What is the science behind the 1 MOhm minimum insulation resistance? What is the basis for this particular value?
It matches perfectly the permitted touch current for double insulated appliances (0.5 mA) for a supply voltage U0 of 500 V.
For U0 = 1000 V, 1 MΩ would lead to a touch current of 1 mA (the accepted threshold of perception).
These values align with Clause 5.2.7 in BS EN 61140 Protection against electric shock - common aspects for installation and equipment, which states the limit of steady-state touch current to be 0.5 mA AC or 2 mA DC (higher levels are permitted in some circumstances).
In fact, there is some science behind these values, and they are based on the IEC 60479-series of standards Effect of current on human beings and livestock which is used as a reference standard for developing electrical safety standards - BS EN 61140 is itself based on this series of standards.
What is the science behind the 1 MOhm minimum insulation resistance? What is the basis for this particular value?
It matches perfectly the permitted touch current for double insulated appliances (0.5 mA) for a supply voltage U0 of 500 V.
For U0 = 1000 V, 1 MΩ would lead to a touch current of 1 mA (the accepted threshold of perception).
These values align with Clause 5.2.7 in BS EN 61140 Protection against electric shock - common aspects for installation and equipment, which states the limit of steady-state touch current to be 0.5 mA AC or 2 mA DC (higher levels are permitted in some circumstances).
In fact, there is some science behind these values, and they are based on the IEC 60479-series of standards Effect of current on human beings and livestock which is used as a reference standard for developing electrical safety standards - BS EN 61140 is itself based on this series of standards.
