What are the xxx_net_builderr tables used for?

Question

What are the xxx_net_builderr tables used for? Can they be deleted?

Solution

These tables contain error messages that occur when creating a geometric network. The tables are informational in nature and can therefore be deleted.

The error codes are explained here:

http://desktop.arcgis.com/de/arcmap/10.3/manage-data/geometric-networks/h-network-build-errors-table.htm