Emergency, Standby, Backup

Understanding emergency power

How to understand generator type, class and level

By Sean C. Hu and Kenneth A. Frazier July 14, 2021
Figure 6: Low-voltage pathways designed for use in fire-rated walls can be more desirable over the life of the building. Courtesy: IMEG Corp.

What is a Type 10, Class X, Level 1 generator?

  • Type identifies the power restoration time in seconds, 10 seconds or less.
  • Class identifies the minimum runtime in hours; X hours. In a health care facility, this often relates to the amount of time to safety complete any ongoing patient care and procedures.
  • Level identifies if the failure of the system will result in loss of life or injury; Level 1 systems represent a life/injury concerns while Level 2 systems do not. The life safety and critical branches of the ESS serve the Level 1 functions of the hospital. Life safety system examples include fire alarm, medical gas, egress lighting and mass notification. Critical branch power serves the necessary patient care functions like lighting, receptacles and medical equipment.

Sean C. Hu and Kenneth A. Frazier
Author Bio: Sean C. Hu is a vice president at WSP. Hu leads engineering teams with a focus on health care and science technology projects. Kenneth A. Frazier is a vice president at WSP. Frazier has completed hundreds of new construction, renovation and infrastructure replacement projects, almost exclusively for health care clients.