What is the most widely used regulation book among operating engineers?

The most widely used regulation book among operating engineers is the EPA (Environmental Protection Agency). The EPA's regulations play a crucial role in ensuring that operating engineers adhere to environmental standards and practices that safeguard public health and the environment. Operating engineers must be aware of the EPA regulations, especially regarding emissions, waste management, and the use of materials that could impact air and water quality.

While OSHA standards focus on workplace safety and health, they do not specifically govern the operational practices of engineers in the same way that EPA regulations do. NFPA standards pertain primarily to fire protection and safety, and although they are important, they are not the central focus for operating engineers as they deal more with fire safety than with operational regulations. ASHRAE guidelines are significant for heating, ventilation, air conditioning, and refrigeration systems but are not as broadly applied across all engineering operations as the regulations set by the EPA. Therefore, the EPA stands out as the key regulatory body for operating engineers in their daily practices.