Arc Flash, Coordination and Short Circuit Study for a School Building Addition and Its Parking Lot Service, Dripping Springs (2026)

Not every arc flash study turns up dangerous numbers, and a small one still needs to be right. In early 2026 an electrical contractor asked us for the study on a new addition to a school building in Dripping Springs, part of a community electrical upgrade.

A small system

The addition has one utility feed, stepped down by a 225 kVA transformer on the northwest side of the building and run overhead to the main panel, which feeds two subpanels. The model held 47 buses, nearly all at 240 V, with the utility primary at 13.2 kV. We issued the study in February 2026, with incident energy per IEEE 1584-2018 and labels per NFPA 70E-2024.

Results

Nothing came close to the levels that call for special measures. The highest values, about 6 cal/cm², were at the two air handling units and their disconnects, not at the main panel, and no bus was above 8 cal/cm². No critical items were found and no setting changes were proposed. Even at these levels the labels matter: they tell a qualified worker what gloves and clothing the job needs and how close an unqualified person may come.

Revision 1

In March 2026 the contractor added a panel to the scope, a separate 600 A service fed overhead from the utility for the site parking lot. We added it to the model and reissued the report, so the labels on the new panel came from the same study as the rest.

Related services

For the modeling side, see our arc flash study services. Fault currents come from the short circuit analysis.