It's not a black wire, it is a line on an picture illustrating the way the transformer is internally wired and where that particular point of the transformer is used. Standard delta/wye transformer secondary is labeled X1, X2, X3, and X0. X1, X2, X3 are line one, two, and three and X0 is the neutral or grounded conductor.
That black line is the connection to XO. XO is the neutral point of the transformer and by definition the conductor connected to it is a neutral conductor.
It's a line on a picture. The whole picture represents a transformer. The curly wires represent transformer windings.
Yes it's just an illustration line. You're overthinking it bud.
The transformer will have some common point usually a piece of bus that is for the connection of the field neutral conductor and it is the point where the one side of each coil terminates. Look at this photo and see if it makes sense. The X0 bus is at the bottom.
It's just a representation of how it's internally connected not the actual way manufacturers wire them. What is shown in the photo in post #13 is typically how they are constructed. Here's another one with the X0 on top.
The whole point of the illustration is to show where you put your grounding electrode conductor and system bonding jumper are placed. Don't size anything off of that illustration. Don't look for any information off of it beyond what it is intended for.
The center point of the transformer is the neutral point. The terminal bar is just that....a terminal bar.
I don't agree. The conductor from the XO point on the transformer to the terminal block is the neutral. The neutral does not start at the terminal block,
I agree with this. If the wire from X-0 to the neutral bus isn't white, it's because the transformer maker put it in and didn't use a white wire.
