There are ten basic areas of safety testing in the IEC601-1 standard. Greater detail on each area is covered in subsequent sections. They are as follows.
1. Earth leakage current. This is essentially the current flowing down through the ground conductor in the line cord back to earth.
2. Enclosure leakage current. This is essentially the current that flows from any enclosure part if you were to touch it.
3. Applied part leakage. Commonly known as patient lead leakage. This is any leakage that flows from an applied part, between applied parts, or into an applied part.
4. Dielectric withstand. Commonly known as hipot testing. A high voltage is applied between insulated parts to be sure insulation will withstand the high voltage for a specified time.
5. Ground bond continuity. Commonly known as the high current ground continuity test. A current of 25 amps or more is run through the ground system to be sure the connections will handle it.
6. Residual voltage. Sometimes called the plug discharge test. This is the voltage present between any plug conductor 1 second after the plug is disconnected from power.
7. Accessible parts voltage. This is the voltage present on any accessible part, including those covered by service or access doors.
8. Retained energy. The energy that is stored in an accessible part.
9. Current draw. Current consumed by the product.
10. Power consumption. Power that is consumed by the product.
http://www.bapcoinfo.com/Articles/iec601safetytestingarticle.htm
Insulation breakdown
IEC601-1 Clause 20This test is actually a series of tests designed to test the strength of insulation. Basically you apply a high voltage, as much as 5500 volts, to an insulation barrier to determine if it will "withstand" the voltage and not short across. This is commonly referred to as the "hipot" test. Clause 20.1 and 20.2 outline the various situations where this test is to be used as well as the insulation types that qualify. The measurement is basically made with a high voltage supply and two test points which are connected across the appropriate insulation barrier. The test voltage varies based on the reference voltage U which is essentially the voltage normally present the insulation barrier. ...
Because the voltage, that is normally present at the insulation barrier in case of the RS232EEG is the +-15V of the com-port, it could be, that the test-voltage will be less than 5500V.
However if the PC, that is connected to the RS232EEG, is viewed as a part of the device under test, it could be, that the 5500V test voltage will be applied to the power supply of the PC (... and I have some doubt that normal PC power supplys are designed to handle this isolation voltage)