Safety Testing of Medical Electrical Equipment
1 Hazards of Medical Electrical Equipment
Medical electrical equipment can present a range of hazards to the patient, the user, or to service personnel. Many such hazards are common to many or all types of medical electrical equipment, whilst others are peculiar to particular categories of equipment. Listed below are various types of common hazards. 
1.1 Mechanical Hazards
All types of medical electrical equipment can present mechanical hazards. These can range from insecure fittings of controls to loose fixings of wheels on equipment trolleys. The former may prevent a piece of life supporting equipment from being operated properly, whilst the latter could cause serious accidents in the clinical environment. 
Such hazards may seem too obvious to warrant mentioning, but it is unfortunately all too common for such mundane problems to be overlooked while more exotic problems are addressed. 
1.2 Risk of fire or explosion
All mains powered electrical equipment can present the risk of fire in the event of certain faults occurring such as internal or external short circuits. In certain environments such fires may cause explosions. Although the use of explosive anaesthetic gases is not common today, it should be recognised that many of the medical gases in use vigorously support combustion. 
1.3 Absence of Function
Since many pieces of medical electrical equipment are life supporting or monitor vital functions, the absence of function of such a piece of equipment would not be merely inconvenient, but could threaten life. 
1.4 Excessive or insufficient output
In order to perform its desired function equipment must deliver its specified output. Too high an output, for example, in the case of surgical diathermy units, would clearly be hazardous. Equally, too low an output would result in inadequate therapy, which in turn may delay patient recovery, cause patient injury or even death. This highlights the importance of correct calibration procedures. 
1.5 Infection
Medical equipment that has been inadequately decontaminated after use may cause infection through the transmission of microorganisms to any person who subsequently comes into contact with it. Clearly, patients, nursing staff and service personnel are potentially at risk here. 
1.6 Misuse
Misuse of equipment is one of the most common causes of adverse incidents involving medical devices. Such misuse may be a result of inadequate user training or of poor user instructions. 
1.7 Risk of exposure to spurious electric currents
All electrical equipment has the potential to expose people to the risk of spurious electric currents. In the case of medical electrical equipment, the risk is potentially greater since patients are intentionally connected to such equipment and may not benefit from the same natural protection factors that apply to people in other circumstances. Whilst all of the hazards listed are important, the prevention of many of them require methods peculiar to the particular type of equipment und

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