Looks fine, as long as the grounding bus and conductor are sized to the greatest need. Remember to not re-bond the neutral downstream.Although the attached drawing is not exactly like that represented in exhibit 250.15, is it wrong? Is there any technical reason why it could not be configured as such?
This figured changed a little bit around in the latest edition of the handbook.
Location of the "ground bus"?Although the attached drawing is not exactly like that represented in exhibit 250.15, is it wrong? Is there any technical reason why it could not be configured as such?
Can you post a photo of the 2017 graphic?I have a similar question about Exhibit 250.15 in the 2017 NEC Handbook (NECH). The "Neutral" bar in the 2011 NECH Exhibit 250.13 has been changed to a "Terminal bar" in the 2017 NECH Exhibit 250.15. To me, this "Terminal bar" is the termination bar required per 450.10, which I'm guessing will be sized like a ground bus and not rated for neutral current. For example: For a K-Rated transformer with a 200% neutral, I doubt the termination bar will be rated 200% to support the neutral current. Shouldn't the neutral be connected as shown in the 2017 NECH Exhibit 250.16, such that the neutral connections are the same for either exhibit?
You can bond the neutral of a transformer secondary at the transformer or in the first disconnect. This has been the way this way as long as I have been alive, it is not unique to the 2017 NEC. If you bond at the first disconnect then there is no reason to separate the neutrals and equipment grounds.Just to clarify, I was calling the "black" wire between the transformer X0 and Terminal Bar in Exhibit 250.15 as the SBJ even though it's not identified as such in the exhibit. If the Terminal Bar needs to accept equipment ground conductors (EGC's), then the Terminal Bar should be treated as a ground bar and not a neutral bar.
No, it's part of the fault current path.Adding to my 10/22/19 question... As you can see from these two exhibits (2017 NECH Exhibit 250.15 & 250.16), the System Bonding Jumper (SBJ) in Exhibit 250.15 is now part of the neutral current return path.
Thus, the SBJ and Terminal Bar would need to be sized for the neutral current. In Exhibit 250.16, the SBJ and Terminal Bar do not carry neutral neutral current. If the "white" wire in Exhibit 250.15 was moved from the Terminal Bar to the transformer X0 terminal, the SBJ and Terminal Bar would not carry neutral current and could be sized similar to Exhibit 250.16. Looking back at the 1st entry of this thread on 6/10/19, the attached file shows a similar configuration of what I think Exhibit 250.15 should be changed to show.