Which is correct, A or B

The numbers in B have been changed to reflect Mexican voltages, so you can ignore the slightly higher voltage. Which image reflects the correct condition? Why?

I emailed you the answer Roy


I am hurting my head trying to answer why

What do you mean “opposite polarity”?

Sorry I confused myself.

It’s definitely A. I think its because those breakers on the bottom are the same Line.

A. 240 v. Circuit should read 240 between the two Hot conductors and 120 between hot and ground or neutral

Voltage is the movement between two different potentials. You will get 0 on the bottom situation because its the same line, and thus the same potential.

B must be wrong

Forgot the 3rd part of diagram Bottom has zero cause on same phase


Looking at the voltage meter B in both images. What will be the relationship of the amperage carried by the grounded conductor compared to the amperage of the ungrounded conductor pair in: Scenario A? vs. scenario B?

I think they are both wrong. A-A should be 240/254V, B-B should be 254V

Edit: I’m wrong. Diagram A is correct

A is right.

It display 120V from phase 1 & 120V from phase 2.

Both phase amount to 240V.

I think both are wrong. A in the first picture should be 240 volts and B in the second picture should be 254 volts.

A in the first is correct at 0. Those breakers are the same line. Voltage is the movement of electrons between different potentials. Since both breakers are on the same line, there is no difference in potential.

Nobody wants to tackle this? It’s important to know.

I am going with B I like to be different!!!:wink:

B in the second image should be 0 those two breakers should be on the same leg if they are on opposite legs you would be correct it would read 240

It took 16 posts for this.

Well who is correct A or B:roll:

A is is correct. In B I tweaked the numbers. Key to understanding this is that there will be 240v potential difference between ungrounded conductors connected to separate supply bus bars. There will be 0 voltage difference between conductors connected to the same bus bar. The two bottom breakers align horizontally and are connected to the same bus bar.

Both A and B show a properly wired MWBC with a shared neutral. The neutral current will be the difference between A and B.