Arc flash hazard analysis is not legally required in all circumstances, but it is generally considered a best practice in the electrical industry. Many countries and regions have regulations or standards that require arc flash hazard analysis to be performed under certain circumstances.

For example, in the United States, OSHA (Occupational Safety and Health Administration) regulations require that employers provide a workplace free from recognized hazards that are likely to cause death or serious physical harm. This includes hazards associated with electrical equipment, such as the potential for an arc flash event. While OSHA regulations do not specifically require arc flash hazard analysis to be performed, employers are required to assess the hazards present in the workplace, and many employers choose to conduct an arc flash hazard analysis as part of this assessment.

Similarly, NFPA 70E Standard for Electrical Safety in the Workplace, which is widely adopted in the US, recommends that an arc flash hazard analysis be performed, and the results are used to develop a safe work practice to ensure the safety of employees working on or near electrical equipment.

In other countries, such as Canada, arc flash hazard analysis is not mandated, but it is widely recognized as best practice by industry and standards organizations. The Canadian Standards Association recommends that an Arc Flash Risk Assessment be performed to meet Health and Safety regulations and industry best practices.

So, even if it is not explicitly required by regulation, it is highly recommended to perform an arc flash hazard analysis to ensure the safety of workers exposed to the hazards associated with electrical equipment and mitigate legal liabilities.