A master electrician is designing the electrical system for a new health care facility. The facility includes operating rooms, intensive care units, and patient care areas. According to NEC Article 517, which of the following areas requires an isolated power system?
- AGeneral patient care rooms for non-critical patients.
- BAdministrative offices and waiting rooms within the facility.
- CDesignated critical care areas where patients are subject to invasive procedures.
- DLaboratories and pharmacies where no direct patient contact occurs.
Show answer & explanationAnswer & explanation
Correct answer: C. Designated critical care areas where patients are subject to invasive procedures.
NEC 517.160(A)(1) specifies that isolated power systems shall be permitted or required where a wet procedure location is designated by the health care facility and where patients are subject to invasive procedures and connected to line-operated equipment. Critical care areas where invasive procedures are performed often fall under this requirement.
Why the other options are wrong
- A. General patient care rooms typically use solidly grounded systems, not isolated power systems.
- B. Administrative offices and waiting rooms do not require isolated power systems; they are considered general occupancy areas.
- D. Laboratories and pharmacies, without direct patient contact in invasive procedures, do not typically require isolated power systems.
Isolated Power System (Health Care)
An isolated power system provides a separate, ungrounded power supply to critical patient care areas in health care facilities, significantly reducing the risk of microshock hazards to patients connected to multiple pieces of electrical equipment.
- Used in wet procedure locations and critical care areas.
- Consists of an isolation transformer, line isolation monitor (LIM), and ungrounded circuits.
- Minimizes current flow through a patient in case of a single fault.
Memory trick: Health Care: Critical Patients demand Isolated Power, General Patients get Grounded Power.