Modern electrical Substation Automation Systems (SAS) are designed following the guidelines defined in the IEC 61850 standard. This standard specifies the necessary information models and communication services for SAS in such a way that they are independent of the implementation. This allows system designers to choose the specific communication technology that best fits their needs. Time-Sensitive Networking (TSN) is arising as one of the most appealing technologies for this purpose. However, it is necessary to map the communication services to TSN, ensuring that the real-time and fault-tolerance requirements of the messages are met. In particular, efficiently mapping the messages of the Generic Object Oriented Substation Events (GOOSE) service is challenging. This is because it exhibits a transmission pattern that does not align with the types of traffic defined in TSN. In this paper we analyze this transmission pattern, identify and characterize its subpatterns, propose the most suitable mapping for each of them and discuss the efficiency gain with respect the typical approaches used to do this mapping.