In some cases, the service overcurrent protection devices (OCPDs) are not readily accessible to occupant(s). The service equipment area may be, for example, fenced off. Or the OCPDs are locked or sealed.
This arrangement is often a good choice for a multi-tenant building. No one tenant can disconnect the power to other tenants. Other types of situations may justify this arrangement, also. But if you go this route, you must provide (on the load side) branch-circuit or feeder OCPDs that are readily accessible to the occupants [230.92]. These must be of a lower ampere rating than the service.
Some types of loads need protection from inadvertent disconnection (e.g., breaker flipping) or tampering. If the service conductors supply only a specific load that requires such protection, the OCPD protecting those conductors can be locked or sealed. But it also must be accessible [230.93].
For services, the OCPD shall protect all circuits and devices [230.94]. But there are six exceptions. One of these is the service switch can be on the supply side (upstream of the OCPD).
