It's now been over a year since this project began and it looks like it may finally come to an end next week. The UPS is connected ahead of the 300A main breaker but that riser is still being back fed by the 600A riser. Next week we will preform a closed transition and the 300A riser will be powered through the UPS.
Just thinking about something that nobody involved seems concerned about (therefore, I must be overthinking the situation) regarding the neutrals. As shown in the diagram they are now connected so that there are two common points. Earlier today myself and another electrician measured 11A with a clamp-on ammeter on the neutral at the UPS. If there wasn't a second second common point then there wouldn't be a measurable load on the neutral at that location at this time - correct? Since there is essentially parallel neutrals I assume that the unbalanced load current is being distributed between them like any other parallel circuit? If this configuration remains after the UPS is brought online is this still acceptable?
