This is why you don't test chiller plant systems at 3pm on a Friday.
We're not (this is an old pic #FBF ha!) ...BUT it still illustrates why it's important to consider risks and timing/staffing when coordinating schedules for functional testing.
Here, the story was that pumps were scoped as minor equipment, and therefore only 50% of start-ups were required to be witnessed by the CxP (to ensure at the very least that the start-up procedures were being followed correctly).
During a pump start-up, motor shaft rotation is checked in 1) hand/manual, 2) auto, and 3) vfd bypass modes (to make sure we're pushing water in the correct direction--real important, easy to check). When you bypass a VFD, that motor shaft gets 100% power immediately (no ramp up...and, well, actually maybe a little spurt more energy than 100% if ya wanna get into electrical details. But full on, right away, either way) So that's one that's important thing to check, but often it gets missed because the need for a bypass isn't always understood (or actually used), and...well, really, it's third on the checklist (less sarcastic, more realistic tone here).
Anyway... one of the pump bypass checks was missed in startup. Water blasted the wrong way and out of the pipes and equipment through system path of least resistance (maybe even our through the fittings, I don't remember). I learned how to help out with squeegee clean up that day. Also, anymore, while it might mean trading off with something non-critical, I include all plant equipment 100% in that "witnessing start-ups" scope item, too!
Tracey Jumper, CCP