Open Neutral Multi-Wire Circuit

The wire connector is removed from the neutral wires for inspection in the A phase electrical box. Find Multimeters

In the A phase outlet box:

The neutral wire that comes from the electrical panel carries 0V.
The neutral wire that goes to the A phase outlet carries no voltage (breaker turned off).
The neutral wire that goes to the B phase electrical box is line voltage.

In the diagram above, the A phase circuit breaker is turned off.

Multi-Wire Branch Circuit Wiring Diagram