Critical power: Selective coordination in health care buildings
Health care facilities, especially hospitals, have more stringent selective coordination requirements than conventional building electrical systems, according to some electrical engineers.
Health care facilities, especially hospitals, have more stringent selective coordination requirements than conventional building electrical systems, according to some electrical engineers. The unique constraints of health care facility electrical distribution systems require engineers to be diligent when designing these systems. The code requirements are less stringent, but the function in these buildings is more important. Selective coordination localizes an overcurrent condition to restrict electrical outages to the affected equipment, circuit, or feeder.
In a properly coordinated system, a fault induces operation of the nearest device on the line side of the fault and limits the outage to only the faulted portion of the system. If overcurrent devices are not selectively coordinated, the fault has the potential to impact one or several devices upstream resulting in a much larger scale outage than necessary for system protection. In extreme cases, faults can open the main overcurrent protective device and cause an outage for the entire facility. In addition, electrical power provided by gensets has less available fault current than the utility. Therefore, selective coordination in the health care environment has different criteria when connected to standby power.
- The audience will understand the applicable codes and standards: NFPA 70: National Electrical Code (NEC), Article 517; NFPA 99: Health Care Facilities Code; and NFPA 110: Standard for Emergency and Standby Power Systems.
- Attendees will understand the selective coordination issues unique to hospitals and health care electrical distribution systems including separation of feeders and branch circuits.
- Viewers will learn the criteria for selectively coordinating electrical power provided by gensets.
- Viewers develop a basic understanding of how to design selectively coordinated electrical systems for hospitals and health care facilities using circuit breakers, fuses, relays, and/or a combination thereof.
Tom Divine, PE, project manager, Smith Seckman Reid, Houston
James Ferris, PE, electrical project engineer, TLC Engineering for Architecture, Orlando, Fla.
Moderator: Jack Smith, Consulting-Specifying Engineer, Pure Power, and CFE Media, LLC