Review Short-Circuit Studies Against Installed Conditions Before Energization

Project Context

Electrical preconstruction and late-construction energization planning where short-circuit coordination studies had to match submitted equipment, feeder lengths, and installed gear.

Specific Condition

The coordination study engineer used an incorrect single-line diagram that did not match the contract drawings, and a late design change added non-fused disconnects that were ordered and installed without approved submittals. The study assumed incorrect ratings, and the gear ultimately needed 40 KAIC thermal magnetic breakers.

Weak Signal

Missing or incorrect single-line diagrams in the study, late equipment changes, missing submittals, assumed KAIC ratings, and coordination settings approaching energization.

What Was Missed

MEP coordinators may avoid coordination studies because they look technical and long, but the key checks often come down to a few sections.

Downstream Consequence

The team had to rush replacement breakers, rewire disconnects, absorb roughly $150,000 in cost, and delay affected chillers by a couple weeks while overall energization stayed under pressure.

Practical Takeaway

Have someone review the study engineer's single-line, confirm every equipment submittal is available, compare it back to contract drawings, and update feeder or conduit length assumptions before settings are needed.

Schedule Impact

Affected chillers were held up by a couple of weeks while replacement breakers were expedited.

Cost Impact

Changing the non-fused disconnects to 40 KAIC breakers added roughly $150,000.