Electrical Safety Testing for Medical Devices

ITC India Pvt Ltd is accredited laboratory to test Medical equipment as per IEC 60601-1. The test procedure followed by the laboratory is mentioned in this article. All the testing is done with the highly accurate and calibrated machines. Even qualified engineers are appointed to do the testing of medical products. Safety testing is required at the point of manufacturing of the equipment and before its launch.  Safety testing ensures that no hazardous voltage or current are accessible to the user.

Why do safety testing of Electrical Equipment?

The answer is for the safety of the operator as well as to block harm to patient and staff. Identifying, correcting and eliminating shock hazards is the motive of electrical safety testing.

Most of current, voltage and frequencies give harm to the operators, patients and staff.  Now, let us discuss about these factors in details.

We would like to consider the frequency first; Low frequency a.c signals accidentally used to human tissues can cause somatic sensation, muscles cramp or even death. Sensitivity is very much dependent on frequency which should be restricted to a maximum of 60 Hz.

Another factor is the patient skin resistance, whenever the resistance decreases, smaller voltage can result in higher and higher current and hence can injure patient. The resistance of human body decreases due to illness. Dry and healthy skin has a resistance of 60 kΩ to 100 kΩ.

Effect of current on Human Body

1Less than 1mAGenerally not recognizable
21mAFaint tingle
46-25 mAPainful shock, loss of muscular control
550 – 150 mAExtreme pain, respiratory arrest, death possible
61000-4300mAMuscular contraction and nerve damage, death likely
710,000mACardiac Arrest, severe burns, even death

Patient contact with leads, catheters, etc. from medical instrumentation reduces skin’s resistance. All of these devices have direct patient contact and can be a conduit for dangerous low frequency a.c. signals. e.g.  EKG leads, Catheters inserted into the body, Probes, ESU devices, Defib paddles, Physical therapy equipment. Keeping all in mind many kinds of current are studied by the standards.

  1. Chassis source current
  2. Ground current
  3. Lead current
  4. Isolation test

The test Plan of IEC 60601-1

S. No.Clause No.Title of test  
14.1-4.10General Requirements  
24.11Power input  
38.4.2Protection against
accidental contact
48.7Leakage Current & Patient Auxiliary current Leakage Current leakage
Current Leakage Current Auxiliary Current  
98.8.3Dielectric Strength Test  
10a.Insulation Resistance
115.7Humidity preconditioning treatment  
127Identification, Marking and Documents.  
138.4.3Voltage Drop test  
148.4.4Internal capacitive circuits APPLIED PARTS/ TYPE B APPLIED PARTS  
168.7.4,LEAKAGE CURRENT tests  
strength test
188.9Creepage Distance and Air Clearance cycling reduction test  
218.6.4Impedance and current-carrying capability  
228.8.4Insulation other than wire insulation  
2311.6Resistance to moisture,  
248.8.3Dielectric strength  
2515.3Mechanical strength test groups classification  
28 Comparative tracking index (CTI) anchorage Pull Test  
Cord guards  
318.11.4.2MAINS TERMINAL Bent Test  
329.4.2.2Stability Test  
339.8.3.2Static forces  
349.8.3.3Dynamic forces due to loading from persons  
3511Protection against excessive temperatures  
3611.6.2Overflow in ME EQUIPMENT/ Dielectric Strength/ Leakage Current Test  
3711.6.3Spillage on ME EQUIPMENT, Dielectric Strength/ Leakage Current Test  
3812Accuracy of controls and instruments and protection against hazardous
3913.1.2limit power
41 15.3Mechanical strength  
4215.3.2Push test  
4315.3.3Impact test  
4415.3.4Drop test  
 4515.3.5Rough handling test  
46a.Ascending step shock  
47b.Descending step shock  
48c.Door frame shock  
4915.3.6Mould stress relief test  
5015.4.6.1Rotating controls torque test  
5115.4.7.3Foot-operated control devices(IP Testing)  
5315.5.1.2Short-circuit test  
5415.5.2Dielectric strength