What must be clearly marked on electrical panels?

The circuit directory and service rating must be clearly marked on electrical panels to ensure safety and proper usage. The circuit directory allows users to quickly identify which circuit breakers control specific areas or equipment within the building, facilitating maintenance, troubleshooting, and safe operation. Knowing the service rating is crucial as it indicates the maximum amount of current that the panel can safely handle. This information is vital for electricians and maintenance personnel to prevent overloading the panel and to ensure safe operation within the rated parameters.

While the manufacturer's name, date of installation, and emergency contact information are relevant for certain contexts, they are not as crucial for the daily function and safety of the electrical system as the circuit directory and service rating. Marking the latter helps prevent accidents and promotes adherence to codes and standards within the electrical industry.