A load controller in a load control system may communicate messages with controllable loads on a plurality of loops for controlling electrical loads. Each controllable load may include a load control device and an associated electrical load. The messages received by the load controller may include a zone identifier. The zone identifier may be associated with the load control devices for being controlled together. The load controller may communicate messages to sets of load control devices for performing common control of the load control devices on each loop using group messages. The load controller may reconfigure the zones that are assigned group identifiers for receiving group messages on the loops, such that the group identifiers are assigned to the zones that have larger numbers of load control devices. The message types on a given loop may be selected based on the type of control being transmitted in the commands.