ANSI NEIS-700-2010 pdf download Overcurrent Protection to Achieve Selective Coordination
4.1 Emergency Systems (NEC Article 700) NEC Article 700 includes a requirement that emer- gency system overcurrent protective devices be selectively coordinated with all supply side overcurrent protective devices. Two exceptions to this requirement are:
1) Transformer primary and secondary overcur- rent protective devices where there is only one set ofprotective devices on the transformer secondary; and
2) Two overcurrent protective devices ofthe same ampere rating that are in series, such as a feeder overcurrent protective device supplying a panelboard that has a main overcurrent protec- tive device.
4.2 Legally-Required Standby Systems (NEC Article 701) NEC Article 701 applies the same language found in NEC Article 700 to legally required standby systems, including the two exceptions for selectively coordi- nated overcurrent protective devices.
4.3 Critical Operations Power Systems (NEC Article 708) NEC Article 708 applies the same language found in NEC Article 700 to critical operations power systems.
4.4 Healthcare Facilities (NEC Article 517) NEC Article 517 includes a requirement that the essential electrical system ofhealthcare facilities meet the requirements ofArticle 700, Emergency Systems. The essential electrical system ofa healthcare facility is a system capable ofsupplying a limited amount of lighting and power service to designated areas and functions ofa health care facility that are considered essential for life safety, effective hospital operation and orderly cessation ofprocedures during the time normal electrical service is interrupted for any rea- son. The essential electrical system is subdivided into the equipment system and the emergency system.
4.4.1 The Equipment System The equipment system ofa healthcare facility is a system ofcircuits and equipment arranged for delayed, automatic, or manual connection to the alternate power source and that primarily supplies three-phase equipment. The equipment system supplies major electrical equipment needed for patient care and for basic hospital operation.
4.4.2 The Emergency System Emergency systems in healthcare facilities are systems ofcircuits and equipment intended to supply alternate power to a limited number ofprescribed functions vital to the protection oflife and safety.