program. Where violations or non-compliance with the OSHA standards are observed by OSHA compliance officers (CSHO's) they are required to propose citations and classifications of violations of OSHA standards on the basis of a careful analysis of the circumstances found during the inspections.

OSHA violations are of four types: Serious, Willful, Repeated, and Other-than-Serious. A violation is cited as "serious" when the CSHO determines that a substantial probability of death or serious physical harm exists due to the violative conditions.

Additionally, when a violation is "serious", the OSH Act requires a proposed penalty of up to $7,000. Otherwise, on "Other-than-Serious" types of violations, penalties up to $7,000 may be assessed. Penalties for the other types of violation, including Failure to Abate situations, are assessed similarly, with the possibility that they may be multiplied up to a factor of ten. The assessment of penalties on these types of violations is determined also on the basis of objective criteria. The enclosed publication, OSHA INSPECTIONS, further explains OSHA's inspection and penalty procedures.

If we can be of further assistance, please feel free to contact James C. Dillard, of my staff, at (202) 219-8031.


Roger A. Clark,
Directorate of Compliance Programs