Which standards are used for testing equipment intended for hazardous locations in the U.S.?

The choice of Underwriters Laboratories (UL) and Factory Mutual (FM) as the standards for testing equipment intended for hazardous locations in the U.S. is correct because these organizations are specifically recognized for establishing safety standards in North America, particularly related to electrical equipment and systems used in potentially explosive environments.

UL primarily focuses on testing and certifying products for safety and performance across a range of industries, including hazardous locations. Their standards cover various aspects of equipment, including its construction, design, and material safety, ensuring that devices can operate safely in environments with flammable gases, vapors, dust, or fibers.

Similarly, FM Global, through Factory Mutual, works to ensure that equipment is not only tested for safety but also for its effectiveness in preventing fire and explosion hazards. Their rigorous testing protocols and certifications are essential for ensuring that equipment can withstand harsh conditions unique to hazardous locations.

In contrast, the other options mention standards and organizations that may relate to safety in general or international standards but do not specifically focus on the requirements for equipment used in hazardous locations within the U.S. For example, ISO and IEC are important in a global context but are not the main standards applied within the U.S. for hazardous areas. NFPA and OSHA have relevant safety implications,