The OnChange (geometry) rule is triggered on a junction feature when a new vertex is added to a connected edge.
Last Published: July 3, 2017ArcGIS for Desktop
Bug ID Number
September 18, 2014
November 24, 2020
ArcGIS for Desktop
Operating System Version
7 64 Bit
After review by the development team, it has been determined that this issue is related to a known limitation with the software that lies outside of Esri's control. The issue's Additional Information section may contain further explanation.
Geometry updates on a complex edge with connected junctions will update the geometry on the edge as well as any connected junctions. This is why adding a vertex 'updates' the attached junction. This is required to support the live network that the Geometric Network relies upon.
Disconnect the valve from the edge, and add the vertex. The edge and junction must be connected for the issue to occur.