For large customers such as apartment buildings or commercial and industrial customers the service can become more complicated. In these systems, the National Electrical Code allows up to six separate disconnects for each electrical service as long as they are grouped together.
An example would be an apartment complex where each electrical service provided power for six apartments. It would be common for the service drop to be connected to six separate disconnect switches, each controlling an individual apartments' electrical service. The electrical wires from one disconnect switch are connected to an electrical meter to measure that particular apartments' energy use and then wires run from the meter to the breaker or fuse box in the corresponding apartment.
If their are more than six electrical disconnects, a main disconnect is required in front of the smaller disconnects.