Case Studies

Arc Flash & Overcurrent Protective Device Coordination Study – Northern Kentucky University

Project Specifications:

Fosdick & Hilmer was retained to perform an electrical system evaluation for over 25 buildings on the 400 acre suburban campus. The campus distribution network and the individual building systems had a total bus count of approximately 2,200.

After initial evaluation determined where arc flash values were “DANGER” (no safe PPE exists to work on live parts) additional analysis was provided to develop mitigation recommendations for equipment rated at Category 3 and above. These recommendations balanced modifications with maintaining a solidly coordinated and protected electrical distribution system.

At Fosdick & Hilmer’s recommendation the university also included evaluation and labeling of local disconnect switches, transformers, VFDs, bus duct plugs, and other electrical equipment or devices that are not explicitly identified by NFPA 70E as requiring labeling. Given our experience it is highly recommended to label all electrical equipment to alleviate confusion by contractors working within the University.

Key Features


  • Single-line drawing validation(service entrance to Category 0), or
  • Field data collection of all electrical system components (service entrance to Category 0).
  • Updating or creation of single-line diagrams.
  • Electrical system modeling of the single-lines.
  • Perform short-circuit and coordination study.
  • Arc flash analysis and reporting.
  • Provided recommendations for limiting identified hazards to Category 2 or below.
  • Printed and attached arc flash labels.
  • Provided Plant O&M staff training.
  • Delivered bound reports for each location including software model output and single-lines drawings in AutoCAD format.