Application on a separately derived system. We have both ungrounded and grounded systems at our plant. A contractor is hooking up a new separately derived system with a 25KV primary and 480V secondary 1500KVA WYE-WYE transformer. The primary is internally grounded to HO. Contractor ran 4 wire plus EGC from transformer and hooked both the neutral and EGC to the same ground buss on a 3 phase 3 wire switchgear (switchboard). The switchgear has a 2500 amp main and does not have a separate neutral buss and therefore no CT on neutral to detect the fault and trip the main. The contractor says since both are hooked essentially to the grounding electrode system then it makes the system grounded and the main should trip on a phase to ground fault or phase to phase fault. I believe he created a parallel path to ground which can cause equipment damage and electrical hazard to personnel. We do not have electrical engineers on site, and my emails to some have not returned. Are there any code violations here, so at least I can use that to stop the project before the system is energized. Help.....
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