What is it that you're calling a Delta MCC? Isn't it really just a 3Ø, 3-wire Wye without a neutral?
That’s what I assumed. I should have probably asked that before answering lol
That's where I get confused, so they're bonding the ground to the neutral at the 208/120 xfmr
Forget "code violation" and think this through. Your MCC is not delta or Y. The code requires a compliant fault return path. Most services today are grounded 480/277Y in this kind of application. This means you have to bring the neutral from the POCO to the first means of disconnect and bond it. From that point you only need an EGC downstream if you have only line to line load.
Forget the Wye Delta supply thing for a moment and just think of it as a 3 phase 3-wire feeder to the MCC. After that you have a 480 Delta/Wye transformer which creates a neutral for the 120 volt loads. That neutral gets bonded as it would in any Delta/Wye transformer.
Yeah ok I didn't need some egotistical boot licker to come and tell me I don't have a grasp on basic code. I was asking because normally most 480v services bring the neutral and I didn't understand why they would allow the bonding of the neutral derived from the 208v xfmr to be bonded to the egc when there's no grounded conductor back to the service disconnect.
The 480 Delta to 208Y/120 volt transformer has no neutral connection on the primary so the bonding of the secondary X0 has no bearing on whether or not the feeder supplying the MCC is 3-wire without a neutral or 4-wire with a neutral.
Those comments put our understanding of your knowledge at risk.
We're confused by the aforementioned 480 Delta. Unless there is a 480-480 Wye/Delta transformer in the feeder there is no Delta. You have a Wye service with 4 conductors to the service disconnect. On the load side of the service disconnect you have a 3-wire feeder to the MCC. That feeder is still Wye. You can confirm this by testing the 3Ø's at the MCC to ground. A-G, B-G, C-G, would all be 277 volts which would indicate that the system connected at the MCC is Wye.
Sorry, I did not mean to offend you. I would only suggest you use this as a career learning opportunity. I happen to have a close relationship with the Chief Electrical Inspector for the State of Wyoming. He likes to educate, not just enforce licensing and code. If you PM me I'll give you his private cell phone number. He won't even require you to tell him your name or job site. I'm certain that he would like to help you better understand your situation.
