Electrical Safety and Protection Technologies
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Electrical Safety and Protection Technologies
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OPERATING ROOM GROUND NETWORK TESTING
Operating Room Grounding Equipment Ground System testing is equally important as LIM testing in an Isolated Power System. Why? What does NFPA 99 say about Isolated Power Systems and the grounding network?
As in "normal" electrical systems, grounding in a patient care or anesthetizing area is important for protection against shock and electrocution. Proper grounding dissipates static charges and diverts fault currents and normal leakage currents away from patients and personnel. Equipment/Appliance Power Cord Grounding: The grounding conductor in equipment power cords prevents static charges from reaching dangerous levels on non-current carrying parts such as cases, housings and boxes of electrical instruments. If these instruments are not properly grounded, a static charge could build up. This charge could then discharge as a static spark. This static charge could be a hazard to the patient and personnel if it ignited some flammable gas, or if it discharged into the patient as a shock (microshock). This grounding conductor also provides a path for leakage current which could be conducted to the case of an appliance or instrument. The level of this leakage current depends on the nature of the instrument and its’ insulation. This leakage current could establish potential differences between pieces of equipment and could flow through vital organs of the patient, if a current path is established. For example, during cardiac catheterization, small amounts of current could lead to ventricular fibrillation. Ground Wiring (Hard Wiring) Between The Isolated Power Panel And The O.R.: All electrical instruments and appliances with good, solid internal grounding characteristics need an equally solid and low impedance ground circuit to be plugged into: ie – the hard-wired ground system between the isolated power panel and the O.R., and receptacles contained therein. Current codes and standards require that all conductive surfaces within the patient vicinity be properly grounded. A high-integrity grounding system allows the intermingling of electric instruments and appliances located near or attached to the patient without the risk of leakage or fault current to the patient. A low impedance ground circuit in the O.R. ensures that potential differences between conductive surfaces and multiple instruments will be kept to a minimum. Considerable debate has taken place in recent years over receptacle testing frequency. In studies on hospital receptacle testing, the issue of proper grounding and ground impedance always emerges as the biggest concern. Recent studies indicate that in U.S hospitals more than 13% of the electrical receptacles in patient care areas and the wiring to which they are connected are not safe per the requirements of NFPA 99! In the Operating Room and Critical Care areas this is never an issue when POWERSERVE is performing Periodic Testing. Our "Level 1" and "Level 2" services both include complete Ground System testing. The ground integrity of the receptacle grounds is verified by measuring the impedance between the room or patient reference ground, and the ground pin of the receptacle under test. For more information on receptacle testing see Receptacles. The following items are checked individually:
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