Tier groups allow you to organize your system in domain networks that have a hierarchical tier definition. They are defined during the configuration stage of a utility network by the administrator using the Add Tier Group tool. Tier groups are required to add tiers to a hierarchical domain network and represent systems such as water, gas, and sewage. Tier groups are used to model the different sectors of those types of networks—for example, gathering, transmission, distribution, and cathodic protection. If you manage or model only one sector—for example, distribution—it's still required that you create one domain network with one tier group to manage your assets. If you need additional sectors in your network—for example, cathodic protection—you can add them without significantly adjusting your model.
Tier groups are not used in the modeling and organization of tiers in partitioned systems, such as electric and telecommunications. Sector organization of these industries is modeled at the domain network level. To learn more, see Domain networks.
The following illustration shows how tiers in a tier group have overlapping definitions in this simple network diagram. The defining features of subnetwork extents in a tier are subnetwork controllers and barriers.