Michael Chow, PE, CxA, LEED AP BD+C, Member/Owner, Metro CD Engineering LLC, Powell, Ohio
George Isherwood, PE, Vice President, Peter Basso Associates, Troy, Mich.
Michael Lentz, Associate, RMF Engineering, Baltimore
CSE: What’s the one factor most commonly overlooked in electrical systems in hospitals?
Chow: Understanding and incorporating the applicable codes and standards for a hospital is commonly overlooked. A hospital may be certified by The Joint Commission and an engineer designing a remodel may inadvertently overlook their standards and requirements.
Lentz: What equipment that the owner would like to see on emergency power and what the code actually allows on emergency power. For example, in a patient room, hospitals would like the lighting on emergency power on the life safety branch, but code does not allow lighting on a life safety branch. So in order to provide that, it would then require additional panels and transfer switches to put the equipment on emergency power, but results in increased project costs and space requirements.
CSE: Describe a recent project in which you had a complex standby, back-up, or emergency power design.
Lentz: Inova Women’s Hospital has three 2 MW 5 kV generators paralleling with the utility system and four distribution sub-stations. Three 2 MW, 4.16 kV enclosed diesel engine electric generators (EGs) and auxiliary systems were provided in a designated outdoor yard, remote from the hospital central plant. The 2 MW emergency generators were paralleled through the emergency generator 5 kV paralleling switchgear (EGPS). The EGPS was configured with two outgoing main breakers to the normal 5 kV switchgear, one bus tie breaker, two emergency generator auxiliary load breakers, existing plant breaker, and three generator breakers. Although the generators were intended to be used as standby generators only, the use of a selective catalyst reduction (SCR) system was provided in the design. The SCR system reduces engine emissions, specifically NOx up to 90%, and has become a required component in most new generator installations to meet state/U.S. Environmental Protection Agency emissions requirements. The SCR system consists of an injection/mixing pipe, catalyst housing, solution storage tanks, solution transfer pumps, and associated control panels. The generator assemblies were contained in pre-engineered sound attenuated enclosures. The enclosures achieve a 40 dB(A) reduction of the generator set source noise, as measured at 1 meter from the enclosure.
CSE: What unique NFPA 99: Health Care Facilities Code issues have you encountered, and how have you resolved them?
Chow: The 2014 NEC has a proposed change to increase the minimum number of receptacles for a patient bed in a critical care area from 6 to 14 receptacles. This would coordinate the requirements between the NEC and NFPA 99.