In designing electrical systems for health care facilities, patient health and safety is a top priority, that’s why special protection devices and systems are used to ensure maximum safety for patients, an example of such systems is IPS.
As the patients under treatment may have their skin resistance broken or their defensive capacity either reduced by medication or nullified while anesthetized, these conditions increase the possible consequences of a shock under fault conditions. To reduce the risk from different leakage currents, the sources of electrical power need to be electrically isolated from the patient in some medical areas where some of the equipment applied parts have direct contact with the patient externally or invasively or both.
1. Isolated Power Supply System (IPS)
IPS alo known as a medical IT (Isolated Terra) system provides safe delivery of electrical power to certain areas in the medical facilities, it provides continuity of supply in the instance of the first insulation fault and offers additional protection from electrical leakage currents. IPS/ IT electrical system has specific requirements for medical installations, the system includes a monitoring device to provide an alarm on loss of Insulation Monitoring Device (IMD) connections, micro current leakage, insulation failure, overload and high temperature.
2. Standards and Guidance Used for IPS in Medical Locations
- IEC 60364-7-710 Electrical installations of buildings for special areas.
- HTM 06-01 & HTM 08-03
- IEE Guidance Note 7 Chapter 10
- NFPA 99 Chapter 6 & NFPA 70 Article 517
3. Classification of Medical Locations/ Area of Application as per Standards
A) IEC 60364-7-710 classified the medical locations in three categories:
- Group 0 Medical Locations, where no applied parts are intended to be used.
- Group 1 Medical Locations, where applied parts are intended to be used externally or invasively to any part of the body, except where Group 2 applications are intended.
- Group 2 Medical Locations, where applied parts are intended to be used in applications like intracardiac procedures, operating theaters, operating plaster room, operating recovery room, heart catheterization room, intensive care unit, angiographic examination room, anesthetic room, and vital treatment where failure of the electrical supply can cause danger to life.
As per IEC 60364-7-710, the area of application for the use of the IPS is intended to be used in Group 2
B) HTM 06-01 (from clinical risk point of view) classified the medical locations in five categories
- Grade E: Support service circulation.
- Grade D: Ambulant care and diagnostics.
- Grade C: Emergency care and diagnostics. These areas relate to the patient environment of group 0 under Chapter 10 in ‘IEE Guidance Note 7’.
- Grade B: Patients in special medical locations. These areas will relate to the patient environment of group 1 under Chapter 10 in ‘IEE Guidance Note 7’.
- Grade A – Life support or complex surgery. These areas will relate to the patient environment of group 2 under Chapter 10 in ‘IEE Guidance Note 7’. The areas are defined as operating theater suites, critical care areas, cardiac wards, catheterizing rooms, accident & emergency resuscitation units, MRI, angiographic rooms, PET and CT scanner rooms. In such location’s patients may have electro-medical equipment, medical monitoring or medical test equipment (for example intracardiac procedures) connected externally or internally to their bodies for a prolonged period. Clinical treatment and patient safety may be compromised by any interruption of electrical supply. A patient’s natural electrical resistance is significantly reduced when electro-medical conductive parts are placed in the body. IPS systems are essentially required in such locations.
As per HTM 06-01, the area of application for the use of the IPS is intended to be used in Grade A
C) NFPA-99 and NFPA-70 classified the medical locations in three categories
- Wet Locations.
- Wet Procedure Locations.
- Critical Care locations. The following patient care areas are identified as "Critical Care Areas" where patients may be subjected to invasive procedures and connected to line-operated electro-medical devices: Operating rooms, Delivery rooms (Labor and Delivery rooms), Cystoscope rooms, Oral Surgery, Maxillofacial surgery, Perodontics, and Endodontics , Recovery (surgery, and labor recovery beds), Coronary care units (patient bedrooms), Intensive care unit (patient bedrooms), Emergency care units (treatment/trauma/urgent care rooms and cubicals), Labor rooms (including stress test and preparation), Intensive care and isolation care nursery, Cardiac catherization, Angiographic exposure room, Hemodialysis (patient station), Surgery suite preparation and hold, Hyperbaric chamber, Hypobaric chamber, Radiation Therapy (including simulator room), Nuclear medicine (camera room), fluoroscopy , CT , MRI, Endoscopy & Pulmonary / Respiratory . IPS systems are essentially required in such locations.
As per NFPA-99 and NFPA-70, the area of application for the use of the IPS is intended to be used in critical care location.