The main breaker should have had an indicator showing the nature of the trip, most likely GF. Sometimes the first breaker to have ground fault sensing is the main. You should look at the trip setting and time dial of the main Vs downstream trip units. The downstream units should always win the race. Main: "A", ".3S" Branch: "A", ".1S"--> Branch should trip first under ground fault conditions.
Main: "A", ".1S" Branch: "A", ".1S" --> It's anybody's guess.
We try to check our Digitrip units every 2 to 3 years, to verify that the pickups and times are as set. Sometimes that's not the case until those little rotary switches get exercised.
Joe
