ELECTRICAL SAFETY IN HEALTHCARE FACILITIES

ELECTRICAL SAFETY IN HEALTHCARE FACILITIESPresented By:B.SOCRETES B.E, B.Tech, M.E M.Tech

Objectives:To highlight:

Safety measures in healthcare facilities recommended by various national and international agenciesGuidelines for design, construction , maintenance and use of electrical medical equipment and devices

IntroductionMost of the equipment used in healthcare facilities are electrically operated, such as:ECG machine, bedside monitor, anesthesia machine, ventilators, catheter machine, suction machine , laboratory equipment, radiology equipment (X-ray, C.T Scan, ultrasound, mammography etc) , incubators, infant warmer etc. Time / Current Zones of AC Effectsas per IEC 60479-1., Ed.4, 2005

AC-1: PerceptionAC-2 :Involuntary muscular contractionsAC-3: Difficulty in breathingAC-4: Serious Pathophysiological effects AC-4.1: Probability of ventricular fibrillation increasing up to about 5% AC-4.2: Probability of ventricular fibrillation up to 50% AC-4.3 : Probability of ventricular fibrillation above 50%Time / current Zones of effects of AC currents ( 15 HZ to 100 HZ) on Persons__________________________________________________________________It is seen that the real danger lies in zones AC-3 ( between curves B and C1) and AC-4 ( located to the right of curve C1) According to the gravity of the Electric Shock and its duration, a person may experience: Discomfort, muscular contraction ,a cardiac arrest (electrocution) .

Direct contact e.g. the person is in contact with a live conductor

Indirect contact e.g. the person is in contact with a metal part of an electrical machine or device with an insulation fault.

Sources of Electrical ShockIMPORTANT MEASURES Selection of correct power supply system

TN-S SystemIT System

Fixed equipmentNon critical equipmentThe TN-S system in combination with a Residual Current Device (RCD) must only be used for following devices: permanently installed or mobile x-ray equipment devices with a connected load > 5 KW room lighting (not theatre)operating theatre table

Use of TN-S System: IT SYSTEM

Recommended for Group 2 locations (IEC 60364-7-710) - where discontinuity of supply can cause danger to life.

.eg:Intra-cardiac procedures, operating theatres and vital treatmentThe Isolated Power Supply remains in operation in the event of a single line - to -earth fault who may be more susceptible to leakage and unable to move.Use of IT (Isolated Power) System: Definition of Group 0, Group 1 and Group 2 locations as per IEC 60364-7-710:Group 0 is a medical location where no applied parts are intended to be used.Group 1 is a medical location where discontinuity of supply is not a threat to life.Group 2 is a medical location where discontinuity of supply can cause danger to life.

11Isolated Power Supply

Improved reliability Reduced leakage currents Reduced Touch Voltage.

A touch voltage of 10 mV can be sufficient to trigger ventricular fibrillation.

Monitoring Devices in IPS SystemMonitoring of resistance with Insulation Monitoring Device ( IMD) - IEC requirement.The IMD is able to sense a developing insulation fault at an early stage and to provide an alarm at an adjustable set-point, thus providing an improved level of safety. The alarm is raised visually and via a mutable audible alarm at the patient locationMonitoring of impedance through Line Isolation Monitor (LIM) - NFPA / UL requirement. The LIM monitors the impedance of the conductors to earth and measures the fault current in milli-Amp.The red LED alarm lights up and sounds an audible warning signal as soon as the prospective fault current reaches the threshold of 5 mA (2 mA in Canada). Monitoring of load and temperature - IEC Requirement.To protect the isolating transformer primary and secondary terminals and the distribution bus from overloading or over-heating.

IECNFPAIEC vs. NFPA IPS Monitoring IEC NFPA The Line Insulation Monitor (LIM) is continuously monitoring the leakage impedance in an ungrounded AC-Network. Based on this information the maximum Total Hazard Current (THC) is calculated and displayed. The LIM will trigger a visible and audible alarm at a preset threshold (2 or 5 mA). Monitoring of load and transformer-temperature is optional.The A-Isometer is continuously measuring the insulation-resistance of an unearthed AC- or DC-Network and will trigger a visible and audible alarm at a preset threshold value. It will display the amount of insulation-resistance in Ohm. It also monitors the load- current and the transformer-temperature. Earth fault location is optional to identify a faulty branch circuit. Alarm at < 50 kohmsAlarm at > 5mA Total Hazard Current EARTH RESISTANCE BAR

The use of an Earth Resistance Bar and Equipotential Bonding has been recommended for Medical Location of Group 1 and Group 2 by MEIGaN ( Medical Electrical Guidance Notes of UK Dept of Health).

The resistance between the ERB and all accessible conductive surfaces of installed equipment should be less than 100 milliohms. The resistance between the earth point of all mains sockets and the ERB should also be less than 100 milliohms. An IPS Panel as per NFPA/ UL/NECMain ComponentsIsolation TransformerLine Isolation Monitor (LIM)Circuit Protection 2-Pole breakersEquipotential Grounding System

Relevant Standards for medical applications:

IEC 60364-7-710Electrical Safety forHospitals and in medical Applications IEC 60364-4-41Protection for Safety andagainst Electrical Shock IEC 60364-5-54Earthing Arrangements IEC 60479-1Effect of current on human beings / livestockRelevant Standards for medical applications:

NFPA 70National Electrical Code NFPA 70BPractice for ElectricalEquipment Maintenance NFPA 70EElectrical Safety in theWorkplace NFPA 99Health Care Facilities UL 1022Standard for Safety Line Isolation Monitors CSA Z32.2Electrical Safety and Essential Electrical Systems in Health Care Facilities NEC Article 516Hazardous location UL 1047Isolated Power Systems Equipment

IEC StandardsNFPA ( American) Standards SAFETY MEASURES FOR MEDICAL ELECTRICAL DEVICES:

Selection of Safe Electrical Device: The electrical devices to be used in hospital must be safe and tested as per IEC 60601-1 . The following tests are required to be conducted: resistance of protective conductor earth leakage current enclosure leakage current patient leakage current and patient auxiliary current .

Utility PowerEmergency Generator / UPS PowerSAFETY THROUGH REDUNDANT POWER SUPPLIESWhatever bethe circumstances , the electrical installations of the Hospitals must help to

Ensure patient safety

Improvehospital personnel efficiencyGuarantee electrical service continuity

SAFETY FROM EXPLOSION IN HEALTHCARE FACILITIESAvoid Explosion in flammable gas environment

ELECTROSTATIC HAZARD IN ANESTHETIZING LOCATIONSAvoid electrostatic sparking hazardFlooring to be of anti-static properties The recommended limits of electrical resistance of antistatic floor, as recommended by NFPA 99 , Standard for Healthcare Facilities 2005 Edition are as follows: Upper limit: The average value shall not be more than be more than 1, 000,000 ohm, measured in accordance with NFPA 99 Article E 6.6.8.2. 7. Lower Limit: The average value shall not be less than 25000 ohms measured in accordance with NFPA99 Article E 6.6.8.2. 7.

ELECTRICAL HAZARD FROM LASERS IN HEALTHCARE FACILITIES The American National Standards Institute Standard ANSI Z136.3 ( Safe Use of Lasers in Healthcare Facilities) outlines electrical safety procedures applicable to lasers equipment in healthcare facilities.

CONCLUSION:The highest degree of safety for the patients, doctors and staff can be achieved when the recommendations of various standards and regulations are practically applied in healthcare facilities and the medical staff are well trained in using electrical medical equipment and devices. THANK YOU QUESTIONS?