We are aware of this issue, and intend to enhance the node feature definitions in the CONNECT Edition so that the minimum depth can be adjusted.
For now though, if you have version 08.11.09.878, then you can use the config variable "DEFAULT_UTILITY_NODE_HEIGHT" to set the height of the minimum depth, which by default is 1 metre in a metric project as you say. For example, "DEFAULT_UTILITY_NODE_HEIGHT=0.25" would set it to 0.25 units.
For now though, if you have version 08.11.09.878, then you can use the config variable "DEFAULT_UTILITY_NODE_HEIGHT" to set the height of the minimum depth, which by default is 1 metre in a metric project as you say. For example, "DEFAULT_UTILITY_NODE_HEIGHT=0.25" would set it to 0.25 units.